Include glyph overflow in SVG text bounding boxes

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

 /*
  * Copyright (C) Research In Motion Limited 2010-2012. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #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"
 #include "core/layout/svg/SVGTextLayoutEngineBaseline.h"
 #include "core/layout/svg/SVGTextLayoutEngineSpacing.h"
 #include "core/layout/svg/line/SVGInlineFlowBox.h"
 #include "core/layout/svg/line/SVGInlineTextBox.h"
 #include "core/svg/SVGElement.h"
 #include "core/svg/SVGLengthContext.h"
 #include "core/svg/SVGTextContentElement.h"
@@ skipping 70 matching lines @@
             m_dy += dy;
         }
 
         return;
     }
 
     m_dx = dx;
     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);
 
     // Figure out length of fragment.
     m_currentTextFragment.length = m_visualMetricsIterator.characterOffset() - m_currentTextFragment.characterOffset;
 
     // Figure out fragment metrics.
     const unsigned visualMetricsListOffset = m_visualMetricsIterator.metricsListOffset();
     const Vector<SVGTextMetrics>& textMetricsValues = m_visualMetricsIterator.metricsList();
     const SVGTextMetrics& lastCharacterMetrics = textMetricsValues.at(visualMetricsListOffset - 1);
     m_currentTextFragment.width = lastCharacterMetrics.width();
     m_currentTextFragment.height = lastCharacterMetrics.height();
 
     if (m_currentTextFragment.length > 1) {
         // SVGTextLayoutAttributesBuilder assures that the length of the range is equal to the sum of the individual lengths of the glyphs.
         float length = 0;
         if (m_isVerticalText) {
             for (unsigned i = m_currentTextFragment.metricsListOffset; i < visualMetricsListOffset; ++i)
                 length += textMetricsValues.at(i).height();
             m_currentTextFragment.height = length;
         } else {
             for (unsigned i = m_currentTextFragment.metricsListOffset; i < visualMetricsListOffset; ++i)
                 length += textMetricsValues.at(i).width();
             m_currentTextFragment.width = length;
         }
     }
 
+    computeGlyphOverflow(textBox, m_currentTextFragment);
     textBox->textFragments().append(m_currentTextFragment);
     m_currentTextFragment = SVGTextFragment();
 }
 
 void SVGTextLayoutEngine::beginTextPathLayout(SVGInlineFlowBox* flowBox)
 {
     // Build text chunks for all <textPath> children, using the line layout algorithm.
     // This is needeed as text-anchor is just an additional startOffset for text paths.
     SVGTextLayoutEngine lineLayout(m_layoutAttributes);
     lineLayout.m_textLengthSpacingInEffect = m_textLengthSpacingInEffect;
@@ skipping 384 matching lines @@
     }
 
     if (!didStartTextFragment)
         return;
 
     // Close last open fragment, if needed.
     recordTextFragment(textBox);
 }
 
 }