Bug 983591 - Add a Moz2d helper to copy pixel data from a B8G8R8X8 surface to a packed B8G8R8 array. r=Bas

gfx/2d/DataSurfaceHelpers.cpp

@@ -48,6 +48,29 @@ CopySurfaceDataToPackedArray(uint8_t* aSrc, uint8_t* aDst, IntSize aSrcSize,
   }
 }
 
+void
+CopyBGRXSurfaceDataToPackedBGRArray(uint8_t* aSrc, uint8_t* aDst,
+                                    IntSize aSrcSize, int32_t aSrcStride)
+{
+  int packedStride = aSrcSize.width * 3;
+
+  uint8_t* srcPx = aSrc;
+  uint8_t* dstPx = aDst;
+
+  for (int row = 0; row < aSrcSize.height; ++row) {
+    for (int col = 0; col < aSrcSize.height; ++col) {
+      dstPx[0] = srcPx[0];
+      dstPx[1] = srcPx[1];
+      dstPx[2] = srcPx[2];
+      // srcPx[3] (unused or alpha component) dropped on floor
+      srcPx += 4;
+      dstPx += 3;
+    }
+    srcPx = aSrc += aSrcStride;
+    dstPx = aDst += packedStride;
+  }
+}
+
 uint8_t*
 SurfaceToPackedBGRA(DataSourceSurface *aSurface)
 {
@@ -82,5 +105,37 @@ SurfaceToPackedBGRA(DataSourceSurface *aSurface)
   return imageBuffer;
 }
 
+uint8_t*
+SurfaceToPackedBGR(DataSourceSurface *aSurface)
+{
+  SurfaceFormat format = aSurface->GetFormat();
+  MOZ_ASSERT(format == SurfaceFormat::B8G8R8X8, "Format not supported");
+
+  if (format != SurfaceFormat::B8G8R8X8) {
+    // To support B8G8R8A8 we'd need to un-pre-multiply alpha
+    return nullptr;
+  }
+
+  IntSize size = aSurface->GetSize();
+
+  uint8_t* imageBuffer = new (std::nothrow) uint8_t[size.width * size.height * 3 * sizeof(uint8_t)];
+  if (!imageBuffer) {
+    return nullptr;
+  }
+
+  DataSourceSurface::MappedSurface map;
+  if (!aSurface->Map(DataSourceSurface::MapType::READ, &map)) {
+    delete [] imageBuffer;
+    return nullptr;
+  }
+
+  CopyBGRXSurfaceDataToPackedBGRArray(map.mData, imageBuffer, size,
+                                      map.mStride);
+
+  aSurface->Unmap();
+
+  return imageBuffer;
+}
+
 }
 }

gfx/2d/DataSurfaceHelpers.h

@@ -30,5 +30,17 @@ CopySurfaceDataToPackedArray(uint8_t* aSrc, uint8_t* aDst, IntSize aSrcSize,
 uint8_t*
 SurfaceToPackedBGRA(DataSourceSurface *aSurface);
 
+/**
+ * Convert aSurface to a packed buffer in BGR format. The pixel data is
+ * returned in a buffer allocated with new uint8_t[].
+ *
+ * This function is currently only intended for use with surfaces of format
+ * SurfaceFormat::B8G8R8X8 since the X components of the pixel data are simply
+ * dropped (no attempt is made to un-pre-multiply alpha from the color
+ * components).
+ */
+uint8_t*
+SurfaceToPackedBGR(DataSourceSurface *aSurface);
+
 }
 }