b=777946 implement SCALE_STRETCH through ComputeEffectiveTransforms r=Bas

--HG--
extra : transplant_source : 6%CC%1F3%D1g%A7%098%7E%24%3DC%1D6N%F5%1Ax%0F

gfx/layers/ImageLayers.cpp

@@ -24,18 +24,26 @@ void ImageLayer::SetContainer(ImageContainer* aContainer)
 
 void ImageLayer::ComputeEffectiveTransforms(const gfx3DMatrix& aTransformToSurface)
 {
+  gfx3DMatrix local = GetLocalTransform();
+
   // Snap image edges to pixel boundaries
-  gfxRect snap(0, 0, 0, 0);
+  gfxRect sourceRect(0, 0, 0, 0);
   if (mContainer) {
-    gfxIntSize size = mContainer->GetCurrentSize();
-    snap.SizeTo(gfxSize(size.width, size.height));
+    sourceRect.SizeTo(mContainer->GetCurrentSize());
+    if (mScaleMode != SCALE_NONE &&
+        sourceRect.width != 0.0 && sourceRect.height != 0.0) {
+      NS_ASSERTION(mScaleMode == SCALE_STRETCH,
+                   "No other scalemodes than stretch and none supported yet.");
+      local.Scale(mScaleToSize.width / sourceRect.width,
+                  mScaleToSize.height / sourceRect.height, 1.0);
+    }
   }
   // Snap our local transform first, and snap the inherited transform as well.
   // This makes our snapping equivalent to what would happen if our content
   // was drawn into a ThebesLayer (gfxContext would snap using the local
   // transform, then we'd snap again when compositing the ThebesLayer).
   mEffectiveTransform =
-      SnapTransform(GetLocalTransform(), snap, nullptr)*
+      SnapTransform(local, sourceRect, nullptr) *
       SnapTransform(aTransformToSurface, gfxRect(0, 0, 0, 0), nullptr);
   ComputeEffectiveTransformForMaskLayer(aTransformToSurface);
 }

gfx/layers/ImageLayers.h

@@ -24,7 +24,7 @@ class THEBES_API ImageLayer : public Layer {
 public:
   enum ScaleMode {
     SCALE_NONE,
-    SCALE_STRETCH // Unimplemented on GL layers and e10s
+    SCALE_STRETCH
   // Unimplemented - SCALE_PRESERVE_ASPECT_RATIO_CONTAIN
   };
 

gfx/layers/basic/BasicImageLayer.cpp

@@ -98,15 +98,6 @@ BasicImageLayer::GetAndPaintCurrentImage(gfxContext* aContext,
   }
 
   pat->SetFilter(mFilter);
-  gfxIntSize sourceSize = surface->GetSize();
-  if (mScaleMode != SCALE_NONE) {
-    NS_ASSERTION(mScaleMode == SCALE_STRETCH,
-      "No other scalemodes than stretch and none supported yet.");
-    gfxMatrix mat = pat->GetMatrix();
-    mat.Scale(float(sourceSize.width) / mScaleToSize.width, float(sourceSize.height) / mScaleToSize.height);
-    pat->SetMatrix(mat);
-    size = mScaleToSize;
-  }
 
   // The visible region can extend outside the image, so just draw
   // within the image bounds.

gfx/layers/d3d10/ImageLayerD3D10.cpp

@@ -181,7 +181,7 @@ ImageLayerD3D10::RenderLayer()
     return;
   }
 
-  gfxIntSize size = mScaleMode == SCALE_NONE ? image->GetSize() : mScaleToSize;
+  gfxIntSize size = image->GetSize();
 
   SetEffectTransformAndOpacity();
 

gfx/layers/d3d9/ImageLayerD3D9.cpp

@@ -368,7 +368,7 @@ ImageLayerD3D9::RenderLayer()
 
   SetShaderTransformAndOpacity();
 
-  gfxIntSize size = mScaleMode == SCALE_NONE ? image->GetSize() : mScaleToSize;
+  gfxIntSize size = image->GetSize();
 
   if (image->GetFormat() == CAIRO_SURFACE ||
       image->GetFormat() == REMOTE_IMAGE_BITMAP)

gfx/layers/opengl/ImageLayerOGL.cpp

@@ -247,8 +247,6 @@ ImageLayerOGL::RenderLayer(int,
 
   NS_ASSERTION(image->GetFormat() != REMOTE_IMAGE_BITMAP,
     "Remote images aren't handled yet in OGL layers!");
-  NS_ASSERTION(mScaleMode == SCALE_NONE,
-    "Scale modes other than none not handled yet in OGL layers!");
 
   if (image->GetFormat() == PLANAR_YCBCR) {
     PlanarYCbCrImage *yuvImage =