Bug 1259529 - Clean up the APZ minimap rendering code a bit. No functional changes. r=BenWa

MozReview-Commit-ID: avf1rlxSpj

gfx/layers/composite/ContainerLayerComposite.cpp

@@ -527,34 +527,15 @@ RenderMinimap(ContainerT* aContainer, LayerManagerComposite* aManager,
   Matrix4x4 transform = Matrix4x4::Scaling(scaleFactor, scaleFactor, 1);
   transform.PostTranslate(horizontalPadding + compositionBounds.x, verticalPadding + compositionBounds.y, 0);
 
-  Rect clipRect = aContainer->GetEffectiveTransform().TransformBounds(
-                    transform.TransformBounds(scrollRect.ToUnknownRect()));
+  Rect transformedScrollRect = transform.TransformBounds(scrollRect.ToUnknownRect());
+
+  Rect clipRect = aContainer->GetEffectiveTransform().TransformBounds(transformedScrollRect);
   clipRect.width++;
   clipRect.height++;
 
-  Rect r;
-  r = transform.TransformBounds(scrollRect.ToUnknownRect());
-  compositor->FillRect(r, backgroundColor, clipRect, aContainer->GetEffectiveTransform());
-
-  /* Disabled because on long pages SlowDrawRect becomes a bottleneck.
-  int tileW = gfxPrefs::LayersTileWidth();
-  int tileH = gfxPrefs::LayersTileHeight();
-
-  for (int x = scrollRect.x; x < scrollRect.XMost(); x += tileW) {
-    for (int y = scrollRect.y; y < scrollRect.YMost(); y += tileH) {
-      LayerRect tileRect = LayerRect(x - x % tileW, y - y % tileH, tileW, tileH);
-      r = transform.TransformBounds(tileRect.ToUnknownRect());
-      if (tileRect.Intersects(dp)) {
-        compositor->FillRect(r, tileActiveColor, clipRect, aContainer->GetEffectiveTransform());
-      }
-      compositor->SlowDrawRect(r, tileBorderColor, clipRect, aContainer->GetEffectiveTransform());
-    }
-  }
-  */
-
   // Render the scrollable area.
-  r = transform.TransformBounds(scrollRect.ToUnknownRect());
-  compositor->SlowDrawRect(r, pageBorderColor, clipRect, aContainer->GetEffectiveTransform());
+  compositor->FillRect(transformedScrollRect, backgroundColor, clipRect, aContainer->GetEffectiveTransform());
+  compositor->SlowDrawRect(transformedScrollRect, pageBorderColor, clipRect, aContainer->GetEffectiveTransform());
 
   // If enabled, render information about visibility.
   if (gfxPrefs::APZMinimapVisibilityEnabled()) {
@@ -585,9 +566,8 @@ RenderMinimap(ContainerT* aContainer, LayerManagerComposite* aManager,
   }
 
   // Render the displayport.
-  r = transform.TransformBounds(dp.ToUnknownRect());
+  Rect r = transform.TransformBounds(dp.ToUnknownRect());
   compositor->FillRect(r, tileActiveColor, clipRect, aContainer->GetEffectiveTransform());
-  r = transform.TransformBounds(dp.ToUnknownRect());
   compositor->SlowDrawRect(r, displayPortColor, clipRect, aContainer->GetEffectiveTransform());
 
   // Render the viewport.