Adding backgroundColor to WebCompositionUnderline and using it for InlineTextBox drawing.

Source/core/rendering/InlineTextBox.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. 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/rendering/InlineTextBox.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/DocumentMarkerController.h"
 #include "core/dom/RenderedDocumentMarker.h"
 #include "core/dom/Text.h"
+#include "core/editing/CompositionUnderline.h"
+#include "core/editing/CompositionUnderlineRangeFilter.h"
 #include "core/editing/Editor.h"
 #include "core/editing/InputMethodController.h"
 #include "core/frame/LocalFrame.h"
 #include "core/page/Page.h"
 #include "core/frame/Settings.h"
 #include "core/rendering/AbstractInlineTextBox.h"
 #include "core/rendering/EllipsisBox.h"
 #include "core/rendering/HitTestResult.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderBR.h"
 #include "core/rendering/RenderBlock.h"
 #include "core/rendering/RenderCombineText.h"
 #include "core/rendering/RenderRubyRun.h"
 #include "core/rendering/RenderRubyText.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/style/ShadowList.h"
 #include "core/rendering/svg/SVGTextRunRenderingContext.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/WidthIterator.h"
 #include "platform/graphics/DrawLooperBuilder.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 #include "wtf/Vector.h"
 #include "wtf/text/CString.h"
 #include "wtf/text/StringBuilder.h"
 
+#include <algorithm>
+
 using namespace std;
 
 namespace WebCore {
 
 struct SameSizeAsInlineTextBox : public InlineBox {
     unsigned variables[1];
     unsigned short variables2[2];
     void* pointers[2];
 };
 
@@ skipping 65 matching lines @@
     return root().selectionBottom();
 }
 
 LayoutUnit InlineTextBox::selectionHeight()
 {
     return root().selectionHeight();
 }
 
 bool InlineTextBox::isSelected(int startPos, int endPos) const
 {
-    int sPos = max(startPos - m_start, 0);
+    int sPos = std::max(startPos - m_start, 0);

[yosin_UTC9, 2014/06/12 06:23:17]

nit: Sorry for confusion about my comment. You only need to to use
|std::min|/|std:max| where you changed rather than all |min|/|max|. We prefer
small changes.

[huangs, 2014/06/12 23:22:10]

Done; undid changes to code I didn't touch.

     // The position after a hard line break is considered to be past its end.
     // See the corresponding code in InlineTextBox::selectionState.
-    int ePos = min(endPos - m_start, int(m_len) + (isLineBreak() ? 0 : 1));
+    int ePos = std::min(endPos - m_start, int(m_len) + (isLineBreak() ? 0 : 1));
     return (sPos < ePos);
 }
 
 RenderObject::SelectionState InlineTextBox::selectionState()
 {
     RenderObject::SelectionState state = renderer().selectionState();
     if (state == RenderObject::SelectionStart || state == RenderObject::SelectionEnd || state == RenderObject::SelectionBoth) {
         int startPos, endPos;
         renderer().selectionStartEnd(startPos, endPos);
         // The position after a hard line break is considered to be past its end.
@@ skipping 31 matching lines @@
                 RenderObject::SelectionInside : RenderObject::SelectionNone);
         } else
             ellipsis->setSelectionState(RenderObject::SelectionNone);
     }
 
     return state;
 }
 
 LayoutRect InlineTextBox::localSelectionRect(int startPos, int endPos)
 {
-    int sPos = max(startPos - m_start, 0);
-    int ePos = min(endPos - m_start, (int)m_len);
+    int sPos = std::max(startPos - m_start, 0);
+    int ePos = std::min(endPos - m_start, static_cast<int>(m_len));

[yosin_UTC9, 2014/06/12 06:23:17]

nit: You don't need to change |(int)| to |static_cast<int>(...)| unless you
changed. We prefer small patch.

[huangs, 2014/06/12 23:22:10]

Done; undid changes to code I didn't touch.

 
     if (sPos > ePos)
         return LayoutRect();
 
     FontCachePurgePreventer fontCachePurgePreventer;
 
     LayoutUnit selTop = selectionTop();
     LayoutUnit selHeight = selectionHeight();
     RenderStyle* styleToUse = textRenderer().style(isFirstLineStyle());
     const Font& font = styleToUse->font();
@@ skipping 80 matching lines @@
             int visibleBoxWidth = visibleRightEdge - visibleLeftEdge  - ellipsisWidth;
             ellipsisX = ltr ? logicalLeft() + visibleBoxWidth : logicalRight() - visibleBoxWidth;
         }
 
         int offset = offsetForPosition(ellipsisX, false);
         if (offset == 0) {
             // No characters should be rendered.  Set ourselves to full truncation and place the ellipsis at the min of our start
             // and the ellipsis edge.
             m_truncation = cFullTruncation;
             truncatedWidth += ellipsisWidth;
-            return min(ellipsisX, logicalLeft());
+            return std::min(ellipsisX, logicalLeft());
         }
 
         // Set the truncation index on the text run.
         m_truncation = offset;
 
         // If we got here that means that we were only partially truncated and we need to return the pixel offset at which
         // to place the ellipsis.
         float widthOfVisibleText = toRenderText(renderer()).width(m_start, offset, textPos(), flowIsLTR ? LTR : RTL, isFirstLineStyle());
 
         // The ellipsis needs to be placed just after the last visible character.
@@ skipping 320 matching lines @@
 
     // Set our font.
     const Font& font = styleToUse->font();
 
     FloatPoint textOrigin = FloatPoint(boxOrigin.x(), boxOrigin.y() + font.fontMetrics().ascent());
 
     if (combinedText)
         combinedText->adjustTextOrigin(textOrigin, boxRect);
 
     // 1. Paint backgrounds behind text if needed. Examples of such backgrounds include selection
-    // and composition underlines.
+    // and composition highlights.
     if (paintInfo.phase != PaintPhaseSelection && paintInfo.phase != PaintPhaseTextClip && !isPrinting) {
+        if (containsComposition) {
+            if (useCustomUnderlines) {
+                // Paint custom background highlights for compositions.
+                const Vector<CompositionUnderline>& underlines = renderer().frame()->inputMethodController().customCompositionUnderlines();
+                CompositionUnderlineRangeFilter filter(underlines, start(), end());
+                for (CompositionUnderlineRangeFilter::ConstIterator it = filter.begin(); it != filter.end(); ++it) {
+                    if ((*it).backgroundColor != Color::transparent) {

[yosin_UTC9, 2014/06/12 06:23:17]

nit: It is better to use |it->backgroundColor|. We may want to have |const
CompositionUnderline* operator->() const| in |CompositionUnderlineRangeFilter|.

[huangs, 2014/06/12 23:22:10]

Done.

+                        unsigned paintStart = underlinePaintStart(*it);
+                        unsigned paintEnd = underlinePaintEnd(*it);
+                        paintCompositionBackground(context, boxOrigin, styleToUse, font, (*it).backgroundColor, paintStart, paintEnd);
+                    }
+                }
 
-        if (containsComposition && !useCustomUnderlines) {
-            paintCompositionBackground(context, boxOrigin, styleToUse, font,
-                renderer().frame()->inputMethodController().compositionStart(),
-                renderer().frame()->inputMethodController().compositionEnd());
+            } else {
+                paintCompositionBackground(context, boxOrigin, styleToUse, font, RenderTheme::theme().platformDefaultCompositionBackgroundColor(),
+                    renderer().frame()->inputMethodController().compositionStart(),
+                    renderer().frame()->inputMethodController().compositionEnd());
+            }
         }
 
         paintDocumentMarkers(context, boxOrigin, styleToUse, font, true);
 
         if (haveSelection && !useCustomUnderlines)
             paintSelection(context, boxOrigin, styleToUse, font, selectionFillColor);
     }
 
     // 2. Now paint the foreground, including text and decorations like underline/overline (in quirks mode only).
     int length = m_len;
@@ skipping 13 matching lines @@
     TextRun textRun = constructTextRun(styleToUse, font, string, maximumLength, hasHyphen() ? &charactersWithHyphen : 0);
     if (hasHyphen())
         length = textRun.length();
 
     int sPos = 0;
     int ePos = 0;
     if (paintSelectedTextOnly || paintSelectedTextSeparately)
         selectionStartEnd(sPos, ePos);
 
     if (m_truncation != cNoTruncation) {
-        sPos = min<int>(sPos, m_truncation);
-        ePos = min<int>(ePos, m_truncation);
+        sPos = std::min<int>(sPos, m_truncation);
+        ePos = std::min<int>(ePos, m_truncation);
         length = m_truncation;
     }
 
     int emphasisMarkOffset = 0;
     TextEmphasisPosition emphasisMarkPosition;
     bool hasTextEmphasis = getEmphasisMarkPosition(styleToUse, emphasisMarkPosition);
     const AtomicString& emphasisMark = hasTextEmphasis ? styleToUse->textEmphasisMarkString() : nullAtom;
     if (!emphasisMark.isEmpty())
         emphasisMarkOffset = emphasisMarkPosition == TextEmphasisPositionOver ? -font.fontMetrics().ascent() - font.emphasisMarkDescent(emphasisMark) : font.fontMetrics().descent() + font.emphasisMarkAscent(emphasisMark);
 
@@ skipping 70 matching lines @@
         if (combinedText)
             context->concatCTM(rotation(boxRect, Clockwise));
         paintDecoration(context, boxOrigin, textDecorations, textShadow);
         if (combinedText)
             context->concatCTM(rotation(boxRect, Counterclockwise));
     }
 
     if (paintInfo.phase == PaintPhaseForeground) {
         paintDocumentMarkers(context, boxOrigin, styleToUse, font, false);
 
+        // Paint custom underlines for compositions.
         if (useCustomUnderlines) {
             const Vector<CompositionUnderline>& underlines = renderer().frame()->inputMethodController().customCompositionUnderlines();
-            size_t numUnderlines = underlines.size();
-
-            for (size_t index = 0; index < numUnderlines; ++index) {
-                const CompositionUnderline& underline = underlines[index];
-
-                if (underline.endOffset <= start())
-                    // underline is completely before this run.  This might be an underline that sits
-                    // before the first run we draw, or underlines that were within runs we skipped
-                    // due to truncation.
-                    continue;
-
-                if (underline.startOffset <= end()) {
-                    // underline intersects this run.  Paint it.
-                    paintCompositionUnderline(context, boxOrigin, underline);
-                    if (underline.endOffset > end() + 1)
-                        // underline also runs into the next run. Bail now, no more marker advancement.
-                        break;
-                } else
-                    // underline is completely after this run, bail.  A later run will paint it.
-                    break;
+            CompositionUnderlineRangeFilter filter(underlines, start(), end());
+            for (CompositionUnderlineRangeFilter::ConstIterator it = filter.begin(); it != filter.end(); ++it) {
+                paintCompositionUnderline(context, boxOrigin, *it);
             }
         }
     }
 
     if (shouldRotate)
         context->concatCTM(rotation(boxRect, Counterclockwise));
 }
 
 void InlineTextBox::selectionStartEnd(int& sPos, int& ePos)
 {
     int startPos, endPos;
     if (renderer().selectionState() == RenderObject::SelectionInside) {
         startPos = 0;
         endPos = textRenderer().textLength();
     } else {
         textRenderer().selectionStartEnd(startPos, endPos);
         if (renderer().selectionState() == RenderObject::SelectionStart)
             endPos = textRenderer().textLength();
         else if (renderer().selectionState() == RenderObject::SelectionEnd)
             startPos = 0;
     }
 
-    sPos = max(startPos - m_start, 0);
-    ePos = min(endPos - m_start, (int)m_len);
+    sPos = std::max(startPos - m_start, 0);
+    ePos = std::min(endPos - m_start, static_cast<int>(m_len));
 }
 
 void alignSelectionRectToDevicePixels(FloatRect& rect)
 {
     float maxX = floorf(rect.maxX());
     rect.setX(floorf(rect.x()));
     rect.setWidth(roundf(maxX - rect.x()));
 }
 
 void InlineTextBox::paintSelection(GraphicsContext* context, const FloatPoint& boxOrigin, RenderStyle* style, const Font& font, Color textColor)
@@ skipping 30 matching lines @@
     StringBuilder charactersWithHyphen;
     bool respectHyphen = ePos == length && hasHyphen();
     TextRun textRun = constructTextRun(style, font, string, textRenderer().textLength() - m_start, respectHyphen ? &charactersWithHyphen : 0);
     if (respectHyphen)
         ePos = textRun.length();
 
     LayoutUnit selectionBottom = root().selectionBottom();
     LayoutUnit selectionTop = root().selectionTopAdjustedForPrecedingBlock();
 
     int deltaY = roundToInt(renderer().style()->isFlippedLinesWritingMode() ? selectionBottom - logicalBottom() : logicalTop() - selectionTop);
-    int selHeight = max(0, roundToInt(selectionBottom - selectionTop));
+    int selHeight = std::max(0, roundToInt(selectionBottom - selectionTop));
 
     FloatPoint localOrigin(boxOrigin.x(), boxOrigin.y() - deltaY);
     FloatRect clipRect(localOrigin, FloatSize(m_logicalWidth, selHeight));
     alignSelectionRectToDevicePixels(clipRect);
 
     context->clip(clipRect);
 
     context->drawHighlightForText(font, textRun, localOrigin, selHeight, c, sPos, ePos);
 }
 
-void InlineTextBox::paintCompositionBackground(GraphicsContext* context, const FloatPoint& boxOrigin, RenderStyle* style, const Font& font, int startPos, int endPos)
+size_t InlineTextBox::underlinePaintStart(const CompositionUnderline& underline)

[yosin_UTC9, 2014/06/12 06:23:17]

nit: |size_t| -> |unsigned|

[huangs, 2014/06/12 23:22:10]

Done.

 {
-    int offset = m_start;
-    int sPos = max(startPos - offset, 0);
-    int ePos = min(endPos - offset, (int)m_len);
+    return std::max(static_cast<unsigned>(m_start), underline.startOffset);
+}
 
+size_t InlineTextBox::underlinePaintEnd(const CompositionUnderline& underline)

[yosin_UTC9, 2014/06/12 06:23:17]

nit: |size_t| -> |unsigned|

It seems both |InlineTextBox| and |CompositeUnderline| use |unsigned|.

[huangs, 2014/06/12 23:22:10]

Done.

+{
+    unsigned paintEnd = std::min(end() + 1, underline.endOffset); // end() points at the last char, not past it.
+    if (m_truncation != cNoTruncation)
+        paintEnd = std::min(paintEnd, static_cast<unsigned>(m_start + m_truncation));
+    return paintEnd;
+}
+
+void InlineTextBox::paintCompositionBackground(GraphicsContext* context, const FloatPoint& boxOrigin, RenderStyle* style, const Font& font, Color backgroundColor, int startPos, int endPos)
+{
+    int sPos = std::max(startPos - m_start, 0);
+    int ePos = std::min(endPos - m_start, static_cast<int>(m_len));
     if (sPos >= ePos)
         return;
 
     GraphicsContextStateSaver stateSaver(*context);
 
-    Color c = Color(225, 221, 85);
-
-    updateGraphicsContext(context, c, c, 0); // Don't draw text at all!
+    updateGraphicsContext(context, backgroundColor, backgroundColor, 0); // Don't draw text at all!
 
     int deltaY = renderer().style()->isFlippedLinesWritingMode() ? selectionBottom() - logicalBottom() : logicalTop() - selectionTop();
     int selHeight = selectionHeight();
     FloatPoint localOrigin(boxOrigin.x(), boxOrigin.y() - deltaY);
-    context->drawHighlightForText(font, constructTextRun(style, font), localOrigin, selHeight, c, sPos, ePos);
+    context->drawHighlightForText(font, constructTextRun(style, font), localOrigin, selHeight, backgroundColor, sPos, ePos);
 }
 
 static StrokeStyle textDecorationStyleToStrokeStyle(TextDecorationStyle decorationStyle)
 {
     StrokeStyle strokeStyle = SolidStroke;
     switch (decorationStyle) {
     case TextDecorationStyleSolid:
         strokeStyle = SolidStroke;
         break;
     case TextDecorationStyleDouble:
@@ skipping 97 matching lines @@
     context->adjustLineToPixelBoundaries(p1, p2, strokeThickness, context->strokeStyle());
 
     Path path;
     path.moveTo(p1);
 
     // Distance between decoration's axis and Bezier curve's control points.
     // The height of the curve is based on this distance. Use a minimum of 6 pixels distance since
     // the actual curve passes approximately at half of that distance, that is 3 pixels.
     // The minimum height of the curve is also approximately 3 pixels. Increases the curve's height
     // as strockThickness increases to make the curve looks better.
-    float controlPointDistance = 3 * max<float>(2, strokeThickness);
+    float controlPointDistance = 3 * std::max<float>(2, strokeThickness);
 
     // Increment used to form the diamond shape between start point (p1), control
     // points and end point (p2) along the axis of the decoration. Makes the
     // curve wider as strockThickness increases to make the curve looks better.
-    float step = 2 * max<float>(2, strokeThickness);
+    float step = 2 * std::max<float>(2, strokeThickness);
 
     bool isVerticalLine = (p1.x() == p2.x());
 
     if (isVerticalLine) {
         ASSERT(p1.x() == p2.x());
 
         float xAxis = p1.x();
         float y1;
         float y2;
 
@@ skipping 108 matching lines @@
 
     RenderStyle* styleToUse = renderer().style(isFirstLineStyle());
     int baseline = styleToUse->fontMetrics().ascent();
 
     size_t shadowCount = shadowList ? shadowList->shadows().size() : 0;
     // Set the thick of the line to be 10% (or something else ?)of the computed font size and not less than 1px.
     // Using computedFontSize should take care of zoom as well.
 
     // Update Underline thickness, in case we have Faulty Font Metrics calculating underline thickness by old method.
     float textDecorationThickness = styleToUse->fontMetrics().underlineThickness();
-    int fontHeightInt  = (int)(styleToUse->fontMetrics().floatHeight() + 0.5);
+    int fontHeightInt = static_cast<int>(styleToUse->fontMetrics().floatHeight() + 0.5);
     if ((textDecorationThickness == 0.f) || (textDecorationThickness >= (fontHeightInt >> 1)))
         textDecorationThickness = std::max(1.f, styleToUse->computedFontSize() / 10.f);
 
     context->setStrokeThickness(textDecorationThickness);
 
     bool antialiasDecoration = shouldSetDecorationAntialias(overline.style, underline.style, linethrough.style)
         && RenderBoxModelObject::shouldAntialiasLines(context);
 
     float extraOffset = 0;
     if (!linesAreOpaque && shadowCount > 1) {
         FloatRect clipRect(localOrigin, FloatSize(width, baseline + 2));
         for (size_t i = shadowCount; i--; ) {
             const ShadowData& s = shadowList->shadows()[i];
             FloatRect shadowRect(localOrigin, FloatSize(width, baseline + 2));
             shadowRect.inflate(s.blur());
             float shadowX = isHorizontal() ? s.x() : s.y();
             float shadowY = isHorizontal() ? s.y() : -s.x();
             shadowRect.move(shadowX, shadowY);
             clipRect.unite(shadowRect);
-            extraOffset = max(extraOffset, max(0.0f, shadowY) + s.blur());
+            extraOffset = std::max(extraOffset, std::max(0.0f, shadowY) + s.blur());
         }
         context->clip(clipRect);
         extraOffset += baseline + 2;
         localOrigin.move(0, extraOffset);
     }
 
-    for (size_t i = max(static_cast<size_t>(1), shadowCount); i--; ) {
+    for (size_t i = std::max(static_cast<size_t>(1), shadowCount); i--; ) {
         // Even if we have no shadows, we still want to run the code below this once.
         if (i < shadowCount) {
             if (!i) {
                 // The last set of lines paints normally inside the clip.
                 localOrigin.move(0, -extraOffset);
                 extraOffset = 0;
             }
             const ShadowData& shadow = shadowList->shadows()[i];
             float shadowX = isHorizontal() ? shadow.x() : shadow.y();
             float shadowY = isHorizontal() ? shadow.y() : -shadow.x();
@@ skipping 37 matching lines @@
         return;
 
     if (m_truncation == cFullTruncation)
         return;
 
     float start = 0; // start of line to draw, relative to tx
     float width = m_logicalWidth; // how much line to draw
 
     // Determine whether we need to measure text
     bool markerSpansWholeBox = true;
-    if (m_start <= (int)marker->startOffset())
+    if (m_start <= static_cast<int>(marker->startOffset()))
         markerSpansWholeBox = false;
     if ((end() + 1) != marker->endOffset()) // end points at the last char, not past it
         markerSpansWholeBox = false;
     if (m_truncation != cNoTruncation)
         markerSpansWholeBox = false;
 
     if (!markerSpansWholeBox || grammar) {
-        int startPosition = max<int>(marker->startOffset() - m_start, 0);
-        int endPosition = min<int>(marker->endOffset() - m_start, m_len);
+        int startPosition = std::max<int>(marker->startOffset() - m_start, 0);
+        int endPosition = std::min<int>(marker->endOffset() - m_start, m_len);
 
         if (m_truncation != cNoTruncation)
-            endPosition = min<int>(endPosition, m_truncation);
+            endPosition = std::min<int>(endPosition, m_truncation);
 
         // Calculate start & width
         int deltaY = renderer().style()->isFlippedLinesWritingMode() ? selectionBottom() - logicalBottom() : logicalTop() - selectionTop();
         int selHeight = selectionHeight();
         FloatPoint startPoint(boxOrigin.x(), boxOrigin.y() - deltaY);
         TextRun run = constructTextRun(style, font);
 
         // FIXME: Convert the document markers to float rects.
         IntRect markerRect = enclosingIntRect(font.selectionRectForText(run, startPoint, selHeight, startPosition, endPosition));
         start = markerRect.x() - startPoint.x();
@@ skipping 28 matching lines @@
     pt->drawLineForDocumentMarker(FloatPoint(boxOrigin.x() + start, boxOrigin.y() + underlineOffset), width, lineStyleForMarkerType(marker->type()));
 }
 
 void InlineTextBox::paintTextMatchMarker(GraphicsContext* pt, const FloatPoint& boxOrigin, DocumentMarker* marker, RenderStyle* style, const Font& font)
 {
     // Use same y positioning and height as for selection, so that when the selection and this highlight are on
     // the same word there are no pieces sticking out.
     int deltaY = renderer().style()->isFlippedLinesWritingMode() ? selectionBottom() - logicalBottom() : logicalTop() - selectionTop();
     int selHeight = selectionHeight();
 
-    int sPos = max(marker->startOffset() - m_start, (unsigned)0);
-    int ePos = min(marker->endOffset() - m_start, (unsigned)m_len);
+    int sPos = std::max(marker->startOffset() - m_start, 0U);
+    int ePos = std::min(marker->endOffset() - m_start, static_cast<unsigned>(m_len));
     TextRun run = constructTextRun(style, font);
 
     // Always compute and store the rect associated with this marker. The computed rect is in absolute coordinates.
     IntRect markerRect = enclosingIntRect(font.selectionRectForText(run, IntPoint(x(), selectionTop()), selHeight, sPos, ePos));
     markerRect = renderer().localToAbsoluteQuad(FloatRect(markerRect)).enclosingBoundingBox();
     toRenderedDocumentMarker(marker)->setRenderedRect(markerRect);
 
     // Optionally highlight the text
     if (renderer().frame()->editor().markedTextMatchesAreHighlighted()) {
         Color color = marker->activeMatch() ?
@@ skipping 59 matching lines @@
         }
 
     }
 }
 
 void InlineTextBox::paintCompositionUnderline(GraphicsContext* ctx, const FloatPoint& boxOrigin, const CompositionUnderline& underline)
 {
     if (m_truncation == cFullTruncation)
         return;
 
-    float start = 0; // start of line to draw, relative to tx
-    float width = m_logicalWidth; // how much line to draw
-    bool useWholeWidth = true;
-    unsigned paintStart = m_start;
-    unsigned paintEnd = end() + 1; // end points at the last char, not past it
-    if (paintStart <= underline.startOffset) {
-        paintStart = underline.startOffset;
-        useWholeWidth = false;
-        start = toRenderText(renderer()).width(m_start, paintStart - m_start, textPos(), isLeftToRightDirection() ? LTR : RTL, isFirstLineStyle());
-    }
-    if (paintEnd != underline.endOffset) {      // end points at the last char, not past it
-        paintEnd = min(paintEnd, (unsigned)underline.endOffset);
-        useWholeWidth = false;
-    }
-    if (m_truncation != cNoTruncation) {
-        paintEnd = min(paintEnd, (unsigned)m_start + m_truncation);
-        useWholeWidth = false;
-    }
-    if (!useWholeWidth) {
-        width = toRenderText(renderer()).width(paintStart, paintEnd - paintStart, textPos() + start, isLeftToRightDirection() ? LTR : RTL, isFirstLineStyle());
-    }
+    unsigned paintStart = underlinePaintStart(underline);
+    unsigned paintEnd = underlinePaintEnd(underline);
+
+    // start of line to draw, relative to tx
+    float start = paintStart == static_cast<unsigned>(m_start) ? 0 :
+        toRenderText(renderer()).width(m_start, paintStart - m_start, textPos(), isLeftToRightDirection() ? LTR : RTL, isFirstLineStyle());
+    // how much line to draw
+    float width = (paintStart == static_cast<unsigned>(m_start) && paintEnd == static_cast<unsigned>(end()) + 1) ? m_logicalWidth :
+        toRenderText(renderer()).width(paintStart, paintEnd - paintStart, textPos() + start, isLeftToRightDirection() ? LTR : RTL, isFirstLineStyle());
 
     // Thick marked text underlines are 2px thick as long as there is room for the 2px line under the baseline.
     // All other marked text underlines are 1px thick.
     // If there's not enough space the underline will touch or overlap characters.
     int lineThickness = 1;
     int baseline = renderer().style(isFirstLineStyle())->fontMetrics().ascent();
     if (underline.thick && logicalHeight() - baseline >= 2)
         lineThickness = 2;
 
     // We need to have some space between underlines of subsequent clauses, because some input methods do not use different underline styles for those.
@@ skipping 174 matching lines @@
     printedCharacters = fprintf(stderr, "\t%s %p", obj.renderName(), &obj);
     const int rendererCharacterOffset = 24;
     for (; printedCharacters < rendererCharacterOffset; printedCharacters++)
         fputc(' ', stderr);
     fprintf(stderr, "(%d,%d) \"%s\"\n", start(), start() + len(), value.utf8().data());
 }
 
 #endif
 
 } // namespace WebCore