/src/FreeRDP/libfreerdp/codec/region.c

Source
/**
 * FreeRDP: A Remote Desktop Protocol Implementation
 *
 * Copyright 2014 Thincast Technologies GmbH
 * Copyright 2014 Hardening <contact@hardening-consulting.com>
 * Copyright 2017 Armin Novak <armin.novak@thincast.com>
 * Copyright 2017 Thincast Technologies GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <winpr/assert.h>
#include <winpr/memory.h>
#include <freerdp/log.h>
#include <freerdp/codec/region.h>

#define TAG FREERDP_TAG("codec")

/*
 * The functions in this file implement the Region abstraction largely inspired from
 * pixman library. The following comment is taken from the pixman code.
 *
 * A Region is simply a set of disjoint(non-overlapping) rectangles, plus an
 * "extent" rectangle which is the smallest single rectangle that contains all
 * the non-overlapping rectangles.
 *
 * A Region is implemented as a "y-x-banded" array of rectangles.  This array
 * imposes two degrees of order.  First, all rectangles are sorted by top side
 * y coordinate first (y1), and then by left side x coordinate (x1).
 *
 * Furthermore, the rectangles are grouped into "bands".  Each rectangle in a
 * band has the same top y coordinate (y1), and each has the same bottom y
 * coordinate (y2).  Thus all rectangles in a band differ only in their left
 * and right side (x1 and x2).  Bands are implicit in the array of rectangles:
 * there is no separate list of band start pointers.
 *
 * The y-x band representation does not minimize rectangles.  In particular,
 * if a rectangle vertically crosses a band (the rectangle has scanlines in
 * the y1 to y2 area spanned by the band), then the rectangle may be broken
 * down into two or more smaller rectangles stacked one atop the other.
 *
 *  -----------                             -----------
 *  |         |                             |         |             band 0
 *  |         |  --------                   -----------  --------
 *  |         |  |      |  in y-x banded    |         |  |      |   band 1
 *  |         |  |      |  form is          |         |  |      |
 *  -----------  |      |                   -----------  --------
 *               |      |                                |      |   band 2
 *               --------                                --------
 *
 * An added constraint on the rectangles is that they must cover as much
 * horizontal area as possible: no two rectangles within a band are allowed
 * to touch.
 *
 * Whenever possible, bands will be merged together to cover a greater vertical
 * distance (and thus reduce the number of rectangles). Two bands can be merged
 * only if the bottom of one touches the top of the other and they have
 * rectangles in the same places (of the same width, of course).
 */

struct S_REGION16_DATA
{
  size_t nbRects;
  RECTANGLE_16* rects;
};

void region16_init(REGION16* region)
{
  WINPR_ASSERT(region);

  const REGION16 empty = WINPR_C_ARRAY_INIT;
  *region = empty;
}

int region16_n_rects(const REGION16* region)
{
  WINPR_ASSERT(region);
  if (!region->data)
    return 0;

  return WINPR_ASSERTING_INT_CAST(int, region->data->nbRects);
}

const RECTANGLE_16* region16_rects(const REGION16* region, UINT32* nbRects)
{
  if (nbRects)
    *nbRects = 0;

  if (!region)
    return nullptr;

  REGION16_DATA* data = region->data;
  if (!data)
    return nullptr;

  if (nbRects)
    *nbRects = WINPR_ASSERTING_INT_CAST(UINT32, data->nbRects);

  return data->rects;
}

static inline RECTANGLE_16* region16_rects_noconst(REGION16* region)
{
  WINPR_ASSERT(region);

  REGION16_DATA* data = region->data;

  if (!data)
    return nullptr;

  return data->rects;
}

const RECTANGLE_16* region16_extents(const REGION16* region)
{
  if (!region)
    return nullptr;

  return &region->extents;
}

static RECTANGLE_16* region16_extents_noconst(REGION16* region)
{
  if (!region)
    return nullptr;

  return &region->extents;
}

BOOL rectangle_is_empty(const RECTANGLE_16* rect)
{
  WINPR_ASSERT(rect);

  /* A rectangle with width <= 0 or height <= 0 should be regarded
   * as empty.
   */
  return ((rect->left >= rect->right) || (rect->top >= rect->bottom));
}

BOOL region16_is_empty(const REGION16* region)
{
  WINPR_ASSERT(region);
  if (!region->data)
    return TRUE;
  return (region->data->nbRects == 0);
}

BOOL rectangles_equal(const RECTANGLE_16* r1, const RECTANGLE_16* r2)
{
  WINPR_ASSERT(r1);
  WINPR_ASSERT(r2);

  return ((r1->left == r2->left) && (r1->top == r2->top) && (r1->right == r2->right) &&
          (r1->bottom == r2->bottom));
}

BOOL rectangles_intersects(const RECTANGLE_16* r1, const RECTANGLE_16* r2)
{
  RECTANGLE_16 tmp = WINPR_C_ARRAY_INIT;
  return rectangles_intersection(r1, r2, &tmp);
}

BOOL rectangles_intersection(const RECTANGLE_16* r1, const RECTANGLE_16* r2, RECTANGLE_16* dst)
{
  WINPR_ASSERT(r1);
  WINPR_ASSERT(r2);
  WINPR_ASSERT(dst);

  dst->left = MAX(r1->left, r2->left);
  dst->right = MIN(r1->right, r2->right);
  dst->top = MAX(r1->top, r2->top);
  dst->bottom = MIN(r1->bottom, r2->bottom);
  return (dst->left < dst->right) && (dst->top < dst->bottom);
}

const char* rectangle_to_string(const RECTANGLE_16* rect, char* buffer, size_t length)
{
  if (!buffer || (length < 2))
    return nullptr;
  if (!rect)
    (void)_snprintf(buffer, length - 1, "{ nullptr }");
  else
    (void)_snprintf(buffer, length - 1, "{%" PRIu16 "x%" PRIu16 "-%" PRIu16 "x%" PRIu16 "}",
                    rect->left, rect->top, rect->right, rect->bottom);
  return buffer;
}

RECTANGLE_16* rectangles_clone(const RECTANGLE_16* rects, size_t count)
{
  if (count == 0)
    return nullptr;
  if (count > SIZE_MAX / sizeof(RECTANGLE_16))
    return nullptr;

  WINPR_ASSERT(rects);

  RECTANGLE_16* clone = calloc(count, sizeof(RECTANGLE_16));
  if (!clone)
    return nullptr;

  memcpy(clone, rects, sizeof(RECTANGLE_16) * count);
  return clone;
}

static void freeRegion(REGION16_DATA* data)
{
  if (data)
    free(data->rects);
  free(data);
}

void region16_clear(REGION16* region)
{
  WINPR_ASSERT(region);

  freeRegion(region->data);
  region->data = nullptr;

  const RECTANGLE_16 empty = WINPR_C_ARRAY_INIT;
  region->extents = empty;
}

WINPR_ATTR_MALLOC(freeRegion, 1)
WINPR_ATTR_NODISCARD
static REGION16_DATA* allocateRegion(size_t nbItems)
{
  REGION16_DATA* data = calloc(1, sizeof(REGION16_DATA));
  if (!data)
    return nullptr;

  if (nbItems > 0)
  {
    data->rects = calloc(nbItems, sizeof(RECTANGLE_16));
    if (!data->rects)
    {
      free(data);
      return nullptr;
    }
  }

  data->nbRects = nbItems;
  return data;
}

static inline RECTANGLE_16* nextRect(REGION16_DATA* data, size_t index)
{
  WINPR_ASSERT(data);
  if (index + 1 > data->nbRects)
  {
    RECTANGLE_16* rects = realloc(data->rects, (index + 1) * sizeof(RECTANGLE_16));
    if (!rects)
    {
      freeRegion(data);
      return nullptr;
    }

    const RECTANGLE_16 empty = WINPR_C_ARRAY_INIT;
    rects[index] = empty;
    data->nbRects = index + 1;
    data->rects = rects;
  }
  return &data->rects[index];
}

static BOOL resizeRegion(REGION16* region, size_t nbItems)
{
  WINPR_ASSERT(region);
  if (nbItems == 0)
  {
    freeRegion(region->data);
    region->data = nullptr;
    return TRUE;
  }

  if (!region->data)
  {
    region->data = allocateRegion(nbItems);
    return region->data != nullptr;
  }

  RECTANGLE_16* rects = realloc(region->data->rects, nbItems * sizeof(RECTANGLE_16));
  if (!rects)
  {
    free(region->data->rects);
    region->data->nbRects = 0;
    region->data->rects = nullptr;
    return FALSE;
  }

  for (size_t x = region->data->nbRects; x < nbItems; x++)
  {
    const RECTANGLE_16 empty = WINPR_C_ARRAY_INIT;
    rects[x] = empty;
  }
  region->data->rects = rects;
  region->data->nbRects = nbItems;
  return TRUE;
}

static inline BOOL region16_copy_data(REGION16* dst, const REGION16* src)
{
  WINPR_ASSERT(dst);
  WINPR_ASSERT(src);

  freeRegion(dst->data);
  dst->data = nullptr;

  if (src->data && (src->data->nbRects > 0))
  {
    dst->data = allocateRegion(src->data->nbRects);
    if (!dst->data || !dst->data->rects)
      return FALSE;
    memcpy(dst->data->rects, src->data->rects, dst->data->nbRects * sizeof(RECTANGLE_16));
  }
  return TRUE;
}

BOOL region16_copy(REGION16* dst, const REGION16* src)
{
  if (dst == src)
    return TRUE;

  WINPR_ASSERT(dst);
  WINPR_ASSERT(src);

  dst->extents = src->extents;

  return region16_copy_data(dst, src);
}

void region16_print(const REGION16* region)
{
  UINT32 nbRects = 0;
  int currentBandY = -1;
  const RECTANGLE_16* rects = region16_rects(region, &nbRects);

  WLog_DBG(TAG, "nrects=%" PRIu32 "", nbRects);

  for (UINT32 i = 0; i < nbRects; i++)
  {
    const RECTANGLE_16* rect = &rects[i];

    if (rect->top != currentBandY)
    {
      currentBandY = rect->top;
      WLog_DBG(TAG, "band %d: ", currentBandY);
    }

    WLog_DBG(TAG, "(%" PRIu16 ",%" PRIu16 "-%" PRIu16 ",%" PRIu16 ")", rect->left, rect->top,
             rect->right, rect->bottom);
  }
}

char* region16_to_string(const REGION16* region)
{
  if (!region)
    return _strdup("REGION16{nullptr}");

  UINT32 nbRects = 0;
  const RECTANGLE_16* rects = region16_rects(region, &nbRects);

  char* str = nullptr;
  size_t slen = 0;
  winpr_asprintf(&str, &slen, "REGION16{nrects=%" PRIu32 " [", nbRects);

  UINT16 currentBandY = 0;
  for (UINT32 i = 0; i < nbRects; i++)
  {
    const RECTANGLE_16* rect = &rects[i];

    if (rect->top != currentBandY)
    {
      currentBandY = rect->top;
      char* tmp = nullptr;
      winpr_asprintf(&tmp, &slen, "%sband %" PRIu16 ":", str, currentBandY);
      free(str);
      str = tmp;
    }

    char buffer[64] = WINPR_C_ARRAY_INIT;
    char* tmp = nullptr;
    winpr_asprintf(&tmp, &slen, "%s, %s", str,
                   rectangle_to_string(rect, buffer, sizeof(buffer)));
    free(str);
    str = tmp;
  }

  char* tmp = nullptr;
  winpr_asprintf(&tmp, &slen, "%s]}", str);
  free(str);
  return tmp;
}

static BOOL region16_copy_band_with_union(REGION16_DATA* region, const RECTANGLE_16* src,
                                          const RECTANGLE_16* end, UINT16 newTop, UINT16 newBottom,
                                          const RECTANGLE_16* unionRect, UINT32* dstCounter,
                                          const RECTANGLE_16** srcPtr)
{
  WINPR_ASSERT(region);
  WINPR_ASSERT(src);
  WINPR_ASSERT(end);
  WINPR_ASSERT(dstCounter);

  UINT16 refY = src->top;

  /* merges a band with the given rect
   * Input:
   *                   unionRect
   *               |               |
   *               |               |
   * ==============+===============+================================
   *   |Item1|  |Item2| |Item3|  |Item4|    |Item5|            Band
   * ==============+===============+================================
   *    before     |    overlap    |          after
   *
   * Resulting band:
   *   +-----+  +----------------------+    +-----+
   *   |Item1|  |      Item2           |    |Item3|
   *   +-----+  +----------------------+    +-----+
   *
   *  We first copy as-is items that are before Item2, the first overlapping
   *  item.
   *  Then we find the last one that overlap unionRect to aggregate Item2, Item3
   *  and Item4 to create Item2.
   *  Finally Item5 is copied as Item3.
   *
   *  When no unionRect is provided, we skip the two first steps to just copy items
   */

  if (unionRect)
  {
    /* items before unionRect */
    while ((src < end) && (src->top == refY) && (src->right < unionRect->left))
    {
      RECTANGLE_16* dst = nextRect(region, (*dstCounter)++);
      if (!dst)
        return FALSE;
      dst->top = newTop;
      dst->bottom = newBottom;
      dst->right = src->right;
      dst->left = src->left;
      src++;
    }

    /* treat items overlapping with unionRect */
    const RECTANGLE_16* startOverlap = unionRect;
    const RECTANGLE_16* endOverlap = unionRect;

    if ((src < end) && (src->top == refY) && (src->left < unionRect->left))
      startOverlap = src;

    while ((src < end) && (src->top == refY) && (src->right < unionRect->right))
    {
      src++;
    }

    if ((src < end) && (src->top == refY) && (src->left < unionRect->right))
    {
      endOverlap = src;
      src++;
    }

    {
      RECTANGLE_16* dst = nextRect(region, (*dstCounter)++);
      if (!dst)
        return FALSE;
      dst->bottom = newBottom;
      dst->top = newTop;
      dst->left = startOverlap->left;
      dst->right = endOverlap->right;
    }
  }

  /* treat remaining items on the same band */
  while ((src < end) && (src->top == refY))
  {
    RECTANGLE_16* dst = nextRect(region, (*dstCounter)++);
    if (!dst)
      return FALSE;

    dst->top = newTop;
    dst->bottom = newBottom;
    dst->right = src->right;
    dst->left = src->left;
    src++;
  }

  if (srcPtr)
    *srcPtr = src;

  return TRUE;
}

static RECTANGLE_16* next_band(RECTANGLE_16* band1, RECTANGLE_16* endPtr, int* nbItems)
{
  WINPR_ASSERT(band1);
  WINPR_ASSERT(endPtr);
  WINPR_ASSERT(nbItems);

  UINT16 refY = band1->top;
  *nbItems = 0;

  while ((band1 < endPtr) && (band1->top == refY))
  {
    band1++;
    *nbItems += 1;
  }

  return band1;
}

static BOOL band_match(const RECTANGLE_16* band1, const RECTANGLE_16* band2,
                       const RECTANGLE_16* endPtr)
{
  int refBand2 = band2->top;
  const RECTANGLE_16* band2Start = band2;

  while ((band1 < band2Start) && (band2 < endPtr) && (band2->top == refBand2))
  {
    if ((band1->left != band2->left) || (band1->right != band2->right))
      return FALSE;

    band1++;
    band2++;
  }

  if (band1 != band2Start)
    return FALSE;

  return (band2 == endPtr) || (band2->top != refBand2);
}

/** compute if the rectangle is fully included in the band
 * @param band a pointer on the beginning of the band
 * @param endPtr end of the region
 * @param rect the rectangle to test
 * @return if rect is fully included in an item of the band
 */
static BOOL rectangle_contained_in_band(const RECTANGLE_16* band, const RECTANGLE_16* endPtr,
                                        const RECTANGLE_16* rect)
{
  WINPR_ASSERT(band);
  WINPR_ASSERT(endPtr);
  WINPR_ASSERT(rect);

  UINT16 refY = band->top;

  if ((band->top > rect->top) || (rect->bottom > band->bottom))
    return FALSE;

  /* note: as the band is sorted from left to right, once we've seen an item
   *    that is after rect->left we're sure that the result is False.
   */
  while ((band < endPtr) && (band->top == refY) && (band->left <= rect->left))
  {
    if (rect->right <= band->right)
      return TRUE;

    band++;
  }

  return FALSE;
}

static BOOL region16_simplify_bands(REGION16* region)
{
  /** Simplify consecutive bands that touch and have the same items
   *
   *  ====================          ====================
   *     | 1 |  | 2   |               |   |  |     |
   *  ====================            |   |  |     |
   *     | 1 |  | 2   |    ====>    | 1 |  |  2  |
   *  ====================            |   |  |     |
   *     | 1 |  | 2   |               |   |  |     |
   *  ====================          ====================
   *
   */

  const int nbRects = region16_n_rects(region);
  int finalNbRects = nbRects;

  if (nbRects < 2)
    return TRUE;

  RECTANGLE_16* band1 = region16_rects_noconst(region);
  RECTANGLE_16* endPtr = band1 + nbRects;

  do
  {
    int bandItems = 0;
    RECTANGLE_16* band2 = next_band(band1, endPtr, &bandItems);

    if (band2 == endPtr)
      break;

    if ((band1->bottom == band2->top) && band_match(band1, band2, endPtr))
    {
      /* adjust the bottom of band1 items */
      RECTANGLE_16* tmp = band1;

      while (tmp < band2)
      {
        tmp->bottom = band2->bottom;
        tmp++;
      }

      /* override band2, we don't move band1 pointer as the band after band2
       * may be merged too */
      const RECTANGLE_16* endBand = band2 + bandItems;
      const size_t toMove =
          WINPR_ASSERTING_INT_CAST(size_t, (endPtr - endBand)) * sizeof(RECTANGLE_16);

      if (toMove)
        MoveMemory(band2, endBand, toMove);

      finalNbRects -= bandItems;
      endPtr -= bandItems;
    }
    else
    {
      band1 = band2;
    }
  } while (TRUE);

  if (finalNbRects != nbRects)
  {
    if (!resizeRegion(region, WINPR_ASSERTING_INT_CAST(size_t, finalNbRects)))
      return FALSE;
  }

  return TRUE;
}

BOOL region16_union_rect(REGION16* dst, const REGION16* src, const RECTANGLE_16* rect)
{
  const RECTANGLE_16* nextBand = nullptr;
  UINT32 srcNbRects = 0;
  UINT16 topInterBand = 0;
  WINPR_ASSERT(src);
  WINPR_ASSERT(dst);

  const RECTANGLE_16* srcExtents = region16_extents(src);
  RECTANGLE_16* dstExtents = region16_extents_noconst(dst);

  const int nrSrcRects = region16_n_rects(src);
  if (nrSrcRects == 0)
  {
    /* source is empty, so the union is rect */
    dst->extents = *rect;

    if (!resizeRegion(dst, 1))
      return FALSE;

    RECTANGLE_16* dstRect = region16_rects_noconst(dst);
    WINPR_ASSERT(dstRect);

    dstRect->top = rect->top;
    dstRect->left = rect->left;
    dstRect->right = rect->right;
    dstRect->bottom = rect->bottom;
    dst->data->nbRects = 1;
    return TRUE;
  }

  REGION16_DATA* newItems = allocateRegion(WINPR_ASSERTING_INT_CAST(size_t, nrSrcRects + 1));

  if (!newItems)
    return FALSE;

  UINT32 usedRects = 0;

  /* adds the piece of rect that is on the top of src */
  if (rect->top < srcExtents->top)
  {
    RECTANGLE_16* dstRect = nextRect(newItems, usedRects++);
    if (!dstRect)
      return FALSE;

    dstRect->top = rect->top;
    dstRect->left = rect->left;
    dstRect->right = rect->right;
    dstRect->bottom = MIN(srcExtents->top, rect->bottom);
  }

  /* treat possibly overlapping region */
  const RECTANGLE_16* currentBand = region16_rects(src, &srcNbRects);
  const RECTANGLE_16* endSrcRect = currentBand + srcNbRects;

  while (currentBand < endSrcRect)
  {
    if ((currentBand->bottom <= rect->top) || (rect->bottom <= currentBand->top) ||
        rectangle_contained_in_band(currentBand, endSrcRect, rect))
    {
      /* no overlap between rect and the band, rect is totally below or totally above
       * the current band, or rect is already covered by an item of the band.
       * let's copy all the rectangles from this band
                  +----+
                  |    |   rect (case 1)
                  +----+

         =================
      band of srcRect
       =================
              +----+
              |    |   rect (case 2)
              +----+
      */
      if (!region16_copy_band_with_union(newItems, currentBand, endSrcRect, currentBand->top,
                                         currentBand->bottom, nullptr, &usedRects, &nextBand))
        return FALSE;
      topInterBand = rect->top;
    }
    else
    {
      /* rect overlaps the band:
                 |    |  |    |
      ====^=================|    |==|    |=========================== band
      |   top split     |    |  |    |
      v                 | 1  |  | 2  |
      ^                 |    |  |    |  +----+   +----+
      |   merge zone    |    |  |    |  |    |   | 4  |
      v                 +----+  |    |  |    |   +----+
      ^                         |    |  | 3  |
      |   bottom split          |    |  |    |
      ====v=========================|    |==|    |===================
                 |    |  |    |

       possible cases:
       1) no top split, merge zone then a bottom split. The band will be split
        in two
       2) not band split, only the merge zone, band merged with rect but not split
       3) a top split, the merge zone and no bottom split. The band will be split
       in two
       4) a top split, the merge zone and also a bottom split. The band will be
       split in 3, but the coalesce algorithm may merge the created bands
       */
      UINT16 mergeTop = currentBand->top;
      UINT16 mergeBottom = currentBand->bottom;

      /* test if we need a top split, case 3 and 4 */
      if (rect->top > currentBand->top)
      {
        if (!region16_copy_band_with_union(newItems, currentBand, endSrcRect,
                                           currentBand->top, rect->top, nullptr, &usedRects,
                                           &nextBand))
          return FALSE;
        mergeTop = rect->top;
      }

      /* do the merge zone (all cases) */
      if (rect->bottom < currentBand->bottom)
        mergeBottom = rect->bottom;

      if (!region16_copy_band_with_union(newItems, currentBand, endSrcRect, mergeTop,
                                         mergeBottom, rect, &usedRects, &nextBand))
        return FALSE;

      /* test if we need a bottom split, case 1 and 4 */
      if (rect->bottom < currentBand->bottom)
      {
        if (!region16_copy_band_with_union(newItems, currentBand, endSrcRect, mergeBottom,
                                           currentBand->bottom, nullptr, &usedRects,
                                           &nextBand))
          return FALSE;
      }

      topInterBand = currentBand->bottom;
    }

    /* test if a piece of rect should be inserted as a new band between
     * the current band and the next one. band n and n+1 shouldn't touch.
     *
     * ==============================================================
     *                                                        band n
     *            +------+                    +------+
     * ===========| rect |====================|      |===============
     *            |      |    +------+        |      |
     *            +------+    | rect |        | rect |
     *                        +------+        |      |
     * =======================================|      |================
     *                                        +------+         band n+1
     * ===============================================================
     *
     */
    if ((nextBand < endSrcRect) && (nextBand->top != currentBand->bottom) &&
        (rect->bottom > currentBand->bottom) && (rect->top < nextBand->top))
    {
      RECTANGLE_16* dstRect = nextRect(newItems, usedRects++);
      if (!dstRect)
        return FALSE;

      dstRect->right = rect->right;
      dstRect->left = rect->left;
      dstRect->top = topInterBand;
      dstRect->bottom = MIN(nextBand->top, rect->bottom);
    }

    currentBand = nextBand;
  }

  /* adds the piece of rect that is below src */
  if (srcExtents->bottom < rect->bottom)
  {
    RECTANGLE_16* dstRect = nextRect(newItems, usedRects++);
    if (!dstRect)
      return FALSE;

    dstRect->top = MAX(srcExtents->bottom, rect->top);
    dstRect->left = rect->left;
    dstRect->right = rect->right;
    dstRect->bottom = rect->bottom;
  }

  dstExtents->top = MIN(rect->top, srcExtents->top);
  dstExtents->left = MIN(rect->left, srcExtents->left);
  dstExtents->bottom = MAX(rect->bottom, srcExtents->bottom);
  dstExtents->right = MAX(rect->right, srcExtents->right);

  newItems->nbRects = usedRects;
  freeRegion(dst->data);
  dst->data = newItems;

  return region16_simplify_bands(dst);
}

BOOL region16_intersects_rect(const REGION16* src, const RECTANGLE_16* arg2)
{
  const RECTANGLE_16* endPtr = nullptr;
  UINT32 nbRects = 0;

  if (!src || !src->data || !arg2)
    return FALSE;

  const RECTANGLE_16* rect = region16_rects(src, &nbRects);

  if (!nbRects)
    return FALSE;

  const RECTANGLE_16* srcExtents = region16_extents(src);

  if (nbRects == 1)
    return rectangles_intersects(srcExtents, arg2);

  if (!rectangles_intersects(srcExtents, arg2))
    return FALSE;

  for (endPtr = rect + nbRects; (rect < endPtr) && (arg2->bottom > rect->top); rect++)
  {
    if (rectangles_intersects(rect, arg2))
      return TRUE;
  }

  return FALSE;
}

BOOL region16_intersect_rect(REGION16* dst, const REGION16* src, const RECTANGLE_16* rect)
{
  const RECTANGLE_16* endPtr = nullptr;
  UINT32 nbRects = 0;
  RECTANGLE_16 common = WINPR_C_ARRAY_INIT;

  WINPR_ASSERT(dst);
  WINPR_ASSERT(src);

  const RECTANGLE_16* srcPtr = region16_rects(src, &nbRects);

  if (!nbRects)
  {
    region16_clear(dst);
    return TRUE;
  }

  const RECTANGLE_16* srcExtents = region16_extents(src);

  if (nbRects == 1)
  {
    BOOL intersects = rectangles_intersection(srcExtents, rect, &common);
    region16_clear(dst);

    if (intersects)
      return region16_union_rect(dst, dst, &common);

    return TRUE;
  }

  REGION16_DATA* newItems = allocateRegion(nbRects);

  if (!newItems)
    return FALSE;

  RECTANGLE_16* dstPtr = newItems->rects;
  UINT32 usedRects = 0;
  RECTANGLE_16 newExtents = WINPR_C_ARRAY_INIT;

  /* accumulate intersecting rectangles, the final region16_simplify_bands() will
   * do all the bad job to recreate correct rectangles
   */
  for (endPtr = srcPtr + nbRects; (srcPtr < endPtr) && (rect->bottom > srcPtr->top); srcPtr++)
  {
    if (usedRects > nbRects)
    {
      freeRegion(newItems);
      return FALSE;
    }

    if (rectangles_intersection(srcPtr, rect, &common))
    {
      *dstPtr = common;
      usedRects++;
      dstPtr++;

      if (rectangle_is_empty(&newExtents))
      {
        /* Check if the existing newExtents is empty. If it is empty, use
         * new common directly. We do not need to check common rectangle
         * because the rectangles_intersection() ensures that it is not empty.
         */
        newExtents = common;
      }
      else
      {
        newExtents.top = MIN(common.top, newExtents.top);
        newExtents.left = MIN(common.left, newExtents.left);
        newExtents.bottom = MAX(common.bottom, newExtents.bottom);
        newExtents.right = MAX(common.right, newExtents.right);
      }
    }
  }

  newItems->nbRects = usedRects;

  freeRegion(dst->data);
  dst->data = newItems;
  dst->extents = newExtents;
  return region16_simplify_bands(dst);
}

void region16_uninit(REGION16* region)
{
  WINPR_ASSERT(region);

  freeRegion(region->data);
  region->data = nullptr;
}

Coverage Report

Created: 2026-07-16 07:10