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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "config.h"
      6 #include "core/rendering/TextPainter.h"
      7 
      8 #include "core/CSSPropertyNames.h"
      9 #include "core/frame/Settings.h"
     10 #include "core/rendering/InlineTextBox.h"
     11 #include "core/rendering/RenderCombineText.h"
     12 #include "core/rendering/RenderObject.h"
     13 #include "core/rendering/style/RenderStyle.h"
     14 #include "core/rendering/style/ShadowList.h"
     15 #include "platform/fonts/Font.h"
     16 #include "platform/graphics/GraphicsContext.h"
     17 #include "platform/graphics/GraphicsContextStateSaver.h"
     18 #include "platform/text/TextRun.h"
     19 #include "wtf/Assertions.h"
     20 #include "wtf/unicode/CharacterNames.h"
     21 
     22 namespace blink {
     23 
     24 TextPainter::TextPainter(GraphicsContext* context, const Font& font, const TextRun& run, const FloatPoint& textOrigin, const FloatRect& textBounds, bool horizontal)
     25     : m_graphicsContext(context)
     26     , m_font(font)
     27     , m_run(run)
     28     , m_textOrigin(textOrigin)
     29     , m_textBounds(textBounds)
     30     , m_horizontal(horizontal)
     31     , m_emphasisMarkOffset(0)
     32     , m_combinedText(0)
     33 {
     34 }
     35 
     36 TextPainter::~TextPainter()
     37 {
     38 }
     39 
     40 void TextPainter::setEmphasisMark(const AtomicString& emphasisMark, TextEmphasisPosition position)
     41 {
     42     m_emphasisMark = emphasisMark;
     43 
     44     if (emphasisMark.isNull()) {
     45         m_emphasisMarkOffset = 0;
     46     } else if (position == TextEmphasisPositionOver) {
     47         m_emphasisMarkOffset = -m_font.fontMetrics().ascent() - m_font.emphasisMarkDescent(emphasisMark);
     48     } else {
     49         ASSERT(position == TextEmphasisPositionUnder);
     50         m_emphasisMarkOffset = m_font.fontMetrics().descent() + m_font.emphasisMarkAscent(emphasisMark);
     51     }
     52 }
     53 
     54 void TextPainter::paint(int startOffset, int endOffset, int length, const Style& textStyle, TextBlobPtr* cachedTextBlob)
     55 {
     56     GraphicsContextStateSaver stateSaver(*m_graphicsContext, false);
     57     updateGraphicsContext(textStyle, stateSaver);
     58     paintInternal<PaintText>(startOffset, endOffset, length, cachedTextBlob);
     59 
     60     if (!m_emphasisMark.isEmpty()) {
     61         if (textStyle.emphasisMarkColor != textStyle.fillColor)
     62             m_graphicsContext->setFillColor(textStyle.emphasisMarkColor);
     63 
     64         if (m_combinedText)
     65             paintEmphasisMarkForCombinedText();
     66         else
     67             paintInternal<PaintEmphasisMark>(startOffset, endOffset, length);
     68     }
     69 }
     70 
     71 // static
     72 void TextPainter::updateGraphicsContext(GraphicsContext* context, const Style& textStyle, bool horizontal, GraphicsContextStateSaver& stateSaver)
     73 {
     74     TextDrawingModeFlags mode = context->textDrawingMode();
     75     if (textStyle.strokeWidth > 0) {
     76         TextDrawingModeFlags newMode = mode | TextModeStroke;
     77         if (mode != newMode) {
     78             if (!stateSaver.saved())
     79                 stateSaver.save();
     80             context->setTextDrawingMode(newMode);
     81             mode = newMode;
     82         }
     83     }
     84 
     85     if (mode & TextModeFill && textStyle.fillColor != context->fillColor())
     86         context->setFillColor(textStyle.fillColor);
     87 
     88     if (mode & TextModeStroke) {
     89         if (textStyle.strokeColor != context->strokeColor())
     90             context->setStrokeColor(textStyle.strokeColor);
     91         if (textStyle.strokeWidth != context->strokeThickness())
     92             context->setStrokeThickness(textStyle.strokeWidth);
     93     }
     94 
     95     // Text shadows are disabled when printing. http://crbug.com/258321
     96     if (textStyle.shadow && !context->printing()) {
     97         if (!stateSaver.saved())
     98             stateSaver.save();
     99         context->setDrawLooper(textStyle.shadow->createDrawLooper(DrawLooperBuilder::ShadowIgnoresAlpha, horizontal));
    100     }
    101 }
    102 
    103 static Color textColorForWhiteBackground(Color textColor)
    104 {
    105     int distanceFromWhite = differenceSquared(textColor, Color::white);
    106     // semi-arbitrarily chose 65025 (255^2) value here after a few tests;
    107     return distanceFromWhite > 65025 ? textColor : textColor.dark();
    108 }
    109 
    110 // static
    111 TextPainter::Style TextPainter::textPaintingStyle(RenderObject& renderer, RenderStyle* style, bool forceBlackText, bool isPrinting)
    112 {
    113     TextPainter::Style textStyle;
    114 
    115     if (forceBlackText) {
    116         textStyle.fillColor = Color::black;
    117         textStyle.strokeColor = Color::black;
    118         textStyle.emphasisMarkColor = Color::black;
    119         textStyle.strokeWidth = style->textStrokeWidth();
    120         textStyle.shadow = 0;
    121     } else {
    122         textStyle.fillColor = renderer.resolveColor(style, CSSPropertyWebkitTextFillColor);
    123         textStyle.strokeColor = renderer.resolveColor(style, CSSPropertyWebkitTextStrokeColor);
    124         textStyle.emphasisMarkColor = renderer.resolveColor(style, CSSPropertyWebkitTextEmphasisColor);
    125         textStyle.strokeWidth = style->textStrokeWidth();
    126         textStyle.shadow = style->textShadow();
    127 
    128         // Adjust text color when printing with a white background.
    129         bool forceBackgroundToWhite = false;
    130         if (isPrinting) {
    131             if (style->printColorAdjust() == PrintColorAdjustEconomy)
    132                 forceBackgroundToWhite = true;
    133             if (renderer.document().settings() && renderer.document().settings()->shouldPrintBackgrounds())
    134                 forceBackgroundToWhite = false;
    135         }
    136         if (forceBackgroundToWhite) {
    137             textStyle.fillColor = textColorForWhiteBackground(textStyle.fillColor);
    138             textStyle.strokeColor = textColorForWhiteBackground(textStyle.strokeColor);
    139             textStyle.emphasisMarkColor = textColorForWhiteBackground(textStyle.emphasisMarkColor);
    140         }
    141 
    142         // Text shadows are disabled when printing. http://crbug.com/258321
    143         if (isPrinting)
    144             textStyle.shadow = 0;
    145     }
    146 
    147     return textStyle;
    148 }
    149 
    150 TextPainter::Style TextPainter::selectionPaintingStyle(RenderObject& renderer, bool haveSelection, bool forceBlackText, bool isPrinting, const TextPainter::Style& textStyle)
    151 {
    152     TextPainter::Style selectionStyle = textStyle;
    153 
    154     if (haveSelection) {
    155         if (!forceBlackText) {
    156             selectionStyle.fillColor = renderer.selectionForegroundColor();
    157             selectionStyle.emphasisMarkColor = renderer.selectionEmphasisMarkColor();
    158         }
    159 
    160         if (RenderStyle* pseudoStyle = renderer.getCachedPseudoStyle(SELECTION)) {
    161             selectionStyle.strokeColor = forceBlackText ? Color::black : renderer.resolveColor(pseudoStyle, CSSPropertyWebkitTextStrokeColor);
    162             selectionStyle.strokeWidth = pseudoStyle->textStrokeWidth();
    163             selectionStyle.shadow = forceBlackText ? 0 : pseudoStyle->textShadow();
    164         }
    165 
    166         // Text shadows are disabled when printing. http://crbug.com/258321
    167         if (isPrinting)
    168             selectionStyle.shadow = 0;
    169     }
    170 
    171     return selectionStyle;
    172 }
    173 
    174 static bool graphicsContextAllowsTextBlobs(GraphicsContext* context)
    175 {
    176     // Text blobs affect the shader coordinate space.
    177     // FIXME: Fix this, most likely in Skia.
    178     return !context->strokeGradient() && !context->strokePattern() && !context->fillGradient() && !context->fillPattern();
    179 }
    180 
    181 template <TextPainter::PaintInternalStep step>
    182 void TextPainter::paintInternalRun(TextRunPaintInfo& textRunPaintInfo, int from, int to, TextBlobPtr* cachedTextBlob)
    183 {
    184     textRunPaintInfo.from = from;
    185     textRunPaintInfo.to = to;
    186 
    187     if (step == PaintEmphasisMark) {
    188         m_graphicsContext->drawEmphasisMarks(m_font, textRunPaintInfo, m_emphasisMark, m_textOrigin + IntSize(0, m_emphasisMarkOffset));
    189         return;
    190     }
    191 
    192     ASSERT(step == PaintText);
    193 
    194     TextBlobPtr localTextBlob;
    195     TextBlobPtr& textBlob = cachedTextBlob ? *cachedTextBlob : localTextBlob;
    196     bool canUseTextBlobs = RuntimeEnabledFeatures::textBlobEnabled() && graphicsContextAllowsTextBlobs(m_graphicsContext);
    197 
    198     if (canUseTextBlobs && !textBlob)
    199         textBlob = m_font.buildTextBlob(textRunPaintInfo, m_textOrigin, m_graphicsContext->couldUseLCDRenderedText());
    200 
    201     if (canUseTextBlobs && textBlob)
    202         m_font.drawTextBlob(m_graphicsContext, textBlob.get(), m_textOrigin.data());
    203     else
    204         m_graphicsContext->drawText(m_font, textRunPaintInfo, m_textOrigin);
    205 }
    206 
    207 template <TextPainter::PaintInternalStep Step>
    208 void TextPainter::paintInternal(int startOffset, int endOffset, int truncationPoint, TextBlobPtr* cachedTextBlob)
    209 {
    210     // FIXME: We should be able to use cachedTextBlob in more cases.
    211     TextRunPaintInfo textRunPaintInfo(m_run);
    212     textRunPaintInfo.bounds = m_textBounds;
    213     if (startOffset <= endOffset) {
    214         paintInternalRun<Step>(textRunPaintInfo, startOffset, endOffset, cachedTextBlob);
    215     } else {
    216         if (endOffset > 0)
    217             paintInternalRun<Step>(textRunPaintInfo, 0, endOffset);
    218         if (startOffset < truncationPoint)
    219             paintInternalRun<Step>(textRunPaintInfo, startOffset, truncationPoint);
    220     }
    221 }
    222 
    223 void TextPainter::paintEmphasisMarkForCombinedText()
    224 {
    225     ASSERT(m_combinedText);
    226     DEFINE_STATIC_LOCAL(TextRun, placeholderTextRun, (&ideographicFullStop, 1));
    227     FloatPoint emphasisMarkTextOrigin(m_textBounds.x(), m_textBounds.y() + m_font.fontMetrics().ascent() + m_emphasisMarkOffset);
    228     TextRunPaintInfo textRunPaintInfo(placeholderTextRun);
    229     textRunPaintInfo.bounds = m_textBounds;
    230     m_graphicsContext->concatCTM(InlineTextBox::rotation(m_textBounds, InlineTextBox::Clockwise));
    231     m_graphicsContext->drawEmphasisMarks(m_combinedText->originalFont(), textRunPaintInfo, m_emphasisMark, emphasisMarkTextOrigin);
    232     m_graphicsContext->concatCTM(InlineTextBox::rotation(m_textBounds, InlineTextBox::Counterclockwise));
    233 }
    234 
    235 } // namespace blink
    236