TextPainter.cpp   [plain text]

/*
 * (C) 1999 Lars Knoll (knoll@kde.org)
 * (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004-2017 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 "TextPainter.h"

#include "DisplayListReplayer.h"
#include "GraphicsContext.h"
#include "InlineTextBox.h"
#include "RenderCombineText.h"
#include "RenderLayer.h"
#include "ShadowData.h"
#include <wtf/NeverDestroyed.h>

namespace WebCore {

ShadowApplier::ShadowApplier(GraphicsContext& context, const ShadowData* shadow, const FilterOperations* colorFilter, const FloatRect& textRect, bool lastShadowIterationShouldDrawText, bool opaque, FontOrientation orientation)
    : m_context { context }
    , m_shadow { shadow }
    , m_onlyDrawsShadow { !isLastShadowIteration() || !lastShadowIterationShouldDrawText }
    , m_avoidDrawingShadow { shadowIsCompletelyCoveredByText(opaque) }
    , m_nothingToDraw { shadow && m_avoidDrawingShadow && m_onlyDrawsShadow }
    , m_didSaveContext { false }
{
    if (!shadow || m_nothingToDraw) {
        m_shadow = nullptr;
        return;
    }

    int shadowX = orientation == FontOrientation::Horizontal ? shadow->x() : shadow->y();
    int shadowY = orientation == FontOrientation::Horizontal ? shadow->y() : -shadow->x();
    FloatSize shadowOffset(shadowX, shadowY);
    int shadowRadius = shadow->radius();
    Color shadowColor = shadow->color();
    if (colorFilter)
        colorFilter->transformColor(shadowColor);

    // When drawing shadows, we usually clip the context to the area the shadow will reside, and then
    // draw the text itself outside the clipped area (so only the shadow shows up). However, we can
    // often draw the *last* shadow and the text itself in a single call.
    if (m_onlyDrawsShadow) {
        FloatRect shadowRect(textRect);
        shadowRect.inflate(shadow->paintingExtent() + 3 * textRect.height());
        shadowRect.move(shadowOffset);
        context.save();
        context.clip(shadowRect);

        m_didSaveContext = true;
        m_extraOffset = FloatSize(0, 2 * shadowRect.height() + std::max(0.0f, shadowOffset.height()) + shadowRadius);
        shadowOffset -= m_extraOffset;
    }

    if (!m_avoidDrawingShadow)
        context.setShadow(shadowOffset, shadowRadius, shadowColor);
}

inline bool ShadowApplier::isLastShadowIteration()
{
    return m_shadow && !m_shadow->next();
}

inline bool ShadowApplier::shadowIsCompletelyCoveredByText(bool textIsOpaque)
{
    return textIsOpaque && m_shadow && m_shadow->location().isZero() && !m_shadow->radius();
}

ShadowApplier::~ShadowApplier()
{
    if (!m_shadow)
        return;
    if (m_onlyDrawsShadow)
        m_context.restore();
    else if (!m_avoidDrawingShadow)
        m_context.clearShadow();
}

TextPainter::TextPainter(GraphicsContext& context)
    : m_context(context)
{
}

void TextPainter::paintTextOrEmphasisMarks(const FontCascade& font, const TextRun& textRun, const AtomicString& emphasisMark,
    float emphasisMarkOffset, const FloatPoint& textOrigin, unsigned startOffset, unsigned endOffset)
{
    ASSERT(startOffset < endOffset);
    if (!emphasisMark.isEmpty())
        m_context.drawEmphasisMarks(font, textRun, emphasisMark, textOrigin + FloatSize(0, emphasisMarkOffset), startOffset, endOffset);
    else if (startOffset || endOffset < textRun.length() || !m_glyphDisplayList)
        m_context.drawText(font, textRun, textOrigin, startOffset, endOffset);
    else {
        // Replaying back a whole cached glyph run to the GraphicsContext.
        m_context.translate(textOrigin);
        DisplayList::Replayer replayer(m_context, *m_glyphDisplayList);
        replayer.replay();
        m_context.translate(-textOrigin);
    }
    m_glyphDisplayList = nullptr;
}

void TextPainter::paintTextWithShadows(const ShadowData* shadow, const FilterOperations* colorFilter, const FontCascade& font, const TextRun& textRun, const FloatRect& boxRect, const FloatPoint& textOrigin,
    unsigned startOffset, unsigned endOffset, const AtomicString& emphasisMark, float emphasisMarkOffset, bool stroked)
{
    if (!shadow) {
        paintTextOrEmphasisMarks(font, textRun, emphasisMark, emphasisMarkOffset, textOrigin, startOffset, endOffset);
        return;
    }

    Color fillColor = m_context.fillColor();
    bool opaque = fillColor.isOpaque();
    bool lastShadowIterationShouldDrawText = !stroked && opaque;
    if (!opaque)
        m_context.setFillColor(Color::black);
    while (shadow) {
        ShadowApplier shadowApplier(m_context, shadow, colorFilter, boxRect, lastShadowIterationShouldDrawText, opaque, m_textBoxIsHorizontal ? FontOrientation::Horizontal : FontOrientation::Vertical);
        if (!shadowApplier.nothingToDraw())
            paintTextOrEmphasisMarks(font, textRun, emphasisMark, emphasisMarkOffset, textOrigin + shadowApplier.extraOffset(), startOffset, endOffset);
        shadow = shadow->next();
    }

    if (!lastShadowIterationShouldDrawText) {
        if (!opaque)
            m_context.setFillColor(fillColor);
        paintTextOrEmphasisMarks(font, textRun, emphasisMark, emphasisMarkOffset, textOrigin, startOffset, endOffset);
    }
}

void TextPainter::paintTextAndEmphasisMarksIfNeeded(const TextRun& textRun, const FloatRect& boxRect, const FloatPoint& textOrigin, unsigned startOffset, unsigned endOffset,
    const TextPaintStyle& paintStyle, const ShadowData* shadow, const FilterOperations* shadowColorFilter)
{
    if (paintStyle.paintOrder == PaintOrder::Normal) {
        // FIXME: Truncate right-to-left text correctly.
        paintTextWithShadows(shadow, shadowColorFilter, *m_font, textRun, boxRect, textOrigin, startOffset, endOffset, nullAtom(), 0, paintStyle.strokeWidth > 0);
    } else {
        auto textDrawingMode = m_context.textDrawingMode();
        auto paintOrder = RenderStyle::paintTypesForPaintOrder(paintStyle.paintOrder);
        auto shadowToUse = shadow;

        for (auto order : paintOrder) {
            switch (order) {
            case PaintType::Fill:
                m_context.setTextDrawingMode(textDrawingMode & ~TextModeStroke);
                paintTextWithShadows(shadowToUse, shadowColorFilter, *m_font, textRun, boxRect, textOrigin, startOffset, endOffset, nullAtom(), 0, false);
                shadowToUse = nullptr;
                m_context.setTextDrawingMode(textDrawingMode);
                break;
            case PaintType::Stroke:
                m_context.setTextDrawingMode(textDrawingMode & ~TextModeFill);
                paintTextWithShadows(shadowToUse, shadowColorFilter, *m_font, textRun, boxRect, textOrigin, startOffset, endOffset, nullAtom(), 0, paintStyle.strokeWidth > 0);
                shadowToUse = nullptr;
                m_context.setTextDrawingMode(textDrawingMode);
                break;
            case PaintType::Markers:
                continue;
            }
        }
    }
    
    if (m_emphasisMark.isEmpty())
        return;

    FloatPoint boxOrigin = boxRect.location();
    updateGraphicsContext(m_context, paintStyle, UseEmphasisMarkColor);
    static NeverDestroyed<TextRun> objectReplacementCharacterTextRun(StringView(&objectReplacementCharacter, 1));
    const TextRun& emphasisMarkTextRun = m_combinedText ? objectReplacementCharacterTextRun.get() : textRun;
    FloatPoint emphasisMarkTextOrigin = m_combinedText ? FloatPoint(boxOrigin.x() + boxRect.width() / 2, boxOrigin.y() + m_font->fontMetrics().ascent()) : textOrigin;
    if (m_combinedText)
        m_context.concatCTM(rotation(boxRect, Clockwise));

    // FIXME: Truncate right-to-left text correctly.
    paintTextWithShadows(shadow, shadowColorFilter, m_combinedText ? m_combinedText->originalFont() : *m_font, emphasisMarkTextRun, boxRect, emphasisMarkTextOrigin, startOffset, endOffset,
        m_emphasisMark, m_emphasisMarkOffset, paintStyle.strokeWidth > 0);

    if (m_combinedText)
        m_context.concatCTM(rotation(boxRect, Counterclockwise));
}

void TextPainter::paint(const TextRun& textRun, const FloatRect& boxRect, const FloatPoint& textOrigin)
{
    paintRange(textRun, boxRect, textOrigin, 0, textRun.length());
}

void TextPainter::paintRange(const TextRun& textRun, const FloatRect& boxRect, const FloatPoint& textOrigin, unsigned start, unsigned end)
{
    ASSERT(m_font);
    ASSERT(start < end);

    GraphicsContextStateSaver stateSaver(m_context, m_style.strokeWidth > 0);
    updateGraphicsContext(m_context, m_style);
    paintTextAndEmphasisMarksIfNeeded(textRun, boxRect, textOrigin, start, end, m_style, m_shadow, m_shadowColorFilter);
}

void TextPainter::clearGlyphDisplayLists()
{
    GlyphDisplayListCache<InlineTextBox>::singleton().clear();
    GlyphDisplayListCache<SimpleLineLayout::Run>::singleton().clear();
}

bool TextPainter::shouldUseGlyphDisplayList(const PaintInfo& paintInfo)
{
    return !paintInfo.context().paintingDisabled() && paintInfo.enclosingSelfPaintingLayer() && paintInfo.enclosingSelfPaintingLayer()->paintingFrequently();
}

} // namespace WebCore