Bug 375403 originally started off as a simple request to enable window translucency when windows or popups use opacity, alpha transparent background or non-zero border radius but mutated to include refactoring non zero side testing r+sr=roc

layout/base/nsDisplayList.cpp

@@ -465,35 +465,6 @@ void nsDisplayList::Sort(nsDisplayListBuilder* aBuilder,
   ::Sort(this, Count(), aCmp, aClosure);
 }
 
-static PRBool
-NonZeroStyleCoord(const nsStyleCoord& aCoord) {
-  switch (aCoord.GetUnit()) {
-  case eStyleUnit_Percent:
-    return aCoord.GetPercentValue() > 0;
-  case eStyleUnit_Coord:
-    return aCoord.GetCoordValue() > 0;
-  case eStyleUnit_Null:
-    return PR_FALSE;
-  default:
-    return PR_TRUE;
-  }
-}
-
-static PRBool
-HasNonZeroSide(const nsStyleSides& aSides) {
-  nsStyleCoord coord;
-  aSides.GetTop(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
-  aSides.GetRight(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
-  aSides.GetBottom(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
-  aSides.GetLeft(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
-
-  return PR_FALSE;
-}
-
 PRBool
 nsDisplayBackground::IsOpaque(nsDisplayListBuilder* aBuilder) {
   // theme background overrides any other background
@@ -506,7 +477,7 @@ nsDisplayBackground::IsOpaque(nsDisplayListBuilder* aBuilder) {
     nsCSSRendering::FindBackground(mFrame->PresContext(), mFrame, &bg, &isCanvas);
   if (!hasBG || (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) ||
       bg->mBackgroundClip != NS_STYLE_BG_CLIP_BORDER ||
-      HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) ||
+      nsLayoutUtils::HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) ||
       NS_GET_A(bg->mBackgroundColor) < 255)
     return PR_FALSE;
   return PR_TRUE;
@@ -525,7 +496,7 @@ nsDisplayBackground::IsUniform(nsDisplayListBuilder* aBuilder) {
   if (!hasBG)
     return PR_TRUE;
   if ((bg->mBackgroundFlags & NS_STYLE_BG_IMAGE_NONE) &&
-      !HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) &&
+      !nsLayoutUtils::HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) &&
       bg->mBackgroundClip == NS_STYLE_BG_CLIP_BORDER)
     return PR_TRUE;
   return PR_FALSE;
@@ -594,7 +565,7 @@ nsDisplayOutline::OptimizeVisibility(nsDisplayListBuilder* aBuilder,
   const nsStyleOutline* outline = mFrame->GetStyleOutline();
   nsPoint origin = aBuilder->ToReferenceFrame(mFrame);
   if (nsRect(origin, mFrame->GetSize()).Contains(aVisibleRegion->GetBounds()) &&
-      !HasNonZeroSide(outline->mOutlineRadius)) {
+      !nsLayoutUtils::HasNonZeroSide(outline->mOutlineRadius)) {
     nscoord outlineOffset;
     outline->GetOutlineOffset(outlineOffset);
     if (outlineOffset >= 0) {
@@ -626,7 +597,7 @@ nsDisplayBorder::OptimizeVisibility(nsDisplayListBuilder* aBuilder,
   nsRect contentRect = GetBounds(aBuilder);
   contentRect.Deflate(border->GetBorder());
   if (contentRect.Contains(aVisibleRegion->GetBounds()) &&
-      !HasNonZeroSide(border->mBorderRadius)) {
+      !nsLayoutUtils::HasNonZeroSide(border->mBorderRadius)) {
     // the visible region is entirely inside the content rect, and no part
     // of the border is rendered inside the content rect, so we are not
     // visible

layout/base/nsLayoutUtils.cpp

@@ -65,6 +65,7 @@
 #include "gfxRect.h"
 #include "nsIImage.h"
 #include "nsIInterfaceRequestorUtils.h"
+#include "nsCSSRendering.h"
 
 #ifdef MOZ_SVG_FOREIGNOBJECT
 #include "nsSVGForeignObjectFrame.h"
@@ -2176,3 +2177,57 @@ nsLayoutUtils::CharsToCoord(const nsStyleCoord& aStyle,
   aRenderingContext->GetWidth('M', fontWidth);
   return aStyle.GetIntValue() * fontWidth;
 }
+
+static PRBool NonZeroStyleCoord(const nsStyleCoord& aCoord)
+{
+  switch (aCoord.GetUnit()) {
+  case eStyleUnit_Percent:
+    return aCoord.GetPercentValue() > 0;
+  case eStyleUnit_Coord:
+    return aCoord.GetCoordValue() > 0;
+  case eStyleUnit_Null:
+    return PR_FALSE;
+  default:
+    return PR_TRUE;
+  }
+}
+
+/* static */ PRBool
+nsLayoutUtils::HasNonZeroSide(const nsStyleSides& aSides)
+{
+  nsStyleCoord coord;
+  aSides.GetTop(coord);
+  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
+  aSides.GetRight(coord);
+  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
+  aSides.GetBottom(coord);
+  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
+  aSides.GetLeft(coord);
+  if (NonZeroStyleCoord(coord)) return PR_TRUE;    
+  return PR_FALSE;
+}
+
+/* static */ PRBool
+nsLayoutUtils::FrameHasTransparency(nsIFrame* aFrame) {
+  if (aFrame->GetStyleContext()->GetStyleDisplay()->mOpacity < 1.0f)
+    return PR_TRUE;
+
+  const nsStyleBorder* border = aFrame->GetStyleContext()->GetStyleBorder();
+  if (HasNonZeroSide(border->mBorderRadius))
+    return PR_TRUE;
+
+  if (aFrame->IsThemed())
+    return PR_FALSE;
+
+  PRBool isCanvas;
+  const nsStyleBackground* bg;
+  if (!nsCSSRendering::FindBackground(aFrame->PresContext(), aFrame, &bg, &isCanvas))
+    return PR_TRUE;
+  if (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT)
+    return PR_TRUE;
+  if (NS_GET_A(bg->mBackgroundColor) < 255)
+    return PR_TRUE;
+  if (bg->mBackgroundClip != NS_STYLE_BG_CLIP_BORDER)
+    return PR_TRUE;
+  return PR_FALSE;
+}

layout/base/nsLayoutUtils.h

@@ -676,6 +676,20 @@ public:
   static nscoord CharsToCoord(const nsStyleCoord& aStyle,
                               nsIRenderingContext* aRenderingContext,
                               nsStyleContext* aStyleContext);
+
+  /**
+   * Determine if any style coordinate is nonzero
+   *   @param aCoord the style sides
+   *   @return PR_TRUE unless all the coordinates are 0%, 0 or null.
+   */
+  static PRBool HasNonZeroSide(const nsStyleSides& aSides);
+
+  /**
+   * Determine if a widget is likely to require transparency or translucency.
+   *   @param aFrame the frame of a <window>, <popup> or <menupopup> element.
+   *   @return a value suitable for passing to SetWindowTranslucency
+   */
+  static PRBool FrameHasTransparency(nsIFrame* aFrame);
 };
 
 #endif // nsLayoutUtils_h__

layout/generic/nsContainerFrame.cpp

@@ -394,37 +394,10 @@ nsContainerFrame::PositionFrameView(nsIFrame* aKidFrame)
   vm->MoveViewTo(view, pt.x, pt.y);
 }
 
-// This code is duplicated in nsDisplayList.cpp. We'll remove the duplication
-// when we remove all this view sync code.
-static PRBool
-NonZeroStyleCoord(const nsStyleCoord& aCoord) {
-  switch (aCoord.GetUnit()) {
-  case eStyleUnit_Percent:
-    return aCoord.GetPercentValue() > 0;
-  case eStyleUnit_Coord:
-    return aCoord.GetCoordValue() > 0;
-  case eStyleUnit_Null:
-    return PR_FALSE;
-  default:
-    return PR_TRUE;
-  }
-}
-
 static PRBool
 HasNonZeroBorderRadius(nsStyleContext* aStyleContext) {
   const nsStyleBorder* border = aStyleContext->GetStyleBorder();
-
+  return nsLayoutUtils::HasNonZeroSide(border->mBorderRadius);
-  nsStyleCoord coord;
-  border->mBorderRadius.GetTop(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;
-  border->mBorderRadius.GetRight(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;
-  border->mBorderRadius.GetBottom(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;
-  border->mBorderRadius.GetLeft(coord);
-  if (NonZeroStyleCoord(coord)) return PR_TRUE;
-
-  return PR_FALSE;
 }
 
 static void
@@ -473,7 +446,7 @@ SyncFrameViewGeometryDependentProperties(nsPresContext*  aPresContext,
         // don't proceed unless this is the root view
         // (sometimes the non-root-view is a canvas)
         if (aView->HasWidget() && aView == rootView) {
-          viewHasTransparentContent = hasBG && (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT);
+          viewHasTransparentContent = nsLayoutUtils::FrameHasTransparency(aFrame);
           aView->GetWidget()->SetWindowTranslucency(viewHasTransparentContent);
         }
       }

layout/xul/base/src/nsMenuPopupFrame.cpp

@@ -220,14 +220,8 @@ nsMenuPopupFrame::CreateWidgetForView(nsIView* aView)
   widgetData.mBorderStyle = eBorderStyle_default;
   widgetData.clipSiblings = PR_TRUE;
 
-  PRBool isCanvas;
+  PRBool viewHasTransparentContent = !mInContentShell &&
-  const nsStyleBackground* bg;
+                                     nsLayoutUtils::FrameHasTransparency(this);
-  PRBool hasBG =
-    nsCSSRendering::FindBackground(PresContext(), this, &bg, &isCanvas);
-  PRBool viewHasTransparentContent = hasBG &&
-    (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) &&
-    !GetStyleDisplay()->mAppearance && !mInContentShell;
-
   nsIContent* parentContent = GetContent()->GetParent();
   nsIAtom *tag = nsnull;
   if (parentContent)