Bug 1099977. Part 3: Skip creating nsDisplayText when all glyphs are invisible. r=jfkthame

--HG--
extra : rebase_source : db9e1e149ea93be298c0515b792186168ccbb9f0

layout/generic/nsFrameStateBits.h

@@ -408,6 +408,9 @@ FRAME_STATE_BIT(Text, 60, TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA)
 
 FRAME_STATE_BIT(Text, 61, TEXT_HAS_FONT_INFLATION)
 
+// Set when this text frame contains nothing that will actually render
+FRAME_STATE_BIT(Text, 62, TEXT_NO_RENDERED_GLYPHS)
+
 // Whether this frame is cached in the Offset Frame Cache
 // (OffsetToFrameProperty)
 FRAME_STATE_BIT(Text, 63, TEXT_IN_OFFSET_CACHE)

layout/generic/nsTextFrame.cpp

@@ -200,13 +200,20 @@ static void DestroyGlyphObserverList(void* aPropertyValue)
  */
 NS_DECLARE_FRAME_PROPERTY(TextFrameGlyphObservers, DestroyGlyphObserverList);
 
-#define TEXT_REFLOW_FLAGS    \
-  (TEXT_FIRST_LETTER|TEXT_START_OF_LINE|TEXT_END_OF_LINE|TEXT_HYPHEN_BREAK| \
-   TEXT_TRIMMED_TRAILING_WHITESPACE|TEXT_JUSTIFICATION_ENABLED| \
-   TEXT_HAS_NONCOLLAPSED_CHARACTERS|TEXT_SELECTION_UNDERLINE_OVERFLOWED)
+static const nsFrameState TEXT_REFLOW_FLAGS =
+   TEXT_FIRST_LETTER |
+   TEXT_START_OF_LINE |
+   TEXT_END_OF_LINE |
+   TEXT_HYPHEN_BREAK |
+   TEXT_TRIMMED_TRAILING_WHITESPACE |
+   TEXT_JUSTIFICATION_ENABLED |
+   TEXT_HAS_NONCOLLAPSED_CHARACTERS |
+   TEXT_SELECTION_UNDERLINE_OVERFLOWED |
+   TEXT_NO_RENDERED_GLYPHS;
 
-#define TEXT_WHITESPACE_FLAGS      (TEXT_IS_ONLY_WHITESPACE | \
-                                    TEXT_ISNOT_ONLY_WHITESPACE)
+static const nsFrameState TEXT_WHITESPACE_FLAGS =
+    TEXT_IS_ONLY_WHITESPACE |
+    TEXT_ISNOT_ONLY_WHITESPACE;
 
 /*
  * Some general notes
@@ -2742,6 +2749,8 @@ nsTextFrame::ClearMetrics(nsHTMLReflowMetrics& aMetrics)
   aMetrics.ClearSize();
   aMetrics.SetBlockStartAscent(0);
   mAscent = 0;
+
+  AddStateBits(TEXT_NO_RENDERED_GLYPHS);
 }
 
 static int32_t FindChar(const nsTextFragment* frag,
@@ -4650,8 +4659,9 @@ nsTextFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   
   DO_GLOBAL_REFLOW_COUNT_DSP("nsTextFrame");
 
-  if (NS_GET_A(StyleColor()->mColor) == 0 &&
-      !IsSVGText() && !IsSelected() && !StyleText()->HasTextShadow()) {
+  if (((GetStateBits() & TEXT_NO_RENDERED_GLYPHS) ||
+       (NS_GET_A(StyleColor()->mColor) == 0 && !StyleText()->HasTextShadow())) &&
+      aBuilder->IsForPainting() && !IsSVGText() && !IsSelected()) {
     TextDecorations textDecs;
     GetTextDecorations(PresContext(), eResolvedColors, textDecs);
     if (!textDecs.HasDecorationLines()) {
@@ -8257,7 +8267,7 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
   gfxFloat availWidth = aAvailableWidth;
   bool canTrimTrailingWhitespace = !textStyle->WhiteSpaceIsSignificant() ||
                                    (GetStateBits() & TEXT_IS_IN_TOKEN_MATHML);
-  int32_t unusedOffset;  
+  int32_t unusedOffset;
   gfxBreakPriority breakPriority;
   aLineLayout.GetLastOptionalBreakPosition(&unusedOffset, &breakPriority);
   gfxTextRun::SuppressBreak suppressBreak = gfxTextRun::eNoSuppressBreak;
@@ -8321,6 +8331,9 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
     AddHyphenToMetrics(this, mTextRun, &textMetrics, boundingBoxType, ctx);
     AddStateBits(TEXT_HYPHEN_BREAK | TEXT_HAS_NONCOLLAPSED_CHARACTERS);
   }
+  if (textMetrics.mBoundingBox.IsEmpty()) {
+    AddStateBits(TEXT_NO_RENDERED_GLYPHS);
+  }
 
   gfxFloat trimmableWidth = 0;
   bool brokeText = forceBreak >= 0 || transformedCharsFit < transformedLength;