// stb_tilemap_editor.h - v0.38 - Sean Barrett - http://nothings.org/stb
// placed in the public domain - not copyrighted - first released 2014-09
//
// Embeddable tilemap editor for C/C++
//
//
// TABLE OF CONTENTS
//    FAQ
//    How to compile/use the library
//    Additional configuration macros
//    API documentation
//    Info on editing multiple levels
//    Revision history
//    Todo
//    Credits
//    License
//
//
// FAQ
//
//   Q: What counts as a tilemap for this library?
//
//   A: An array of rectangles, where each rectangle contains a small
//      stack of images.
//
//   Q: What are the limitations?
//
//   A: Maps are limited to 4096x4096 in dimension.
//      Each map square can only contain a stack of at most 32 images.
//      A map can only use up to 32768 distinct image tiles.
//
//   Q: How do I compile this?
//
//   A: You need to #define several symbols before #including it, but only
//      in one file. This will cause all the function definitions to be
//      generated in that file. See the "HOW TO COMPILE" section.
//
//   Q: What advantages does this have over a standalone editor?
//
//   A: For one, you can integrate the editor into your game so you can
//      flip between editing and testing without even switching windows.
//      For another, you don't need an XML parser to get at the map data.
//
//   Q: Can I live-edit my game maps?
//
//   A: Not really, the editor keeps its own map representation.
//
//   Q: How do I save and load maps?
//
//   A: You have to do this yourself. The editor provides serialization
//      functions (get & set) for reading and writing the map it holds.
//      You can choose whatever format you want to store the map to on
//      disk; you just need to provide functions to convert. (For example,
//      I actually store the editor's map representation to disk basically
//      as-is; then I have a single function that converts from the editor
//      map representation to the game representation, which is used both
//      to go from editor-to-game and from loaded-map-to-game.)
//
//   Q: I want to have tiles change appearance based on what's
//      adjacent, or other tile-display/substitution trickiness.
//
//   A: You can do this when you convert from the editor's map
//      representation to the game representation, but there's
//      no way to show this live in the editor.
//
//   Q: The editor appears to be put map location (0,0) at the top left?
//      I want to use a different coordinate system in my game (e.g. y
//      increasing upwards, or origin at the center).
//
//   A: You can do this when you convert from the editor's map
//      representation to the game representation. (Don't forget to
//      translate link coordinates as well!)
//
//   Q: The editor appears to put pixel (0,0) at the top left? I want
//      to use a different coordinate system in my game.
//
//   A: The editor defines an "editor pixel coordinate system" with
//      (0,0) at the top left and requires you to display things in
//      that coordinate system. You can freely remap those coordinates
//      to anything you want on screen.
//
//   Q: How do I scale the user interface?
//
//   A: Since you do all the rendering, you can scale up all the rendering
//      calls that the library makes to you. If you do, (a) you need
//      to also scale up the mouse coordinates, and (b) you may want
//      to scale the map display back down so that you're only scaling
//      the UI and not everything. See the next question.
//
//   Q: How do I scale the map display?
//
//   A: Use stbte_set_spacing() to change the size that the map is displayed
//      at. Note that the "callbacks" to draw tiles are used for both drawing
//      the map and drawing the tile palette, so that callback may need to
//      draw at two different scales. You should choose the scales to match
//       You can tell them apart because the
//      tile palette gets NULL for the property pointer.
//
//   Q: How does object editing work?
//
//   A: One way to think of this is that in the editor, you're placing
//      spawners, not objects. Each spawner must be tile-aligned, because
//      it's only a tile editor. Each tile (stack of layers) gets
//      an associated set of properties, and it's up to you to
//      determine what properties should appear for a given tile,
//      based on e.g. the spawners that are in it.
//
//   Q: How are properties themselves handled?
//
//   A: All properties, regardless of UI behavior, are internally floats.
//      Each tile has an array of floats associated with it, which is
//      passed back to you when drawing the tiles so you can draw
//      objects appropriately modified by the properties.
//
//   Q: What if I want to have two different objects/spawners in
//      one tile, both of which have their own properties?
//
//   A: Make sure STBTE_MAX_PROPERTIES is large enough for the sum of
//      properties in both objects, and then you have to explicitly
//      map the property slot #s to the appropriate objects. They'll
//      still all appear in a single property panel; there's no way
//      to get multiple panels.
//
//   Q: Can I do one-to-many linking?
//
//   A: The library only supports one link per tile. However, you
//      can have multiple tiles all link to a single tile. So, you
//      can fake one-to-many linking by linking in the reverse
//      direction.
//
//   Q: What if I have two objects in the same tile, and they each
//      need an independent link? Or I have two kinds of link associated
//      with a single object?
//
//   A: There is no way to do this. (Unless you can reverse one link.)
//
//   Q: How does cut & paste interact with object properties & links?
//
//   A: Currently the library has no idea which properties or links
//      are associated with which layers of a tile. So currently, the
//      library will only copy properties & links if the layer panel
//      is set to allow all layers to be copied, OR if you set the
//      "props" in the layer panel to "always". Similarly, you can
//      set "props" to "none" so it will never copy.
//
//   Q: What happens if the library gets a memory allocation failure
//      while I'm editing? Will I lose my work?
//
//   A: The library allocates all editor memory when you create
//      the tilemap. It allocates a maximally-sized map and a 
//      fixed-size undo buffer (and the fixed-size copy buffer
//      is static), and never allocates memory while it's running.
//      So it can't fail due to running out of memory.
//
//   Q: What happens if the library crashes while I'm editing? Will
//      I lose my work?
//
//   A: Yes. Save often.
//
//
// HOW TO COMPILE
//
//   This header file contains both the header file and the
//   implementation file in one. To create the implementation,
//   in one source file define a few symbols first and then
//   include this header:
//
//      #define STB_TILEMAP_EDITOR_IMPLEMENTATION
//      // this triggers the implementation
//
//      void STBTE_DRAW_RECT(int x0, int y0, int x1, int y1, uint color);
//      // this must draw a filled rectangle (exclusive on right/bottom)
//      // color = (r<<16)|(g<<8)|(b)
//      
//      void STBTE_DRAW_TILE(int x0, int y0,
//                    unsigned short id, int highlight, float *data);
//      // this draws the tile image identified by 'id' in one of several
//      // highlight modes (see STBTE_drawmode_* in the header section);
//      // if 'data' is NULL, it's drawing the tile in the palette; if 'data'
//      // is not NULL, it's drawing a tile on the map, and that is the data
//      // associated with that map tile
//
//      #include "stb_tilemap_editor.h"
//
//   Optionally you can define the following functions before the include;
//   note these must be macros (but they can just call a function) so
//   this library can #ifdef to detect if you've defined them:
//
//      #define STBTE_PROP_TYPE(int n, short *tiledata, float *params) ...
//      // Returns the type of the n'th property of a given tile, which
//      // controls how it is edited. Legal types are:
//      //     0                    /* no editable property in this slot */
//      //     STBTE_PROP_int       /* uses a slider to adjust value     */
//      //     STBTE_PROP_float     /* uses a weird multi-axis control   */
//      //     STBTE_PROP_bool      /* uses a checkbox to change value   */
//      // And you can bitwise-OR in the following flags:
//      //     STBTE_PROP_disabled
//      // Note that all of these are stored as floats in the param array.
//      // The integer slider is limited in precision based on the space
//      // available on screen, so for wide-ranged integers you may want
//      // to use floats instead.
//      //
//      // Since the tiledata is passed to you, you can choose which property
//      // is bound to that slot based on that data.
//      //
//      // Changing the type of a parameter does not cause the underlying
//      // value to be clamped to the type min/max except when the tile is
//      // explicitly selected.
// 
//      #define STBTE_PROP_NAME(int n, short *tiledata, float *params) ...
//      // these return a string with the name for slot #n in the float
//      // property list for the tile.
//
//      #define STBTE_PROP_MIN(int n, short *tiledata) ...your code here...
//      #define STBTE_PROP_MAX(int n, short *tiledata) ...your code here...
//      // These return the allowable range for the property values for
//      // the specified slot. It is never called for boolean types.
//
//      #define STBTE_PROP_FLOAT_SCALE(int n, short *tiledata, float *params)
//      // This rescales the float control for a given property; by default
//      // left mouse drags add integers, right mouse drags adds fractions,
//      // but you can rescale this per-property.
//
//      #define STBTE_FLOAT_CONTROL_GRANULARITY       ... value ...
//      // This returns the number of pixels of mouse motion necessary
//      // to advance the object float control. Default is 4
//
//      #define STBTE_ALLOW_LINK(short *src, float *src_data,  \
//                               short *dest, float *dest_data) ...your code...
//      // this returns true or false depending on whether you allow a link
//      // to be drawn from a tile 'src' to a tile 'dest'. if you don't
//      // define this, linking will not be supported
//
//      #define STBTE_LINK_COLOR(short *src, float *src_data,  \
//                               short *dest, float *dest_data) ...your code...
//      // return a color encoded as a 24-bit unsigned integer in the
//      // form 0xRRGGBB. If you don't define this, default colors will
//      // be used.
//
//
//      [[ support for those below is not implemented yet ]]
//
//      #define STBTE_HITTEST_TILE(x0,y0,id,mx,my)   ...your code here...
//      // this returns true or false depending on whether the mouse
//      // pointer at mx,my is over (touching) a tile of type 'id'
//      // displayed at x0,y0. Normally stb_tilemap_editor just does
//      // this hittest based on the tile geometry, but if you have
//      // tiles whose images extend out of the tile, you'll need this.
//
// ADDITIONAL CONFIGURATION
//
//   The following symbols set static limits which determine how much
//   memory will be allocated for the editor. You can override them
//   by making similiar definitions, but memory usage will increase.
//
//      #define STBTE_MAX_TILEMAP_X      200   // max 4096
//      #define STBTE_MAX_TILEMAP_Y      200   // max 4096
//      #define STBTE_MAX_LAYERS         8     // max 32
//      #define STBTE_MAX_CATEGORIES     100
//      #define STBTE_UNDO_BUFFER_BYTES  (1 << 24) // 16 MB
//      #define STBTE_MAX_COPY           90000  // e.g. 300x300
//      #define STBTE_MAX_PROPERTIES     10     // max properties per tile
//
// API
//
//   Further documentation appears in the header-file section below.
//
// EDITING MULTIPLE LEVELS
//
//   You can only have one active editor instance. To switch between multiple
//   levels, you can either store the levels in your own format and copy them
//   in and out of the editor format, or you can create multiple stbte_tilemap
//   objects and switch between them. The latter has the advantage that each
//   stbte_tilemap keeps its own undo state. (The clipboard is global, so
//   either approach allows cut&pasting between levels.)
//
// REVISION HISTORY
//   0.38  fix warning
//   0.37  fix warning
//   0.36  minor compiler support
//   0.35  layername button changes
//          - layername buttons grow with the layer panel
//          - fix stbte_create_map being declared as stbte_create
//          - fix declaration of stbte_create_map
//   0.30  properties release
//          - properties panel for editing user-defined "object" properties
//          - can link each tile to one other tile
//          - keyboard interface
//          - fix eraser tool bug (worked in complex cases, failed in simple)
//          - undo/redo tools have visible disabled state
//          - tiles on higher layers draw on top of adjacent lower-layer tiles
//   0.20  erasable release
//          - eraser tool
//          - fix bug when pasting into protected layer
//          - better color scheme
//          - internal-use color picker
//   0.10  initial release 
//
// TODO
//
//   Separate scroll state for each category
//   Implement paint bucket
//   Support STBTE_HITTEST_TILE above
//  ?Cancel drags by clicking other button? - may be fixed
//   Finish support for toolbar at side
//
// CREDITS
//
//
//   Main editor & features
//      Sean Barrett
//   Additional features:
//      Josh Huelsman
//   Bugfixes:
//      Ryan Whitworth
//      Eugene Opalev
//
// LICENSE
//
//   This software is dual-licensed to the public domain and under the following
//   license: you are granted a perpetual, irrevocable license to copy, modify,
//   publish, and distribute this file as you see fit.



///////////////////////////////////////////////////////////////////////
//
//   HEADER SECTION

#ifndef STB_TILEMAP_INCLUDE_STB_TILEMAP_EDITOR_H
#define STB_TILEMAP_INCLUDE_STB_TILEMAP_EDITOR_H

#ifdef _WIN32
  #ifndef _CRT_SECURE_NO_WARNINGS
  #define _CRT_SECURE_NO_WARNINGS
  #endif
  #include <stdlib.h>
  #include <stdio.h>
#endif

typedef struct stbte_tilemap stbte_tilemap;

// these are the drawmodes used in STBTE_DRAW_TILE
enum
{
   STBTE_drawmode_deemphasize = -1,
   STBTE_drawmode_normal      =  0,
   STBTE_drawmode_emphasize   =  1,
};

// these are the property types
#define STBTE_PROP_none     0
#define STBTE_PROP_int      1
#define STBTE_PROP_float    2
#define STBTE_PROP_bool     3
#define STBTE_PROP_disabled 4

////////
//
// creation
//

extern stbte_tilemap *stbte_create_map(int map_x, int map_y, int map_layers, int spacing_x, int spacing_y, int max_tiles);
// create an editable tilemap
//   map_x      : dimensions of map horizontally (user can change this in editor), <= STBTE_MAX_TILEMAP_X
//   map_y      : dimensions of map vertically (user can change this in editor)    <= STBTE_MAX_TILEMAP_Y
//   map_layers : number of layers to use (fixed), <= STBTE_MAX_LAYERS
//   spacing_x  : initial horizontal distance between left edges of map tiles in stb_tilemap_editor pixels
//   spacing_y  : initial vertical distance between top edges of map tiles in stb_tilemap_editor pixels
//   max_tiles  : maximum number of tiles that can defined
//
// If insufficient memory, returns NULL

extern void stbte_define_tile(stbte_tilemap *tm, unsigned short id, unsigned int layermask, const char * category);
// call this repeatedly for each tile to install the tile definitions into the editable tilemap
//   tm        : tilemap created by stbte_create_map
//   id        : unique identifier for each tile, 0 <= id < 32768
//   layermask : bitmask of which layers tile is allowed on: 1 = layer 0, 255 = layers 0..7
//               (note that onscreen, the editor numbers the layers from 1 not 0)
//               layer 0 is the furthest back, layer 1 is just in front of layer 0, etc
//   category  : which category this tile is grouped in

extern void stbte_set_display(int x0, int y0, int x1, int y1);
// call this once to set the size; if you resize, call it again


/////////
//
// every frame
//

extern void stbte_draw(stbte_tilemap *tm);

extern void stbte_tick(stbte_tilemap *tm, float time_in_seconds_since_last_frame);

////////////
//
//  user input
//

// if you're using SDL, call the next function for SDL_MOUSEMOVE, SDL_MOUSEBUTTON, SDL_MOUSEWHEEL;
// the transformation lets you scale from SDL mouse coords to stb_tilemap_editor coords
extern void stbte_mouse_sdl(stbte_tilemap *tm, const void *sdl_event, float xscale, float yscale, int xoffset, int yoffset);

// otherwise, hook these up explicitly:
extern void stbte_mouse_move(stbte_tilemap *tm, int x, int y, int shifted, int scrollkey);
extern void stbte_mouse_button(stbte_tilemap *tm, int x, int y, int right, int down, int shifted, int scrollkey);
extern void stbte_mouse_wheel(stbte_tilemap *tm, int x, int y, int vscroll);

// for keyboard, define your own mapping from keys to the following actions.
// this is totally optional, as all features are accessible with the mouse
enum stbte_action
{
   STBTE_tool_select,
   STBTE_tool_brush,
   STBTE_tool_erase,
   STBTE_tool_rectangle,
   STBTE_tool_eyedropper,
   STBTE_tool_link,
   STBTE_act_toggle_grid,
   STBTE_act_toggle_links,
   STBTE_act_undo,
   STBTE_act_redo,
   STBTE_act_cut,
   STBTE_act_copy,
   STBTE_act_paste,
   STBTE_scroll_left,
   STBTE_scroll_right,
   STBTE_scroll_up,
   STBTE_scroll_down,
};
extern void stbte_action(stbte_tilemap *tm, enum stbte_action act);

////////////////
//
//  save/load 
//
//  There is no editor file format. You have to save and load the data yourself
//  through the following functions. You can also use these functions to get the
//  data to generate game-formatted levels directly. (But make sure you save
//  first! You may also want to autosave to a temp file periodically, etc etc.)

#define STBTE_EMPTY    -1

extern void stbte_get_dimensions(stbte_tilemap *tm, int *max_x, int *max_y);
// get the dimensions of the level, since the user can change them

extern short* stbte_get_tile(stbte_tilemap *tm, int x, int y);
// returns an array of shorts that is 'map_layers' in length. each short is
// either one of the tile_id values from define_tile, or STBTE_EMPTY.

extern float *stbte_get_properties(stbte_tilemap *tm, int x, int y);
// get the property array associated with the tile at x,y. this is an
// array of floats that is STBTE_MAX_PROPERTIES in length; you have to
// interpret the slots according to the semantics you've chosen

extern void stbte_get_link(stbte_tilemap *tm, int x, int y, int *destx, int *desty);
// gets the link associated with the tile at x,y.

extern void stbte_set_dimensions(stbte_tilemap *tm, int max_x, int max_y);
// set the dimensions of the level, overrides previous stbte_create_map()
// values or anything the user has changed

extern void stbte_clear_map(stbte_tilemap *tm);
// clears the map, including the region outside the defined region, so if the
// user expands the map, they won't see garbage there

extern void stbte_set_tile(stbte_tilemap *tm, int x, int y, int layer, signed short tile);
// tile is your tile_id from define_tile, or STBTE_EMPTY

extern void stbte_set_property(stbte_tilemap *tm, int x, int y, int n, float val);
// set the value of the n'th slot of the tile at x,y

extern void stbte_set_link(stbte_tilemap *tm, int x, int y, int destx, int desty);
// set a link going from x,y to destx,desty. to force no link,
// use destx=desty=-1

////////
//
// optional
//

extern void stbte_set_background_tile(stbte_tilemap *tm, short id);
// selects the tile to fill the bottom layer with and used to clear bottom tiles to;
// should be same ID as 

extern void stbte_set_sidewidths(int left, int right);
// call this once to set the left & right side widths. don't call
// it again since the user can change it

extern void stbte_set_spacing(stbte_tilemap *tm, int spacing_x, int spacing_y, int palette_spacing_x, int palette_spacing_y);
// call this to set the spacing of map tiles and the spacing of palette tiles.
// if you rescale your display, call it again (e.g. you can implement map zooming yourself)

extern void stbte_set_layername(stbte_tilemap *tm, int layer, const char *layername);
// sets a string name for your layer that shows in the layer selector. note that this
// makes the layer selector wider. 'layer' is from 0..(map_layers-1)

#endif

#ifdef STB_TILEMAP_EDITOR_IMPLEMENTATION

#ifndef STBTE_ASSERT
#define STBTE_ASSERT assert
#include <assert.h>
#endif

#ifdef _MSC_VER
#define STBTE__NOTUSED(v)  (void)(v)
#else
#define STBTE__NOTUSED(v)  (void)sizeof(v)
#endif

#ifndef STBTE_MAX_TILEMAP_X
#define STBTE_MAX_TILEMAP_X      200
#endif

#ifndef STBTE_MAX_TILEMAP_Y
#define STBTE_MAX_TILEMAP_Y      200
#endif

#ifndef STBTE_MAX_LAYERS
#define STBTE_MAX_LAYERS         8
#endif

#ifndef STBTE_MAX_CATEGORIES
#define STBTE_MAX_CATEGORIES     100
#endif

#ifndef STBTE_MAX_COPY
#define STBTE_MAX_COPY           65536
#endif

#ifndef STBTE_UNDO_BUFFER_BYTES
#define STBTE_UNDO_BUFFER_BYTES  (1 << 24) // 16 MB
#endif

#ifndef STBTE_PROP_TYPE
#define STBTE__NO_PROPS
#define STBTE_PROP_TYPE(n,td,tp)   0
#endif

#ifndef STBTE_PROP_NAME
#define STBTE_PROP_NAME(n,td,tp)  ""
#endif

#ifndef STBTE_MAX_PROPERTIES
#define STBTE_MAX_PROPERTIES           10
#endif

#ifndef STBTE_PROP_MIN
#define STBTE_PROP_MIN(n,td,tp)  0
#endif

#ifndef STBTE_PROP_MAX
#define STBTE_PROP_MAX(n,td,tp)  100.0
#endif

#ifndef STBTE_PROP_FLOAT_SCALE
#define STBTE_PROP_FLOAT_SCALE(n,td,tp)  1   // default scale size
#endif

#ifndef STBTE_FLOAT_CONTROL_GRANULARITY
#define STBTE_FLOAT_CONTROL_GRANULARITY 4
#endif


#define STBTE__UNDO_BUFFER_COUNT  (STBTE_UNDO_BUFFER_BYTES>>1)

#if STBTE_MAX_TILEMAP_X > 4096 || STBTE_MAX_TILEMAP_Y > 4096
#error "Maximum editable map size is 4096 x 4096"
#endif
#if STBTE_MAX_LAYERS > 32
#error "Maximum layers allowed is 32"
#endif
#if STBTE_UNDO_BUFFER_COUNT & (STBTE_UNDO_BUFFER_COUNT-1)
#error "Undo buffer size must be a power of 2"
#endif

#if STBTE_MAX_PROPERTIES == 0
#define STBTE__NO_PROPS
#endif

#ifdef STBTE__NO_PROPS
#undef STBTE_MAX_PROPERTIES
#define STBTE_MAX_PROPERTIES 1  // so we can declare arrays
#endif

typedef struct
{
   short x,y;
} stbte__link;

enum
{
   STBTE__base,
   STBTE__outline,
   STBTE__text,

   STBTE__num_color_aspects,
};

enum
{
   STBTE__idle,
   STBTE__over,
   STBTE__down,
   STBTE__over_down,
   STBTE__selected,
   STBTE__selected_over,
   STBTE__disabled,
   STBTE__num_color_states,
};

enum
{
   STBTE__cexpander,
   STBTE__ctoolbar,
   STBTE__ctoolbar_button,
   STBTE__cpanel,
   STBTE__cpanel_sider,
   STBTE__cpanel_sizer,
   STBTE__cscrollbar,
   STBTE__cmapsize,
   STBTE__clayer_button,
   STBTE__clayer_hide,
   STBTE__clayer_lock,
   STBTE__clayer_solo,
   STBTE__ccategory_button,

   STBTE__num_color_modes,
};

#ifdef STBTE__COLORPICKER
static char *stbte__color_names[] =
{
   "expander", "toolbar", "tool button", "panel",
   "panel c1", "panel c2", "scollbar", "map button",
   "layer", "hide", "lock", "solo",
   "category",
};
#endif // STBTE__COLORPICKER

      // idle,    over,     down,    over&down, selected, sel&over, disabled
static int stbte__color_table[STBTE__num_color_modes][STBTE__num_color_aspects][STBTE__num_color_states] =
{
   {
      { 0x000000, 0x84987c, 0xdcdca8, 0xdcdca8, 0x40c040, 0x60d060, 0x505050, },
      { 0xa4b090, 0xe0ec80, 0xffffc0, 0xffffc0, 0x80ff80, 0x80ff80, 0x606060, },
      { 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0x808890, 0x606060, 0x606060, 0x606060, 0x606060, 0x606060, 0x606060, },
      { 0x605860, 0x606060, 0x606060, 0x606060, 0x606060, 0x606060, 0x606060, },
      { 0x000000, 0x000000, 0x000000, 0x000000, 0x000000, 0x000000, 0x000000, },
   }, {
      { 0x3c5068, 0x7088a8, 0x647488, 0x94b4dc, 0x8890c4, 0x9caccc, 0x404040, },
      { 0x889cb8, 0x889cb8, 0x889cb8, 0x889cb8, 0x84c4e8, 0xacc8ff, 0x0c0c08, },
      { 0xbcc4cc, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x707074, },
   }, {
      { 0x403848, 0x403010, 0x403010, 0x403010, 0x403010, 0x403010, 0x303024, },
      { 0x68546c, 0xc08040, 0xc08040, 0xc08040, 0xc08040, 0xc08040, 0x605030, },
      { 0xf4e4ff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0xb4b04c, 0xacac60, 0xc0ffc0, 0xc0ffc0, 0x40c040, 0x60d060, 0x505050, },
      { 0xa0a04c, 0xd0d04c, 0xffff80, 0xffff80, 0x80ff80, 0x80ff80, 0x606060, },
      { 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0x40c440, 0x60d060, 0xc0ffc0, 0xc0ffc0, 0x40c040, 0x60d060, 0x505050, },
      { 0x40c040, 0x80ff80, 0x80ff80, 0x80ff80, 0x80ff80, 0x80ff80, 0x606060, },
      { 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0x9090ac, 0xa0a0b8, 0xbcb8cc, 0xbcb8cc, 0x909040, 0x909040, 0x909040, },
      { 0xa0a0b8, 0xb0b4d0, 0xa0a0b8, 0xa0a0b8, 0xa0a050, 0xa0a050, 0xa0a050, },
      { 0x808088, 0x808030, 0x808030, 0x808030, 0x808030, 0x808030, 0x808030, },
   }, {
      { 0x704c70, 0x885c8c, 0x9c68a4, 0xb870bc, 0xb490bc, 0xb490bc, 0x302828, },
      { 0x646064, 0xcca8d4, 0xc060c0, 0xa07898, 0xe0b8e0, 0xe0b8e0, 0x403838, },
      { 0xdccce4, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0x704c70, 0x885c8c, 0x9c68a4, 0xb870bc, 0xb490bc, 0xb490bc, 0x302828, },
      { 0xb09cb4, 0xcca8d4, 0xc060c0, 0xa07898, 0xe0b8e0, 0xe0b8e0, 0x403838, },
      { 0xdccce4, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x909090, },
   }, {
      { 0x646494, 0x888cb8, 0xb0b0b0, 0xb0b0cc, 0x9c9cf4, 0x8888b0, 0x50506c, },
      { 0x9090a4, 0xb0b4d4, 0xb0b0dc, 0xb0b0cc, 0xd0d0fc, 0xd0d4f0, 0x606060, },
      { 0xb4b4d4, 0xe4e4ff, 0xffffff, 0xffffff, 0xe0e4ff, 0xececff, 0x909090, },
   }, {
      { 0x646444, 0x888c64, 0xb0b0b0, 0xb0b088, 0xaca858, 0x88886c, 0x505050, },
      { 0x88886c, 0xb0b490, 0xb0b0b0, 0xb0b088, 0xd8d898, 0xd0d4b0, 0x606060, },
      { 0xb4b49c, 0xffffd8, 0xffffff, 0xffffd4, 0xffffdc, 0xffffcc, 0x909090, },
   }, {
      { 0x906464, 0xb48c8c, 0xd4b0b0, 0xdcb0b0, 0xff9c9c, 0xc88888, 0x505050, },
      { 0xb47c80, 0xd4b4b8, 0xc4a8a8, 0xdcb0b0, 0xffc0c0, 0xfce8ec, 0x606060, },
      { 0xe0b4b4, 0xffdcd8, 0xffd8d4, 0xffe0e4, 0xffece8, 0xffffff, 0x909090, },
   }, {
      { 0x403848, 0x403848, 0x403848, 0x886894, 0x7c80c8, 0x7c80c8, 0x302828, },
      { 0x403848, 0x403848, 0x403848, 0x403848, 0x7c80c8, 0x7c80c8, 0x403838, },
      { 0xc8c4c8, 0xffffff, 0xffffff, 0xffffff, 0xe8e8ec, 0xffffff, 0x909090, },
   },
};

#define STBTE_COLOR_TILEMAP_BACKGROUND      0x000000
#define STBTE_COLOR_TILEMAP_BORDER          0x203060
#define STBTE_COLOR_TILEMAP_HIGHLIGHT       0xffffff
#define STBTE_COLOR_GRID                    0x404040
#define STBTE_COLOR_SELECTION_OUTLINE1      0xdfdfdf
#define STBTE_COLOR_SELECTION_OUTLINE2      0x303030
#define STBTE_COLOR_TILEPALETTE_OUTLINE     0xffffff
#define STBTE_COLOR_TILEPALETTE_BACKGROUND  0x000000

#ifndef STBTE_LINK_COLOR
#define STBTE_LINK_COLOR(src,sp,dest,dp)    0x5030ff
#endif

#ifndef STBTE_LINK_COLOR_DRAWING
#define STBTE_LINK_COLOR_DRAWING            0xff40ff
#endif

#ifndef STBTE_LINK_COLOR_DISALLOWED
#define STBTE_LINK_COLOR_DISALLOWED         0x602060
#endif


// disabled, selected, down, over
static unsigned char stbte__state_to_index[2][2][2][2] =
{
   {
      { { STBTE__idle    , STBTE__over          }, { STBTE__down    , STBTE__over_down }, },
      { { STBTE__selected, STBTE__selected_over }, { STBTE__down    , STBTE__over_down }, },
   },{
      { { STBTE__disabled, STBTE__disabled      }, { STBTE__disabled, STBTE__disabled  }, },
      { { STBTE__selected, STBTE__selected_over }, { STBTE__disabled, STBTE__disabled  }, },
   }
};
#define STBTE__INDEX_FOR_STATE(disable,select,down,over) stbte__state_to_index[disable][select][down][over]
#define STBTE__INDEX_FOR_ID(id,disable,select) STBTE__INDEX_FOR_STATE(disable,select,STBTE__IS_ACTIVE(id),STBTE__IS_HOT(id))

#define STBTE__FONT_HEIGHT    9
static short stbte__font_offset[95+16];
static short stbte__fontdata[769] =
{
   4,9,6,9,9,9,9,8,9,8,4,9,7,7,7,7,4,2,6,8,6,6,7,3,4,4,8,6,3,6,2,6,6,6,6,6,6,
   6,6,6,6,6,2,3,5,4,5,6,6,6,6,6,6,6,6,6,6,6,6,7,6,7,7,7,6,7,6,6,6,6,7,7,6,6,
   6,4,6,4,7,7,3,6,6,5,6,6,5,6,6,4,5,6,4,7,6,6,6,6,6,6,6,6,6,7,6,6,6,5,2,5,8,
   0,0,0,0,2,253,130,456,156,8,72,184,64,2,125,66,64,160,64,146,511,146,146,
   511,146,146,511,146,511,257,341,297,341,297,341,257,511,16,56,124,16,16,16,
   124,56,16,96,144,270,261,262,136,80,48,224,192,160,80,40,22,14,15,3,448,496,
   496,240,232,20,10,5,2,112,232,452,450,225,113,58,28,63,30,60,200,455,257,
   257,0,0,0,257,257,455,120,204,132,132,159,14,4,4,14,159,132,132,204,120,8,
   24,56,120,56,24,8,32,48,56,60,56,48,32,0,0,0,0,111,111,7,7,0,0,7,7,34,127,
   127,34,34,127,127,34,36,46,107,107,58,18,99,51,24,12,102,99,48,122,79,93,
   55,114,80,4,7,3,62,127,99,65,65,99,127,62,8,42,62,28,28,62,42,8,8,8,62,62,
   8,8,128,224,96,8,8,8,8,8,8,96,96,96,48,24,12,6,3,62,127,89,77,127,62,64,66,
   127,127,64,64,98,115,89,77,71,66,33,97,73,93,119,35,24,28,22,127,127,16,39,
   103,69,69,125,57,62,127,73,73,121,48,1,1,113,121,15,7,54,127,73,73,127,54,
   6,79,73,105,63,30,54,54,128,246,118,8,28,54,99,65,20,20,20,20,65,99,54,28,
   8,2,3,105,109,7,2,30,63,33,45,47,46,124,126,19,19,126,124,127,127,73,73,127,
   54,62,127,65,65,99,34,127,127,65,99,62,28,127,127,73,73,73,65,127,127,9,9,
   9,1,62,127,65,73,121,121,127,127,8,8,127,127,65,65,127,127,65,65,32,96,64,
   64,127,63,127,127,8,28,54,99,65,127,127,64,64,64,64,127,127,6,12,6,127,127,
   127,127,6,12,24,127,127,62,127,65,65,65,127,62,127,127,9,9,15,6,62,127,65,
   81,49,127,94,127,127,9,25,127,102,70,79,73,73,121,49,1,1,127,127,1,1,63,127,
   64,64,127,63,15,31,48,96,48,31,15,127,127,48,24,48,127,127,99,119,28,28,119,
   99,7,15,120,120,15,7,97,113,89,77,71,67,127,127,65,65,3,6,12,24,48,96,65,
   65,127,127,8,12,6,3,6,12,8,64,64,64,64,64,64,64,3,7,4,32,116,84,84,124,120,
   127,127,68,68,124,56,56,124,68,68,68,56,124,68,68,127,127,56,124,84,84,92,
   24,8,124,126,10,10,56,380,324,324,508,252,127,127,4,4,124,120,72,122,122,
   64,256,256,256,506,250,126,126,16,56,104,64,66,126,126,64,124,124,24,56,28,
   124,120,124,124,4,4,124,120,56,124,68,68,124,56,508,508,68,68,124,56,56,124,
   68,68,508,508,124,124,4,4,12,8,72,92,84,84,116,36,4,4,62,126,68,68,60,124,
   64,64,124,124,28,60,96,96,60,28,28,124,112,56,112,124,28,68,108,56,56,108,
   68,284,316,352,320,508,252,68,100,116,92,76,68,8,62,119,65,65,127,127,65,
   65,119,62,8,16,24,12,12,24,24,12,4,
};

typedef struct
{
   short id;
   unsigned short category_id;
   char *category;
   unsigned int layermask;
} stbte__tileinfo;

#define MAX_LAYERMASK    (1 << (8*sizeof(unsigned int)))

typedef short stbte__tiledata;

#define STBTE__NO_TILE   -1

enum
{
   STBTE__panel_toolbar,
   STBTE__panel_colorpick,
   STBTE__panel_info,
   STBTE__panel_layers,
   STBTE__panel_props,
   STBTE__panel_categories,
   STBTE__panel_tiles,

   STBTE__num_panel,
};

enum
{
   STBTE__side_left,
   STBTE__side_right,
   STBTE__side_top,
   STBTE__side_bottom,
};

enum
{
   STBTE__tool_select,
   STBTE__tool_brush,
   STBTE__tool_erase,
   STBTE__tool_rect,
   STBTE__tool_eyedrop,
   STBTE__tool_fill,
   STBTE__tool_link,

   STBTE__tool_showgrid,
   STBTE__tool_showlinks,

   STBTE__tool_undo,
   STBTE__tool_redo,
   // copy/cut/paste aren't included here because they're displayed differently

   STBTE__num_tool,
};

// icons are stored in the 0-31 range of ASCII in the font
static int toolchar[] = { 26,24,25,20,23,22,18, 19,17, 29,28, };

enum
{
   STBTE__propmode_default,
   STBTE__propmode_always,
   STBTE__propmode_never,
};

enum
{
   STBTE__paint,

   // from here down does hittesting
   STBTE__tick,
   STBTE__mousemove,
   STBTE__mousewheel,
   STBTE__leftdown,
   STBTE__leftup,
   STBTE__rightdown,
   STBTE__rightup,
};

typedef struct
{
   int expanded, mode;
   int delta_height;     // number of rows they've requested for this
   int side;
   int width,height;
   int x0,y0;
} stbte__panel;

typedef struct
{
   int x0,y0,x1,y1,color;
} stbte__colorrect;

#define STBTE__MAX_DELAYRECT 256

typedef struct
{
   int tool, active_event;
   int active_id, hot_id, next_hot_id;
   int event;
   int mx,my, dx,dy;
   int ms_time;
   int shift, scrollkey;
   int initted;
   int side_extended[2];
   stbte__colorrect delayrect[STBTE__MAX_DELAYRECT];
   int delaycount;
   int show_grid, show_links;
   int brush_state; // used to decide which kind of erasing
   int eyedrop_x, eyedrop_y, eyedrop_last_layer;
   int pasting, paste_x, paste_y;
   int scrolling, start_x, start_y;
   int last_mouse_x, last_mouse_y;
   int accum_x, accum_y;
   int linking;
   int dragging;
   int drag_x, drag_y, drag_w, drag_h;
   int drag_offx, drag_offy, drag_dest_x, drag_dest_y;
   int undoing;
   int has_selection, select_x0, select_y0, select_x1, select_y1;
   int sx,sy;
   int x0,y0,x1,y1, left_width, right_width; // configurable widths
   float alert_timer;
   const char *alert_msg;
   float dt;
   stbte__panel panel[STBTE__num_panel];
   short copybuffer[STBTE_MAX_COPY][STBTE_MAX_LAYERS];
   float copyprops[STBTE_MAX_COPY][STBTE_MAX_PROPERTIES];
#ifdef STBTE_ALLOW_LINK
   stbte__link copylinks[STBTE_MAX_COPY];
#endif
   int copy_src_x, copy_src_y;
   stbte_tilemap *copy_src;
   int copy_width,copy_height,has_copy,copy_has_props;
} stbte__ui_t;

// there's only one UI system at a time, so we can globalize this
static stbte__ui_t stbte__ui = { STBTE__tool_brush, 0 };

#define STBTE__INACTIVE()     (stbte__ui.active_id == 0)
#define STBTE__IS_ACTIVE(id)  (stbte__ui.active_id == (id))
#define STBTE__IS_HOT(id)     (stbte__ui.hot_id    == (id))

#define STBTE__BUTTON_HEIGHT            (STBTE__FONT_HEIGHT + 2 * STBTE__BUTTON_INTERNAL_SPACING)
#define STBTE__BUTTON_INTERNAL_SPACING  (2 + (STBTE__FONT_HEIGHT>>4))

typedef struct
{
   const char *name;
   int locked;
   int hidden;
} stbte__layer;

enum
{
   STBTE__unlocked,
   STBTE__protected,
   STBTE__locked,
};

struct stbte_tilemap
{
    stbte__tiledata data[STBTE_MAX_TILEMAP_Y][STBTE_MAX_TILEMAP_X][STBTE_MAX_LAYERS];
    float props[STBTE_MAX_TILEMAP_Y][STBTE_MAX_TILEMAP_X][STBTE_MAX_PROPERTIES];
    #ifdef STBTE_ALLOW_LINK
    stbte__link link[STBTE_MAX_TILEMAP_Y][STBTE_MAX_TILEMAP_X];
    int linkcount[STBTE_MAX_TILEMAP_Y][STBTE_MAX_TILEMAP_X];
    #endif
    int max_x, max_y, num_layers;
    int spacing_x, spacing_y;
    int palette_spacing_x, palette_spacing_y;
    int scroll_x,scroll_y;
    int cur_category, cur_tile, cur_layer;
    char *categories[STBTE_MAX_CATEGORIES];
    int num_categories, category_scroll;
    stbte__tileinfo *tiles;
    int num_tiles, max_tiles, digits;
    unsigned char undo_available_valid;
    unsigned char undo_available;
    unsigned char redo_available;
    unsigned char padding;
    int cur_palette_count;
    int palette_scroll;
    int tileinfo_dirty;
    stbte__layer layerinfo[STBTE_MAX_LAYERS];
    int has_layer_names;
    int layername_width;
    int layer_scroll;
    int propmode;
    int solo_layer;
    int undo_pos, undo_len, redo_len;
    short background_tile;
    unsigned char id_in_use[32768>>3];
    short *undo_buffer;
};

static char *default_category = "[unassigned]";

static void stbte__init_gui(void)
{
   int i,n;
   stbte__ui.initted = 1;
   // init UI state
   stbte__ui.show_links = 1;
   for (i=0; i < STBTE__num_panel; ++i) {
      stbte__ui.panel[i].expanded     = 1; // visible if not autohidden
      stbte__ui.panel[i].delta_height = 0;
      stbte__ui.panel[i].side         = STBTE__side_left;
   }
   stbte__ui.panel[STBTE__panel_toolbar  ].side = STBTE__side_top;
   stbte__ui.panel[STBTE__panel_colorpick].side = STBTE__side_right;

   if (stbte__ui.left_width == 0)
      stbte__ui.left_width = 80;
   if (stbte__ui.right_width == 0)
      stbte__ui.right_width = 80;

   // init font
   n=95+16;
   for (i=0; i < 95+16; ++i) {
      stbte__font_offset[i] = n;
      n += stbte__fontdata[i];
   }
}

stbte_tilemap *stbte_create_map(int map_x, int map_y, int map_layers, int spacing_x, int spacing_y, int max_tiles)
{
   int i;
   stbte_tilemap *tm;
   STBTE_ASSERT(map_layers >= 0 && map_layers <= STBTE_MAX_LAYERS);
   STBTE_ASSERT(map_x >= 0 && map_x <= STBTE_MAX_TILEMAP_X);
   STBTE_ASSERT(map_y >= 0 && map_y <= STBTE_MAX_TILEMAP_Y);
   if (map_x < 0 || map_y < 0 || map_layers < 0 ||
       map_x > STBTE_MAX_TILEMAP_X || map_y > STBTE_MAX_TILEMAP_Y || map_layers > STBTE_MAX_LAYERS)
      return NULL;
   
   if (!stbte__ui.initted)
      stbte__init_gui();

   tm = (stbte_tilemap *) malloc(sizeof(*tm) + sizeof(*tm->tiles) * max_tiles + STBTE_UNDO_BUFFER_BYTES);
   if (tm == NULL)
      return NULL;

   tm->tiles = (stbte__tileinfo *) (tm+1);
   tm->undo_buffer = (short *) (tm->tiles + max_tiles);
   tm->num_layers = map_layers;
   tm->max_x = map_x;
   tm->max_y = map_y;
   tm->spacing_x = spacing_x;
   tm->spacing_y = spacing_y;
   tm->scroll_x = 0;
   tm->scroll_y = 0;
   tm->palette_scroll = 0;
   tm->palette_spacing_x = spacing_x+1;
   tm->palette_spacing_y = spacing_y+1;
   tm->cur_category = -1;
   tm->cur_tile = 0;
   tm->solo_layer = -1;
   tm->undo_len = 0;
   tm->redo_len = 0;
   tm->undo_pos = 0;
   tm->category_scroll = 0;
   tm->layer_scroll = 0;
   tm->propmode = 0;
   tm->has_layer_names = 0;
   tm->layername_width = 0;
   tm->undo_available_valid = 0;

   for (i=0; i < tm->num_layers; ++i) {
      tm->layerinfo[i].hidden = 0;
      tm->layerinfo[i].locked = STBTE__unlocked;
      tm->layerinfo[i].name   = 0;
   }

   tm->background_tile = STBTE__NO_TILE;
   stbte_clear_map(tm);

   tm->max_tiles = max_tiles;
   tm->num_tiles = 0;
   for (i=0; i < 32768/8; ++i)
      tm->id_in_use[i] = 0;
   tm->tileinfo_dirty = 1;
   return tm;
}

void stbte_set_background_tile(stbte_tilemap *tm, short id)
{
   int i;
   STBTE_ASSERT(id >= -1 && id < 32768);
   if (id >= 32768 || id < -1)
      return;
   for (i=0; i < STBTE_MAX_TILEMAP_X * STBTE_MAX_TILEMAP_Y; ++i)
      if (tm->data[0][i][0] == -1)
         tm->data[0][i][0] = id;
   tm->background_tile = id;
}

void stbte_set_spacing(stbte_tilemap *tm, int spacing_x, int spacing_y, int palette_spacing_x, int palette_spacing_y)
{
   tm->spacing_x = spacing_x;
   tm->spacing_y = spacing_y;
   tm->palette_spacing_x = palette_spacing_x;
   tm->palette_spacing_y = palette_spacing_y;
}

void stbte_set_sidewidths(int left, int right)
{
   stbte__ui.left_width  = left;
   stbte__ui.right_width = right;
}

void stbte_set_display(int x0, int y0, int x1, int y1)
{
   stbte__ui.x0 = x0;
   stbte__ui.y0 = y0;
   stbte__ui.x1 = x1;
   stbte__ui.y1 = y1;
}

void stbte_define_tile(stbte_tilemap *tm, unsigned short id, unsigned int layermask, const char * category_c)
{
   char *category = (char *) category_c;
   STBTE_ASSERT(id < 32768);
   STBTE_ASSERT(tm->num_tiles < tm->max_tiles);
   STBTE_ASSERT((tm->id_in_use[id>>3]&(1<<(id&7))) == 0);
   if (id >= 32768 || tm->num_tiles >= tm->max_tiles || (tm->id_in_use[id>>3]&(1<<(id&7))))
      return;

   if (category == NULL)
      category = (char*) default_category;
   tm->id_in_use[id>>3] |= 1 << (id&7);
   tm->tiles[tm->num_tiles].category    = category;
   tm->tiles[tm->num_tiles].id        = id;
   tm->tiles[tm->num_tiles].layermask = layermask;
   ++tm->num_tiles;
   tm->tileinfo_dirty = 1;
}

static int stbte__text_width(const char *str);

void stbte_set_layername(stbte_tilemap *tm, int layer, const char *layername)
{
   STBTE_ASSERT(layer >= 0 && layer < tm->num_layers);
   if (layer >= 0 && layer < tm->num_layers) {
      int width;
      tm->layerinfo[layer].name = layername;
      tm->has_layer_names = 1;
      width = stbte__text_width(layername);
      tm->layername_width = (width > tm->layername_width ? width : tm->layername_width);
   }
}

void stbte_get_dimensions(stbte_tilemap *tm, int *max_x, int *max_y)
{
   *max_x = tm->max_x;
   *max_y = tm->max_y;
}

short* stbte_get_tile(stbte_tilemap *tm, int x, int y)
{
   STBTE_ASSERT(x >= 0 && x < tm->max_x && y >= 0 && y < tm->max_y);
   if (x < 0 || x >= STBTE_MAX_TILEMAP_X || y < 0 || y >= STBTE_MAX_TILEMAP_Y)
      return NULL;
   return tm->data[y][x];
}

float *stbte_get_properties(stbte_tilemap *tm, int x, int y)
{
   STBTE_ASSERT(x >= 0 && x < tm->max_x && y >= 0 && y < tm->max_y);
   if (x < 0 || x >= STBTE_MAX_TILEMAP_X || y < 0 || y >= STBTE_MAX_TILEMAP_Y)
      return NULL;
   return tm->props[y][x];
}

void stbte_get_link(stbte_tilemap *tm, int x, int y, int *destx, int *desty)
{
   int gx=-1,gy=-1;
   STBTE_ASSERT(x >= 0 && x < tm->max_x && y >= 0 && y < tm->max_y);
#ifdef STBTE_ALLOW_LINK
   if (x >= 0 && x < STBTE_MAX_TILEMAP_X && y >= 0 && y < STBTE_MAX_TILEMAP_Y) {
      gx = tm->link[y][x].x;
      gy = tm->link[y][x].y;
      if (gx >= 0)
         if (!STBTE_ALLOW_LINK(tm->data[y][x], tm->props[y][x], tm->data[gy][gx], tm->props[gy][gx]))
            gx = gy = -1;
   }
#endif
   *destx = gx;
   *desty = gy;
}

void stbte_set_property(stbte_tilemap *tm, int x, int y, int n, float val)
{
   tm->props[y][x][n] = val;
}

static void stbte__set_link(stbte_tilemap *tm, int src_x, int src_y, int dest_x, int dest_y, int undo_mode);

enum
{
   STBTE__undo_none,
   STBTE__undo_record,
   STBTE__undo_block,
};

void stbte_set_link(stbte_tilemap *tm, int x, int y, int destx, int desty)
{
#ifdef STBTE_ALLOW_LINK
   stbte__set_link(tm, x, y, destx, desty, STBTE__undo_none);
#else
   STBTE_ASSERT(0);
#endif
}


// returns an array of map_layers shorts. each short is either
// one of the tile_id values from define_tile, or STBTE_EMPTY

void stbte_set_dimensions(stbte_tilemap *tm, int map_x, int map_y)
{
   STBTE_ASSERT(map_x >= 0 && map_x <= STBTE_MAX_TILEMAP_X);
   STBTE_ASSERT(map_y >= 0 && map_y <= STBTE_MAX_TILEMAP_Y);
   if (map_x < 0 || map_y < 0 || map_x > STBTE_MAX_TILEMAP_X || map_y > STBTE_MAX_TILEMAP_Y)
      return;
   tm->max_x = map_x;
   tm->max_y = map_y;
}

void stbte_clear_map(stbte_tilemap *tm)
{
   int i,j;
   for (i=0; i < STBTE_MAX_TILEMAP_X * STBTE_MAX_TILEMAP_Y; ++i) {
      tm->data[0][i][0] = tm->background_tile;
      for (j=1; j < tm->num_layers; ++j)
         tm->data[0][i][j] = STBTE__NO_TILE;
      for (j=0; j < STBTE_MAX_PROPERTIES; ++j)
         tm->props[0][i][j] = 0;
      #ifdef STBTE_ALLOW_LINK
      tm->link[0][i].x = -1;
      tm->link[0][i].y = -1;
      tm->linkcount[0][i] = 0;
      #endif
   }
}

void stbte_set_tile(stbte_tilemap *tm, int x, int y, int layer, signed short tile)
{
   STBTE_ASSERT(x >= 0 && x < tm->max_x && y >= 0 && y < tm->max_y);
   STBTE_ASSERT(layer >= 0 && layer < tm->num_layers);
   STBTE_ASSERT(tile >= -1 && tile < 32768);
   if (x < 0 || x >= STBTE_MAX_TILEMAP_X || y < 0 || y >= STBTE_MAX_TILEMAP_Y)
      return;
   if (layer < 0 || layer >= tm->num_layers || tile < -1)
      return;
   tm->data[y][x][layer] = tile;
}

static void stbte__choose_category(stbte_tilemap *tm, int category)
{
   int i,n=0;
   tm->cur_category = category;
   for (i=0; i < tm->num_tiles; ++i)
      if (tm->tiles[i].category_id == category || category == -1)
         ++n;
   tm->cur_palette_count = n;
   tm->palette_scroll = 0;
}

static int stbte__strequal(char *p, char *q)
{
   while (*p)
      if (*p++ != *q++) return 0;
   return *q == 0;
}

static void stbte__compute_tileinfo(stbte_tilemap *tm)
{
   int i,j,n=0;

   tm->num_categories=0;

   for (i=0; i < tm->num_tiles; ++i) {
      stbte__tileinfo *t = &tm->tiles[i];
      // find category
      for (j=0; j < tm->num_categories; ++j)
         if (stbte__strequal(t->category, tm->categories[j]))
            goto found;
      tm->categories[j] = t->category;
      ++tm->num_categories;
     found:
      t->category_id = (unsigned short) j;
   }

   // currently number of categories can never decrease because you
   // can't remove tile definitions, but let's get it right anyway
   if (tm->cur_category > tm->num_categories) {
      tm->cur_category = -1;
   }

   stbte__choose_category(tm, tm->cur_category);

   tm->tileinfo_dirty = 0;
}

static void stbte__prepare_tileinfo(stbte_tilemap *tm)
{
   if (tm->tileinfo_dirty)
      stbte__compute_tileinfo(tm);
}


/////////////////////// undo system ////////////////////////

// the undo system works by storing "commands" into a buffer, and
// then playing back those commands. undo and redo have to store
// the commands in different order. 
//
// the commands are:
//
// 1)  end_of_undo_record
//       -1:short
//
// 2)  end_of_redo_record
//       -2:short
//
// 3)  tile update
//       tile_id:short (-1..32767)
//       x_coord:short
//       y_coord:short
//       layer:short (0..31)
//
// 4)  property update (also used for links)
//       value_hi:short
//       value_lo:short
//       y_coord:short
//       x_coord:short
//       property:short (256+prop#)
//
// Since we use a circular buffer, we might overwrite the undo storage.
// To detect this, before playing back commands we scan back and see
// if we see an end_of_undo_record before hitting the relevant boundary,
// it's wholly contained.
//
// When we read back through, we see them in reverse order, so
// we'll see the layer number or property number first
//
// To be clearer about the circular buffer, there are two cases:
//     1. a single record is larger than the whole buffer.
//        this is caught because the end_of_undo_record will
//        get overwritten.
//     2. multiple records written are larger than the whole
//        buffer, so some of them have been overwritten by
//        the later ones. this is handled by explicitly tracking
//        the undo length; we never try to parse the data that
//        got overwritten

// given two points, compute the length between them
#define stbte__wrap(pos)            ((pos) & (STBTE__UNDO_BUFFER_COUNT-1))

#define STBTE__undo_record  -2
#define STBTE__redo_record  -3
#define STBTE__undo_junk    -4  // this is written underneath the undo pointer, never used

static void stbte__write_undo(stbte_tilemap *tm, short value)
{
   int pos = tm->undo_pos;
   tm->undo_buffer[pos] = value;
   tm->undo_pos = stbte__wrap(pos+1);
   tm->undo_len += (tm->undo_len < STBTE__UNDO_BUFFER_COUNT-2);
   tm->redo_len -= (tm->redo_len > 0);
   tm->undo_available_valid = 0;
}

static void stbte__write_redo(stbte_tilemap *tm, short value)
{
   int pos = tm->undo_pos;
   tm->undo_buffer[pos] = value;
   tm->undo_pos = stbte__wrap(pos-1);
   tm->redo_len += (tm->redo_len < STBTE__UNDO_BUFFER_COUNT-2);
   tm->undo_len -= (tm->undo_len > 0);
   tm->undo_available_valid = 0;
}

static void stbte__begin_undo(stbte_tilemap *tm)
{
   tm->redo_len = 0;
   stbte__write_undo(tm, STBTE__undo_record);
   stbte__ui.undoing = 1;
   stbte__ui.alert_msg = 0; // clear alert if they start doing something
}

static void stbte__end_undo(stbte_tilemap *tm)
{
   if (stbte__ui.undoing) {
      // check if anything got written
      int pos = stbte__wrap(tm->undo_pos-1);
      if (tm->undo_buffer[pos] == STBTE__undo_record) {
         // empty undo record, move back
         tm->undo_pos = pos;
         STBTE_ASSERT(tm->undo_len > 0);
         tm->undo_len -= 1;
      }
      tm->undo_buffer[tm->undo_pos] = STBTE__undo_junk;
      // otherwise do nothing

      stbte__ui.undoing = 0;
   }
}

static void stbte__undo_record(stbte_tilemap *tm, int x, int y, int i, int v)
{
   STBTE_ASSERT(stbte__ui.undoing);
   if (stbte__ui.undoing) {
      stbte__write_undo(tm, v);
      stbte__write_undo(tm, x);
      stbte__write_undo(tm, y);
      stbte__write_undo(tm, i);
   }
}

static void stbte__redo_record(stbte_tilemap *tm, int x, int y, int i, int v)
{
   stbte__write_redo(tm, v);
   stbte__write_redo(tm, x);
   stbte__write_redo(tm, y);
   stbte__write_redo(tm, i);
}

static float stbte__extract_float(short s0, short s1)
{
   union { float f; short s[2]; } converter;
   converter.s[0] = s0;
   converter.s[1] = s1;
   return converter.f;
}

static short stbte__extract_short(float f, int slot)
{
   union { float f; short s[2]; } converter;
   converter.f = f;
   return converter.s[slot];
}

static void stbte__undo_record_prop(stbte_tilemap *tm, int x, int y, int i, short s0, short s1)
{
   STBTE_ASSERT(stbte__ui.undoing);
   if (stbte__ui.undoing) {
      stbte__write_undo(tm, s1);
      stbte__write_undo(tm, s0);
      stbte__write_undo(tm, x);
      stbte__write_undo(tm, y);
      stbte__write_undo(tm, 256+i);
   }
}

static void stbte__undo_record_prop_float(stbte_tilemap *tm, int x, int y, int i, float f)
{
   stbte__undo_record_prop(tm, x,y,i, stbte__extract_short(f,0), stbte__extract_short(f,1));
}

static void stbte__redo_record_prop(stbte_tilemap *tm, int x, int y, int i, short s0, short s1)
{
   stbte__write_redo(tm, s1);
   stbte__write_redo(tm, s0);
   stbte__write_redo(tm, x);
   stbte__write_redo(tm, y);
   stbte__write_redo(tm, 256+i);
}


static int stbte__undo_find_end(stbte_tilemap *tm)
{
   // first scan through for the end record
   int i, pos = stbte__wrap(tm->undo_pos-1);
   for (i=0; i < tm->undo_len;) {
      STBTE_ASSERT(tm->undo_buffer[pos] != STBTE__undo_junk);
      if (tm->undo_buffer[pos] == STBTE__undo_record)
         break;
      if (tm->undo_buffer[pos] >= 255)
         pos = stbte__wrap(pos-5), i += 5;
      else
         pos = stbte__wrap(pos-4), i += 4;
   }
   if (i >= tm->undo_len)
      return -1;
   return pos;
}

static void stbte__undo(stbte_tilemap *tm)
{
   int i, pos, endpos;
   endpos = stbte__undo_find_end(tm);
   if (endpos < 0)
      return;

   // we found a complete undo record
   pos = stbte__wrap(tm->undo_pos-1);

   // start a redo record
   stbte__write_redo(tm, STBTE__redo_record);

   // so now go back through undo and apply in reverse
   // order, and copy it to redo
   for (i=0; endpos != pos; i += 4) {
      int x,y,n,v;
      // get the undo entry
      n = tm->undo_buffer[pos];
      y = tm->undo_buffer[stbte__wrap(pos-1)];
      x = tm->undo_buffer[stbte__wrap(pos-2)];
      v = tm->undo_buffer[stbte__wrap(pos-3)];
      if (n >= 255) {
         short s0=0,s1=0;
         int v2 = tm->undo_buffer[stbte__wrap(pos-4)];
         pos = stbte__wrap(pos-5);
         if (n > 255) {
            float vf = stbte__extract_float(v, v2);
            s0 = stbte__extract_short(tm->props[y][x][n-256], 0);
            s1 = stbte__extract_short(tm->props[y][x][n-256], 1);
            tm->props[y][x][n-256] = vf;
         } else {
#ifdef STBTE_ALLOW_LINK
            s0 = tm->link[y][x].x;
            s1 = tm->link[y][x].y;
            stbte__set_link(tm, x,y, v, v2, STBTE__undo_none);
#endif
         }
         // write the redo entry
         stbte__redo_record_prop(tm, x, y, n-256, s0,s1);
         // apply the undo entry
      } else {
         pos = stbte__wrap(pos-4);
         // write the redo entry
         stbte__redo_record(tm, x, y, n, tm->data[y][x][n]);
         // apply the undo entry
         tm->data[y][x][n] = (short) v;
      }
   }
   // overwrite undo record with junk
   tm->undo_buffer[tm->undo_pos] = STBTE__undo_junk;
}

static int stbte__redo_find_end(stbte_tilemap *tm)
{
   // first scan through for the end record
   int i, pos = stbte__wrap(tm->undo_pos+1);
   for (i=0; i < tm->redo_len;) {
      STBTE_ASSERT(tm->undo_buffer[pos] != STBTE__undo_junk);
      if (tm->undo_buffer[pos] == STBTE__redo_record)
         break;
      if (tm->undo_buffer[pos] >= 255)
         pos = stbte__wrap(pos+5), i += 5;
      else
         pos = stbte__wrap(pos+4), i += 4;
   }
   if (i >= tm->redo_len)
      return -1; // this should only ever happen if redo buffer is empty
   return pos;
}

static void stbte__redo(stbte_tilemap *tm)
{
   // first scan through for the end record
   int i, pos, endpos;
   endpos = stbte__redo_find_end(tm);
   if (endpos < 0)
      return;

   // we found a complete redo record
   pos = stbte__wrap(tm->undo_pos+1);
   
   // start an undo record
   stbte__write_undo(tm, STBTE__undo_record);

   for (i=0; pos != endpos; i += 4) {
      int x,y,n,v;
      n = tm->undo_buffer[pos];
      y = tm->undo_buffer[stbte__wrap(pos+1)];
      x = tm->undo_buffer[stbte__wrap(pos+2)];
      v = tm->undo_buffer[stbte__wrap(pos+3)];
      if (n >= 255) {
         int v2 = tm->undo_buffer[stbte__wrap(pos+4)];
         short s0=0,s1=0;
         pos = stbte__wrap(pos+5);
         if (n > 255) {
            float vf = stbte__extract_float(v, v2);
            s0 = stbte__extract_short(tm->props[y][x][n-256],0);
            s1 = stbte__extract_short(tm->props[y][x][n-256],1);
            tm->props[y][x][n-256] = vf;
         } else {
#ifdef STBTE_ALLOW_LINK
            s0 = tm->link[y][x].x;
            s1 = tm->link[y][x].y;
            stbte__set_link(tm, x,y,v,v2, STBTE__undo_none);
#endif
         }
         // don't use stbte__undo_record_prop because it's guarded
         stbte__write_undo(tm, s1);
         stbte__write_undo(tm, s0);
         stbte__write_undo(tm, x);
         stbte__write_undo(tm, y);
         stbte__write_undo(tm, n);
      } else {
         pos = stbte__wrap(pos+4);
         // don't use stbte__undo_record because it's guarded
         stbte__write_undo(tm, tm->data[y][x][n]);
         stbte__write_undo(tm, x);
         stbte__write_undo(tm, y);
         stbte__write_undo(tm, n);
         tm->data[y][x][n] = (short) v;
      }
   }
   tm->undo_buffer[tm->undo_pos] = STBTE__undo_junk;
}

// because detecting that undo is available 
static void stbte__recompute_undo_available(stbte_tilemap *tm)
{
   tm->undo_available = (stbte__undo_find_end(tm) >= 0);
   tm->redo_available = (stbte__redo_find_end(tm) >= 0);
}

static int stbte__undo_available(stbte_tilemap *tm)
{
   if (!tm->undo_available_valid)
      stbte__recompute_undo_available(tm);
   return tm->undo_available;
}

static int stbte__redo_available(stbte_tilemap *tm)
{
   if (!tm->undo_available_valid)
      stbte__recompute_undo_available(tm);
   return tm->redo_available;
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#ifdef STBTE_ALLOW_LINK
static void stbte__set_link(stbte_tilemap *tm, int src_x, int src_y, int dest_x, int dest_y, int undo_mode)
{
   stbte__link *a;
   STBTE_ASSERT(src_x >= 0 && src_x < STBTE_MAX_TILEMAP_X && src_y >= 0 && src_y < STBTE_MAX_TILEMAP_Y);
   a = &tm->link[src_y][src_x];
   // check if it's a do nothing
   if (a->x == dest_x && a->y == dest_y)
      return;
   if (undo_mode != STBTE__undo_none ) {
      if (undo_mode == STBTE__undo_block) stbte__begin_undo(tm);
      stbte__undo_record_prop(tm, src_x, src_y, -1, a->x, a->y);
      if (undo_mode == STBTE__undo_block) stbte__end_undo(tm);
   }
   // check if there's an existing link
   if (a->x >= 0) {
      // decrement existing link refcount
      STBTE_ASSERT(tm->linkcount[a->y][a->x] > 0);
      --tm->linkcount[a->y][a->x];
   }
   // increment new dest
   if (dest_x >= 0) {
      ++tm->linkcount[dest_y][dest_x];
   }
   a->x = dest_x;
   a->y = dest_y;
}
#endif


static void stbte__draw_rect(int x0, int y0, int x1, int y1, unsigned int color)
{
   STBTE_DRAW_RECT(x0,y0,x1,y1, color);
}

static void stbte__draw_line(int x0, int y0, int x1, int y1, unsigned int color)
{
   int temp;
   if (x1 < x0) temp=x0,x0=x1,x1=temp;
   if (y1 < y0) temp=y0,y0=y1,y1=temp;
   stbte__draw_rect(x0,y0,x1+1,y1+1,color);
}

static void stbte__draw_link(int x0, int y0, int x1, int y1, unsigned int color)
{
   stbte__draw_line(x0,y0,x0,y1, color);
   stbte__draw_line(x0,y1,x1,y1, color);
}

static void stbte__draw_frame(int x0, int y0, int x1, int y1, unsigned int color)
{
   stbte__draw_rect(x0,y0,x1-1,y0+1,color);
   stbte__draw_rect(x1-1,y0,x1,y1-1,color);
   stbte__draw_rect(x0+1,y1-1,x1,y1,color);
   stbte__draw_rect(x0,y0+1,x0+1,y1,color);
}

static void stbte__draw_halfframe(int x0, int y0, int x1, int y1, unsigned int color)
{
   stbte__draw_rect(x0,y0,x1,y0+1,color);
   stbte__draw_rect(x0,y0+1,x0+1,y1,color);
}

static int stbte__get_char_width(int ch)
{
   return stbte__fontdata[ch-16];
}

static short *stbte__get_char_bitmap(int ch)
{
   return stbte__fontdata + stbte__font_offset[ch-16];
}

static void stbte__draw_bitmask_as_columns(int x, int y, short bitmask, int color)
{
   int start_i = -1, i=0;
   while (bitmask) {
      if (bitmask & (1<<i)) {
         if (start_i < 0)
            start_i = i;   
      } else if (start_i >= 0) {
         stbte__draw_rect(x, y+start_i, x+1, y+i, color);
         start_i = -1;
         bitmask &= ~((1<<i)-1); // clear all the old bits; we don't clear them as we go to save code
      }
      ++i;
   }
}

static void stbte__draw_bitmap(int x, int y, int w, short *bitmap, int color)
{
   int i;
   for (i=0; i < w; ++i)
      stbte__draw_bitmask_as_columns(x+i, y, *bitmap++, color);
}

static void stbte__draw_text_core(int x, int y, const char *str, int w, int color, int digitspace)
{
   int x_end = x+w;
   while (*str) {
      int c = *str++;
      int cw = stbte__get_char_width(c);
      if (x + cw > x_end)
         break;
      stbte__draw_bitmap(x, y, cw, stbte__get_char_bitmap(c), color);
      if (digitspace && c == ' ')
         cw = stbte__get_char_width('0');
      x += cw+1;
   }
}

static void stbte__draw_text(int x, int y, const char *str, int w, int color)
{
   stbte__draw_text_core(x,y,str,w,color,0);
}

static int stbte__text_width(const char *str)
{
   int x = 0;
   while (*str) {
      int c = *str++;
      int cw = stbte__get_char_width(c);
      x += cw+1;
   }
   return x;
}

static void stbte__draw_frame_delayed(int x0, int y0, int x1, int y1, int color)
{
   if (stbte__ui.delaycount < STBTE__MAX_DELAYRECT) {
      stbte__colorrect r = { x0,y0,x1,y1,color };
      stbte__ui.delayrect[stbte__ui.delaycount++] = r;
   }
}

static void stbte__flush_delay(void)
{
   stbte__colorrect *r;
   int i;
   r = stbte__ui.delayrect;
   for (i=0; i < stbte__ui.delaycount; ++i,++r)
      stbte__draw_frame(r->x0,r->y0,r->x1,r->y1,r->color);
   stbte__ui.delaycount = 0;
}

static void stbte__activate(int id)
{
   stbte__ui.active_id = id;
   stbte__ui.active_event = stbte__ui.event;
   stbte__ui.accum_x = 0;
   stbte__ui.accum_y = 0;
}

static int stbte__hittest(int x0, int y0, int x1, int y1, int id)
{
   int over =    stbte__ui.mx >= x0 && stbte__ui.my >= y0
              && stbte__ui.mx <  x1 && stbte__ui.my <  y1;

   if (over && stbte__ui.event >= STBTE__tick)
      stbte__ui.next_hot_id = id;

   return over;
}

static int stbte__button_core(int id)
{
   switch (stbte__ui.event) {
      case STBTE__leftdown:
         if (stbte__ui.hot_id == id && STBTE__INACTIVE())
            stbte__activate(id);
         break;
      case STBTE__leftup:
         if (stbte__ui.active_id == id && STBTE__IS_HOT(id)) {
            stbte__activate(0);
            return 1;
         }
         break;
      case STBTE__rightdown:
         if (stbte__ui.hot_id == id && STBTE__INACTIVE())
            stbte__activate(id);
         break;
      case STBTE__rightup:
         if (stbte__ui.active_id == id && STBTE__IS_HOT(id)) {
            stbte__activate(0);
            return -1;
         }
         break;
   }
   return 0;
}

static void stbte__draw_box(int x0, int y0, int x1, int y1, int colormode, int colorindex)
{
   stbte__draw_rect (x0,y0,x1,y1, stbte__color_table[colormode][STBTE__base   ][colorindex]);
   stbte__draw_frame(x0,y0,x1,y1, stbte__color_table[colormode][STBTE__outline][colorindex]);
}

static void stbte__draw_textbox(int x0, int y0, int x1, int y1, char *text, int xoff, int yoff, int colormode, int colorindex)
{
   stbte__draw_box(x0,y0,x1,y1,colormode,colorindex);
   stbte__draw_text(x0+xoff,y0+yoff, text, x1-x0-xoff-1, stbte__color_table[colormode][STBTE__text][colorindex]);
}

static int stbte__button(int colormode, char *label, int x, int y, int textoff, int width, int id, int toggled, int disabled)
{
   int x0=x,y0=y, x1=x+width,y1=y+STBTE__BUTTON_HEIGHT;
   int s = STBTE__BUTTON_INTERNAL_SPACING;

   int over = !disabled && stbte__hittest(x0,y0,x1,y1,id);
      
   if (stbte__ui.event == STBTE__paint)
      stbte__draw_textbox(x0,y0,x1,y1, label,s+textoff,s, colormode, STBTE__INDEX_FOR_ID(id,disabled,toggled));
   if (disabled)
      return 0;
   return (stbte__button_core(id) == 1);
}

static int stbte__button_icon(int colormode, char ch, int x, int y, int width, int id, int toggled, int disabled)
{
   int x0=x,y0=y, x1=x+width,y1=y+STBTE__BUTTON_HEIGHT;
   int s = STBTE__BUTTON_INTERNAL_SPACING;

   int over = stbte__hittest(x0,y0,x1,y1,id);
      
   if (stbte__ui.event == STBTE__paint) {
      char label[2] = { ch, 0 };
      int pad = (9 - stbte__get_char_width(ch))/2;
      stbte__draw_textbox(x0,y0,x1,y1, label,s+pad,s, colormode, STBTE__INDEX_FOR_ID(id,disabled,toggled));
   }
   if (disabled)
      return 0;
   return (stbte__button_core(id) == 1);
}

static int stbte__minibutton(int colormode, int x, int y, int ch, int id)
{
   int x0 = x, y0 = y, x1 = x+8, y1 = y+7;
   int over = stbte__hittest(x0,y0,x1,y1,id);
   if (stbte__ui.event == STBTE__paint) {
      char str[2] = { ch,0 };
      stbte__draw_textbox(x0,y0,x1,y1, str,1,0,colormode, STBTE__INDEX_FOR_ID(id,0,0));
   }
   return stbte__button_core(id);
}

static int stbte__layerbutton(int x, int y, int ch, int id, int toggled, int disabled, int colormode)
{
   int x0 = x, y0 = y, x1 = x+10, y1 = y+11;
   int over = !disabled && stbte__hittest(x0,y0,x1,y1,id);
   if (stbte__ui.event == STBTE__paint) {
      char str[2] = { ch,0 };
      int off = (9-stbte__get_char_width(ch))/2;
      stbte__draw_textbox(x0,y0,x1,y1, str, off+1,2, colormode, STBTE__INDEX_FOR_ID(id,disabled,toggled));
   }
   if (disabled)
      return 0;
   return stbte__button_core(id);
}

static int stbte__microbutton(int x, int y, int size, int id, int colormode)
{
   int x0 = x, y0 = y, x1 = x+size, y1 = y+size;
   int over = stbte__hittest(x0,y0,x1,y1,id);
   if (stbte__ui.event == STBTE__paint) {
      stbte__draw_box(x0,y0,x1,y1, colormode, STBTE__INDEX_FOR_ID(id,0,0));
   }
   return stbte__button_core(id);
}

static int stbte__microbutton_dragger(int x, int y, int size, int id, int *pos)
{
   int x0 = x, y0 = y, x1 = x+size, y1 = y+size;
   int over = stbte__hittest(x0,y0,x1,y1,id);
   switch (stbte__ui.event) {
      case STBTE__paint:
         stbte__draw_box(x0,y0,x1,y1, STBTE__cexpander, STBTE__INDEX_FOR_ID(id,0,0));
         break;
      case STBTE__leftdown:
         if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
            stbte__activate(id);
            stbte__ui.sx = stbte__ui.mx - *pos;
         }
         break;
      case STBTE__mousemove:
         if (STBTE__IS_ACTIVE(id) && stbte__ui.active_event == STBTE__leftdown) {
            *pos = stbte__ui.mx - stbte__ui.sx;  
         }
         break;
      case STBTE__leftup:
         if (STBTE__IS_ACTIVE(id))
            stbte__activate(0);
         break;
      default:
         return stbte__button_core(id);
   }
   return 0;
}

static int stbte__category_button(char *label, int x, int y, int width, int id, int toggled)
{
   int x0=x,y0=y, x1=x+width,y1=y+STBTE__BUTTON_HEIGHT;
   int s = STBTE__BUTTON_INTERNAL_SPACING;

   int over = stbte__hittest(x0,y0,x1,y1,id);
      
   if (stbte__ui.event == STBTE__paint)
      stbte__draw_textbox(x0,y0,x1,y1, label, s,s, STBTE__ccategory_button, STBTE__INDEX_FOR_ID(id,0,toggled));

   return (stbte__button_core(id) == 1);
}

enum
{
   STBTE__none,
   STBTE__begin,
   STBTE__end,
   STBTE__change,
};

// returns -1 if value changes, 1 at end of drag
static int stbte__slider(int x0, int w, int y, int range, int *value, int id)
{
   int x1 = x0+w;
   int pos = *value * w / (range+1);
   int over = stbte__hittest(x0,y-2,x1,y+3,id);
   int event_mouse_move = STBTE__change;
   switch (stbte__ui.event) {
      case STBTE__paint:
         stbte__draw_rect(x0,y,x1,y+1, 0x808080);
         stbte__draw_rect(x0+pos-1,y-1,x0+pos+2,y+2, 0xffffff);
         break;
      case STBTE__leftdown:
         if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
            stbte__activate(id);
            event_mouse_move = STBTE__begin;
         }
         // fall through
      case STBTE__mousemove:
         if (STBTE__IS_ACTIVE(id)) {
            int v = (stbte__ui.mx-x0)*(range+1)/w;
            if (v < 0) v = 0; else if (v > range) v = range;
            *value = v;
            return event_mouse_move;
         }
         break;
      case STBTE__leftup:
         if (STBTE__IS_ACTIVE(id)) {
            stbte__activate(0);
            return STBTE__end;
         }
         break;
   }
   return STBTE__none;
}

static int stbte__float_control(int x0, int y0, int w, float minv, float maxv, float scale, char *fmt, float *value, int colormode, int id)
{
   int x1 = x0+w;
   int y1 = y0+11;
   int over = stbte__hittest(x0,y0,x1,y1,id);
   switch (stbte__ui.event) {
      case STBTE__paint: {
         char text[32];
         sprintf(text, fmt ? fmt : "%6.2f", *value);
         stbte__draw_textbox(x0,y0,x1,y1, text, 1,2, colormode, STBTE__INDEX_FOR_ID(id,0,0));
         break;
      }
      case STBTE__leftdown:
      case STBTE__rightdown:
         if (STBTE__IS_HOT(id) && STBTE__INACTIVE())
            stbte__activate(id);
            return STBTE__begin;
         break;
      case STBTE__leftup:
      case STBTE__rightup:
         if (STBTE__IS_ACTIVE(id)) {
            stbte__activate(0);
            return STBTE__end;
         }
         break;
      case STBTE__mousemove:
         if (STBTE__IS_ACTIVE(id)) {
            float v = *value, delta;
            int ax = stbte__ui.accum_x/STBTE_FLOAT_CONTROL_GRANULARITY;
            int ay = stbte__ui.accum_y/STBTE_FLOAT_CONTROL_GRANULARITY;
            stbte__ui.accum_x -= ax*STBTE_FLOAT_CONTROL_GRANULARITY;
            stbte__ui.accum_y -= ay*STBTE_FLOAT_CONTROL_GRANULARITY;
            if (stbte__ui.shift) {
               if (stbte__ui.active_event == STBTE__leftdown)
                  delta = ax * 16.0f + ay;
               else
                  delta = ax / 16.0f + ay / 256.0f;
            } else {
               if (stbte__ui.active_event == STBTE__leftdown)
                  delta = ax*10.0f + ay;
               else
                  delta = ax * 0.1f + ay * 0.01f;
            }
            v += delta * scale;
            if (v < minv) v = minv;
            if (v > maxv) v = maxv;
            *value = v;
            return STBTE__change;
         }
         break;
   }
   return STBTE__none;
}

static void stbte__scrollbar(int x, int y0, int y1, int *val, int v0, int v1, int num_vis, int id)
{
   int over;
   int thumbpos;
   if (v1 - v0 <= num_vis)
      return;

   // generate thumbpos from numvis
   thumbpos = y0+2 + (y1-y0-4) * *val / (v1 - v0 - num_vis);
   if (thumbpos < y0) thumbpos = y0;
   if (thumbpos >= y1) thumbpos = y1;
   over = stbte__hittest(x-1,y0,x+2,y1,id);
   switch (stbte__ui.event) {
      case STBTE__paint:
         stbte__draw_rect(x,y0,x+1,y1, stbte__color_table[STBTE__cscrollbar][STBTE__text][STBTE__idle]);
         stbte__draw_box(x-1,thumbpos-3,x+2,thumbpos+4, STBTE__cscrollbar, STBTE__INDEX_FOR_ID(id,0,0));
         break;
      case STBTE__leftdown:
         if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
            // check if it's over the thumb
            stbte__activate(id);
            *val = ((stbte__ui.my-y0) * (v1 - v0 - num_vis) + (y1-y0)/2)/ (y1-y0);
         }
         break;
      case STBTE__mousemove:
         if (STBTE__IS_ACTIVE(id) && stbte__ui.mx >= x-15 && stbte__ui.mx <= x+15)
            *val = ((stbte__ui.my-y0) * (v1 - v0 - num_vis) + (y1-y0)/2)/ (y1-y0);
         break;
      case STBTE__leftup:
         if (STBTE__IS_ACTIVE(id))
            stbte__activate(0);
         break;

   }

   if (*val >= v1-num_vis)
      *val = v1-num_vis;
   if (*val <= v0)
      *val = v0;
}


static void stbte__compute_digits(stbte_tilemap *tm)
{
   if (tm->max_x >= 1000 || tm->max_y >= 1000)
      tm->digits = 4;
   else if (tm->max_x >= 100 || tm->max_y >= 100)
      tm->digits = 3;
   else
      tm->digits = 2;
}

static int stbte__is_single_selection(void)
{
   return stbte__ui.has_selection
       && stbte__ui.select_x0 == stbte__ui.select_x1
       && stbte__ui.select_y0 == stbte__ui.select_y1;
}

typedef struct
{
   int width, height;
   int x,y;
   int active;
   float retracted;
} stbte__region_t;

static stbte__region_t stbte__region[4];

#define STBTE__TOOLBAR_ICON_SIZE   (9+2*2)
#define STBTE__TOOLBAR_PASTE_SIZE  (34+2*2)

// This routine computes where every panel goes onscreen: computes
// a minimum width for each side based on which panels are on that
// side, and accounts for width-dependent layout of certain panels.
static void stbte__compute_panel_locations(stbte_tilemap *tm)
{
   int i, limit, w, k;
   int window_width  = stbte__ui.x1 - stbte__ui.x0;
   int window_height = stbte__ui.y1 - stbte__ui.y0;
   int min_width[STBTE__num_panel]={0,0,0,0,0,0,0};
   int height[STBTE__num_panel]={0,0,0,0,0,0,0};
   int panel_active[STBTE__num_panel]={1,0,1,1,1,1,1};
   int vpos[4] = { 0,0,0,0 };
   stbte__panel *p = stbte__ui.panel;
   stbte__panel *pt = &p[STBTE__panel_toolbar];
#ifdef STBTE__NO_PROPS
   int props = 0;
#else
   int props = 1;
#endif

   for (i=0; i < 4; ++i) {
      stbte__region[i].active = 0;
      stbte__region[i].width = 0;
      stbte__region[i].height = 0;
   }

   // compute number of digits needs for info panel
   stbte__compute_digits(tm);

   // determine which panels are active
   panel_active[STBTE__panel_categories] = tm->num_categories != 0;
   panel_active[STBTE__panel_layers    ] = tm->num_layers     >  1;
#ifdef STBTE__COLORPICKER
   panel_active[STBTE__panel_colorpick ] = 1;
#endif

   panel_active[STBTE__panel_props     ] = props && stbte__is_single_selection();

   // compute minimum widths for each panel (assuming they're on sides not top)
   min_width[STBTE__panel_info      ] = 8 + 11 + 7*tm->digits+17+7;               // estimate min width of "w:0000"
   min_width[STBTE__panel_colorpick ] = 120;
   min_width[STBTE__panel_tiles     ] = 4 + tm->palette_spacing_x + 5;            // 5 for scrollbar
   min_width[STBTE__panel_categories] = 4 + 42 + 5;                               // 42 is enough to show ~7 chars; 5 for scrollbar
   min_width[STBTE__panel_layers    ] = 4 + 54 + 30*tm->has_layer_names;          // 2 digits plus 3 buttons plus scrollbar
   min_width[STBTE__panel_toolbar   ] = 4 + STBTE__TOOLBAR_PASTE_SIZE;            // wide enough for 'Paste' button
   min_width[STBTE__panel_props     ] = 80;                    // narrowest info panel

   // compute minimum widths for left & right panels based on the above
   stbte__region[0].width = stbte__ui.left_width;
   stbte__region[1].width = stbte__ui.right_width;

   for (i=0; i < STBTE__num_panel; ++i) {
      if (panel_active[i]) {
         int side = stbte__ui.panel[i].side;
         if (min_width[i] > stbte__region[side].width)
            stbte__region[side].width = min_width[i];
         stbte__region[side].active = 1;
      }
   }

   // now compute the heights of each panel

   // if toolbar at top, compute its size & push the left and right start points down
   if (stbte__region[STBTE__side_top].active) {
      int height = STBTE__TOOLBAR_ICON_SIZE+2;
      pt->x0     = stbte__ui.x0;
      pt->y0     = stbte__ui.y0;
      pt->width  = window_width;
      pt->height = height;
      vpos[STBTE__side_left] = vpos[STBTE__side_right] = height;
   } else {
      int num_rows = STBTE__num_tool * ((stbte__region[pt->side].width-4)/STBTE__TOOLBAR_ICON_SIZE);
      height[STBTE__panel_toolbar] = num_rows*13 + 3*15 + 4; // 3*15 for cut/copy/paste, which are stacked vertically
   }

   for (i=0; i < 4; ++i)
      stbte__region[i].y = stbte__ui.y0 + vpos[i];

   for (i=0; i < 2; ++i) {
      int anim = (int) (stbte__region[i].width * stbte__region[i].retracted);
      stbte__region[i].x = (i == STBTE__side_left) ? stbte__ui.x0 - anim : stbte__ui.x1 - stbte__region[i].width + anim;
   }

   // color picker
   height[STBTE__panel_colorpick] = 300;

   // info panel
   w = stbte__region[p[STBTE__panel_info].side].width;
   p[STBTE__panel_info].mode = (w >= 8 + (11+7*tm->digits+17)*2 + 4);
   if (p[STBTE__panel_info].mode)
      height[STBTE__panel_info] = 5 + 11*2 + 2 + tm->palette_spacing_y;
   else
      height[STBTE__panel_info] = 5 + 11*4 + 2 + tm->palette_spacing_y;

   // layers
   limit = 6 + stbte__ui.panel[STBTE__panel_layers].delta_height;
   height[STBTE__panel_layers] = (tm->num_layers > limit ? limit : tm->num_layers)*15 + 7 + (tm->has_layer_names ? 0 : 11) + props*13;

   // categories
   limit = 6 + stbte__ui.panel[STBTE__panel_categories].delta_height;
   height[STBTE__panel_categories] = (tm->num_categories+1 > limit ? limit : tm->num_categories+1)*11 + 14;
   if (stbte__ui.panel[STBTE__panel_categories].side == stbte__ui.panel[STBTE__panel_categories].side)
      height[STBTE__panel_categories] -= 4;   

   // palette
   k =  (stbte__region[p[STBTE__panel_tiles].side].width - 8) / tm->palette_spacing_x;
   if (k == 0) k = 1;
   height[STBTE__panel_tiles] = ((tm->num_tiles+k-1)/k) * tm->palette_spacing_y + 8;

   // properties panel
   height[STBTE__panel_props] = 9 + STBTE_MAX_PROPERTIES*14;

   // now compute the locations of all the panels
   for (i=0; i < STBTE__num_panel; ++i) {
      if (panel_active[i]) {
         int side = p[i].side;
         if (side == STBTE__side_left || side == STBTE__side_right) {
            p[i].width  = stbte__region[side].width;
            p[i].x0     = stbte__region[side].x;
            p[i].y0     = stbte__ui.y0 + vpos[side];
            p[i].height = height[i];
            vpos[side] += height[i];
            if (vpos[side] > window_height) {
               vpos[side] = window_height;
               p[i].height = stbte__ui.y1 - p[i].y0;
            }
         } else {
            ; // it's at top, it's already been explicitly set up earlier
         }
      } else {
         // inactive panel
         p[i].height = 0;
         p[i].width  = 0;
         p[i].x0     = stbte__ui.x1;
         p[i].y0     = stbte__ui.y1;
      }
   }
}

// unique identifiers for imgui
enum
{
   STBTE__map=1,
   STBTE__region,
   STBTE__panel,                          // panel background to hide map, and misc controls
   STBTE__info,                           // info data
   STBTE__toolbarA, STBTE__toolbarB,      // toolbar buttons: param is tool number
   STBTE__palette,                        // palette selectors: param is tile index
   STBTE__categories,                     // category selectors: param is category index
   STBTE__layer,                          //
   STBTE__solo, STBTE__hide, STBTE__lock, // layer controls: param is layer
   STBTE__scrollbar,                      // param is panel ID
   STBTE__panel_mover,                    // p1 is panel ID, p2 is destination side
   STBTE__panel_sizer,                    // param panel ID
   STBTE__scrollbar_id,
   STBTE__colorpick_id,
   STBTE__prop_flag,
   STBTE__prop_float,
   STBTE__prop_int,
};

// id is:      [      24-bit data     : 7-bit identifer ]
// map id is:  [  12-bit y : 12 bit x : 7-bit identifier ]

#define STBTE__ID(n,p)     ((n) + ((p)<<7))
#define STBTE__ID2(n,p,q)  STBTE__ID(n, ((p)<<12)+(q) )
#define STBTE__IDMAP(x,y)  STBTE__ID2(STBTE__map, x,y)

static void stbte__activate_map(int x, int y)
{
   stbte__ui.active_id = STBTE__IDMAP(x,y);
   stbte__ui.active_event = stbte__ui.event;
   stbte__ui.sx = x;
   stbte__ui.sy = y;
}

static void stbte__alert(const char *msg)
{
   stbte__ui.alert_msg = msg;
   stbte__ui.alert_timer = 3;
}

#define STBTE__BG(tm,layer) ((layer) == 0 ? (tm)->background_tile : STBTE__NO_TILE)



static void stbte__brush_predict(stbte_tilemap *tm, short result[])
{
   int layer_to_paint = tm->cur_layer;
   stbte__tileinfo *ti;
   int i;

   if (tm->cur_tile < 0) return;

   ti = &tm->tiles[tm->cur_tile];

   // find lowest legit layer to paint it on, and put it there
   for (i=0; i < tm->num_layers; ++i) {
      // check if object is allowed on layer
      if (!(ti->layermask & (1 << i)))
         continue;

      if (i != tm->solo_layer) {
         // if there's a selected layer, can only paint on that
         if (tm->cur_layer >= 0 && i != tm->cur_layer)
            continue;

         // if the layer is hidden, we can't see it
         if (tm->layerinfo[i].hidden)
            continue;

         // if the layer is locked, we can't write to it
         if (tm->layerinfo[i].locked == STBTE__locked)
            continue;

         // if the layer is non-empty and protected, can't write to it
         if (tm->layerinfo[i].locked == STBTE__protected && result[i] != STBTE__BG(tm,i))
            continue;
      }

      result[i] = ti->id;
      return;
   }
}

static void stbte__brush(stbte_tilemap *tm, int x, int y)
{
   int layer_to_paint = tm->cur_layer;
   stbte__tileinfo *ti;

   // find lowest legit layer to paint it on, and put it there
   int i;

   if (tm->cur_tile < 0) return;

   ti = &tm->tiles[tm->cur_tile];

   for (i=0; i < tm->num_layers; ++i) {
      // check if object is allowed on layer
      if (!(ti->layermask & (1 << i)))
         continue;

      if (i != tm->solo_layer) {
         // if there's a selected layer, can only paint on that
         if (tm->cur_layer >= 0 && i != tm->cur_layer)
            continue;

         // if the layer is hidden, we can't see it
         if (tm->layerinfo[i].hidden)
            continue;

         // if the layer is locked, we can't write to it
         if (tm->layerinfo[i].locked == STBTE__locked)
            continue;

         // if the layer is non-empty and protected, can't write to it
         if (tm->layerinfo[i].locked == STBTE__protected && tm->data[y][x][i] != STBTE__BG(tm,i))
            continue;
      }

      stbte__undo_record(tm,x,y,i,tm->data[y][x][i]);
      tm->data[y][x][i] = ti->id;
      return;
   }

   //stbte__alert("Selected tile not valid on active layer(s)");
}

enum
{
   STBTE__erase_none = -1,
   STBTE__erase_brushonly = 0,
   STBTE__erase_any = 1,
   STBTE__erase_all = 2,
};

static int stbte__erase_predict(stbte_tilemap *tm, short result[], int allow_any)
{
   stbte__tileinfo *ti = tm->cur_tile >= 0 ? &tm->tiles[tm->cur_tile] : NULL;
   int i;

   if (allow_any == STBTE__erase_none)
      return allow_any;

   // first check if only one layer is legit
   i = tm->cur_layer;
   if (tm->solo_layer >= 0)
      i = tm->solo_layer;

   // if only one layer is legit, directly process that one for clarity
   if (i >= 0) {
      short bg = (i == 0 ? tm->background_tile : -1);
      if (tm->solo_layer < 0) {
         // check that we're allowed to write to it
         if (tm->layerinfo[i].hidden) return STBTE__erase_none;
         if (tm->layerinfo[i].locked) return STBTE__erase_none;
      }
      if (result[i] == bg)
         return STBTE__erase_none; // didn't erase anything
      if (ti && result[i] == ti->id && (i != 0 || ti->id != tm->background_tile)) {
         result[i] = bg;
         return STBTE__erase_brushonly;
      }
      if (allow_any == STBTE__erase_any) {
         result[i] = bg;
         return STBTE__erase_any;
      }
      return STBTE__erase_none;
   }

   // if multiple layers are legit, first scan all for brush data

   if (ti && allow_any != STBTE__erase_all) {
      for (i=tm->num_layers-1; i >= 0; --i) {
         if (result[i] != ti->id)
            continue;
         if (tm->layerinfo[i].locked || tm->layerinfo[i].hidden)
            continue;
         if (i == 0 && result[i] == tm->background_tile)
            return STBTE__erase_none;
         result[i] = STBTE__BG(tm,i);
         return STBTE__erase_brushonly;
      }
   }

   if (allow_any != STBTE__erase_any && allow_any != STBTE__erase_all)
      return STBTE__erase_none;

   // apply layer filters, erase from top
   for (i=tm->num_layers-1; i >= 0; --i) {
      if (result[i] < 0)
         continue;
      if (tm->layerinfo[i].locked || tm->layerinfo[i].hidden)
         continue;
      if (i == 0 && result[i] == tm->background_tile)
         return STBTE__erase_none;
      result[i] = STBTE__BG(tm,i);
      if (allow_any != STBTE__erase_all)
         return STBTE__erase_any;
   }

   if (allow_any == STBTE__erase_all)
      return allow_any;
   return STBTE__erase_none;
}

static int stbte__erase(stbte_tilemap *tm, int x, int y, int allow_any)
{
   stbte__tileinfo *ti = tm->cur_tile >= 0 ? &tm->tiles[tm->cur_tile] : NULL;
   int i;

   if (allow_any == STBTE__erase_none)
      return allow_any;

   // first check if only one layer is legit
   i = tm->cur_layer;
   if (tm->solo_layer >= 0)
      i = tm->solo_layer;

   // if only one layer is legit, directly process that one for clarity
   if (i >= 0) {
      short bg = (i == 0 ? tm->background_tile : -1);
      if (tm->solo_layer < 0) {
         // check that we're allowed to write to it
         if (tm->layerinfo[i].hidden) return STBTE__erase_none;
         if (tm->layerinfo[i].locked) return STBTE__erase_none;
      }
      if (tm->data[y][x][i] == bg)
         return -1; // didn't erase anything
      if (ti && tm->data[y][x][i] == ti->id && (i != 0 || ti->id != tm->background_tile)) {
         stbte__undo_record(tm,x,y,i,tm->data[y][x][i]);
         tm->data[y][x][i] = bg;
         return STBTE__erase_brushonly;
      }
      if (allow_any == STBTE__erase_any) {
         stbte__undo_record(tm,x,y,i,tm->data[y][x][i]);
         tm->data[y][x][i] = bg;
         return STBTE__erase_any;
      }
      return STBTE__erase_none;
   }

   // if multiple layers are legit, first scan all for brush data

   if (ti && allow_any != STBTE__erase_all) {
      for (i=tm->num_layers-1; i >= 0; --i) {
         if (tm->data[y][x][i] != ti->id)
            continue;
         if (tm->layerinfo[i].locked || tm->layerinfo[i].hidden)
            continue;
         if (i == 0 && tm->data[y][x][i] == tm->background_tile)
            return STBTE__erase_none;
         stbte__undo_record(tm,x,y,i,tm->data[y][x][i]);
         tm->data[y][x][i] = STBTE__BG(tm,i);
         return STBTE__erase_brushonly;
      }
   }

   if (allow_any != STBTE__erase_any && allow_any != STBTE__erase_all)
      return STBTE__erase_none;

   // apply layer filters, erase from top
   for (i=tm->num_layers-1; i >= 0; --i) {
      if (tm->data[y][x][i] < 0)
         continue;
      if (tm->layerinfo[i].locked || tm->layerinfo[i].hidden)
         continue;
      if (i == 0 && tm->data[y][x][i] == tm->background_tile)
         return STBTE__erase_none;
      stbte__undo_record(tm,x,y,i,tm->data[y][x][i]);
      tm->data[y][x][i] = STBTE__BG(tm,i);
      if (allow_any != STBTE__erase_all)
         return STBTE__erase_any;
   }
   if (allow_any == STBTE__erase_all)
      return allow_any;
   return STBTE__erase_none;
}

static int stbte__find_tile(stbte_tilemap *tm, int tile_id)
{
   int i;
   for (i=0; i < tm->num_tiles; ++i)
      if (tm->tiles[i].id == tile_id)
         return i;
   stbte__alert("Eyedropped tile that isn't in tileset");
   return -1;
}

static void stbte__eyedrop(stbte_tilemap *tm, int x, int y)
{
   int i,j;

   // flush eyedropper state
   if (stbte__ui.eyedrop_x != x || stbte__ui.eyedrop_y != y) {
      stbte__ui.eyedrop_x = x;
      stbte__ui.eyedrop_y = y;
      stbte__ui.eyedrop_last_layer = tm->num_layers;
   }

   // if only one layer is active, query that
   i = tm->cur_layer;
   if (tm->solo_layer >= 0)
      i = tm->solo_layer;
   if (i >= 0) {
      if (tm->data[y][x][i] == STBTE__NO_TILE)
         return;
      tm->cur_tile = stbte__find_tile(tm, tm->data[y][x][i]);
      return;
   }

   // if multiple layers, continue from previous
   i = stbte__ui.eyedrop_last_layer;
   for (j=0; j < tm->num_layers; ++j) {
      if (--i < 0)
         i = tm->num_layers-1;
      if (tm->layerinfo[i].hidden)
         continue;
      if (tm->data[y][x][i] == STBTE__NO_TILE)
         continue;
      stbte__ui.eyedrop_last_layer = i;
      tm->cur_tile = stbte__find_tile(tm, tm->data[y][x][i]);
      return;
   }
}

static int stbte__should_copy_properties(stbte_tilemap *tm)
{
   int i;
   if (tm->propmode == STBTE__propmode_always)
      return 1;
   if (tm->propmode == STBTE__propmode_never)
      return 0;
   if (tm->solo_layer >= 0 || tm->cur_layer >= 0)
      return 0;
   for (i=0; i < tm->num_layers; ++i)
      if (tm->layerinfo[i].hidden || tm->layerinfo[i].locked)
         return 0;
   return 1;
}

// compute the result of pasting into a tile non-destructively so we can preview it
static void stbte__paste_stack(stbte_tilemap *tm, short result[], short dest[], short src[], int dragging)
{
   int i;

   // special case single-layer
   i = tm->cur_layer;
   if (tm->solo_layer >= 0)
      i = tm->solo_layer;
   if (i >= 0) {
      if (tm->solo_layer < 0) {
         // check that we're allowed to write to it
         if (tm->layerinfo[i].hidden) return;
         if (tm->layerinfo[i].locked == STBTE__locked) return;
         // if protected, dest has to be empty
         if (tm->layerinfo[i].locked == STBTE__protected && dest[i] != STBTE__BG(tm,i)) return;
         // if dragging w/o copy, we will try to erase stuff, which protection disallows
         if (dragging && tm->layerinfo[i].locked == STBTE__protected)
             return;
      }
      result[i] = dest[i];
      if (src[i] != STBTE__BG(tm,i))
         result[i] = src[i];
      return;
   }

   for (i=0; i < tm->num_layers; ++i) {
      result[i] = dest[i];
      if (src[i] != STBTE__NO_TILE)
         if (!tm->layerinfo[i].hidden && tm->layerinfo[i].locked != STBTE__locked)
            if (tm->layerinfo[i].locked == STBTE__unlocked || (!dragging && dest[i] == STBTE__BG(tm,i)))
               result[i] = src[i];
   }
}

// compute the result of dragging away from a tile
static void stbte__clear_stack(stbte_tilemap *tm, short result[])
{
   int i;
   // special case single-layer
   i = tm->cur_layer;
   if (tm->solo_layer >= 0)
      i = tm->solo_layer;
   if (i >= 0)
      result[i] = STBTE__BG(tm,i);
   else
      for (i=0; i < tm->num_layers; ++i)
         if (!tm->layerinfo[i].hidden && tm->layerinfo[i].locked == STBTE__unlocked)
            result[i] = STBTE__BG(tm,i);
}

// check if some map square is active
#define STBTE__IS_MAP_ACTIVE()  ((stbte__ui.active_id & 127) == STBTE__map)
#define STBTE__IS_MAP_HOT()     ((stbte__ui.hot_id & 127) == STBTE__map)

static void stbte__fillrect(stbte_tilemap *tm, int x0, int y0, int x1, int y1, int fill)
{
   int i,j;
   int x=x0,y=y0;

   stbte__begin_undo(tm);
   if (x0 > x1) i=x0,x0=x1,x1=i;
   if (y0 > y1) j=y0,y0=y1,y1=j;
   for (j=y0; j <= y1; ++j)
      for (i=x0; i <= x1; ++i)
         if (fill)
            stbte__brush(tm, i,j);
         else
            stbte__erase(tm, i,j,STBTE__erase_any);
   stbte__end_undo(tm);
   // suppress warning from brush
   stbte__ui.alert_msg = 0;
}

static void stbte__select_rect(stbte_tilemap *tm, int x0, int y0, int x1, int y1)
{
   stbte__ui.has_selection = 1;
   stbte__ui.select_x0 = (x0 < x1 ? x0 : x1);
   stbte__ui.select_x1 = (x0 < x1 ? x1 : x0);
   stbte__ui.select_y0 = (y0 < y1 ? y0 : y1);
   stbte__ui.select_y1 = (y0 < y1 ? y1 : y0);
}

static void stbte__copy_properties(float *dest, float *src)
{
   int i;
   for (i=0; i < STBTE_MAX_PROPERTIES; ++i)
      dest[i] = src[i];
}

static void stbte__copy_cut(stbte_tilemap *tm, int cut)
{
   int i,j,n,w,h,p=0;
   int copy_props = stbte__should_copy_properties(tm);
   if (!stbte__ui.has_selection)
      return;
   w = stbte__ui.select_x1 - stbte__ui.select_x0 + 1;
   h = stbte__ui.select_y1 - stbte__ui.select_y0 + 1;
   if (STBTE_MAX_COPY / w < h) {
      stbte__alert("Selection too large for copy buffer, increase STBTE_MAX_COPY");
      return;
   }

   for (i=0; i < w*h; ++i)
      for (n=0; n < tm->num_layers; ++n)
         stbte__ui.copybuffer[i][n] = STBTE__NO_TILE;

   if (cut)
      stbte__begin_undo(tm);
   for (j=stbte__ui.select_y0; j <= stbte__ui.select_y1; ++j) {
      for (i=stbte__ui.select_x0; i <= stbte__ui.select_x1; ++i) {
         for (n=0; n < tm->num_layers; ++n) {
            if (tm->solo_layer >= 0) {
               if (tm->solo_layer != n)
                  continue;
            } else {
               if (tm->cur_layer >= 0)
                  if (tm->cur_layer != n)
                     continue;
               if (tm->layerinfo[n].hidden)
                  continue;
               if (cut && tm->layerinfo[n].locked)
                  continue;
            }
            stbte__ui.copybuffer[p][n] = tm->data[j][i][n];
            if (cut) {
               stbte__undo_record(tm,i,j,n, tm->data[j][i][n]);
               tm->data[j][i][n] = (n==0 ? tm->background_tile : -1);
            }
         }
         if (copy_props) {
            stbte__copy_properties(stbte__ui.copyprops[p], tm->props[j][i]);
#ifdef STBTE_ALLOW_LINK
            stbte__ui.copylinks[p] = tm->link[j][i];
            if (cut)
               stbte__set_link(tm, i,j,-1,-1, STBTE__undo_record);
#endif
         }
         ++p;
      }
   }
   if (cut)
      stbte__end_undo(tm);
   stbte__ui.copy_width = w;
   stbte__ui.copy_height = h;
   stbte__ui.has_copy = 1;
   //stbte__ui.has_selection = 0;
   stbte__ui.copy_has_props = copy_props;
   stbte__ui.copy_src = tm; // used to give better semantics when copying links
   stbte__ui.copy_src_x = stbte__ui.select_x0;
   stbte__ui.copy_src_y = stbte__ui.select_y0;
}

static int stbte__in_rect(int x, int y, int x0, int y0, int w, int h)
{
   return x >= x0 && x < x0+w && y >= y0 && y < y0+h;
}

static int stbte__in_src_rect(int x, int y)
{
   return stbte__in_rect(x,y, stbte__ui.copy_src_x, stbte__ui.copy_src_y, stbte__ui.copy_width, stbte__ui.copy_height);
}

static int stbte__in_dest_rect(int x, int y, int destx, int desty)
{
   return stbte__in_rect(x,y, destx, desty, stbte__ui.copy_width, stbte__ui.copy_height);
}

static void stbte__paste(stbte_tilemap *tm, int mapx, int mapy)
{
   int w = stbte__ui.copy_width;
   int h = stbte__ui.copy_height;
   int i,j,k,p;
   int x = mapx - (w>>1);
   int y = mapy - (h>>1);
   int copy_props = stbte__should_copy_properties(tm) && stbte__ui.copy_has_props;
   if (stbte__ui.has_copy == 0)
      return;
   stbte__begin_undo(tm);
   p = 0;
   for (j=0; j < h; ++j) {
      for (i=0; i < w; ++i) {
         if (y+j >= 0 && y+j < tm->max_y && x+i >= 0 && x+i < tm->max_x) {
            // compute the new stack
            short tilestack[STBTE_MAX_LAYERS];
            for (k=0; k < tm->num_layers; ++k)
               tilestack[k] = tm->data[y+j][x+i][k];
            stbte__paste_stack(tm, tilestack, tilestack, stbte__ui.copybuffer[p], 0);
            // update anything that changed
            for (k=0; k < tm->num_layers; ++k) {
               if (tilestack[k] != tm->data[y+j][x+i][k]) {
                  stbte__undo_record(tm, x+i,y+j,k, tm->data[y+j][x+i][k]);
                  tm->data[y+j][x+i][k] = tilestack[k];
               }
            }
         }
         if (copy_props) {
#ifdef STBTE_ALLOW_LINK
            // need to decide how to paste a link, so there's a few cases
            int destx = -1, desty = -1;
            stbte__link *link = &stbte__ui.copylinks[p];

            // check if link is within-rect
            if (stbte__in_src_rect(link->x, link->y)) {
               // new link should point to copy (but only if copy is within map)
               destx = x + (link->x - stbte__ui.copy_src_x);
               desty = y + (link->y - stbte__ui.copy_src_y);
            } else if (tm == stbte__ui.copy_src) {
               // if same map, then preserve link unless target is overwritten
               if (!stbte__in_dest_rect(link->x,link->y,x,y)) {
                  destx = link->x;
                  desty = link->y;
               }
            }
            // this is necessary for offset-copy, but also in case max_x/max_y has changed
            if (destx < 0 || destx >= tm->max_x || desty < 0 || desty >= tm->max_y)
               destx = -1, desty = -1;
            stbte__set_link(tm, x+i, y+j, destx, desty, STBTE__undo_record);
#endif
            for (k=0; k < STBTE_MAX_PROPERTIES; ++k) {
               if (tm->props[y+j][x+i][k] != stbte__ui.copyprops[p][k])
                  stbte__undo_record_prop_float(tm, x+i, y+j, k, tm->props[y+j][x+i][k]);
            }
            stbte__copy_properties(tm->props[y+j][x+i], stbte__ui.copyprops[p]);
         }
         ++p;
      }
   }
   stbte__end_undo(tm);
}

static void stbte__drag_update(stbte_tilemap *tm, int mapx, int mapy, int copy_props)
{
   int w = stbte__ui.drag_w, h = stbte__ui.drag_h;
   int ox,oy,i,deleted=0,written=0;
   short temp[STBTE_MAX_LAYERS];
   short *data = NULL;
   if (!stbte__ui.shift) {
      ox = mapx - stbte__ui.drag_x;
      oy = mapy - stbte__ui.drag_y;
      if (ox >= 0 && ox < w && oy >= 0 && oy < h) {
         deleted=1;
         for (i=0; i < tm->num_layers; ++i)
            temp[i] = tm->data[mapy][mapx][i];
         data = temp;
         stbte__clear_stack(tm, data);
      }
   }
   ox = mapx - stbte__ui.drag_dest_x;
   oy = mapy - stbte__ui.drag_dest_y;
   // if this map square is in the target drag region
   if (ox >= 0 && ox < w && oy >= 0 && oy < h) {
      // and the src map square is on the map
      if (stbte__in_rect(stbte__ui.drag_x+ox, stbte__ui.drag_y+oy, 0, 0, tm->max_x, tm->max_y)) {
         written = 1;
         if (data == NULL) {
            for (i=0; i < tm->num_layers; ++i)
               temp[i] = tm->data[mapy][mapx][i];
            data = temp;
         }
         stbte__paste_stack(tm, data, data, tm->data[stbte__ui.drag_y+oy][stbte__ui.drag_x+ox], !stbte__ui.shift);
         if (copy_props) {
            for (i=0; i < STBTE_MAX_PROPERTIES; ++i) {
               if (tm->props[mapy][mapx][i] != tm->props[stbte__ui.drag_y+oy][stbte__ui.drag_x+ox][i]) {
                  stbte__undo_record_prop_float(tm, mapx, mapy, i, tm->props[mapy][mapx][i]);
                  tm->props[mapy][mapx][i] = tm->props[stbte__ui.drag_y+oy][stbte__ui.drag_x+ox][i];
               }
            }
         }
      }
   }
   if (data) {
      for (i=0; i < tm->num_layers; ++i) {
         if (tm->data[mapy][mapx][i] != data[i]) {
            stbte__undo_record(tm, mapx, mapy, i, tm->data[mapy][mapx][i]);
            tm->data[mapy][mapx][i] = data[i];
         }
      }
   }
   #ifdef STBTE_ALLOW_LINK
   if (copy_props) {
      int overwritten=0, moved=0, copied=0;
      // since this function is called on EVERY tile, we can fix up even tiles not
      // involved in the move

      stbte__link *k;
      // first, determine what src link ends up here
      k = &tm->link[mapy][mapx]; // by default, it's the one currently here
      if (deleted)               // if dragged away, it's erased
         k = NULL;
      if (written)               // if dragged into, it gets that link
         k = &tm->link[stbte__ui.drag_y+oy][stbte__ui.drag_x+ox];

      // now check whether the *target* gets moved or overwritten
      if (k && k->x >= 0) {
         overwritten = stbte__in_rect(k->x, k->y, stbte__ui.drag_dest_x, stbte__ui.drag_dest_y, w, h);
         if (!stbte__ui.shift)
            moved    = stbte__in_rect(k->x, k->y, stbte__ui.drag_x     , stbte__ui.drag_y     , w, h);
         else
            copied   = stbte__in_rect(k->x, k->y, stbte__ui.drag_x     , stbte__ui.drag_y     , w, h);
      }

      if (deleted || written || overwritten || moved || copied) {
         // choose the final link value based on the above
         if (k == NULL || k->x < 0)
            stbte__set_link(tm, mapx, mapy, -1, -1, STBTE__undo_record);
         else if (moved || (copied && written)) {
            // if we move the target, we update to point to the new target;
            // or, if we copy the target and the source is part ofthe copy, then update to new target
            int x = k->x + (stbte__ui.drag_dest_x - stbte__ui.drag_x);
            int y = k->y + (stbte__ui.drag_dest_y - stbte__ui.drag_y);
            if (!(x >= 0 && y >= 0 && x < tm->max_x && y < tm->max_y))
               x = -1, y = -1;
            stbte__set_link(tm, mapx, mapy, x, y, STBTE__undo_record);
         } else if (overwritten) {
            stbte__set_link(tm, mapx, mapy, -1, -1, STBTE__undo_record);
         } else
            stbte__set_link(tm, mapx, mapy, k->x, k->y, STBTE__undo_record);
      }
   }
   #endif
}

static void stbte__drag_place(stbte_tilemap *tm, int mapx, int mapy)
{
   int i,j;
   int copy_props = stbte__should_copy_properties(tm);
   int move_x = (stbte__ui.drag_dest_x - stbte__ui.drag_x);
   int move_y = (stbte__ui.drag_dest_y - stbte__ui.drag_y);
   if (move_x == 0 && move_y == 0)
      return;

   stbte__begin_undo(tm);
   // we now need a 2D memmove-style mover that doesn't
   // overwrite any data as it goes. this requires being
   // direction sensitive in the same way as memmove
   if (move_y > 0 || (move_y == 0 && move_x > 0)) {
      for (j=tm->max_y-1; j >= 0; --j)
         for (i=tm->max_x-1; i >= 0; --i)
            stbte__drag_update(tm,i,j,copy_props);
   } else {
      for (j=0; j < tm->max_y; ++j)
         for (i=0; i < tm->max_x; ++i)
            stbte__drag_update(tm,i,j,copy_props);
   }
   stbte__end_undo(tm);

   stbte__ui.has_selection = 1;
   stbte__ui.select_x0 = stbte__ui.drag_dest_x;
   stbte__ui.select_y0 = stbte__ui.drag_dest_y;
   stbte__ui.select_x1 = stbte__ui.select_x0 + stbte__ui.drag_w - 1;
   stbte__ui.select_y1 = stbte__ui.select_y0 + stbte__ui.drag_h - 1;
}

static void stbte__tile_paint(stbte_tilemap *tm, int sx, int sy, int mapx, int mapy, int layer)
{
   int i;
   int id = STBTE__IDMAP(mapx,mapy);
   int x0=sx, y0=sy;
   int x1=sx+tm->spacing_x, y1=sy+tm->spacing_y;
   int over = stbte__hittest(x0,y0,x1,y1, id);
   short *data = tm->data[mapy][mapx];
   short temp[STBTE_MAX_LAYERS];

   if (STBTE__IS_MAP_HOT()) {
      if (stbte__ui.pasting) {
         int ox = mapx - stbte__ui.paste_x;
         int oy = mapy - stbte__ui.paste_y;
         if (ox >= 0 && ox < stbte__ui.copy_width && oy >= 0 && oy < stbte__ui.copy_height) {
            stbte__paste_stack(tm, temp, tm->data[mapy][mapx], stbte__ui.copybuffer[oy*stbte__ui.copy_width+ox], 0);
            data = temp;
         }
      } else if (stbte__ui.dragging) {
         int ox,oy;
         for (i=0; i < tm->num_layers; ++i)
            temp[i] = tm->data[mapy][mapx][i];
         data = temp;

         // if it's in the source area, remove things unless shift-dragging
         ox = mapx - stbte__ui.drag_x;
         oy = mapy - stbte__ui.drag_y;
         if (!stbte__ui.shift && ox >= 0 && ox < stbte__ui.drag_w && oy >= 0 && oy < stbte__ui.drag_h) {
            stbte__clear_stack(tm, temp);
         }

         ox = mapx - stbte__ui.drag_dest_x;
         oy = mapy - stbte__ui.drag_dest_y;
         if (ox >= 0 && ox < stbte__ui.drag_w && oy >= 0 && oy < stbte__ui.drag_h) {
            stbte__paste_stack(tm, temp, temp, tm->data[stbte__ui.drag_y+oy][stbte__ui.drag_x+ox], !stbte__ui.shift);
         }
      } else if (STBTE__IS_MAP_ACTIVE()) {
         if (stbte__ui.tool == STBTE__tool_rect) {
            if ((stbte__ui.ms_time & 511) < 380) {
               int ex = ((stbte__ui.hot_id >> 19) & 4095);
               int ey = ((stbte__ui.hot_id >>  7) & 4095);
               int sx = stbte__ui.sx;
               int sy = stbte__ui.sy;

               if (   ((mapx >= sx && mapx < ex+1) || (mapx >= ex && mapx < sx+1))
                   && ((mapy >= sy && mapy < ey+1) || (mapy >= ey && mapy < sy+1))) {
                  int i;
                  for (i=0; i < tm->num_layers; ++i)
                     temp[i] = tm->data[mapy][mapx][i];
                  data = temp;
                  if (stbte__ui.active_event == STBTE__leftdown)
                     stbte__brush_predict(tm, temp);
                  else
                     stbte__erase_predict(tm, temp, STBTE__erase_any);
               }
            }
         }
      }
   }

   if (STBTE__IS_HOT(id) && STBTE__INACTIVE() && !stbte__ui.pasting) {
      if (stbte__ui.tool == STBTE__tool_brush) {
         if ((stbte__ui.ms_time & 511) < 300) {
            data = temp;
            for (i=0; i < tm->num_layers; ++i)
               temp[i] = tm->data[mapy][mapx][i];
            stbte__brush_predict(tm, temp);
         }
      }
   }

   {
      i = layer;
      if (i == tm->solo_layer || (!tm->layerinfo[i].hidden && tm->solo_layer < 0))
         if (data[i] >= 0)
            STBTE_DRAW_TILE(x0,y0, (unsigned short) data[i], 0, tm->props[mapy][mapx]);
   }
}

static void stbte__tile(stbte_tilemap *tm, int sx, int sy, int mapx, int mapy)
{
   int tool = stbte__ui.tool;
   int x0=sx, y0=sy;
   int x1=sx+tm->spacing_x, y1=sy+tm->spacing_y;
   int id = STBTE__IDMAP(mapx,mapy);
   int over = stbte__hittest(x0,y0,x1,y1, id);
   switch (stbte__ui.event) {
      case STBTE__paint: {
         if (stbte__ui.pasting || stbte__ui.dragging || stbte__ui.scrolling)
            break;
         if (stbte__ui.scrollkey && !STBTE__IS_MAP_ACTIVE())
            break;
         if (STBTE__IS_HOT(id) && STBTE__IS_MAP_ACTIVE() && (tool == STBTE__tool_rect || tool == STBTE__tool_select)) {
            int rx0,ry0,rx1,ry1,t;
            // compute the center of each rect
            rx0 = x0 + tm->spacing_x/2;
            ry0 = y0 + tm->spacing_y/2;
            rx1 = rx0 + (stbte__ui.sx - mapx) * tm->spacing_x;
            ry1 = ry0 + (stbte__ui.sy - mapy) * tm->spacing_y;
            if (rx0 > rx1) t=rx0,rx0=rx1,rx1=t;
            if (ry0 > ry1) t=ry0,ry0=ry1,ry1=t;
            rx0 -= tm->spacing_x/2;
            ry0 -= tm->spacing_y/2;
            rx1 += tm->spacing_x/2;
            ry1 += tm->spacing_y/2;
            stbte__draw_frame(rx0-1,ry0-1,rx1+1,ry1+1, STBTE_COLOR_TILEMAP_HIGHLIGHT);
            break;
         }
         if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
            stbte__draw_frame(x0-1,y0-1,x1+1,y1+1, STBTE_COLOR_TILEMAP_HIGHLIGHT);
         }
#ifdef STBTE_ALLOW_LINK
         if (stbte__ui.show_links && tm->link[mapy][mapx].x >= 0) {
            int tx = tm->link[mapy][mapx].x;
            int ty = tm->link[mapy][mapx].y;
            int lx0,ly0,lx1,ly1;
            if (STBTE_ALLOW_LINK(tm->data[mapy][mapx], tm->props[mapy][mapx],
                                 tm->data[ty  ][tx  ], tm->props[ty  ][tx  ]))
            {
               lx0 =  x0 + (tm->spacing_x >> 1) - 1;
               ly0 =  y0 + (tm->spacing_y >> 1) - 1;
               lx1 = lx0 + (tx - mapx) * tm->spacing_x + 2;
               ly1 = ly0 + (ty - mapy) * tm->spacing_y + 2;
               stbte__draw_link(lx0,ly0,lx1,ly1,
                   STBTE_LINK_COLOR(tm->data[mapy][mapx], tm->props[mapy][mapx],
                                    tm->data[ty  ][tx  ], tm->props[ty  ][tx]));
            }
         }
#endif
         break;
      }
   }

   if (stbte__ui.pasting) {
      switch (stbte__ui.event) {
         case STBTE__leftdown:
            if (STBTE__IS_HOT(id)) {
               stbte__ui.pasting = 0;
               stbte__paste(tm, mapx, mapy);
               stbte__activate(0);
            }
            break;
         case STBTE__leftup:
            // just clear it no matter what, since they might click away to clear it
            stbte__activate(0);
            break;
         case STBTE__rightdown:
            if (STBTE__IS_HOT(id)) {
               stbte__activate(0);
               stbte__ui.pasting = 0;
            }
            break;
      }
      return;
   }

   if (stbte__ui.scrolling) {
      if (stbte__ui.event == STBTE__leftup) {
         stbte__activate(0);
         stbte__ui.scrolling = 0;
      }
      if (stbte__ui.event == STBTE__mousemove) {
         tm->scroll_x += (stbte__ui.start_x - stbte__ui.mx);
         tm->scroll_y += (stbte__ui.start_y - stbte__ui.my);
         stbte__ui.start_x = stbte__ui.mx;
         stbte__ui.start_y = stbte__ui.my;
      }
      return;
   }

   // regardless of tool, leftdown is a scrolldrag
   if (STBTE__IS_HOT(id) && stbte__ui.scrollkey && stbte__ui.event == STBTE__leftdown) {
      stbte__ui.scrolling = 1;
      stbte__ui.start_x = stbte__ui.mx;
      stbte__ui.start_y = stbte__ui.my;
      return;
   }

   switch (tool) {
      case STBTE__tool_brush:
         switch (stbte__ui.event) {
            case STBTE__mousemove:
               if (STBTE__IS_MAP_ACTIVE() && over) {
                  // don't brush/erase same tile multiple times unless they move away and back @TODO should just be only once, but that needs another data structure
                  if (!STBTE__IS_ACTIVE(id)) {
                     if (stbte__ui.active_event == STBTE__leftdown)
                        stbte__brush(tm, mapx, mapy);
                     else
                        stbte__erase(tm, mapx, mapy, stbte__ui.brush_state);
                     stbte__ui.active_id = id; // switch to this map square so we don't rebrush IT multiple times
                  }
               }
               break;
            case STBTE__leftdown:
               if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
                  stbte__activate(id);
                  stbte__begin_undo(tm);
                  stbte__brush(tm, mapx, mapy);
               }
               break;
            case STBTE__rightdown:
               if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
                  stbte__activate(id);
                  stbte__begin_undo(tm);
                  if (stbte__erase(tm, mapx, mapy, STBTE__erase_any) == STBTE__erase_brushonly)
                     stbte__ui.brush_state = STBTE__erase_brushonly;
                  else
                     stbte__ui.brush_state = STBTE__erase_any;
               }
               break;
            case STBTE__leftup:
            case STBTE__rightup:
               if (STBTE__IS_MAP_ACTIVE()) {
                  stbte__end_undo(tm);
                  stbte__activate(0);
               }
               break;
         }
         break;

#ifdef STBTE_ALLOW_LINK
      case STBTE__tool_link:
         switch (stbte__ui.event) {
            case STBTE__leftdown:
               if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
                  stbte__activate(id);
                  stbte__ui.linking = 1;
                  stbte__ui.sx = mapx;
                  stbte__ui.sy = mapy;
                  // @TODO: undo
               }
               break;
            case STBTE__leftup:
               if (STBTE__IS_HOT(id) && STBTE__IS_MAP_ACTIVE()) {
                  if ((mapx != stbte__ui.sx || mapy != stbte__ui.sy) &&
                         STBTE_ALLOW_LINK(tm->data[stbte__ui.sy][stbte__ui.sx], tm->props[stbte__ui.sy][stbte__ui.sx],
                                          tm->data[mapy][mapx], tm->props[mapy][mapx]))
                     stbte__set_link(tm, stbte__ui.sx, stbte__ui.sy, mapx, mapy, STBTE__undo_block);
                  else
                     stbte__set_link(tm, stbte__ui.sx, stbte__ui.sy, -1,-1, STBTE__undo_block);
                  stbte__ui.linking = 0;
                  stbte__activate(0);
               }
               break;

            case STBTE__rightdown:
               if (STBTE__IS_ACTIVE(id)) {
                  stbte__activate(0);
                  stbte__ui.linking = 0;
               }
               break;
         }
         break;
#endif

      case STBTE__tool_erase:
         switch (stbte__ui.event) {
            case STBTE__mousemove:
               if (STBTE__IS_MAP_ACTIVE() && over)
                  stbte__erase(tm, mapx, mapy, STBTE__erase_all);
               break;
            case STBTE__leftdown:
               if (STBTE__IS_HOT(id) && STBTE__INACTIVE()) {
                  stbte__activate(id);
                  stbte__begin_undo(tm);
                  stbte__erase(tm, mapx, mapy, STBTE__erase_all);
               }
               break;
            case STBTE__leftup:
               if (STBTE__IS_MAP_ACTIVE()) {
                  stbte__end_undo(tm);
                  stbte__activate(0);
               }
               break;
         }
         break;

      case STBTE__tool_select:
         if (STBTE__IS_HOT(id)) {
            switch (stbte__ui.event) {
               case STBTE__leftdown:
                  if (STBTE__INACTIVE()) {
                     // if we're clicking in an existing selection...
                     if (stbte__ui.has_selection) {
                        if (  mapx >= stbte__ui.select_x0 && mapx <= stbte__ui.select_x1
                           && mapy >= stbte__ui.select_y0 && mapy <= stbte__ui.select_y1)
                        {
                           stbte__ui.dragging = 1;
                           stbte__ui.drag_x = stbte__ui.select_x0;
                           stbte__ui.drag_y = stbte__ui.select_y0;
                           stbte__ui.drag_w = stbte__ui.select_x1 - stbte__ui.select_x0 + 1;
                           stbte__ui.drag_h = stbte__ui.select_y1 - stbte__ui.select_y0 + 1;
                           stbte__ui.drag_offx = mapx - stbte__ui.select_x0;
                           stbte__ui.drag_offy = mapy - stbte__ui.select_y0;
                        }
                     }
                     stbte__ui.has_selection = 0; // no selection until it completes
                     stbte__activate_map(mapx,mapy);
                  }
                  break;
               case STBTE__leftup:
                  if (STBTE__IS_MAP_ACTIVE()) {
                     if (stbte__ui.dragging) {
                        stbte__drag_place(tm, mapx,mapy);
                        stbte__ui.dragging = 0;
                        stbte__activate(0);
                     } else {
                        stbte__select_rect(tm, stbte__ui.sx, stbte__ui.sy, mapx, mapy);
                        stbte__activate(0);
                     }
                  }
                  break;
               case STBTE__rightdown:
                  stbte__ui.has_selection = 0;
                  break;
            }
         }
         break;

      case STBTE__tool_rect:
         if (STBTE__IS_HOT(id)) {
            switch (stbte__ui.event) {
               case STBTE__leftdown:
                  if (STBTE__INACTIVE())
                     stbte__activate_map(mapx,mapy);
                  break;
               case STBTE__leftup:
                  if (STBTE__IS_MAP_ACTIVE()) {
                     stbte__fillrect(tm, stbte__ui.sx, stbte__ui.sy, mapx, mapy, 1);
                     stbte__activate(0);
                  }
                  break;
               case STBTE__rightdown:
                  if (STBTE__INACTIVE())
                     stbte__activate_map(mapx,mapy);
                  break;
               case STBTE__rightup:
                  if (STBTE__IS_MAP_ACTIVE()) {
                     stbte__fillrect(tm, stbte__ui.sx, stbte__ui.sy, mapx, mapy, 0);
                     stbte__activate(0);
                  }
                  break;
            }
         }
         break;


      case STBTE__tool_eyedrop:
         switch (stbte__ui.event) {
            case STBTE__leftdown:
               if (STBTE__IS_HOT(id) && STBTE__INACTIVE())
                  stbte__eyedrop(tm,mapx,mapy);
               break;
         }
         break;
   }
}

static void stbte__start_paste(stbte_tilemap *tm)
{
   if (stbte__ui.has_copy) {
      stbte__ui.pasting = 1;
      stbte__activate(STBTE__ID(STBTE__toolbarB,3));
   }
}

static void stbte__toolbar(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   int i;
   int estimated_width = 13 * STBTE__num_tool + 8+8+ 120+4 - 30;
   int x = x0 + w/2 - estimated_width/2;
   int y = y0+1;

   for (i=0; i < STBTE__num_tool; ++i) {
      int highlight=0, disable=0;
      highlight = (stbte__ui.tool == i);
      if (i == STBTE__tool_undo || i == STBTE__tool_showgrid)
          x += 8;
      if (i == STBTE__tool_showgrid && stbte__ui.show_grid)
         highlight = 1;
      if (i == STBTE__tool_showlinks && stbte__ui.show_links)
         highlight = 1;
      if (i == STBTE__tool_fill)
         continue;
      #ifndef STBTE_ALLOW_LINK
      if (i == STBTE__tool_link || i == STBTE__tool_showlinks)
         disable = 1;
      #endif
      if (i == STBTE__tool_undo && !stbte__undo_available(tm))
         disable = 1;
      if (i == STBTE__tool_redo && !stbte__redo_available(tm))
         disable = 1;
      if (stbte__button_icon(STBTE__ctoolbar_button, toolchar[i], x, y, 13, STBTE__ID(STBTE__toolbarA, i), highlight, disable)) {
         switch (i) {
            case STBTE__tool_eyedrop:
               stbte__ui.eyedrop_last_layer = tm->num_layers; // flush eyedropper state
               // fallthrough
            default:
               stbte__ui.tool = i;
               stbte__ui.has_selection = 0;
               break;
            case STBTE__tool_showlinks:
               stbte__ui.show_links = !stbte__ui.show_links;
               break;
            case STBTE__tool_showgrid:
               stbte__ui.show_grid = (stbte__ui.show_grid+1)%3;
               break;
            case STBTE__tool_undo:
               stbte__undo(tm);
               break;
            case STBTE__tool_redo:
               stbte__redo(tm);
               break;
         }
      }
      x += 13;
   }

   x += 8;
   if (stbte__button(STBTE__ctoolbar_button, "cut"  , x, y,10, 40, STBTE__ID(STBTE__toolbarB,0), 0, !stbte__ui.has_selection))
      stbte__copy_cut(tm, 1);
   x += 42;
   if (stbte__button(STBTE__ctoolbar_button, "copy" , x, y, 5, 40, STBTE__ID(STBTE__toolbarB,1), 0, !stbte__ui.has_selection))
      stbte__copy_cut(tm, 0);
   x += 42;
   if (stbte__button(STBTE__ctoolbar_button, "paste", x, y, 0, 40, STBTE__ID(STBTE__toolbarB,2), stbte__ui.pasting, !stbte__ui.has_copy))
      stbte__start_paste(tm);
}

#define STBTE__TEXTCOLOR(n)  stbte__color_table[n][STBTE__text][STBTE__idle]

static int stbte__info_value(const char *label, int x, int y, int val, int digits, int id)
{
   if (stbte__ui.event == STBTE__paint) {
      int off = 9-stbte__get_char_width(label[0]);
      char text[16];
      sprintf(text, label, digits, val);
      stbte__draw_text_core(x+off,y, text, 999, STBTE__TEXTCOLOR(STBTE__cpanel),1);
   }
   if (id) {
      x += 9+7*digits+4;
      if (stbte__minibutton(STBTE__cmapsize, x,y, '+', STBTE__ID2(id,1,0)))
         val += (stbte__ui.shift ? 10 : 1);
      x += 9;
      if (stbte__minibutton(STBTE__cmapsize, x,y, '-', STBTE__ID2(id,2,0)))
         val -= (stbte__ui.shift ? 10 : 1);
      if (val < 1) val = 1; else if (val > 4096) val = 4096;
   }
   return val;
}

static void stbte__info(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   int mode = stbte__ui.panel[STBTE__panel_info].mode;
   int s = 11+7*tm->digits+4+15;
   int x,y;
   int in_region;

   x = x0+2;
   y = y0+2;
   tm->max_x = stbte__info_value("w:%*d",x,y, tm->max_x, tm->digits, STBTE__ID(STBTE__info,0));
   if (mode)
      x += s;
   else
      y += 11;
   tm->max_y = stbte__info_value("h:%*d",x,y, tm->max_y, tm->digits, STBTE__ID(STBTE__info,1));
   x = x0+2;
   y += 11;
   in_region = (stbte__ui.hot_id & 127) == STBTE__map;
   stbte__info_value(in_region ? "x:%*d" : "x:",x,y, (stbte__ui.hot_id>>19)&4095, tm->digits, 0);
   if (mode)
      x += s;
   else
      y += 11;
   stbte__info_value(in_region ? "y:%*d" : "y:",x,y, (stbte__ui.hot_id>> 7)&4095, tm->digits, 0);
   y += 15;
   x = x0+2;
   stbte__draw_text(x,y,"brush:",40,STBTE__TEXTCOLOR(STBTE__cpanel));
   if (tm->cur_tile >= 0)
      STBTE_DRAW_TILE(x+43,y-3,tm->tiles[tm->cur_tile].id,1,0);
}

static void stbte__layers(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   static char *propmodes[3] = {
      "default", "always", "never"
   };
   int num_rows;
   int i, y, n;
   int x1 = x0+w;
   int y1 = y0+h;
   int xoff = 20;
   
   if (tm->has_layer_names) {
      int side = stbte__ui.panel[STBTE__panel_layers].side;
      xoff = stbte__region[side].width - 42;
      xoff = (xoff < tm->layername_width + 10 ? xoff : tm->layername_width + 10);
   }

   x0 += 2;
   y0 += 5;
   if (!tm->has_layer_names) {
      if (stbte__ui.event == STBTE__paint) {
         stbte__draw_text(x0,y0, "Layers", w-4, STBTE__TEXTCOLOR(STBTE__cpanel));
      }
      y0 += 11;
   }
   num_rows = (y1-y0)/15;
#ifndef STBTE_NO_PROPS
   --num_rows;
#endif
   y = y0;
   for (i=0; i < tm->num_layers; ++i) {
      char text[3], *str = (char *) tm->layerinfo[i].name;
      static char lockedchar[3] = { 'U', 'P', 'L' };
      int locked = tm->layerinfo[i].locked;
      int disabled = (tm->solo_layer >= 0 && tm->solo_layer != i);
      if (i-tm->layer_scroll >= 0 && i-tm->layer_scroll < num_rows) {
         if (str == NULL)
            sprintf(str=text, "%2d", i+1);
         if (stbte__button(STBTE__clayer_button, str, x0,y,(i+1<10)*2,xoff-2, STBTE__ID(STBTE__layer,i), tm->cur_layer==i,0))
            tm->cur_layer = (tm->cur_layer == i ? -1 : i);
         if (stbte__layerbutton(x0+xoff +  0,y+1,'H',STBTE__ID(STBTE__hide,i), tm->layerinfo[i].hidden,disabled,STBTE__clayer_hide))
            tm->layerinfo[i].hidden = !tm->layerinfo[i].hidden;
         if (stbte__layerbutton(x0+xoff + 12,y+1,lockedchar[locked],STBTE__ID(STBTE__lock,i), locked!=0,disabled,STBTE__clayer_lock))
            tm->layerinfo[i].locked = (locked+1)%3;
         if (stbte__layerbutton(x0+xoff + 24,y+1,'S',STBTE__ID(STBTE__solo,i), tm->solo_layer==i,0,STBTE__clayer_solo))
            tm->solo_layer = (tm->solo_layer == i ? -1 : i);
         y += 15;
      }
   }
   stbte__scrollbar(x1-4, y0,y-2, &tm->layer_scroll, 0, tm->num_layers, num_rows, STBTE__ID(STBTE__scrollbar_id, STBTE__layer));
#ifndef STBTE_NO_PROPS
   n = stbte__text_width("prop:")+2;
   stbte__draw_text(x0,y+2, "prop:", w, STBTE__TEXTCOLOR(STBTE__cpanel));
   i = w - n - 4;
   if (i > 50) i = 50;
   if (stbte__button(STBTE__clayer_button, propmodes[tm->propmode], x0+n,y,0,i, STBTE__ID(STBTE__layer,256), 0,0))
      tm->propmode = (tm->propmode+1)%3;
#endif
}

static void stbte__categories(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   int s=11, x,y, i;
   int num_rows = h / s;

   w -= 4;
   x = x0+2;
   y = y0+4;
   if (tm->category_scroll == 0) {
      if (stbte__category_button("*ALL*", x,y, w, STBTE__ID(STBTE__categories, 65535), tm->cur_category == -1)) {
         stbte__choose_category(tm, -1);
      }
      y += s;
   }

   for (i=0; i < tm->num_categories; ++i) {
      if (i+1 - tm->category_scroll >= 0 && i+1 - tm->category_scroll < num_rows) {
         if (y + 10 > y0+h)
            return;
         if (stbte__category_button(tm->categories[i], x,y,w, STBTE__ID(STBTE__categories,i), tm->cur_category == i))
            stbte__choose_category(tm, i);
         y += s;
      }
   }
   stbte__scrollbar(x0+w, y0+4, y0+h-4, &tm->category_scroll, 0, tm->num_categories+1, num_rows, STBTE__ID(STBTE__scrollbar_id, STBTE__categories));
}

static void stbte__tile_in_palette(stbte_tilemap *tm, int x, int y, int slot)
{
   stbte__tileinfo *t = &tm->tiles[slot];
   int x0=x, y0=y, x1 = x+tm->palette_spacing_x - 1, y1 = y+tm->palette_spacing_y;
   int id = STBTE__ID(STBTE__palette, slot);
   int over = stbte__hittest(x0,y0,x1,y1, id);
   switch (stbte__ui.event) {
      case STBTE__paint:
         stbte__draw_rect(x,y,x+tm->palette_spacing_x-1,y+tm->palette_spacing_x-1, STBTE_COLOR_TILEPALETTE_BACKGROUND);
         STBTE_DRAW_TILE(x,y,t->id, slot == tm->cur_tile,0);
         if (slot == tm->cur_tile)
            stbte__draw_frame_delayed(x-1,y-1,x+tm->palette_spacing_x,y+tm->palette_spacing_y, STBTE_COLOR_TILEPALETTE_OUTLINE);
         break;
      default:
         if (stbte__button_core(id))
            tm->cur_tile = slot;
         break;
   }
}

static void stbte__palette_of_tiles(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   int i,x,y;
   int num_vis_rows = (h-6) / tm->palette_spacing_y;
   int num_columns = (w-2-6) / tm->palette_spacing_x;
   int num_total_rows;
   int column,row;
   int x1 = x0+w, y1=y0+h;
   x = x0+2;
   y = y0+6;

   if (num_columns == 0)
      return;

   num_total_rows = (tm->cur_palette_count + num_columns-1) / num_columns; // ceil()

   column = 0;
   row    = -tm->palette_scroll;   
   for (i=0; i < tm->num_tiles; ++i) {
      stbte__tileinfo *t = &tm->tiles[i];

      // filter based on category
      if (tm->cur_category >= 0 && t->category_id != tm->cur_category)
         continue;

      // display it
      if (row >= 0 && row < num_vis_rows) {
         x = x0 + 2 + tm->palette_spacing_x * column;
         y = y0 + 6 + tm->palette_spacing_y * row;
         stbte__tile_in_palette(tm,x,y,i);
      }

      ++column;
      if (column == num_columns) {
         column = 0;
         ++row;
      }
   }
   stbte__flush_delay();
   stbte__scrollbar(x1-4, y0+6, y1-2, &tm->palette_scroll, 0, num_total_rows, num_vis_rows, STBTE__ID(STBTE__scrollbar_id, STBTE__palette));
}

static float stbte__linear_remap(float n, float x0, float x1, float y0, float y1)
{
   return (n-x0)/(x1-x0)*(y1-y0) + y0;
}

static float stbte__saved;
static void stbte__props_panel(stbte_tilemap *tm, int x0, int y0, int w, int h)
{
   int x1 = x0+w, y1 = y0+h;
   int i;
   int y = y0 + 5, x = x0+2;
   int slider_width = 60;
   int mx,my;
   float *p;
   short *data;
   if (!stbte__is_single_selection())
      return;
   mx = stbte__ui.select_x0;
   my = stbte__ui.select_y0;
   p = tm->props[my][mx];
   data = tm->data[my][mx];
   for (i=0; i < STBTE_MAX_PROPERTIES; ++i) {
      unsigned int n = STBTE_PROP_TYPE(i, data, p);
      if (n) {
         char *s = STBTE_PROP_NAME(i, data, p);
         if (s == NULL) s = "";
         switch (n & 3) {
            case STBTE_PROP_bool: {
               int flag = (int) p[i];
               if (stbte__layerbutton(x,y, flag ? 'x' : ' ', STBTE__ID(STBTE__prop_flag,i), flag, 0, 2)) {
                  stbte__begin_undo(tm);
                  stbte__undo_record_prop_float(tm,mx,my,i,(float) flag);
                  p[i] = (float) !flag;
                  stbte__end_undo(tm);
               }
               stbte__draw_text(x+13,y+1,s,x1-(x+13)-2,STBTE__TEXTCOLOR(STBTE__cpanel));
               y += 13;
               break;
            }
            case STBTE_PROP_int: {
               int a = (int) STBTE_PROP_MIN(i,data,p);
               int b = (int) STBTE_PROP_MAX(i,data,p);
               int v = (int) p[i] - a;
               if (a+v != p[i] || v < 0 || v > b-a) {
                  if (v < 0) v = 0;
                  if (v > b-a) v = b-a;
                  p[i] = (float) (a+v); // @TODO undo
               }
               switch (stbte__slider(x, slider_width, y+7, b-a, &v, STBTE__ID(STBTE__prop_int,i)))
               {
                  case STBTE__begin:
                     stbte__saved = p[i];
                     // fallthrough
                  case STBTE__change:
                     p[i] = (float) (a+v); // @TODO undo
                     break;
                  case STBTE__end:
                     if (p[i] != stbte__saved) {
                        stbte__begin_undo(tm);
                        stbte__undo_record_prop_float(tm,mx,my,i,stbte__saved);
                        stbte__end_undo(tm);
                     }
                     break;
               }
               stbte__draw_text(x+slider_width+2,y+2, s, x1-1-(x+slider_width+2), STBTE__TEXTCOLOR(STBTE__cpanel));
               y += 12;
               break;
            }
            case STBTE_PROP_float: {
               float a = (float) STBTE_PROP_MIN(i, data,p);
               float b = (float) STBTE_PROP_MAX(i, data,p);
               float c = STBTE_PROP_FLOAT_SCALE(i, data, p);
               float old;
               if (p[i] < a || p[i] > b) {
                  // @TODO undo
                  if (p[i] < a) p[i] = a;
                  if (p[i] > b) p[i] = b;
               }
               old = p[i];
               switch (stbte__float_control(x, y, 50, a, b, c, "%8.4f", &p[i], STBTE__layer,STBTE__ID(STBTE__prop_float,i))) {
                  case STBTE__begin:
                     stbte__saved = old;
                     break;
                  case STBTE__end:
                     if (stbte__saved != p[i]) {
                        stbte__begin_undo(tm);
                        stbte__undo_record_prop_float(tm,mx,my,i, stbte__saved);
                        stbte__end_undo(tm);
                     }
                     break;
               }
               stbte__draw_text(x+53,y+1, s, x1-1-(x+53), STBTE__TEXTCOLOR(STBTE__cpanel));
               y += 12;
               break;
            }
         }
      }
   }
}

static int stbte__cp_mode, stbte__cp_aspect, stbte__cp_state, stbte__cp_index, stbte__save, stbte__cp_altered, stbte__color_copy;
#ifdef STBTE__COLORPICKER
static void stbte__dump_colorstate(void)
{
   int i,j,k;
   printf("static int stbte__color_table[STBTE__num_color_modes][STBTE__num_color_aspects][STBTE__num_color_states] =\n");
   printf("{\n");
   printf("   {\n");
   for (k=0; k < STBTE__num_color_modes; ++k) {
      for (j=0; j < STBTE__num_color_aspects; ++j) {
         printf("      { ");
         for (i=0; i < STBTE__num_color_states; ++i) {
            printf("0x%06x, ", stbte__color_table[k][j][i]);
         }
         printf("},\n");
      }
      if (k+1 < STBTE__num_color_modes)
         printf("   }, {\n");
      else
         printf("   },\n");
   }
   printf("};\n");
}

static void stbte__colorpicker(int x0, int y0, int w, int h)
{
   int x1 = x0+w, y1 = y0+h, x,y, i;

   x =  x0+2; y = y0+6;

   y += 5;
   x += 8;
   
   
   {
      int color = stbte__color_table[stbte__cp_mode][stbte__cp_aspect][stbte__cp_index];
      int rgb[3];
      if (stbte__cp_altered && stbte__cp_index == STBTE__idle)
         color = stbte__save;

      if (stbte__minibutton(STBTE__cmapsize, x1-20,y+ 5, 'C', STBTE__ID2(STBTE__colorpick_id,4,0)))
         stbte__color_copy = color;
      if (stbte__minibutton(STBTE__cmapsize, x1-20,y+15, 'P', STBTE__ID2(STBTE__colorpick_id,4,1)))
         color = stbte__color_copy;

      rgb[0] = color >> 16; rgb[1] = (color>>8)&255; rgb[2] = color & 255;
      for (i=0; i < 3; ++i) {
         if (stbte__slider(x+8,64, y, 255, rgb+i, STBTE__ID2(STBTE__colorpick_id,3,i)) > 0)
            stbte__dump_colorstate();
         y += 15;
      }
      if (stbte__ui.event != STBTE__paint && stbte__ui.event != STBTE__tick)
         stbte__color_table[stbte__cp_mode][stbte__cp_aspect][stbte__cp_index] = (rgb[0]<<16)|(rgb[1]<<8)|(rgb[2]);
   }

   y += 5;

   // states
   x = x0+2+35;
   if (stbte__ui.event == STBTE__paint) {
      static char *states[] = { "idle", "over", "down", "down&over", "selected", "selected&over", "disabled" };
      stbte__draw_text(x, y+1, states[stbte__cp_index], x1-x-1, 0xffffff);
   }

   x = x0+24; y += 12;

   for (i=3; i >= 0; --i) {
      int state = 0 != (stbte__cp_state & (1 << i));
      if (stbte__layerbutton(x,y, "OASD"[i], STBTE__ID2(STBTE__colorpick_id, 0,i), state,0, STBTE__clayer_button)) {
         stbte__cp_state ^= (1 << i);
         stbte__cp_index = stbte__state_to_index[0][0][0][stbte__cp_state];
      }
      x += 16;
   }
   x = x0+2; y += 18;

   for (i=0; i < 3; ++i) {
      static char *labels[] = { "Base", "Edge", "Text" };
      if (stbte__button(STBTE__ctoolbar_button, labels[i], x,y,0,36, STBTE__ID2(STBTE__colorpick_id,1,i), stbte__cp_aspect==i,0))
         stbte__cp_aspect = i;
      x += 40;
   }

   y += 18;
   x = x0+2;

   for (i=0; i < STBTE__num_color_modes; ++i) {
      if (stbte__button(STBTE__ctoolbar_button, stbte__color_names[i], x, y, 0,80, STBTE__ID2(STBTE__colorpick_id,2,i), stbte__cp_mode == i,0))
         stbte__cp_mode = i;
      y += 12;
   }

   // make the currently selected aspect flash, unless we're actively dragging color slider etc
   if (stbte__ui.event == STBTE__tick) {
      stbte__save = stbte__color_table[stbte__cp_mode][stbte__cp_aspect][STBTE__idle];
      if ((stbte__ui.active_id & 127) != STBTE__colorpick_id) {
         if ((stbte__ui.ms_time & 2047) < 200) {
            stbte__color_table[stbte__cp_mode][stbte__cp_aspect][STBTE__idle] ^= 0x1f1f1f;
            stbte__cp_altered = 1;
         }
      }
   }
}
#endif

static void stbte__editor_traverse(stbte_tilemap *tm)
{
   int i,j,i0,j0,i1,j1,n;

   if (tm == NULL)
      return;
   if (stbte__ui.x0 == stbte__ui.x1 || stbte__ui.y0 == stbte__ui.y1)
      return;

   stbte__prepare_tileinfo(tm);

   stbte__compute_panel_locations(tm); // @OPTIMIZE: we don't need to recompute this every time

   if (stbte__ui.event == STBTE__paint) {
      // fill screen with border
      stbte__draw_rect(stbte__ui.x0, stbte__ui.y0, stbte__ui.x1, stbte__ui.y1, STBTE_COLOR_TILEMAP_BORDER);
      // fill tilemap with tilemap background
      stbte__draw_rect(stbte__ui.x0 - tm->scroll_x, stbte__ui.y0 - tm->scroll_y,
                       stbte__ui.x0 - tm->scroll_x + tm->spacing_x * tm->max_x,
                       stbte__ui.y0 - tm->scroll_y + tm->spacing_y * tm->max_y, STBTE_COLOR_TILEMAP_BACKGROUND);
   }

   // step 1: traverse all the tilemap data...

   i0 = (tm->scroll_x - tm->spacing_x) / tm->spacing_x;
   j0 = (tm->scroll_y - tm->spacing_y) / tm->spacing_y;
   i1 = (tm->scroll_x + stbte__ui.x1 - stbte__ui.x0) / tm->spacing_x + 1;
   j1 = (tm->scroll_y + stbte__ui.y1 - stbte__ui.y0) / tm->spacing_y + 1;

   if (i0 < 0) i0 = 0;
   if (j0 < 0) j0 = 0;
   if (i1 > tm->max_x) i1 = tm->max_x;
   if (j1 > tm->max_y) j1 = tm->max_y;

   if (stbte__ui.event == STBTE__paint) {
      // draw all of layer 0, then all of layer 1, etc, instead of old
      // way which drew entire stack of each tile at once
      for (n=0; n < tm->num_layers; ++n) {
         for (j=j0; j < j1; ++j) {
            for (i=i0; i < i1; ++i) {
               int x = stbte__ui.x0 + i * tm->spacing_x - tm->scroll_x;
               int y = stbte__ui.y0 + j * tm->spacing_y - tm->scroll_y;
               stbte__tile_paint(tm, x, y, i, j, n);
            }
         }
         if (n == 0 && stbte__ui.show_grid == 1) {
            int x = stbte__ui.x0 + i0 * tm->spacing_x - tm->scroll_x;
            int y = stbte__ui.y0 + j0 * tm->spacing_y - tm->scroll_y;
            for (i=0; x < stbte__ui.x1 && i <= i1; ++i, x += tm->spacing_x)
               stbte__draw_rect(x, stbte__ui.y0, x+1, stbte__ui.y1, STBTE_COLOR_GRID);
            for (j=0; y < stbte__ui.y1 && j <= j1; ++j, y += tm->spacing_y)
               stbte__draw_rect(stbte__ui.x0, y, stbte__ui.x1, y+1, STBTE_COLOR_GRID);
         }
      }
   }

   if (stbte__ui.event == STBTE__paint) {
      // draw grid on top of everything except UI
      if (stbte__ui.show_grid == 2) {
         int x = stbte__ui.x0 + i0 * tm->spacing_x - tm->scroll_x;
         int y = stbte__ui.y0 + j0 * tm->spacing_y - tm->scroll_y;
         for (i=0; x < stbte__ui.x1 && i <= i1; ++i, x += tm->spacing_x)
            stbte__draw_rect(x, stbte__ui.y0, x+1, stbte__ui.y1, STBTE_COLOR_GRID);
         for (j=0; y < stbte__ui.y1 && j <= j1; ++j, y += tm->spacing_y)
            stbte__draw_rect(stbte__ui.x0, y, stbte__ui.x1, y+1, STBTE_COLOR_GRID);
      }
   }

   for (j=j0; j < j1; ++j) {
      for (i=i0; i < i1; ++i) {
         int x = stbte__ui.x0 + i * tm->spacing_x - tm->scroll_x;
         int y = stbte__ui.y0 + j * tm->spacing_y - tm->scroll_y;
         stbte__tile(tm, x, y, i, j);
      }
   }

   if (stbte__ui.event == STBTE__paint) {
      // draw the selection border
      if (stbte__ui.has_selection) {
         int x0,y0,x1,y1;
         x0 = stbte__ui.x0 + (stbte__ui.select_x0    ) * tm->spacing_x - tm->scroll_x;
         y0 = stbte__ui.y0 + (stbte__ui.select_y0    ) * tm->spacing_y - tm->scroll_y;
         x1 = stbte__ui.x0 + (stbte__ui.select_x1 + 1) * tm->spacing_x - tm->scroll_x + 1;
         y1 = stbte__ui.y0 + (stbte__ui.select_y1 + 1) * tm->spacing_y - tm->scroll_y + 1;
         stbte__draw_frame(x0,y0,x1,y1, (stbte__ui.ms_time & 256 ? STBTE_COLOR_SELECTION_OUTLINE1 : STBTE_COLOR_SELECTION_OUTLINE2));
      }

      stbte__flush_delay(); // draw a dynamic link on top of the queued links

      #ifdef STBTE_ALLOW_LINK
      if (stbte__ui.linking && STBTE__IS_MAP_HOT()) {
         int x0,y0,x1,y1;
         int color;
         int ex = ((stbte__ui.hot_id >> 19) & 4095);
         int ey = ((stbte__ui.hot_id >>  7) & 4095);
         x0 = stbte__ui.x0 + (stbte__ui.sx    ) * tm->spacing_x - tm->scroll_x + (tm->spacing_x>>1)+1;
         y0 = stbte__ui.y0 + (stbte__ui.sy    ) * tm->spacing_y - tm->scroll_y + (tm->spacing_y>>1)+1;
         x1 = stbte__ui.x0 + (ex              ) * tm->spacing_x - tm->scroll_x + (tm->spacing_x>>1)-1;
         y1 = stbte__ui.y0 + (ey              ) * tm->spacing_y - tm->scroll_y + (tm->spacing_y>>1)-1;
         if (STBTE_ALLOW_LINK(tm->data[stbte__ui.sy][stbte__ui.sx], tm->props[stbte__ui.sy][stbte__ui.sx], tm->data[ey][ex], tm->props[ey][ex]))
            color = STBTE_LINK_COLOR_DRAWING;
         else
            color = STBTE_LINK_COLOR_DISALLOWED;
         stbte__draw_link(x0,y0,x1,y1, color);
      }
      #endif
   }
   stbte__flush_delay();

   // step 2: traverse the panels
   for (i=0; i < STBTE__num_panel; ++i) {
      stbte__panel *p = &stbte__ui.panel[i];
      if (stbte__ui.event == STBTE__paint) {
         stbte__draw_box(p->x0,p->y0,p->x0+p->width,p->y0+p->height, STBTE__cpanel, STBTE__idle);
      }
      // obscure tilemap data underneath panel
      stbte__hittest(p->x0,p->y0,p->x0+p->width,p->y0+p->height, STBTE__ID2(STBTE__panel, i, 0));
      switch (i) {
         case STBTE__panel_toolbar:
            if (stbte__ui.event == STBTE__paint)
               stbte__draw_rect(p->x0,p->y0,p->x0+p->width,p->y0+p->height, stbte__color_table[STBTE__ctoolbar][STBTE__base][STBTE__idle]);
            stbte__toolbar(tm,p->x0,p->y0,p->width,p->height);
            break;
         case STBTE__panel_info:
            stbte__info(tm,p->x0,p->y0,p->width,p->height);
            break;
         case STBTE__panel_layers:
            stbte__layers(tm,p->x0,p->y0,p->width,p->height);
            break;
         case STBTE__panel_categories:
            stbte__categories(tm,p->x0,p->y0,p->width,p->height);
            break;
         case STBTE__panel_colorpick:
#ifdef STBTE__COLORPICKER
            stbte__colorpicker(p->x0,p->y0,p->width,p->height);
#endif
            break;
         case STBTE__panel_tiles:
            // erase boundary between categories and tiles if they're on same side
            if (stbte__ui.event == STBTE__paint && p->side == stbte__ui.panel[STBTE__panel_categories].side)
               stbte__draw_rect(p->x0+1,p->y0-1,p->x0+p->width-1,p->y0+1, stbte__color_table[STBTE__cpanel][STBTE__base][STBTE__idle]);
            stbte__palette_of_tiles(tm,p->x0,p->y0,p->width,p->height);
            break;
         case STBTE__panel_props:
            stbte__props_panel(tm,p->x0,p->y0,p->width,p->height);
            break;
      }
      // draw the panel side selectors
      for (j=0; j < 2; ++j) {
         int result;
         if (i == STBTE__panel_toolbar) continue;
         result = stbte__microbutton(p->x0+p->width - 1 - 2*4 + 4*j,p->y0+2,3, STBTE__ID2(STBTE__panel, i, j+1), STBTE__cpanel_sider+j);
         if (result) {
            switch (j) {
               case 0: p->side = result > 0 ? STBTE__side_left : STBTE__side_right; break;
               case 1: p->delta_height += result; break;
            }
         }
      }
   }

   if (stbte__ui.panel[STBTE__panel_categories].delta_height < -5) stbte__ui.panel[STBTE__panel_categories].delta_height = -5;
   if (stbte__ui.panel[STBTE__panel_layers    ].delta_height < -5) stbte__ui.panel[STBTE__panel_layers    ].delta_height = -5;


   // step 3: traverse the regions to place expander controls on them
   for (i=0; i < 2; ++i) {
      if (stbte__region[i].active) {
         int x = stbte__region[i].x;
         int width;
         if (i == STBTE__side_left)
            width =  stbte__ui.left_width , x += stbte__region[i].width + 1;
         else
            width = -stbte__ui.right_width, x -= 6;
         if (stbte__microbutton_dragger(x, stbte__region[i].y+2, 5, STBTE__ID(STBTE__region,i), &width)) {
            // if non-0, it is expanding, so retract it
            if (stbte__region[i].retracted == 0.0)
               stbte__region[i].retracted = 0.01f;
            else
               stbte__region[i].retracted = 0.0;
         }
         if (i == STBTE__side_left)
            stbte__ui.left_width  =  width;
         else
            stbte__ui.right_width = -width;
         if (stbte__ui.event == STBTE__tick) {
            if (stbte__region[i].retracted && stbte__region[i].retracted < 1.0f) {
               stbte__region[i].retracted += stbte__ui.dt*4;
               if (stbte__region[i].retracted > 1)
                  stbte__region[i].retracted = 1;
            }
         }
      }
   }

   if (stbte__ui.event == STBTE__paint && stbte__ui.alert_msg) {
      int w = stbte__text_width(stbte__ui.alert_msg);
      int x = (stbte__ui.x0+stbte__ui.x1)/2;
      int y = (stbte__ui.y0+stbte__ui.y1)*5/6;
      stbte__draw_rect (x-w/2-4,y-8, x+w/2+4,y+8, 0x604020);
      stbte__draw_frame(x-w/2-4,y-8, x+w/2+4,y+8, 0x906030);
      stbte__draw_text (x-w/2,y-4, stbte__ui.alert_msg, w+1, 0xff8040);
   }

#ifdef STBTE_SHOW_CURSOR
   if (stbte__ui.event == STBTE__paint)
      stbte__draw_bitmap(stbte__ui.mx, stbte__ui.my, stbte__get_char_width(26), stbte__get_char_bitmap(26), 0xe0e0e0);
#endif

   if (stbte__ui.event == STBTE__tick && stbte__ui.alert_msg) {
      stbte__ui.alert_timer -= stbte__ui.dt;
      if (stbte__ui.alert_timer < 0) {
         stbte__ui.alert_timer = 0;
         stbte__ui.alert_msg = 0;
      }
   }

   if (stbte__ui.event == STBTE__paint) {
      stbte__color_table[stbte__cp_mode][stbte__cp_aspect][STBTE__idle] = stbte__save;
      stbte__cp_altered = 0;
   }
}

static void stbte__do_event(stbte_tilemap *tm)
{
   stbte__ui.next_hot_id = 0;
   stbte__editor_traverse(tm);
   stbte__ui.hot_id = stbte__ui.next_hot_id;

   // automatically cancel on mouse-up in case the object that triggered it
   // doesn't exist anymore
   if (stbte__ui.active_id) {
      if (stbte__ui.event == STBTE__leftup || stbte__ui.event == STBTE__rightup) {
         if (!stbte__ui.pasting) {
            stbte__activate(0);
            if (stbte__ui.undoing)
               stbte__end_undo(tm);
            stbte__ui.scrolling = 0;
            stbte__ui.dragging = 0;
            stbte__ui.linking = 0;
         }
      }
   }

   // we could do this stuff in the widgets directly, but it would keep recomputing
   // the same thing on every tile, which seems dumb.

   if (stbte__ui.pasting) {
      if (STBTE__IS_MAP_HOT()) {
         // compute pasting location based on last hot
         stbte__ui.paste_x = ((stbte__ui.hot_id >> 19) & 4095) - (stbte__ui.copy_width >> 1);
         stbte__ui.paste_y = ((stbte__ui.hot_id >>  7) & 4095) - (stbte__ui.copy_height >> 1);
      }
   }
   if (stbte__ui.dragging) {
      if (STBTE__IS_MAP_HOT()) {
         stbte__ui.drag_dest_x = ((stbte__ui.hot_id >> 19) & 4095) - stbte__ui.drag_offx;
         stbte__ui.drag_dest_y = ((stbte__ui.hot_id >>  7) & 4095) - stbte__ui.drag_offy;
      }
   }
}

static void stbte__set_event(int event, int x, int y)
{
   stbte__ui.event = event;
   stbte__ui.mx    = x;
   stbte__ui.my    = y;
   stbte__ui.dx    = x - stbte__ui.last_mouse_x;
   stbte__ui.dy    = y - stbte__ui.last_mouse_y;
   stbte__ui.last_mouse_x = x;
   stbte__ui.last_mouse_y = y;
   stbte__ui.accum_x += stbte__ui.dx;
   stbte__ui.accum_y += stbte__ui.dy;
}

void stbte_draw(stbte_tilemap *tm)
{
   stbte__ui.event = STBTE__paint;
   stbte__editor_traverse(tm);
}

void stbte_mouse_move(stbte_tilemap *tm, int x, int y, int shifted, int scrollkey)
{
   stbte__set_event(STBTE__mousemove, x,y);
   stbte__ui.shift = shifted;
   stbte__ui.scrollkey = scrollkey;
   stbte__do_event(tm);
}

void stbte_mouse_button(stbte_tilemap *tm, int x, int y, int right, int down, int shifted, int scrollkey)
{
   static int events[2][2] = { { STBTE__leftup , STBTE__leftdown  },
                               { STBTE__rightup, STBTE__rightdown } };
   stbte__set_event(events[right][down], x,y);
   stbte__ui.shift = shifted;
   stbte__ui.scrollkey = scrollkey;

   stbte__do_event(tm);
}

void stbte_mouse_wheel(stbte_tilemap *tm, int x, int y, int vscroll)
{
   // not implemented yet -- need different way of hittesting
}

void stbte_action(stbte_tilemap *tm, enum stbte_action act)
{
   switch (act) {
      case STBTE_tool_select:      stbte__ui.tool = STBTE__tool_select;               break;
      case STBTE_tool_brush:       stbte__ui.tool = STBTE__tool_brush;                break;
      case STBTE_tool_erase:       stbte__ui.tool = STBTE__tool_erase;                break;
      case STBTE_tool_rectangle:   stbte__ui.tool = STBTE__tool_rect;                 break;
      case STBTE_tool_eyedropper:  stbte__ui.tool = STBTE__tool_eyedrop;              break;
      case STBTE_tool_link:        stbte__ui.tool = STBTE__tool_link;                 break;
      case STBTE_act_toggle_grid:  stbte__ui.show_grid = (stbte__ui.show_grid+1) % 3; break;
      case STBTE_act_toggle_links: stbte__ui.show_links ^= 1;                         break;
      case STBTE_act_undo:         stbte__undo(tm);                                   break;
      case STBTE_act_redo:         stbte__redo(tm);                                   break;
      case STBTE_act_cut:          stbte__copy_cut(tm, 1);                            break;
      case STBTE_act_copy:         stbte__copy_cut(tm, 0);                            break;
      case STBTE_act_paste:        stbte__start_paste(tm);                            break;
      case STBTE_scroll_left:      tm->scroll_x -= tm->spacing_x;                     break;
      case STBTE_scroll_right:     tm->scroll_x += tm->spacing_x;                     break;
      case STBTE_scroll_up:        tm->scroll_y -= tm->spacing_y;                     break;
      case STBTE_scroll_down:      tm->scroll_y += tm->spacing_y;                     break;
   }
}

void stbte_tick(stbte_tilemap *tm, float dt)
{
   stbte__ui.event = STBTE__tick;
   stbte__ui.dt    = dt;
   stbte__do_event(tm);
   stbte__ui.ms_time += (int) (dt * 1024) + 1; // make sure if time is superfast it always updates a little
}

void stbte_mouse_sdl(stbte_tilemap *tm, const void *sdl_event, float xs, float ys, int xo, int yo)
{
#ifdef _SDL_H
   SDL_Event *event = (SDL_Event *) sdl_event;
   SDL_Keymod km = SDL_GetModState();
   int shift = (km & KMOD_LCTRL) || (km & KMOD_RCTRL);
   int scrollkey = 0 != SDL_GetKeyboardState(NULL)[SDL_SCANCODE_SPACE];
   switch (event->type) {
      case SDL_MOUSEMOTION:
         stbte_mouse_move(tm, (int) (xs*event->motion.x+xo), (int) (ys*event->motion.y+yo), shift, scrollkey);
         break;
      case SDL_MOUSEBUTTONUP:
         stbte_mouse_button(tm, (int) (xs*event->button.x+xo), (int) (ys*event->button.y+yo), event->button.button != SDL_BUTTON_LEFT, 0, shift, scrollkey);
         break;
      case SDL_MOUSEBUTTONDOWN:
         stbte_mouse_button(tm, (int) (xs*event->button.x+xo), (int) (ys*event->button.y+yo), event->button.button != SDL_BUTTON_LEFT, 1, shift, scrollkey);
         break;
      case SDL_MOUSEWHEEL:
         stbte_mouse_wheel(tm, stbte__ui.mx, stbte__ui.my, event->wheel.y);
         break;
   }
#else
   STBTE__NOTUSED(tm);
   STBTE__NOTUSED(sdl_event);
   STBTE__NOTUSED(xs);
   STBTE__NOTUSED(ys);
   STBTE__NOTUSED(xo);
   STBTE__NOTUSED(yo);
#endif
}

#endif // STB_TILEMAP_EDITOR_IMPLEMENTATION