Explicitly set text direction for TextRuns

Source/core/rendering/RenderText.cpp

Index: Source/core/rendering/RenderText.cpp
diff --git a/Source/core/rendering/RenderText.cpp b/Source/core/rendering/RenderText.cpp
index b89ddc756ba895becf08f1e0450384710bd4f2af..edf856dc8eacfa95f3013b1bded6622308244a23 100644
--- a/Source/core/rendering/RenderText.cpp
+++ b/Source/core/rendering/RenderText.cpp
@@ -40,7 +40,9 @@
 #include "core/rendering/RenderView.h"
 #include "core/rendering/break_lines.h"
 #include "platform/geometry/FloatQuad.h"
+#include "platform/text/BidiResolver.h"
 #include "platform/text/TextBreakIterator.h"
+#include "platform/text/TextRunIterator.h"
 #include "wtf/text/StringBuffer.h"
 #include "wtf/text/StringBuilder.h"
 #include "wtf/unicode/CharacterNames.h"
@@ -720,7 +722,7 @@ LayoutRect RenderText::localCaretRect(InlineBox* inlineBox, int caretOffset, Lay
     return style()->isHorizontalWritingMode() ? IntRect(left, top, caretWidth, height) : IntRect(top, left, height, caretWidth);
 }
 
-ALWAYS_INLINE float RenderText::widthFromCache(const Font& f, int start, int len, float xPos, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
+ALWAYS_INLINE float RenderText::widthFromCache(const Font& f, int start, int len, float xPos, TextDirection textDirection, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
 {
     if (style()->hasTextCombine() && isCombineText()) {
         const RenderCombineText* combineText = toRenderCombineText(this);
@@ -760,7 +762,7 @@ ALWAYS_INLINE float RenderText::widthFromCache(const Font& f, int start, int len
         return w;
     }
 
-    TextRun run = RenderBlockFlow::constructTextRun(const_cast<RenderText*>(this), f, this, start, len, style());
+    TextRun run = RenderBlockFlow::constructTextRun(const_cast<RenderText*>(this), f, this, start, len, style(), textDirection);
     run.setCharactersLength(textLength() - start);
     ASSERT(run.charactersLength() >= run.length());
 
@@ -839,7 +841,7 @@ void RenderText::trimmedPrefWidths(float leadWidth,
                 linelen++;
 
             if (linelen) {
-                lastLineMaxWidth = widthFromCache(f, i, linelen, leadWidth + lastLineMaxWidth, 0, 0);
+                lastLineMaxWidth = widthFromCache(f, i, linelen, leadWidth + lastLineMaxWidth, LTR, 0, 0);
                 if (firstLine) {
                     firstLine = false;
                     leadWidth = 0;
@@ -937,11 +939,27 @@ void RenderText::computePreferredLogicalWidths(float leadWidth, HashSet<const Si
 
     bool breakAll = (styleToUse->wordBreak() == BreakAllWordBreak || styleToUse->wordBreak() == BreakWordBreak) && styleToUse->autoWrap();
 
+    TextRun textRun(text());

[leviw_travelin_and_unemployed, 2014/01/09 00:49:54]

I worry about the performance implications of this, since we're effectively
doubling this work now when we need to compute the preferred logical widths.
It'd be great if we could hold onto and re-use these runs!

+    BidiResolver<TextRunIterator, BidiCharacterRun> bidiResolver;
+    bidiResolver.setStatus(BidiStatus(textRun.direction(), textRun.directionalOverride()));
+    bidiResolver.setPositionIgnoringNestedIsolates(TextRunIterator(&textRun, 0));
+    bool hardLineBreak = false;
+    bool reorderRuns = false;
+    bidiResolver.createBidiRunsForLine(TextRunIterator(&textRun, textRun.length()), NoVisualOverride, hardLineBreak, reorderRuns);
+
+    BidiRunList<BidiCharacterRun>& bidiRuns = bidiResolver.runs();
+    BidiCharacterRun* run = bidiRuns.firstRun();
     for (int i = 0; i < len; i++) {
         UChar c = uncheckedCharacterAt(i);
 
-        bool previousCharacterIsSpace = isSpace;
+        while (i > run->stop())
+            run = run->next();
 
+        ASSERT(run);
+        ASSERT(i >= run->start() && i <= run->stop());
+        TextDirection textDirection = run->reversed(false) ? RTL : LTR;
+
+        bool previousCharacterIsSpace = isSpace;
         bool isNewline = false;
         if (c == '\n') {
             if (styleToUse->preserveNewline()) {
@@ -979,7 +997,7 @@ void RenderText::computePreferredLogicalWidths(float leadWidth, HashSet<const Si
             lastWordBoundary++;
             continue;
         } else if (c == softHyphen) {
-            currMaxWidth += widthFromCache(f, lastWordBoundary, i - lastWordBoundary, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow);
+            currMaxWidth += widthFromCache(f, lastWordBoundary, i - lastWordBoundary, leadWidth + currMaxWidth, textDirection, &fallbackFonts, &glyphOverflow);
             if (firstGlyphLeftOverflow < 0)
                 firstGlyphLeftOverflow = glyphOverflow.left;
             lastWordBoundary = i + 1;
@@ -1007,9 +1025,9 @@ void RenderText::computePreferredLogicalWidths(float leadWidth, HashSet<const Si
             bool isSpace = (j < len) && c == ' ';
             float w;
             if (wordTrailingSpaceWidth && isSpace)
-                w = widthFromCache(f, i, wordLen + 1, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow) - wordTrailingSpaceWidth;
+                w = widthFromCache(f, i, wordLen + 1, leadWidth + currMaxWidth, textDirection, &fallbackFonts, &glyphOverflow) - wordTrailingSpaceWidth;
             else {
-                w = widthFromCache(f, i, wordLen, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow);
+                w = widthFromCache(f, i, wordLen, leadWidth + currMaxWidth, textDirection, &fallbackFonts, &glyphOverflow);
                 if (c == softHyphen)
                     currMinWidth += hyphenWidth(this, f);
             }
@@ -1023,7 +1041,7 @@ void RenderText::computePreferredLogicalWidths(float leadWidth, HashSet<const Si
                 if (lastWordBoundary == i)
                     currMaxWidth += w;
                 else
-                    currMaxWidth += widthFromCache(f, lastWordBoundary, j - lastWordBoundary, leadWidth + currMaxWidth, &fallbackFonts, &glyphOverflow);
+                    currMaxWidth += widthFromCache(f, lastWordBoundary, j - lastWordBoundary, leadWidth + currMaxWidth, textDirection, &fallbackFonts, &glyphOverflow);
                 lastWordBoundary = j;
             }
 
@@ -1445,7 +1463,7 @@ void RenderText::positionLineBox(InlineBox* box)
     m_containsReversedText |= !s->isLeftToRightDirection();
 }
 
-float RenderText::width(unsigned from, unsigned len, float xPos, bool firstLine, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
+float RenderText::width(unsigned from, unsigned len, float xPos, TextDirection textDirection, bool firstLine, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
 {
     if (from >= textLength())
         return 0;
@@ -1453,10 +1471,10 @@ float RenderText::width(unsigned from, unsigned len, float xPos, bool firstLine,
     if (from + len > textLength())
         len = textLength() - from;
 
-    return width(from, len, style(firstLine)->font(), xPos, fallbackFonts, glyphOverflow);
+    return width(from, len, style(firstLine)->font(), xPos, textDirection, fallbackFonts, glyphOverflow);
 }
 
-float RenderText::width(unsigned from, unsigned len, const Font& f, float xPos, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
+float RenderText::width(unsigned from, unsigned len, const Font& f, float xPos, TextDirection textDirection, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
 {
     ASSERT(from + len <= textLength());
     if (!textLength())
@@ -1475,10 +1493,11 @@ float RenderText::width(unsigned from, unsigned len, const Font& f, float xPos,
                 w = m_maxWidth;
             } else
                 w = maxLogicalWidth();
-        } else
-            w = widthFromCache(f, from, len, xPos, fallbackFonts, glyphOverflow);
+        } else {
+            w = widthFromCache(f, from, len, xPos, textDirection, fallbackFonts, glyphOverflow);
+        }
     } else {
-        TextRun run = RenderBlockFlow::constructTextRun(const_cast<RenderText*>(this), f, this, from, len, style());
+        TextRun run = RenderBlockFlow::constructTextRun(const_cast<RenderText*>(this), f, this, from, len, style(), textDirection);
         run.setCharactersLength(textLength() - from);
         ASSERT(run.charactersLength() >= run.length());