Fix gap for "text-underline-position:under"

third_party/WebKit/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 "core/paint/InlineTextBoxPainter.h"
 
 #include "core/editing/CompositionUnderline.h"
 #include "core/editing/Editor.h"
 #include "core/editing/markers/DocumentMarkerController.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 59 matching lines @@
     LayoutUnit position = inlineTextBox->logicalTop();
     return position -
            root.minLogicalTopForUnderline(decorationObject, position);
   } else {
     LayoutUnit position = inlineTextBox->logicalBottom();
     return root.maxLogicalBottomForUnderline(decorationObject, position) -
            position;
   }
 }
 
+static int computeUnderlineOffsetForRoman(const FontMetrics& fontMetrics,
+                                          const float textDecorationThickness) {
+  // Compute the gap between the font and the underline. Use at least one
+  // pixel gap, if underline is thick then use a bigger gap.
+  int gap = 0;
+
+  // Underline position of zero means draw underline on Baseline Position,
+  // in Blink we need at least 1-pixel gap to adding following check.
+  // Positive underline Position means underline should be drawn above baseline
+  // and negative value means drawing below baseline, negating the value as in
+  // Blink downward Y-increases.
+
+  if (fontMetrics.underlinePosition())
+    gap = -fontMetrics.underlinePosition();
+  else
+    gap = std::max<int>(1, ceilf(textDecorationThickness / 2.f));
+
+  // Position underline near the alphabetic baseline.
+  return fontMetrics.ascent() + gap;
+}
+
 static int computeUnderlineOffset(const ComputedStyle& style,
                                   const FontMetrics& fontMetrics,
                                   const InlineTextBox* inlineTextBox,
                                   const float textDecorationThickness) {
-  // Compute the gap between the font and the underline. Use at least one
-  // pixel gap, if underline is thick then use a bigger gap.
-  int gap = 0;
-
-  // Underline position of zero means draw underline on Baseline Position,
-  // in Blink we need at least 1-pixel gap to adding following check.
-  // Positive underline Position means underline should be drawn above baselin e
-  // and negative value means drawing below baseline, negating the value as in
-  // Blink
-  // downward Y-increases.
-
-  if (fontMetrics.underlinePosition())
-    gap = -fontMetrics.underlinePosition();
-  else
-    gap = std::max<int>(1, ceilf(textDecorationThickness / 2.f));
-
   // FIXME: We support only horizontal text for now.
   switch (style.getTextUnderlinePosition()) {
+    default:
+      NOTREACHED();
+    // Fall through.
     case TextUnderlinePositionAuto:
-      return fontMetrics.ascent() +
-             gap;  // Position underline near the alphabetic baseline.
+      return computeUnderlineOffsetForRoman(fontMetrics,
+                                            textDecorationThickness);
     case TextUnderlinePositionUnder: {
-      // Position underline relative to the under edge of the lowest element's
+      // Position underline at the under edge of the lowest element's
       // content box.
       LayoutUnit offset = computeUnderlineOffsetForUnder(style, inlineTextBox);
       offset = inlineTextBox->logicalHeight() + std::max(offset, LayoutUnit());
-      return offset.toInt() + gap;
+      return offset.toInt();
     }
   }
-
-  NOTREACHED();
-  return fontMetrics.ascent() + gap;
 }
 
 static bool shouldSetDecorationAntialias(
     const Vector<AppliedTextDecoration>& decorations) {
   for (const AppliedTextDecoration& decoration : decorations) {
     TextDecorationStyle decorationStyle = decoration.style();
     if (decorationStyle == TextDecorationStyleDotted ||
         decorationStyle == TextDecorationStyleDashed)
       return true;
   }
@@ skipping 1197 matching lines @@
 
   LayoutRect boxRect(boxOrigin, LayoutSize(m_inlineTextBox.logicalWidth(),
                                            m_inlineTextBox.logicalHeight()));
   context.clip(FloatRect(boxRect));
   context.drawHighlightForText(font, run, FloatPoint(boxOrigin),
                                boxRect.height().toInt(), color,
                                paintOffsets.first, paintOffsets.second);
 }
 
 }  // namespace blink