gtk/gsk/gl/stb_rect_pack.c

#include "stb_rect_pack.h"
#define STB_RECT_PACK_IMPLEMENTATION
//////////////////////////////////////////////////////////////////////////////
//
//     IMPLEMENTATION SECTION
//

#ifdef STB_RECT_PACK_IMPLEMENTATION
#ifndef STBRP_SORT
#include <stdlib.h>
#define STBRP_SORT qsort
#endif

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

#ifdef _MSC_VER
#define STBRP__NOTUSED(v)  (void)(v)
#define STBRP__CDECL       __cdecl
#else
#define STBRP__NOTUSED(v)  (void)sizeof(v)
#define STBRP__CDECL
#endif

enum
{
   STBRP__INIT_skyline = 1
};

STBRP_DEF void stbrp_setup_heuristic(stbrp_context *context, int heuristic)
{
   switch (context->init_mode) {
      case STBRP__INIT_skyline:
         STBRP_ASSERT(heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight || heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight);
         context->heuristic = heuristic;
         break;
      default:
         STBRP_ASSERT(0);
   }
}

STBRP_DEF void stbrp_setup_allow_out_of_mem(stbrp_context *context, int allow_out_of_mem)
{
   if (allow_out_of_mem)
      // if it's ok to run out of memory, then don't bother aligning them;
      // this gives better packing, but may fail due to OOM (even though
      // the rectangles easily fit). @TODO a smarter approach would be to only
      // quantize once we've hit OOM, then we could get rid of this parameter.
      context->align = 1;
   else {
      // if it's not ok to run out of memory, then quantize the widths
      // so that num_nodes is always enough nodes.
      //
      // I.e. num_nodes * align >= width
      //                  align >= width / num_nodes
      //                  align = ceil(width/num_nodes)

      context->align = (context->width + context->num_nodes-1) / context->num_nodes;
   }
}

STBRP_DEF void stbrp_init_target(stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes)
{
   int i;

   for (i=0; i < num_nodes-1; ++i)
      nodes[i].next = &nodes[i+1];
   nodes[i].next = NULL;
   context->init_mode = STBRP__INIT_skyline;
   context->heuristic = STBRP_HEURISTIC_Skyline_default;
   context->free_head = &nodes[0];
   context->active_head = &context->extra[0];
   context->width = width;
   context->height = height;
   context->num_nodes = num_nodes;
   stbrp_setup_allow_out_of_mem(context, 0);

   // node 0 is the full width, node 1 is the sentinel (lets us not store width explicitly)
   context->extra[0].x = 0;
   context->extra[0].y = 0;
   context->extra[0].next = &context->extra[1];
   context->extra[1].x = (stbrp_coord) width;
   context->extra[1].y = (1<<30);
   context->extra[1].next = NULL;
}

// find minimum y position if it starts at x1
static int stbrp__skyline_find_min_y(stbrp_context *c, stbrp_node *first, int x0, int width, int *pwaste)
{
   stbrp_node *node = first;
   int x1 = x0 + width;
   int min_y, visited_width, waste_area;

   STBRP__NOTUSED(c);

   STBRP_ASSERT(first->x <= x0);

   #if 0
   // skip in case we're past the node
   while (node->next->x <= x0)
      ++node;
   #else
   STBRP_ASSERT(node->next->x > x0); // we ended up handling this in the caller for efficiency
   #endif

   STBRP_ASSERT(node->x <= x0);

   min_y = 0;
   waste_area = 0;
   visited_width = 0;
   while (node->x < x1) {
      if (node->y > min_y) {
         // raise min_y higher.
         // we've accounted for all waste up to min_y,
         // but we'll now add more waste for everything we've visited
         waste_area += visited_width * (node->y - min_y);
         min_y = node->y;
         // the first time through, visited_width might be reduced
         if (node->x < x0)
            visited_width += node->next->x - x0;
         else
            visited_width += node->next->x - node->x;
      } else {
         // add waste area
         int under_width = node->next->x - node->x;
         if (under_width + visited_width > width)
            under_width = width - visited_width;
         waste_area += under_width * (min_y - node->y);
         visited_width += under_width;
      }
      node = node->next;
   }

   *pwaste = waste_area;
   return min_y;
}

typedef struct
{
   int x,y;
   stbrp_node **prev_link;
} stbrp__findresult;

static stbrp__findresult stbrp__skyline_find_best_pos(stbrp_context *c, int width, int height)
{
   int best_waste = (1<<30), best_x, best_y = (1 << 30);
   stbrp__findresult fr;
   stbrp_node **prev, *node, *tail, **best = NULL;

   // align to multiple of c->align
   width = (width + c->align - 1);
   width -= width % c->align;
   STBRP_ASSERT(width % c->align == 0);

   // if it can't possibly fit, bail immediately
   if (width > c->width || height > c->height) {
      fr.prev_link = NULL;
      fr.x = fr.y = 0;
      return fr;
   }

   node = c->active_head;
   prev = &c->active_head;
   while (node->x + width <= c->width) {
      int y,waste;
      y = stbrp__skyline_find_min_y(c, node, node->x, width, &waste);
      if (c->heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight) { // actually just want to test BL
         // bottom left
         if (y < best_y) {
            best_y = y;
            best = prev;
         }
      } else {
         // best-fit
         if (y + height <= c->height) {
            // can only use it if it first vertically
            if (y < best_y || (y == best_y && waste < best_waste)) {
               best_y = y;
               best_waste = waste;
               best = prev;
            }
         }
      }
      prev = &node->next;
      node = node->next;
   }

   best_x = (best == NULL) ? 0 : (*best)->x;

   // if doing best-fit (BF), we also have to try aligning right edge to each node position
   //
   // e.g, if fitting
   //
   //     ____________________
   //    |____________________|
   //
   //            into
   //
   //   |                         |
   //   |             ____________|
   //   |____________|
   //
   // then right-aligned reduces waste, but bottom-left BL is always chooses left-aligned
   //
   // This makes BF take about 2x the time

   if (c->heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight) {
      tail = c->active_head;
      node = c->active_head;
      prev = &c->active_head;
      // find first node that's admissible
      while (tail->x < width)
         tail = tail->next;
      while (tail) {
         int xpos = tail->x - width;
         int y,waste;
         STBRP_ASSERT(xpos >= 0);
         // find the left position that matches this
         while (node->next->x <= xpos) {
            prev = &node->next;
            node = node->next;
         }
         STBRP_ASSERT(node->next->x > xpos && node->x <= xpos);
         y = stbrp__skyline_find_min_y(c, node, xpos, width, &waste);
         if (y + height <= c->height) {
            if (y <= best_y) {
               if (y < best_y || waste < best_waste || (waste==best_waste && xpos < best_x)) {
                  best_x = xpos;
                  STBRP_ASSERT(y <= best_y);
                  best_y = y;
                  best_waste = waste;
                  best = prev;
               }
            }
         }
         tail = tail->next;
      }
   }

   fr.prev_link = best;
   fr.x = best_x;
   fr.y = best_y;
   return fr;
}

static stbrp__findresult stbrp__skyline_pack_rectangle(stbrp_context *context, int width, int height)
{
   // find best position according to heuristic
   stbrp__findresult res = stbrp__skyline_find_best_pos(context, width, height);
   stbrp_node *node, *cur;

   // bail if:
   //    1. it failed
   //    2. the best node doesn't fit (we don't always check this)
   //    3. we're out of memory
   if (res.prev_link == NULL || res.y + height > context->height || context->free_head == NULL) {
      res.prev_link = NULL;
      return res;
   }

   // on success, create new node
   node = context->free_head;
   node->x = (stbrp_coord) res.x;
   node->y = (stbrp_coord) (res.y + height);

   context->free_head = node->next;

   // insert the new node into the right starting point, and
   // let 'cur' point to the remaining nodes needing to be
   // stiched back in

   cur = *res.prev_link;
   if (cur->x < res.x) {
      // preserve the existing one, so start testing with the next one
      stbrp_node *next = cur->next;
      cur->next = node;
      cur = next;
   } else {
      *res.prev_link = node;
   }

   // from here, traverse cur and free the nodes, until we get to one
   // that shouldn't be freed
   while (cur->next && cur->next->x <= res.x + width) {
      stbrp_node *next = cur->next;
      // move the current node to the free list
      cur->next = context->free_head;
      context->free_head = cur;
      cur = next;
   }

   // stitch the list back in
   node->next = cur;

   if (cur->x < res.x + width)
      cur->x = (stbrp_coord) (res.x + width);

#ifdef _DEBUG
   cur = context->active_head;
   while (cur->x < context->width) {
      STBRP_ASSERT(cur->x < cur->next->x);
      cur = cur->next;
   }
   STBRP_ASSERT(cur->next == NULL);

   {
      int count=0;
      cur = context->active_head;
      while (cur) {
         cur = cur->next;
         ++count;
      }
      cur = context->free_head;
      while (cur) {
         cur = cur->next;
         ++count;
      }
      STBRP_ASSERT(count == context->num_nodes+2);
   }
#endif

   return res;
}

static int STBRP__CDECL rect_height_compare(const void *a, const void *b)
{
   const stbrp_rect *p = (const stbrp_rect *) a;
   const stbrp_rect *q = (const stbrp_rect *) b;
   if (p->h > q->h)
      return -1;
   if (p->h < q->h)
      return  1;
   return (p->w > q->w) ? -1 : (p->w < q->w);
}

static int STBRP__CDECL rect_original_order(const void *a, const void *b)
{
   const stbrp_rect *p = (const stbrp_rect *) a;
   const stbrp_rect *q = (const stbrp_rect *) b;
   return (p->was_packed < q->was_packed) ? -1 : (p->was_packed > q->was_packed);
}

STBRP_DEF int stbrp_pack_rects(stbrp_context *context, stbrp_rect *rects, int num_rects)
{
   int i, all_rects_packed = 1;

   // we use the 'was_packed' field internally to allow sorting/unsorting
   for (i=0; i < num_rects; ++i) {
      rects[i].was_packed = i;
   }

   // sort according to heuristic
   STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_height_compare);

   for (i=0; i < num_rects; ++i) {
      if (rects[i].w == 0 || rects[i].h == 0) {
         rects[i].x = rects[i].y = 0;  // empty rect needs no space
      } else {
         stbrp__findresult fr = stbrp__skyline_pack_rectangle(context, rects[i].w, rects[i].h);
         if (fr.prev_link) {
            rects[i].x = (stbrp_coord) fr.x;
            rects[i].y = (stbrp_coord) fr.y;
         } else {
            rects[i].x = rects[i].y = STBRP__MAXVAL;
         }
      }
   }

   // unsort
   STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_original_order);

   // set was_packed flags and all_rects_packed status
   for (i=0; i < num_rects; ++i) {
      rects[i].was_packed = !(rects[i].x == STBRP__MAXVAL && rects[i].y == STBRP__MAXVAL);
      if (!rects[i].was_packed)
         all_rects_packed = 0;
   }

   // return the all_rects_packed status
   return all_rects_packed;
}
#endif

/*
------------------------------------------------------------------------------
This software is available under 2 licenses -- choose whichever you prefer.
------------------------------------------------------------------------------
ALTERNATIVE A - MIT License
Copyright (c) 2017 Sean Barrett
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
------------------------------------------------------------------------------
ALTERNATIVE B - Public Domain (www.unlicense.org)
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
software, either in source code form or as a compiled binary, for any purpose,
commercial or non-commercial, and by any means.
In jurisdictions that recognize copyright laws, the author or authors of this
software dedicate any and all copyright interest in the software to the public
domain. We make this dedication for the benefit of the public at large and to
the detriment of our heirs and successors. We intend this dedication to be an
overt act of relinquishment in perpetuity of all present and future rights to
this software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
------------------------------------------------------------------------------
*/