[common] rects: refactor rect buffer copy code to common module

This also fixes a bug of accidentally multiplying the stride by 4 when
the stride is already in bytes and not pixels.

host/platform/Windows/capture/DXGI/src/dxgi.c

@@ -26,6 +26,7 @@
 #include "common/option.h"
 #include "common/locking.h"
 #include "common/event.h"
+#include "common/rects.h"
 #include "common/runningavg.h"
 #include "common/KVMFR.h"
 
@@ -1027,144 +1028,6 @@ static CaptureResult dxgi_waitFrame(CaptureFrame * frame, const size_t maxFrameS
   return CAPTURE_RESULT_OK;
 }
 
-struct Corner
-{
-  int x;
-  int y;
-  int delta;
-};
-
-struct Edge
-{
-  int x;
-  int delta;
-};
-
-static int cornerCompare(const void * a_, const void * b_)
-{
-  const struct Corner * a = a_;
-  const struct Corner * b = b_;
-
-  if (a->y < b->y) return -1;
-  if (a->y > b->y) return +1;
-  if (a->x < b->x) return -1;
-  if (a->x > b->x) return +1;
-  return 0;
-}
-
-inline static void rectCopyUnaligned(uint8_t * dest, const uint8_t * src, int ystart,
-    int yend, int dx, int stride, int width)
-{
-  for (int i = ystart; i < yend; ++i)
-  {
-    unsigned int offset = i * stride + dx;
-    memcpy(dest + offset, src + offset, width);
-  }
-}
-
-static void copyRects(struct FrameDamage * damage, FrameBuffer * frame, int height,
-  const uint8_t * src, int stride)
-{
-  uint8_t * frameData = framebuffer_get_data(frame);
-  struct Corner corners[4 * KVMFR_MAX_DAMAGE_RECTS];
-  const int cornerCount = 4 * damage->count;
-
-  for (int i = 0; i < damage->count; ++i)
-  {
-    FrameDamageRect * rect = damage->rects + i;
-    corners[4 * i + 0] = (struct Corner) {
-      .x = rect->x, .y = rect->y, .delta = 1
-    };
-    corners[4 * i + 1] = (struct Corner) {
-      .x = rect->x + rect->width, .y = rect->y, .delta = -1
-    };
-    corners[4 * i + 2] = (struct Corner) {
-      .x = rect->x, .y = rect->y + rect->height, .delta = -1
-    };
-    corners[4 * i + 3] = (struct Corner) {
-      .x = rect->x + rect->width, .y = rect->y + rect->height, .delta = 1
-    };
-  }
-  qsort(corners, cornerCount, sizeof(struct Corner), cornerCompare);
-
-  struct Edge active_[2][4 * KVMFR_MAX_DAMAGE_RECTS];
-  struct Edge change[4 * KVMFR_MAX_DAMAGE_RECTS];
-  int prev_y = 0;
-  int activeRow = 0;
-  int actives = 0;
-
-  for (int rs = 0;;)
-  {
-    int y = corners[rs].y;
-    int re = rs;
-    while (re < cornerCount && corners[re].y == y)
-      ++re;
-
-    if (y > height)
-      y = height;
-
-    int changes = 0;
-    for (int i = rs; i < re; )
-    {
-      int x = corners[i].x;
-      int delta = 0;
-      while (i < re && corners[i].x == x)
-        delta += corners[i++].delta;
-      change[changes++] = (struct Edge) { .x = x, .delta = delta };
-    }
-
-    struct Edge * active = active_[activeRow];
-    int x1 = 0;
-    int in_rect = 0;
-    for (int i = 0; i < actives; ++i)
-    {
-      if (!in_rect)
-        x1 = active[i].x;
-      in_rect += active[i].delta;
-      if (!in_rect)
-        rectCopyUnaligned(frameData, src, prev_y, y, x1 * 4, stride, (active[i].x - x1) * 4);
-    }
-
-    if (re >= cornerCount || y == height)
-      break;
-
-    framebuffer_set_write_ptr(frame, y * stride * 4);
-
-    struct Edge * new = active_[activeRow ^ 1];
-    int ai = 0;
-    int ci = 0;
-    int ni = 0;
-
-    while (ai < actives && ci < changes)
-    {
-      if (active[ai].x < change[ci].x)
-        new[ni++] = active[ai++];
-      else if (active[ai].x > change[ci].x)
-        new[ni++] = change[ci++];
-      else
-      {
-        active[ai].delta += change[ci++].delta;
-        if (active[ai].delta != 0)
-          new[ni++] = active[ai];
-        ++ai;
-      }
-    }
-
-    // only one of (actives - ai) and (changes - ci) will be non-zero.
-    memcpy(new + ni, active + ai, (actives - ai) * sizeof(struct Edge));
-    memcpy(new + ni, change + ci, (changes - ci) * sizeof(struct Edge));
-    ni += actives - ai;
-    ni += changes - ci;
-
-    actives = ni;
-    prev_y = y;
-    rs = re;
-    activeRow ^= 1;
-  }
-
-  framebuffer_set_write_ptr(frame, height * stride * 4);
-}
-
 static CaptureResult dxgi_getFrame(FrameBuffer * frame,
     const unsigned int height, int frameIndex)
 {
@@ -1184,7 +1047,8 @@ static CaptureResult dxgi_getFrame(FrameBuffer * frame,
     memcpy(damage->rects + damage->count, tex->damageRects,
       tex->damageRectsCount * sizeof(FrameDamageRect));
     damage->count += tex->damageRectsCount;
-    copyRects(damage, frame, height, tex->map.pData, this->pitch);
+    rectsBufferToFramebuffer(damage->rects, damage->count, frame, this->pitch,
+      height, tex->map.pData, this->pitch);
   }
 
   for (int i = 0; i < LGMP_Q_FRAME_LEN; ++i)