Include glyph overflow in SVG text bounding boxes

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 0e36470b531e96a7606c2db91c1a1ddbee5d4923..ff43950d1eb64cc72eec1ed29b1e8ffcc5df8e96 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngine.cpp
@@ -20,6 +20,7 @@
 #include "config.h"
 #include "core/layout/svg/SVGTextLayoutEngine.h"
 
+#include "core/layout/line/GlyphOverflow.h"
 #include "core/layout/svg/LayoutSVGInlineText.h"
 #include "core/layout/svg/LayoutSVGTextPath.h"
 #include "core/layout/svg/SVGTextChunkBuilder.h"
@@ -110,6 +111,27 @@ void SVGTextLayoutEngine::updateRelativePositionAdjustmentsIfNeeded(float dx, fl
     m_dy = dy;
 }
 
+// Computes the glyph overflow without integer clamping (see: GlyphOverflow.h).
+static void computeGlyphOverflow(SVGInlineTextBox* textBox, SVGTextFragment& textFragment)
+{
+    LineLayoutSVGInlineText textLineLayout = LineLayoutSVGInlineText(textBox->lineLayoutItem());
+    TextRun run = SVGTextMetrics::constructTextRun(textLineLayout, textFragment.characterOffset, textFragment.length, textLineLayout.styleRef().direction());
+
+    float scalingFactor = textLineLayout.scalingFactor();
+    ASSERT(scalingFactor);
+    const Font& scaledFont = textLineLayout.scaledFont();
+    FloatRect glyphOverflowBounds;
+
+    float width = scaledFont.width(run, nullptr, &glyphOverflowBounds);
+    float ascent = scaledFont.fontMetrics().floatAscent();
+    float descent = scaledFont.fontMetrics().floatDescent();
+
+    textFragment.glyphOverflowTop = GlyphOverflow::topOverflow(glyphOverflowBounds, ascent) / scalingFactor;
+    textFragment.glyphOverflowBottom = GlyphOverflow::bottomOverflow(glyphOverflowBounds, descent) / scalingFactor;
+    textFragment.glyphOverflowLeft = GlyphOverflow::leftOverflow(glyphOverflowBounds) / scalingFactor;
+    textFragment.glyphOverflowRight = GlyphOverflow::rightOverflow(glyphOverflowBounds, width) / scalingFactor;
+}
+
 void SVGTextLayoutEngine::recordTextFragment(SVGInlineTextBox* textBox)
 {
     ASSERT(!m_currentTextFragment.length);
@@ -138,6 +160,7 @@ void SVGTextLayoutEngine::recordTextFragment(SVGInlineTextBox* textBox)
         }
     }
 
+    computeGlyphOverflow(textBox, m_currentTextFragment);
     textBox->textFragments().append(m_currentTextFragment);
     m_currentTextFragment = SVGTextFragment();
 }