Bug 1407752 - Avoid taking the webrender fallback path for empty borders. r=jrmuizel

MozReview-Commit-ID: BTSljrUuKcH

--HG--
extra : rebase_source : f5370968de71c9b46dee32b743908f971c1ed3df

layout/forms/nsButtonFrameRenderer.cpp

@@ -265,7 +265,10 @@ class nsDisplayButtonBorder : public nsDisplayItem {
 public:
   nsDisplayButtonBorder(nsDisplayListBuilder* aBuilder,
                                   nsButtonFrameRenderer* aRenderer)
-    : nsDisplayItem(aBuilder, aRenderer->GetFrame()), mBFR(aRenderer) {
+    : nsDisplayItem(aBuilder, aRenderer->GetFrame())
+    , mBFR(aRenderer)
+    , mBorderIsEmpty(false)
+  {
     MOZ_COUNT_CTOR(nsDisplayButtonBorder);
   }
 #ifdef NS_BUILD_REFCNT_LOGGING
@@ -303,6 +306,7 @@ public:
 private:
   nsButtonFrameRenderer* mBFR;
   Maybe<nsCSSBorderRenderer> mBorderRenderer;
+  bool mBorderIsEmpty;
 };
 
 nsDisplayItemGeometry*
@@ -329,6 +333,7 @@ nsDisplayButtonBorder::GetLayerState(nsDisplayListBuilder* aBuilder,
       return LAYER_NONE;
     }
 
+    mBorderIsEmpty = false;
     Maybe<nsCSSBorderRenderer> br =
     nsCSSRendering::CreateBorderRenderer(mFrame->PresContext(),
                                          nullptr,
@@ -336,8 +341,12 @@ nsDisplayButtonBorder::GetLayerState(nsDisplayListBuilder* aBuilder,
                                          nsRect(),
                                          nsRect(offset, mFrame->GetSize()),
                                          mFrame->StyleContext(),
-                                         mFrame->GetSkipSides());
+                                         mFrame->GetSkipSides(),
+                                         &mBorderIsEmpty);
     if (!br) {
+      if (mBorderIsEmpty) {
+        return LAYER_ACTIVE;
+      }
       return LAYER_NONE;
     }
 
@@ -372,7 +381,11 @@ nsDisplayButtonBorder::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&
     return false;
   }
 
-  MOZ_ASSERT(mBorderRenderer);
+  if (!mBorderRenderer) {
+    // empty border, nothing to do
+    MOZ_ASSERT(mBorderIsEmpty);
+    return true;
+  }
 
   // This is really a combination of paint box shadow inner +
   // paint border.

layout/painting/nsCSSRendering.cpp

@@ -667,7 +667,8 @@ nsCSSRendering::CreateBorderRenderer(nsPresContext* aPresContext,
                                      const nsRect& aDirtyRect,
                                      const nsRect& aBorderArea,
                                      nsStyleContext* aStyleContext,
-                                     Sides aSkipSides)
+                                     Sides aSkipSides,
+                                     bool* aOutBorderIsEmpty)
 {
   nsStyleContext *styleIfVisited = aStyleContext->GetStyleIfVisited();
   const nsStyleBorder *styleBorder = aStyleContext->StyleBorder();
@@ -677,7 +678,8 @@ nsCSSRendering::CreateBorderRenderer(nsPresContext* aPresContext,
     return CreateBorderRendererWithStyleBorder(aPresContext, aDrawTarget,
                                                aForFrame, aDirtyRect,
                                                aBorderArea, *styleBorder,
-                                               aStyleContext, aSkipSides);
+                                               aStyleContext, aSkipSides,
+                                               aOutBorderIsEmpty);
   }
 
   nsStyleBorder newStyleBorder(*styleBorder);
@@ -690,7 +692,7 @@ nsCSSRendering::CreateBorderRenderer(nsPresContext* aPresContext,
   return CreateBorderRendererWithStyleBorder(aPresContext, aDrawTarget,
                                              aForFrame, aDirtyRect, aBorderArea,
                                              newStyleBorder, aStyleContext,
-                                             aSkipSides);
+                                             aSkipSides, aOutBorderIsEmpty);
 }
 
 
@@ -982,7 +984,8 @@ nsCSSRendering::CreateBorderRendererWithStyleBorder(nsPresContext* aPresContext,
                                                     const nsRect& aBorderArea,
                                                     const nsStyleBorder& aStyleBorder,
                                                     nsStyleContext* aStyleContext,
-                                                    Sides aSkipSides)
+                                                    Sides aSkipSides,
+                                                    bool* aOutBorderIsEmpty)
 {
   const nsStyleDisplay* displayData = aStyleContext->StyleDisplay();
   if (displayData->mAppearance) {
@@ -1002,6 +1005,9 @@ nsCSSRendering::CreateBorderRendererWithStyleBorder(nsPresContext* aPresContext,
   if (0 == border.left && 0 == border.right &&
       0 == border.top  && 0 == border.bottom) {
     // Empty border area
+    if (aOutBorderIsEmpty) {
+      *aOutBorderIsEmpty = true;
+    }
     return Nothing();
   }
 

layout/painting/nsCSSRendering.h

@@ -193,7 +193,8 @@ struct nsCSSRendering {
                        const nsRect& aDirtyRect,
                        const nsRect& aBorderArea,
                        nsStyleContext* aStyleContext,
-                       Sides aSkipSides = Sides());
+                       Sides aSkipSides = Sides(),
+                       bool* aOutBorderIsEmpty = nullptr);
 
   static mozilla::Maybe<nsCSSBorderRenderer>
   CreateBorderRendererWithStyleBorder(nsPresContext* aPresContext,
@@ -203,7 +204,8 @@ struct nsCSSRendering {
                                       const nsRect& aBorderArea,
                                       const nsStyleBorder& aBorderStyle,
                                       nsStyleContext* aStyleContext,
-                                      Sides aSkipSides = Sides());
+                                      Sides aSkipSides = Sides(),
+                                      bool* aOutBorderIsEmpty = nullptr);
 
   static mozilla::Maybe<nsCSSBorderRenderer>
   CreateBorderRendererForOutline(nsPresContext* aPresContext,