Bug 1368776 - Part 11. Add ImageResource::GetImageContainerSize to determine the appropriate size for a requested container. r=tnikkel

image/Image.cpp

@@ -108,7 +108,8 @@ ImageResource::GetImageContainerImpl(LayerManager* aManager,
                == FLAG_NONE,
              "Unsupported flag passed to GetImageContainer");
 
-  if (!IsImageContainerAvailable(aManager, aFlags)) {
+  IntSize size = GetImageContainerSize(aManager, aSize, aFlags);
+  if (size.IsEmpty()) {
     return nullptr;
   }
 
@@ -122,7 +123,7 @@ ImageResource::GetImageContainerImpl(LayerManager* aManager,
   for (; i >= 0; --i) {
     entry = &mImageContainers[i];
     container = entry->mContainer.get();
-    if (aSize == entry->mSize) {
+    if (size == entry->mSize) {
       // Lack of a container is handled below.
       break;
     } else if (!container) {
@@ -156,7 +157,7 @@ ImageResource::GetImageContainerImpl(LayerManager* aManager,
       entry->mContainer = container;
     } else {
       entry = mImageContainers.AppendElement(
-        ImageContainerEntry(aSize, container.get()));
+        ImageContainerEntry(size, container.get()));
     }
   }
 
@@ -165,7 +166,7 @@ ImageResource::GetImageContainerImpl(LayerManager* aManager,
 #endif
 
   entry->mLastDrawResult =
-    AddCurrentImage(container, aSize, aFlags, true);
+    AddCurrentImage(container, size, aFlags, true);
   return container.forget();
 }
 

image/Image.h

@@ -344,6 +344,19 @@ protected:
     return MakePair(DrawResult::BAD_IMAGE, RefPtr<gfx::SourceSurface>());
   }
 
+  /**
+   * Calculate the estimated size to use for an image container with the given
+   * parameters. It may not be the same as the given size, and it may not be
+   * the same as the size of the surface in the image container, but it is the
+   * best effort estimate.
+   */
+  virtual gfx::IntSize GetImageContainerSize(layers::LayerManager* aManager,
+                                             const gfx::IntSize& aSize,
+                                             uint32_t aFlags)
+  {
+    return gfx::IntSize(0, 0);
+  }
+
   already_AddRefed<layers::ImageContainer>
     GetImageContainerImpl(layers::LayerManager* aManager,
                           const gfx::IntSize& aSize,

image/RasterImage.cpp

@@ -620,6 +620,22 @@ RasterImage::GetFrameInternal(const IntSize& aSize,
   return MakePair(DrawResult::SUCCESS, Move(sourceSurface));
 }
 
+IntSize
+RasterImage::GetImageContainerSize(LayerManager* aManager,
+                                   const IntSize& aSize,
+                                   uint32_t aFlags)
+{
+  if (!IsImageContainerAvailableAtSize(aManager, aSize, aFlags)) {
+    return IntSize(0, 0);
+  }
+
+  if (!CanDownscaleDuringDecode(aSize, aFlags)) {
+    return mSize;
+  }
+
+  return aSize;
+}
+
 NS_IMETHODIMP_(bool)
 RasterImage::IsImageContainerAvailable(LayerManager* aManager, uint32_t aFlags)
 {

image/RasterImage.h

@@ -131,6 +131,7 @@ namespace mozilla {
 namespace layers {
 class ImageContainer;
 class Image;
+class LayersManager;
 } // namespace layers
 
 namespace image {
@@ -312,6 +313,10 @@ private:
                      uint32_t aWhichFrame,
                      uint32_t aFlags) override;
 
+  gfx::IntSize GetImageContainerSize(layers::LayerManager* aManager,
+                                     const gfx::IntSize& aSize,
+                                     uint32_t aFlags) override;
+
   //////////////////////////////////////////////////////////////////////////////
   // Decoding.
   //////////////////////////////////////////////////////////////////////////////