[TextBlob] Permit drawing selected text from cache, if possible.

Source/core/paint/InlineTextBoxPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/InlineTextBoxPainter.h"
 
 #include "core/dom/DocumentMarkerController.h"
 #include "core/dom/RenderedDocumentMarker.h"
 #include "core/editing/CompositionUnderline.h"
@@ skipping 15 matching lines @@
 static InlineTextBoxBlobCacheMap* gTextBlobCache;
 
 static const int misspellingLineThickness = 3;
 
 void InlineTextBoxPainter::removeFromTextBlobCache(InlineTextBox& inlineTextBox)
 {
     if (gTextBlobCache)
         gTextBlobCache->remove(&inlineTextBox);
 }
 
+static TextBlobPtr* addToTextBlobCache(InlineTextBox& inlineTextBox)
+{
+    if (!gTextBlobCache)
+        gTextBlobCache = new InlineTextBoxBlobCacheMap;
+    return &gTextBlobCache->add(&inlineTextBox, nullptr).storedValue->value;
+}
+
 void InlineTextBoxPainter::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (m_inlineTextBox.isLineBreak() || !paintInfo.shouldPaintWithinRoot(&m_inlineTextBox.renderer()) || m_inlineTextBox.renderer().style()->visibility() != VISIBLE
         || m_inlineTextBox.truncation() == cFullTruncation || paintInfo.phase == PaintPhaseOutline || !m_inlineTextBox.len())
         return;
 
     ASSERT(paintInfo.phase != PaintPhaseSelfOutline && paintInfo.phase != PaintPhaseChildOutlines);
 
     LayoutRect logicalVisualOverflow = m_inlineTextBox.logicalOverflowRect();
     LayoutUnit logicalStart = logicalVisualOverflow.x() + (m_inlineTextBox.isHorizontal() ? paintOffset.x() : paintOffset.y());
@@ skipping 134 matching lines @@
         if (paintSelectedTextSeparately && selectionStart < selectionEnd) {
             startOffset = selectionEnd;
             endOffset = selectionStart;
         }
 
         // FIXME: This cache should probably ultimately be held somewhere else.
         // A hashmap is convenient to avoid a memory hit when the
         // RuntimeEnabledFeature is off.
         bool textBlobIsCacheable = RuntimeEnabledFeatures::textBlobEnabled() && startOffset == 0 && endOffset == length;
         TextBlobPtr* cachedTextBlob = 0;
-        if (textBlobIsCacheable) {
-            if (!gTextBlobCache)
-                gTextBlobCache = new InlineTextBoxBlobCacheMap;
-            cachedTextBlob = &gTextBlobCache->add(&m_inlineTextBox, nullptr).storedValue->value;
-        }
+        if (textBlobIsCacheable)
+            cachedTextBlob = addToTextBlobCache(m_inlineTextBox);
         textPainter.paint(startOffset, endOffset, length, textStyle, cachedTextBlob);
     }
 
     if ((paintSelectedTextOnly || paintSelectedTextSeparately) && selectionStart < selectionEnd) {
         // paint only the text that is selected
-        textPainter.paint(selectionStart, selectionEnd, length, selectionStyle);
+        bool textBlobIsCacheable = RuntimeEnabledFeatures::textBlobEnabled() && selectionStart == 0 && selectionEnd == length;
+        TextBlobPtr* cachedTextBlob = 0;
+        if (textBlobIsCacheable)
+            cachedTextBlob = addToTextBlobCache(m_inlineTextBox);
+        textPainter.paint(selectionStart, selectionEnd, length, selectionStyle, cachedTextBlob);
     }
 
     // Paint decorations
     TextDecoration textDecorations = styleToUse->textDecorationsInEffect();
     if (textDecorations != TextDecorationNone && !paintSelectedTextOnly) {
         GraphicsContextStateSaver stateSaver(*context, false);
         TextPainter::updateGraphicsContext(context, textStyle, m_inlineTextBox.isHorizontal(), stateSaver);
         if (combinedText)
 
             context->concatCTM(InlineTextBox::rotation(boxRect, InlineTextBox::Clockwise));
@@ skipping 572 matching lines @@
             RenderTheme::theme().platformActiveTextSearchHighlightColor() :
             RenderTheme::theme().platformInactiveTextSearchHighlightColor();
         GraphicsContextStateSaver stateSaver(*pt);
         pt->clip(FloatRect(boxOrigin.x(), boxOrigin.y() - deltaY, m_inlineTextBox.logicalWidth(), selHeight));
         pt->drawHighlightForText(font, run, FloatPoint(boxOrigin.x(), boxOrigin.y() - deltaY), selHeight, color, sPos, ePos);
     }
 }
 
 
 } // namespace blink