flutter_flutter/sky/engine/platform/fonts/SimpleFontData.cpp

/*
 * Copyright (C) 2005, 2008, 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Alexey Proskuryakov
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "flutter/sky/engine/platform/fonts/SimpleFontData.h"

#include "flutter/sky/engine/wtf/MathExtras.h"

namespace blink {

const float smallCapsFontSizeMultiplier = 0.7f;
const float emphasisMarkFontSizeMultiplier = 0.5f;

SimpleFontData::SimpleFontData(const FontPlatformData& platformData,
                               PassRefPtr<CustomFontData> customData,
                               bool isTextOrientationFallback)
    : m_maxCharWidth(-1),
      m_avgCharWidth(-1),
      m_platformData(platformData),
      m_treatAsFixedPitch(false),
      m_isTextOrientationFallback(isTextOrientationFallback),
      m_isBrokenIdeographFallback(false)
#if ENABLE(OPENTYPE_VERTICAL)
      ,
      m_verticalData(nullptr)
#endif
      ,
      m_hasVerticalGlyphs(false),
      m_customFontData(customData) {
  platformInit();
  platformGlyphInit();
  platformCharWidthInit();
#if ENABLE(OPENTYPE_VERTICAL)
  if (platformData.orientation() == Vertical && !isTextOrientationFallback) {
    m_verticalData = platformData.verticalData();
    m_hasVerticalGlyphs =
        m_verticalData.get() && m_verticalData->hasVerticalMetrics();
  }
#endif
}

SimpleFontData::SimpleFontData(PassRefPtr<CustomFontData> customData,
                               float fontSize,
                               bool syntheticBold,
                               bool syntheticItalic)
    : m_platformData(
          FontPlatformData(fontSize, syntheticBold, syntheticItalic)),
      m_treatAsFixedPitch(false),
      m_isTextOrientationFallback(false),
      m_isBrokenIdeographFallback(false)
#if ENABLE(OPENTYPE_VERTICAL)
      ,
      m_verticalData(nullptr)
#endif
      ,
      m_hasVerticalGlyphs(false),
      m_customFontData(customData) {
  if (m_customFontData)
    m_customFontData->initializeFontData(this, fontSize);
}

// Estimates of avgCharWidth and maxCharWidth for platforms that don't support
// accessing these values from the font.
void SimpleFontData::initCharWidths() {
  GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();

  // Treat the width of a '0' as the avgCharWidth.
  if (m_avgCharWidth <= 0.f && glyphPageZero) {
    static const UChar32 digitZeroChar = '0';
    Glyph digitZeroGlyph = glyphPageZero->glyphForCharacter(digitZeroChar);
    if (digitZeroGlyph)
      m_avgCharWidth = widthForGlyph(digitZeroGlyph);
  }

  // If we can't retrieve the width of a '0', fall back to the x height.
  if (m_avgCharWidth <= 0.f)
    m_avgCharWidth = m_fontMetrics.xHeight();

  if (m_maxCharWidth <= 0.f)
    m_maxCharWidth = std::max(m_avgCharWidth, m_fontMetrics.floatAscent());
}

void SimpleFontData::platformGlyphInit() {
  GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
  if (!glyphPageZero) {
    WTF_LOG_ERROR("Failed to get glyph page zero.");
    m_spaceGlyph = 0;
    m_spaceWidth = 0;
    m_zeroGlyph = 0;
    determinePitch();
    m_zeroWidthSpaceGlyph = 0;
    m_missingGlyphData.fontData = this;
    m_missingGlyphData.glyph = 0;
    return;
  }

  m_zeroWidthSpaceGlyph = glyphPageZero->glyphForCharacter(0);

  // Nasty hack to determine if we should round or ceil space widths.
  // If the font is monospace or fake monospace we ceil to ensure that
  // every character and the space are the same width.  Otherwise we round.
  m_spaceGlyph = glyphPageZero->glyphForCharacter(' ');
  float width = widthForGlyph(m_spaceGlyph);
  m_spaceWidth = width;
  m_zeroGlyph = glyphPageZero->glyphForCharacter('0');
  m_fontMetrics.setZeroWidth(widthForGlyph(m_zeroGlyph));
  determinePitch();

  // Force the glyph for ZERO WIDTH SPACE to have zero width, unless it is
  // shared with SPACE. Helvetica is an example of a non-zero width ZERO WIDTH
  // SPACE glyph. See <http://bugs.webkit.org/show_bug.cgi?id=13178> Ask for the
  // glyph for 0 to avoid paging in ZERO WIDTH SPACE. Control characters,
  // including 0, are mapped to the ZERO WIDTH SPACE glyph.
  if (m_zeroWidthSpaceGlyph == m_spaceGlyph) {
    m_zeroWidthSpaceGlyph = 0;
  }

  m_missingGlyphData.fontData = this;
  m_missingGlyphData.glyph = 0;
}

SimpleFontData::~SimpleFontData() {
  if (!isSVGFont())
    platformDestroy();

  if (isCustomFont())
    GlyphPageTreeNode::pruneTreeCustomFontData(this);
  else
    GlyphPageTreeNode::pruneTreeFontData(this);
}

const SimpleFontData* SimpleFontData::fontDataForCharacter(UChar32) const {
  return this;
}

Glyph SimpleFontData::glyphForCharacter(UChar32 character) const {
  // As GlyphPage::size is power of 2 so shifting is valid
  GlyphPageTreeNode* node =
      GlyphPageTreeNode::getRootChild(this, character >> GlyphPage::sizeBits);
  return node->page() ? node->page()->glyphAt(character & 0xFF) : 0;
}

bool SimpleFontData::isSegmented() const {
  return false;
}

PassRefPtr<SimpleFontData> SimpleFontData::verticalRightOrientationFontData()
    const {
  if (!m_derivedFontData)
    m_derivedFontData = DerivedFontData::create(isCustomFont());
  if (!m_derivedFontData->verticalRightOrientation) {
    FontPlatformData verticalRightPlatformData(m_platformData);
    verticalRightPlatformData.setOrientation(Horizontal);
    m_derivedFontData->verticalRightOrientation =
        create(verticalRightPlatformData,
               isCustomFont() ? CustomFontData::create() : nullptr, true);
  }
  return m_derivedFontData->verticalRightOrientation;
}

PassRefPtr<SimpleFontData> SimpleFontData::uprightOrientationFontData() const {
  if (!m_derivedFontData)
    m_derivedFontData = DerivedFontData::create(isCustomFont());
  if (!m_derivedFontData->uprightOrientation)
    m_derivedFontData->uprightOrientation =
        create(m_platformData,
               isCustomFont() ? CustomFontData::create() : nullptr, true);
  return m_derivedFontData->uprightOrientation;
}

PassRefPtr<SimpleFontData> SimpleFontData::smallCapsFontData(
    const FontDescription& fontDescription) const {
  if (!m_derivedFontData)
    m_derivedFontData = DerivedFontData::create(isCustomFont());
  if (!m_derivedFontData->smallCaps)
    m_derivedFontData->smallCaps =
        createScaledFontData(fontDescription, smallCapsFontSizeMultiplier);

  return m_derivedFontData->smallCaps;
}

PassRefPtr<SimpleFontData> SimpleFontData::emphasisMarkFontData(
    const FontDescription& fontDescription) const {
  if (!m_derivedFontData)
    m_derivedFontData = DerivedFontData::create(isCustomFont());
  if (!m_derivedFontData->emphasisMark)
    m_derivedFontData->emphasisMark =
        createScaledFontData(fontDescription, emphasisMarkFontSizeMultiplier);

  return m_derivedFontData->emphasisMark;
}

PassRefPtr<SimpleFontData> SimpleFontData::brokenIdeographFontData() const {
  if (!m_derivedFontData)
    m_derivedFontData = DerivedFontData::create(isCustomFont());
  if (!m_derivedFontData->brokenIdeograph) {
    m_derivedFontData->brokenIdeograph = create(
        m_platformData, isCustomFont() ? CustomFontData::create() : nullptr);
    m_derivedFontData->brokenIdeograph->m_isBrokenIdeographFallback = true;
  }
  return m_derivedFontData->brokenIdeograph;
}

#ifndef NDEBUG
String SimpleFontData::description() const {
  if (isSVGFont())
    return "[SVG font]";
  if (isCustomFont())
    return "[custom font]";

  return platformData().description();
}
#endif

PassOwnPtr<SimpleFontData::DerivedFontData>
SimpleFontData::DerivedFontData::create(bool forCustomFont) {
  return adoptPtr(new DerivedFontData(forCustomFont));
}

SimpleFontData::DerivedFontData::~DerivedFontData() {
  if (!forCustomFont)
    return;

  if (smallCaps)
    GlyphPageTreeNode::pruneTreeCustomFontData(smallCaps.get());
  if (emphasisMark)
    GlyphPageTreeNode::pruneTreeCustomFontData(emphasisMark.get());
  if (brokenIdeograph)
    GlyphPageTreeNode::pruneTreeCustomFontData(brokenIdeograph.get());
  if (verticalRightOrientation)
    GlyphPageTreeNode::pruneTreeCustomFontData(verticalRightOrientation.get());
  if (uprightOrientation)
    GlyphPageTreeNode::pruneTreeCustomFontData(uprightOrientation.get());
}

PassRefPtr<SimpleFontData> SimpleFontData::createScaledFontData(
    const FontDescription& fontDescription,
    float scaleFactor) const {
  // FIXME: Support scaled SVG fonts. Given that SVG is scalable in general this
  // should be achievable.
  if (isSVGFont())
    return nullptr;

  return platformCreateScaledFontData(fontDescription, scaleFactor);
}

}  // namespace blink