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1 // [DEAR IMGUI]
2 // This is a slightly modified version of stb_rect_pack.h 0.99.
3 // Those changes would need to be pushed into nothings/stb:
4 // - Added STBRP__CDECL
5 // Grep for [DEAR IMGUI] to find the changes.
6 
7 // stb_rect_pack.h - v0.99 - public domain - rectangle packing
8 // Sean Barrett 2014
9 //
10 // Useful for e.g. packing rectangular textures into an atlas.
11 // Does not do rotation.
12 //
13 // Not necessarily the awesomest packing method, but better than
14 // the totally naive one in stb_truetype (which is primarily what
15 // this is meant to replace).
16 //
17 // Has only had a few tests run, may have issues.
18 //
19 // More docs to come.
20 //
21 // No memory allocations; uses qsort() and assert() from stdlib.
22 // Can override those by defining STBRP_SORT and STBRP_ASSERT.
23 //
24 // This library currently uses the Skyline Bottom-Left algorithm.
25 //
26 // Please note: better rectangle packers are welcome! Please
27 // implement them to the same API, but with a different init
28 // function.
29 //
30 // Credits
31 //
32 //  Library
33 //    Sean Barrett
34 //  Minor features
35 //    Martins Mozeiko
36 //    github:IntellectualKitty
37 //
38 //  Bugfixes / warning fixes
39 //    Jeremy Jaussaud
40 //
41 // Version history:
42 //
43 //     0.99  (2019-02-07)  warning fixes
44 //     0.11  (2017-03-03)  return packing success/fail result
45 //     0.10  (2016-10-25)  remove cast-away-const to avoid warnings
46 //     0.09  (2016-08-27)  fix compiler warnings
47 //     0.08  (2015-09-13)  really fix bug with empty rects (w=0 or h=0)
48 //     0.07  (2015-09-13)  fix bug with empty rects (w=0 or h=0)
49 //     0.06  (2015-04-15)  added STBRP_SORT to allow replacing qsort
50 //     0.05:  added STBRP_ASSERT to allow replacing assert
51 //     0.04:  fixed minor bug in STBRP_LARGE_RECTS support
52 //     0.01:  initial release
53 //
54 // LICENSE
55 //
56 //   See end of file for license information.
57 
58 //////////////////////////////////////////////////////////////////////////////
59 //
60 //       INCLUDE SECTION
61 //
62 
63 #ifndef STB_INCLUDE_STB_RECT_PACK_H
64 #define STB_INCLUDE_STB_RECT_PACK_H
65 
66 #define STB_RECT_PACK_VERSION  1
67 
68 #ifdef STBRP_STATIC
69 #define STBRP_DEF static
70 #else
71 #define STBRP_DEF extern
72 #endif
73 
74 #ifdef __cplusplus
75 extern "C" {
76 #endif
77 
78 typedef struct stbrp_context stbrp_context;
79 typedef struct stbrp_node    stbrp_node;
80 typedef struct stbrp_rect    stbrp_rect;
81 
82 #ifdef STBRP_LARGE_RECTS
83 typedef int            stbrp_coord;
84 #else
85 typedef unsigned short stbrp_coord;
86 #endif
87 
88 STBRP_DEF int stbrp_pack_rects (stbrp_context *context, stbrp_rect *rects, int num_rects);
89 // Assign packed locations to rectangles. The rectangles are of type
90 // 'stbrp_rect' defined below, stored in the array 'rects', and there
91 // are 'num_rects' many of them.
92 //
93 // Rectangles which are successfully packed have the 'was_packed' flag
94 // set to a non-zero value and 'x' and 'y' store the minimum location
95 // on each axis (i.e. bottom-left in cartesian coordinates, top-left
96 // if you imagine y increasing downwards). Rectangles which do not fit
97 // have the 'was_packed' flag set to 0.
98 //
99 // You should not try to access the 'rects' array from another thread
100 // while this function is running, as the function temporarily reorders
101 // the array while it executes.
102 //
103 // To pack into another rectangle, you need to call stbrp_init_target
104 // again. To continue packing into the same rectangle, you can call
105 // this function again. Calling this multiple times with multiple rect
106 // arrays will probably produce worse packing results than calling it
107 // a single time with the full rectangle array, but the option is
108 // available.
109 //
110 // The function returns 1 if all of the rectangles were successfully
111 // packed and 0 otherwise.
112 
113 struct stbrp_rect
114 {
115    // reserved for your use:
116    int            id;
117 
118    // input:
119    stbrp_coord    w, h;
120 
121    // output:
122    stbrp_coord    x, y;
123    int            was_packed;  // non-zero if valid packing
124 
125 }; // 16 bytes, nominally
126 
127 
128 STBRP_DEF void stbrp_init_target (stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes);
129 // Initialize a rectangle packer to:
130 //    pack a rectangle that is 'width' by 'height' in dimensions
131 //    using temporary storage provided by the array 'nodes', which is 'num_nodes' long
132 //
133 // You must call this function every time you start packing into a new target.
134 //
135 // There is no "shutdown" function. The 'nodes' memory must stay valid for
136 // the following stbrp_pack_rects() call (or calls), but can be freed after
137 // the call (or calls) finish.
138 //
139 // Note: to guarantee best results, either:
140 //       1. make sure 'num_nodes' >= 'width'
141 //   or  2. call stbrp_allow_out_of_mem() defined below with 'allow_out_of_mem = 1'
142 //
143 // If you don't do either of the above things, widths will be quantized to multiples
144 // of small integers to guarantee the algorithm doesn't run out of temporary storage.
145 //
146 // If you do #2, then the non-quantized algorithm will be used, but the algorithm
147 // may run out of temporary storage and be unable to pack some rectangles.
148 
149 STBRP_DEF void stbrp_setup_allow_out_of_mem (stbrp_context *context, int allow_out_of_mem);
150 // Optionally call this function after init but before doing any packing to
151 // change the handling of the out-of-temp-memory scenario, described above.
152 // If you call init again, this will be reset to the default (false).
153 
154 
155 STBRP_DEF void stbrp_setup_heuristic (stbrp_context *context, int heuristic);
156 // Optionally select which packing heuristic the library should use. Different
157 // heuristics will produce better/worse results for different data sets.
158 // If you call init again, this will be reset to the default.
159 
160 enum
161 {
162    STBRP_HEURISTIC_Skyline_default=0,
163    STBRP_HEURISTIC_Skyline_BL_sortHeight = STBRP_HEURISTIC_Skyline_default,
164    STBRP_HEURISTIC_Skyline_BF_sortHeight
165 };
166 
167 
168 //////////////////////////////////////////////////////////////////////////////
169 //
170 // the details of the following structures don't matter to you, but they must
171 // be visible so you can handle the memory allocations for them
172 
173 struct stbrp_node
174 {
175    stbrp_coord  x,y;
176    stbrp_node  *next;
177 };
178 
179 struct stbrp_context
180 {
181    int width;
182    int height;
183    int align;
184    int init_mode;
185    int heuristic;
186    int num_nodes;
187    stbrp_node *active_head;
188    stbrp_node *free_head;
189    stbrp_node extra[2]; // we allocate two extra nodes so optimal user-node-count is 'width' not 'width+2'
190 };
191 
192 #ifdef __cplusplus
193 }
194 #endif
195 
196 #endif
197 
198 //////////////////////////////////////////////////////////////////////////////
199 //
200 //     IMPLEMENTATION SECTION
201 //
202 
203 #ifdef STB_RECT_PACK_IMPLEMENTATION
204 #ifndef STBRP_SORT
205 #include <stdlib.h>
206 #define STBRP_SORT qsort
207 #endif
208 
209 #ifndef STBRP_ASSERT
210 #include <assert.h>
211 #define STBRP_ASSERT assert
212 #endif
213 
214 // [DEAR IMGUI] Added STBRP__CDECL
215 #ifdef _MSC_VER
216 #define STBRP__NOTUSED(v)  (void)(v)
217 #define STBRP__CDECL __cdecl
218 #else
219 #define STBRP__NOTUSED(v)  (void)sizeof(v)
220 #define STBRP__CDECL
221 #endif
222 
223 enum
224 {
225    STBRP__INIT_skyline = 1
226 };
227 
stbrp_setup_heuristic(stbrp_context * context,int heuristic)228 STBRP_DEF void stbrp_setup_heuristic(stbrp_context *context, int heuristic)
229 {
230    switch (context->init_mode) {
231       case STBRP__INIT_skyline:
232          STBRP_ASSERT(heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight || heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight);
233          context->heuristic = heuristic;
234          break;
235       default:
236          STBRP_ASSERT(0);
237    }
238 }
239 
stbrp_setup_allow_out_of_mem(stbrp_context * context,int allow_out_of_mem)240 STBRP_DEF void stbrp_setup_allow_out_of_mem(stbrp_context *context, int allow_out_of_mem)
241 {
242    if (allow_out_of_mem)
243       // if it's ok to run out of memory, then don't bother aligning them;
244       // this gives better packing, but may fail due to OOM (even though
245       // the rectangles easily fit). @TODO a smarter approach would be to only
246       // quantize once we've hit OOM, then we could get rid of this parameter.
247       context->align = 1;
248    else {
249       // if it's not ok to run out of memory, then quantize the widths
250       // so that num_nodes is always enough nodes.
251       //
252       // I.e. num_nodes * align >= width
253       //                  align >= width / num_nodes
254       //                  align = ceil(width/num_nodes)
255 
256       context->align = (context->width + context->num_nodes-1) / context->num_nodes;
257    }
258 }
259 
stbrp_init_target(stbrp_context * context,int width,int height,stbrp_node * nodes,int num_nodes)260 STBRP_DEF void stbrp_init_target(stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes)
261 {
262    int i;
263 #ifndef STBRP_LARGE_RECTS
264    STBRP_ASSERT(width <= 0xffff && height <= 0xffff);
265 #endif
266 
267    for (i=0; i < num_nodes-1; ++i)
268       nodes[i].next = &nodes[i+1];
269    nodes[i].next = NULL;
270    context->init_mode = STBRP__INIT_skyline;
271    context->heuristic = STBRP_HEURISTIC_Skyline_default;
272    context->free_head = &nodes[0];
273    context->active_head = &context->extra[0];
274    context->width = width;
275    context->height = height;
276    context->num_nodes = num_nodes;
277    stbrp_setup_allow_out_of_mem(context, 0);
278 
279    // node 0 is the full width, node 1 is the sentinel (lets us not store width explicitly)
280    context->extra[0].x = 0;
281    context->extra[0].y = 0;
282    context->extra[0].next = &context->extra[1];
283    context->extra[1].x = (stbrp_coord) width;
284 #ifdef STBRP_LARGE_RECTS
285    context->extra[1].y = (1<<30);
286 #else
287    context->extra[1].y = 65535;
288 #endif
289    context->extra[1].next = NULL;
290 }
291 
292 // find minimum y position if it starts at x1
stbrp__skyline_find_min_y(stbrp_context * c,stbrp_node * first,int x0,int width,int * pwaste)293 static int stbrp__skyline_find_min_y(stbrp_context *c, stbrp_node *first, int x0, int width, int *pwaste)
294 {
295    stbrp_node *node = first;
296    int x1 = x0 + width;
297    int min_y, visited_width, waste_area;
298 
299    STBRP__NOTUSED(c);
300 
301    STBRP_ASSERT(first->x <= x0);
302 
303    #if 0
304    // skip in case we're past the node
305    while (node->next->x <= x0)
306       ++node;
307    #else
308    STBRP_ASSERT(node->next->x > x0); // we ended up handling this in the caller for efficiency
309    #endif
310 
311    STBRP_ASSERT(node->x <= x0);
312 
313    min_y = 0;
314    waste_area = 0;
315    visited_width = 0;
316    while (node->x < x1) {
317       if (node->y > min_y) {
318          // raise min_y higher.
319          // we've accounted for all waste up to min_y,
320          // but we'll now add more waste for everything we've visted
321          waste_area += visited_width * (node->y - min_y);
322          min_y = node->y;
323          // the first time through, visited_width might be reduced
324          if (node->x < x0)
325             visited_width += node->next->x - x0;
326          else
327             visited_width += node->next->x - node->x;
328       } else {
329          // add waste area
330          int under_width = node->next->x - node->x;
331          if (under_width + visited_width > width)
332             under_width = width - visited_width;
333          waste_area += under_width * (min_y - node->y);
334          visited_width += under_width;
335       }
336       node = node->next;
337    }
338 
339    *pwaste = waste_area;
340    return min_y;
341 }
342 
343 typedef struct
344 {
345    int x,y;
346    stbrp_node **prev_link;
347 } stbrp__findresult;
348 
stbrp__skyline_find_best_pos(stbrp_context * c,int width,int height)349 static stbrp__findresult stbrp__skyline_find_best_pos(stbrp_context *c, int width, int height)
350 {
351    int best_waste = (1<<30), best_x, best_y = (1 << 30);
352    stbrp__findresult fr;
353    stbrp_node **prev, *node, *tail, **best = NULL;
354 
355    // align to multiple of c->align
356    width = (width + c->align - 1);
357    width -= width % c->align;
358    STBRP_ASSERT(width % c->align == 0);
359 
360    node = c->active_head;
361    prev = &c->active_head;
362    while (node->x + width <= c->width) {
363       int y,waste;
364       y = stbrp__skyline_find_min_y(c, node, node->x, width, &waste);
365       if (c->heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight) { // actually just want to test BL
366          // bottom left
367          if (y < best_y) {
368             best_y = y;
369             best = prev;
370          }
371       } else {
372          // best-fit
373          if (y + height <= c->height) {
374             // can only use it if it first vertically
375             if (y < best_y || (y == best_y && waste < best_waste)) {
376                best_y = y;
377                best_waste = waste;
378                best = prev;
379             }
380          }
381       }
382       prev = &node->next;
383       node = node->next;
384    }
385 
386    best_x = (best == NULL) ? 0 : (*best)->x;
387 
388    // if doing best-fit (BF), we also have to try aligning right edge to each node position
389    //
390    // e.g, if fitting
391    //
392    //     ____________________
393    //    |____________________|
394    //
395    //            into
396    //
397    //   |                         |
398    //   |             ____________|
399    //   |____________|
400    //
401    // then right-aligned reduces waste, but bottom-left BL is always chooses left-aligned
402    //
403    // This makes BF take about 2x the time
404 
405    if (c->heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight) {
406       tail = c->active_head;
407       node = c->active_head;
408       prev = &c->active_head;
409       // find first node that's admissible
410       while (tail->x < width)
411          tail = tail->next;
412       while (tail) {
413          int xpos = tail->x - width;
414          int y,waste;
415          STBRP_ASSERT(xpos >= 0);
416          // find the left position that matches this
417          while (node->next->x <= xpos) {
418             prev = &node->next;
419             node = node->next;
420          }
421          STBRP_ASSERT(node->next->x > xpos && node->x <= xpos);
422          y = stbrp__skyline_find_min_y(c, node, xpos, width, &waste);
423          if (y + height < c->height) {
424             if (y <= best_y) {
425                if (y < best_y || waste < best_waste || (waste==best_waste && xpos < best_x)) {
426                   best_x = xpos;
427                   STBRP_ASSERT(y <= best_y);
428                   best_y = y;
429                   best_waste = waste;
430                   best = prev;
431                }
432             }
433          }
434          tail = tail->next;
435       }
436    }
437 
438    fr.prev_link = best;
439    fr.x = best_x;
440    fr.y = best_y;
441    return fr;
442 }
443 
stbrp__skyline_pack_rectangle(stbrp_context * context,int width,int height)444 static stbrp__findresult stbrp__skyline_pack_rectangle(stbrp_context *context, int width, int height)
445 {
446    // find best position according to heuristic
447    stbrp__findresult res = stbrp__skyline_find_best_pos(context, width, height);
448    stbrp_node *node, *cur;
449 
450    // bail if:
451    //    1. it failed
452    //    2. the best node doesn't fit (we don't always check this)
453    //    3. we're out of memory
454    if (res.prev_link == NULL || res.y + height > context->height || context->free_head == NULL) {
455       res.prev_link = NULL;
456       return res;
457    }
458 
459    // on success, create new node
460    node = context->free_head;
461    node->x = (stbrp_coord) res.x;
462    node->y = (stbrp_coord) (res.y + height);
463 
464    context->free_head = node->next;
465 
466    // insert the new node into the right starting point, and
467    // let 'cur' point to the remaining nodes needing to be
468    // stiched back in
469 
470    cur = *res.prev_link;
471    if (cur->x < res.x) {
472       // preserve the existing one, so start testing with the next one
473       stbrp_node *next = cur->next;
474       cur->next = node;
475       cur = next;
476    } else {
477       *res.prev_link = node;
478    }
479 
480    // from here, traverse cur and free the nodes, until we get to one
481    // that shouldn't be freed
482    while (cur->next && cur->next->x <= res.x + width) {
483       stbrp_node *next = cur->next;
484       // move the current node to the free list
485       cur->next = context->free_head;
486       context->free_head = cur;
487       cur = next;
488    }
489 
490    // stitch the list back in
491    node->next = cur;
492 
493    if (cur->x < res.x + width)
494       cur->x = (stbrp_coord) (res.x + width);
495 
496 #ifdef _DEBUG
497    cur = context->active_head;
498    while (cur->x < context->width) {
499       STBRP_ASSERT(cur->x < cur->next->x);
500       cur = cur->next;
501    }
502    STBRP_ASSERT(cur->next == NULL);
503 
504    {
505       int count=0;
506       cur = context->active_head;
507       while (cur) {
508          cur = cur->next;
509          ++count;
510       }
511       cur = context->free_head;
512       while (cur) {
513          cur = cur->next;
514          ++count;
515       }
516       STBRP_ASSERT(count == context->num_nodes+2);
517    }
518 #endif
519 
520    return res;
521 }
522 
523 // [DEAR IMGUI] Added STBRP__CDECL
rect_height_compare(const void * a,const void * b)524 static int STBRP__CDECL rect_height_compare(const void *a, const void *b)
525 {
526    const stbrp_rect *p = (const stbrp_rect *) a;
527    const stbrp_rect *q = (const stbrp_rect *) b;
528    if (p->h > q->h)
529       return -1;
530    if (p->h < q->h)
531       return  1;
532    return (p->w > q->w) ? -1 : (p->w < q->w);
533 }
534 
535 // [DEAR IMGUI] Added STBRP__CDECL
rect_original_order(const void * a,const void * b)536 static int STBRP__CDECL rect_original_order(const void *a, const void *b)
537 {
538    const stbrp_rect *p = (const stbrp_rect *) a;
539    const stbrp_rect *q = (const stbrp_rect *) b;
540    return (p->was_packed < q->was_packed) ? -1 : (p->was_packed > q->was_packed);
541 }
542 
543 #ifdef STBRP_LARGE_RECTS
544 #define STBRP__MAXVAL  0xffffffff
545 #else
546 #define STBRP__MAXVAL  0xffff
547 #endif
548 
stbrp_pack_rects(stbrp_context * context,stbrp_rect * rects,int num_rects)549 STBRP_DEF int stbrp_pack_rects(stbrp_context *context, stbrp_rect *rects, int num_rects)
550 {
551    int i, all_rects_packed = 1;
552 
553    // we use the 'was_packed' field internally to allow sorting/unsorting
554    for (i=0; i < num_rects; ++i) {
555       rects[i].was_packed = i;
556    }
557 
558    // sort according to heuristic
559    STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_height_compare);
560 
561    for (i=0; i < num_rects; ++i) {
562       if (rects[i].w == 0 || rects[i].h == 0) {
563          rects[i].x = rects[i].y = 0;  // empty rect needs no space
564       } else {
565          stbrp__findresult fr = stbrp__skyline_pack_rectangle(context, rects[i].w, rects[i].h);
566          if (fr.prev_link) {
567             rects[i].x = (stbrp_coord) fr.x;
568             rects[i].y = (stbrp_coord) fr.y;
569          } else {
570             rects[i].x = rects[i].y = STBRP__MAXVAL;
571          }
572       }
573    }
574 
575    // unsort
576    STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_original_order);
577 
578    // set was_packed flags and all_rects_packed status
579    for (i=0; i < num_rects; ++i) {
580       rects[i].was_packed = !(rects[i].x == STBRP__MAXVAL && rects[i].y == STBRP__MAXVAL);
581       if (!rects[i].was_packed)
582          all_rects_packed = 0;
583    }
584 
585    // return the all_rects_packed status
586    return all_rects_packed;
587 }
588 #endif
589 
590 /*
591 ------------------------------------------------------------------------------
592 This software is available under 2 licenses -- choose whichever you prefer.
593 ------------------------------------------------------------------------------
594 ALTERNATIVE A - MIT License
595 Copyright (c) 2017 Sean Barrett
596 Permission is hereby granted, free of charge, to any person obtaining a copy of
597 this software and associated documentation files (the "Software"), to deal in
598 the Software without restriction, including without limitation the rights to
599 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
600 of the Software, and to permit persons to whom the Software is furnished to do
601 so, subject to the following conditions:
602 The above copyright notice and this permission notice shall be included in all
603 copies or substantial portions of the Software.
604 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
605 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
606 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
607 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
608 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
609 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
610 SOFTWARE.
611 ------------------------------------------------------------------------------
612 ALTERNATIVE B - Public Domain (www.unlicense.org)
613 This is free and unencumbered software released into the public domain.
614 Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
615 software, either in source code form or as a compiled binary, for any purpose,
616 commercial or non-commercial, and by any means.
617 In jurisdictions that recognize copyright laws, the author or authors of this
618 software dedicate any and all copyright interest in the software to the public
619 domain. We make this dedication for the benefit of the public at large and to
620 the detriment of our heirs and successors. We intend this dedication to be an
621 overt act of relinquishment in perpetuity of all present and future rights to
622 this software under copyright law.
623 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
624 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
625 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
626 AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
627 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
628 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
629 ------------------------------------------------------------------------------
630 */
631