flutter_flutter/sky/engine/platform/fonts/linux/FontCacheLinux.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "flutter/sky/engine/platform/fonts/FontCache.h"

#include <fontconfig/fontconfig.h>
#include <string.h>
#include <unicode/utf16.h>
#include <unistd.h>

#include "flutter/sky/engine/public/platform/Platform.h"
#include "flutter/sky/engine/wtf/HashMap.h"
#include "flutter/sky/engine/wtf/Noncopyable.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"
#include "flutter/sky/engine/wtf/PassOwnPtr.h"
#include "flutter/sky/engine/wtf/Vector.h"
#include "flutter/sky/engine/wtf/text/AtomicString.h"
#include "flutter/sky/engine/wtf/text/AtomicStringHash.h"
#include "flutter/sky/engine/wtf/text/CString.h"

namespace blink {

class CachedFont {
 public:
  // Note: We pass the charset explicitly as callers
  // should not create CachedFont entries without knowing
  // that the FcPattern contains a valid charset.
  CachedFont(FcPattern* pattern, FcCharSet* charSet)
      : m_supportedCharacters(charSet) {
    ASSERT(pattern);
    ASSERT(charSet);
    m_fallbackFont.name = fontName(pattern);
    m_fallbackFont.filename = fontFilename(pattern);
    m_fallbackFont.ttcIndex = fontTtcIndex(pattern);
    m_fallbackFont.isBold = fontIsBold(pattern);
    m_fallbackFont.isItalic = fontIsItalic(pattern);
  }

  const FontCache::PlatformFallbackFont& fallbackFont() const {
    return m_fallbackFont;
  }
  bool hasGlyphForCharacter(UChar32 c) {
    return m_supportedCharacters && FcCharSetHasChar(m_supportedCharacters, c);
  }

 private:
  static String fontName(FcPattern* pattern) {
    FcChar8* familyName = nullptr;
    if (FcPatternGetString(pattern, FC_FAMILY, 0, &familyName) != FcResultMatch)
      return String();

    // FCChar8 is unsigned char, so we cast to char for CString.
    const char* charFamily = reinterpret_cast<char*>(familyName);
    return String::fromUTF8(charFamily, strlen(charFamily));
  }

  static CString fontFilename(FcPattern* pattern) {
    FcChar8* cFilename = nullptr;
    if (FcPatternGetString(pattern, FC_FILE, 0, &cFilename) != FcResultMatch)
      return CString();
    const char* fontFilename = reinterpret_cast<char*>(cFilename);
    return CString(fontFilename, strlen(fontFilename));
  }

  static int fontTtcIndex(FcPattern* pattern) {
    int ttcIndex = -1;
    if (FcPatternGetInteger(pattern, FC_INDEX, 0, &ttcIndex) != FcResultMatch ||
        ttcIndex < 0)
      return 0;
    return ttcIndex;
  }

  static bool fontIsBold(FcPattern* pattern) {
    int weight = 0;
    if (FcPatternGetInteger(pattern, FC_WEIGHT, 0, &weight) != FcResultMatch)
      return false;
    return weight >= FC_WEIGHT_BOLD;
  }

  static bool fontIsItalic(FcPattern* pattern) {
    int slant = 0;
    if (FcPatternGetInteger(pattern, FC_SLANT, 0, &slant) != FcResultMatch)
      return false;
    return slant != FC_SLANT_ROMAN;
  }

  FontCache::PlatformFallbackFont m_fallbackFont;
  // m_supportedCharaters is owned by the parent
  // FcFontSet and should never be freed.
  FcCharSet* m_supportedCharacters;
};

class CachedFontSet {
  WTF_MAKE_NONCOPYABLE(CachedFontSet);

 public:
  // CachedFontSet takes ownership of the passed FcFontSet.
  static PassOwnPtr<CachedFontSet> createForLocale(const char* locale) {
    FcFontSet* fontSet = createFcFontSetForLocale(locale);
    return adoptPtr(new CachedFontSet(fontSet));
  }

  ~CachedFontSet() {
    m_fallbackList.clear();
    FcFontSetDestroy(m_fontSet);
  }

  FontCache::PlatformFallbackFont fallbackFontForChar(UChar32 c) {
    Vector<CachedFont>::iterator itr = m_fallbackList.begin();
    for (; itr != m_fallbackList.end(); itr++) {
      if (itr->hasGlyphForCharacter(c))
        return itr->fallbackFont();
    }
    // The previous code just returned garbage if the user didn't
    // have the necessary fonts, this seems better than garbage.
    // Current callers happen to ignore any values with an empty family string.
    return FontCache::PlatformFallbackFont();
  }

 private:
  static FcFontSet* createFcFontSetForLocale(const char* locale) {
    FcPattern* pattern = FcPatternCreate();

    if (locale) {
      // FcChar* is unsigned char* so we have to cast.
      FcPatternAddString(pattern, FC_LANG,
                         reinterpret_cast<const FcChar8*>(locale));
    }

    FcValue fcvalue;
    fcvalue.type = FcTypeBool;
    fcvalue.u.b = FcTrue;
    FcPatternAdd(pattern, FC_SCALABLE, fcvalue, FcFalse);

    FcConfigSubstitute(0, pattern, FcMatchPattern);
    FcDefaultSubstitute(pattern);

    if (!locale)
      FcPatternDel(pattern, FC_LANG);

    // The result parameter returns if any fonts were found.
    // We already handle 0 fonts correctly, so we ignore the param.
    FcResult result;
    FcFontSet* fontSet = FcFontSort(0, pattern, 0, 0, &result);
    FcPatternDestroy(pattern);

    // The caller will take ownership of this FcFontSet.
    return fontSet;
  }

  CachedFontSet(FcFontSet* fontSet) : m_fontSet(fontSet) { fillFallbackList(); }

  void fillFallbackList() {
    ASSERT(m_fallbackList.isEmpty());
    if (!m_fontSet)
      return;

    for (int i = 0; i < m_fontSet->nfont; ++i) {
      FcPattern* pattern = m_fontSet->fonts[i];

      // Ignore any bitmap fonts users may still have installed from last
      // century.
      FcBool isScalable;
      if (FcPatternGetBool(pattern, FC_SCALABLE, 0, &isScalable) !=
              FcResultMatch ||
          !isScalable)
        continue;

      // Ignore any fonts FontConfig knows about, but that we don't have
      // permission to read.
      FcChar8* cFilename;
      if (FcPatternGetString(pattern, FC_FILE, 0, &cFilename) != FcResultMatch)
        continue;
      if (access(reinterpret_cast<char*>(cFilename), R_OK))
        continue;

      // Make sure this font can tell us what characters it has glyphs for.
      FcCharSet* charSet;
      if (FcPatternGetCharSet(pattern, FC_CHARSET, 0, &charSet) !=
          FcResultMatch)
        continue;

      m_fallbackList.append(CachedFont(pattern, charSet));
    }
  }

  FcFontSet* m_fontSet;  // Owned by this object.
  // CachedFont has a FcCharset* which points into the FcFontSet.
  // If the FcFontSet is ever destroyed, the fallbackList
  // must be cleared first.
  Vector<CachedFont> m_fallbackList;
};

class FontSetCache {
 public:
  static FontSetCache& shared() {
    DEFINE_STATIC_LOCAL(FontSetCache, cache, ());
    return cache;
  }

  FontCache::PlatformFallbackFont fallbackFontForCharInLocale(
      UChar32 c,
      const char* locale) {
    DEFINE_STATIC_LOCAL(AtomicString, kNoLocale, ("NO_LOCALE_SPECIFIED"));
    AtomicString localeKey;
    if (locale && strlen(locale)) {
      localeKey = AtomicString(locale);
    } else {
      // String hash computation the m_setsByLocale map needs
      // a non-empty string.
      localeKey = kNoLocale;
    }

    LocaleToCachedFont::iterator itr = m_setsByLocale.find(localeKey);
    if (itr == m_setsByLocale.end()) {
      OwnPtr<CachedFontSet> newEntry =
          CachedFontSet::createForLocale(strlen(locale) ? locale : 0);
      return m_setsByLocale.add(localeKey, newEntry.release())
          .storedValue->value->fallbackFontForChar(c);
    }
    return itr.get()->value->fallbackFontForChar(c);
  }
  // FIXME: We may wish to add a way to prune the cache at a later time.

 private:
  // FIXME: This shouldn't need to be AtomicString, but
  // currently HashTraits<const char*> isn't smart enough
  // to hash the string (only does pointer compares).
  typedef HashMap<AtomicString, OwnPtr<CachedFontSet>> LocaleToCachedFont;
  LocaleToCachedFont m_setsByLocale;
};

void FontCache::getFontForCharacter(
    UChar32 c,
    const char* locale,
    FontCache::PlatformFallbackFont* fallbackFont) {
  *fallbackFont = FontSetCache::shared().fallbackFontForCharInLocale(c, locale);
}

}  // namespace blink