Add SVG Text to support the CSS 'text-orientation' property

third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp

Index: third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp b/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
index 3822998668a128b6ae09dca2fbfea70c030b3ddc..209e6bc3e03f2d94f6985fa6bf496cc32ad6c6d6 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
@@ -334,8 +334,6 @@ void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, cons
     if (m_inPathLayout && !m_textPathCalculator)
         return;
 
-    const SVGComputedStyle& svgStyle = style.svgStyle();
-
     // Find the start of the current text box in the metrics list.
     m_visualMetricsIterator.advanceToTextStart(&text, textBox->start());
 
@@ -386,13 +384,17 @@ void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, cons
         float angle = SVGTextLayoutAttributes::isEmptyValue(data.rotate) ? 0 : data.rotate;
 
         // Calculate glyph orientation angle.
+        // Font::width() calculates the resolved FontOrientation for each character,
+        // but does not expose today to avoid the API becomes too complex.

[fs, 2015/10/16 10:54:50]

Nit: "but does not expose today" -> "but is not exposed today" (and "becomes" ->
"becoming" or just "avoid API complexity" or something maybe)

Also, should this be a TODO for the SVGTextMetricsBuilder (i.e. SVGTextMetrics
would store logical values instead of width7height as it does today)?

         UChar32 currentCharacter = text.codepointAt(m_visualMetricsIterator.characterOffset());
-        float orientationAngle = baselineLayout.calculateGlyphOrientationAngle(m_isVerticalText, svgStyle, currentCharacter);
+        FontOrientation fontOrientation = font.fontDescription().orientation();
+        fontOrientation = resolveMixedFontOrientation(fontOrientation, currentCharacter);
 
-        // Calculate glyph advance & x/y orientation shifts.
+        // Calculate glyph advance.
+        // Shaping engine takes care of x/y orientation shifts for different fontOrientation values.
         float xOrientationShift = 0;
         float yOrientationShift = 0;

[fs, 2015/10/16 10:54:50]

These two are now only used for <textPath> related adjustments - could you move
them down to just before the m_inPathLayout check and maybe rename them to
textPath<something> (textPathGlyphMidpointX/Y maybe. I think I have a patch
somewhere that would be able to simplify that even more.)

-        float glyphAdvance = baselineLayout.calculateGlyphAdvanceAndOrientation(m_isVerticalText, visualMetrics, orientationAngle, xOrientationShift, yOrientationShift);
+        float glyphAdvance = visualMetrics.advance(fontOrientation);
 
         // Assign current text position to x/y values, if needed.
         updateCharacterPositionIfNeeded(x, y);
@@ -469,7 +471,7 @@ void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, cons
 
         // Determine whether we have to start a new fragment.
         bool shouldStartNewFragment = m_dx || m_dy || m_isVerticalText || m_inPathLayout || angle || angle != lastAngle
-            || orientationAngle || applySpacingToNextCharacter || m_textLengthSpacingInEffect;
+            || applySpacingToNextCharacter || m_textLengthSpacingInEffect;
 
         // If we already started a fragment, close it now.
         if (didStartTextFragment && shouldStartNewFragment) {
@@ -495,8 +497,10 @@ void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, cons
             if (xOrientationShift || yOrientationShift)
                 m_currentTextFragment.transform.translate(xOrientationShift, yOrientationShift);
 
-            if (orientationAngle)
-                m_currentTextFragment.transform.rotate(orientationAngle);
+            // In vertical text, always rotate by 90 degrees regardless of fontOrientation.
+            // Shaping engine takes care of the necessary orientation.
+            if (m_isVerticalText)
+                m_currentTextFragment.transform.rotate(90);
 
             m_currentTextFragment.isTextOnPath = m_inPathLayout && m_textPathScaling != 1;
             if (m_currentTextFragment.isTextOnPath) {