Bug 1418816 - Part 2: Handle repeated image layers in ImageLayerComposite. r=mattwoodrow

Depends on D6024

Differential Revision: https://phabricator.services.mozilla.com/D6025

--HG--
extra : moz-landing-system : lando

gfx/layers/ImageLayers.cpp

@@ -60,5 +60,23 @@ void ImageLayer::ComputeEffectiveTransforms(const gfx::Matrix4x4& aTransformToSu
   ComputeEffectiveTransformForMaskLayers(aTransformToSurface);
 }
 
+gfx::IntPoint
+ImageLayer::GetTopLeftTilePos(const gfx::IntRect& aDestRect,
+                              const gfx::IntRect& aFillRect,
+                              const gfx::IntSize& aRepeatSize)
+{
+  int x = aDestRect.x;
+  while (aRepeatSize.width && x > aFillRect.x) {
+    x -= aRepeatSize.width;
+  }
+
+  int y = aDestRect.y;
+  while (aRepeatSize.width && y > aFillRect.y) {
+    y -= aRepeatSize.height;
+  }
+
+  return gfx::IntPoint(x, y);
+}
+
 } // namespace layers
 } // namespace mozilla

gfx/layers/ImageLayers.h

@@ -98,6 +98,13 @@ protected:
   virtual void PrintInfo(std::stringstream& aStream, const char* aPrefix) override;
   virtual void DumpPacket(layerscope::LayersPacket* aPacket, const void* aParent) override;
 
+  /*
+   * Calculate the position of the top-left tile for repeated images.
+   */
+  static gfx::IntPoint GetTopLeftTilePos(const gfx::IntRect& aDestRect,
+                                         const gfx::IntRect& aFillRect,
+                                         const gfx::IntSize& aRepeatSize);
+
   RefPtr<ImageContainer> mContainer;
   gfx::SamplingFilter mSamplingFilter;
   gfx::IntSize mScaleToSize;

gfx/layers/composite/ImageLayerComposite.cpp

@@ -103,11 +103,31 @@ ImageLayerComposite::RenderLayer(const IntRect& aClipRect,
   RenderWithAllMasks(this, mCompositor, aClipRect,
                      [&](EffectChain& effectChain, const IntRect& clipRect) {
     mImageHost->SetTextureSourceProvider(mCompositor);
-    mImageHost->Composite(mCompositor, this, effectChain,
-                          GetEffectiveOpacity(),
-                          GetEffectiveTransformForBuffer(),
-                          GetSamplingFilter(),
-                          clipRect);
+
+    const IntRect destRect(IntPoint(0, 0), mImageHost->GetImageSize());
+    const IntRect fillRect = mVisibleRegion.GetBounds().ToUnknownRect();
+    const IntPoint topLeft = GetTopLeftTilePos(destRect, fillRect, mRepeatSize);
+
+    for (int x = topLeft.x; x < fillRect.XMost(); x += mRepeatSize.width) {
+      for (int y = topLeft.y; y < fillRect.YMost(); y += mRepeatSize.height) {
+        Matrix4x4 tileTransform = GetEffectiveTransformForBuffer();
+        tileTransform.PreTranslate(x - destRect.x, y - destRect.y, 0);
+
+        mImageHost->Composite(mCompositor, this, effectChain,
+                              GetEffectiveOpacity(),
+                              tileTransform,
+                              GetSamplingFilter(),
+                              clipRect);
+
+        if (!mRepeatSize.height) {
+          break;
+        }
+      }
+      if (!mRepeatSize.width) {
+        break;
+      }
+    }
+
   });
   mImageHost->BumpFlashCounter();
 }