Bug 1395312 part 1. Add a method on nsTableCellFrame to determine whether it should paint borders and backgrounds. r=heycam

MozReview-Commit-ID: 7bLn4Fa3qP8

layout/tables/nsTableCellFrame.cpp

@@ -470,18 +470,33 @@ PaintTableCellSelection(nsIFrame* aFrame, DrawTarget* aDrawTarget,
                                                                aPt);
 }
 
+bool
+nsTableCellFrame::ShouldPaintBordersAndBackgrounds() const
+{
+  // If we're not visible, we don't paint.
+  if (!StyleVisibility()->IsVisible()) {
+    return false;
+  }
+
+  // Consider 'empty-cells', but only in separated borders mode.
+  if (!GetContentEmpty()) {
+    return true;
+  }
+
+  nsTableFrame* tableFrame = GetTableFrame();
+  if (tableFrame->IsBorderCollapse()) {
+    return true;
+  }
+
+  return StyleTableBorder()->mEmptyCells == NS_STYLE_TABLE_EMPTY_CELLS_SHOW;
+}
+
 void
 nsTableCellFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                    const nsDisplayListSet& aLists)
 {
   DO_GLOBAL_REFLOW_COUNT_DSP("nsTableCellFrame");
-  nsTableFrame* tableFrame = GetTableFrame();
-  int32_t emptyCellStyle = GetContentEmpty() && !tableFrame->IsBorderCollapse() ?
-                              StyleTableBorder()->mEmptyCells
-                              : NS_STYLE_TABLE_EMPTY_CELLS_SHOW;
-  // take account of 'empty-cells'
-  if (StyleVisibility()->IsVisible() &&
-      (NS_STYLE_TABLE_EMPTY_CELLS_HIDE != emptyCellStyle)) {
+  if (ShouldPaintBordersAndBackgrounds()) {
     // display outset box-shadows if we need to.
     bool hasBoxShadow = !!StyleEffects()->mBoxShadow;
     if (hasBoxShadow) {
@@ -506,7 +521,7 @@ nsTableCellFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
     }
 
     // display borders if we need to
-    ProcessBorders(tableFrame, aBuilder, aLists);
+    ProcessBorders(GetTableFrame(), aBuilder, aLists);
 
     // and display the selection border if we need to
     if (IsSelected()) {

layout/tables/nsTableCellFrame.h

@@ -196,7 +196,7 @@ public:
   /** set the desired size returned by this frame during its last reflow */
   inline void SetDesiredSize(const ReflowOutput & aDesiredSize);
 
-  bool GetContentEmpty();
+  bool GetContentEmpty() const;
   void SetContentEmpty(bool aContentEmpty);
 
   bool HasPctOverBSize();
@@ -224,6 +224,8 @@ public:
   virtual void InvalidateFrameWithRect(const nsRect& aRect, uint32_t aDisplayItemKey = 0) override;
   virtual void InvalidateFrameForRemoval() override { InvalidateFrameSubtree(); }
 
+  bool ShouldPaintBordersAndBackgrounds() const;
+
 protected:
   nsTableCellFrame(nsStyleContext* aContext, nsTableFrame* aTableFrame,
                    ClassID aID);
@@ -264,7 +266,7 @@ inline void nsTableCellFrame::SetDesiredSize(const ReflowOutput & aDesiredSize)
   mDesiredSize = aDesiredSize.Size(wm).ConvertTo(GetWritingMode(), wm);
 }
 
-inline bool nsTableCellFrame::GetContentEmpty()
+inline bool nsTableCellFrame::GetContentEmpty() const
 {
   return HasAnyStateBits(NS_TABLE_CELL_CONTENT_EMPTY);
 }