Source/WebCore/platform/graphics/FontCache.h

/*
 * Copyright (C) 2006, 2008 Apple Computer, Inc.  All rights reserved.
 * Copyright (C) 2007-2008 Torch Mobile, Inc.
 *
 * 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.
 */

#ifndef FontCache_h
#define FontCache_h

#include "FontDescription.h"
#include <limits.h>
#include <wtf/Forward.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefPtr.h>
#include <wtf/Vector.h>
#include <wtf/text/WTFString.h>
#include <wtf/unicode/Unicode.h>

#if OS(WINDOWS)
#include <windows.h>
#include <objidl.h>
#include <mlang.h>
#endif

namespace WebCore {

class Font;
class FontPlatformData;
class FontData;
class FontSelector;
class OpenTypeVerticalData;
class SimpleFontData;

#if PLATFORM(WIN)
#if USE(IMLANG_FONT_LINK2)
typedef IMLangFontLink2 IMLangFontLinkType;
#else
typedef IMLangFontLink IMLangFontLinkType;
#endif
#endif

// This key contains the FontDescription fields other than family that matter when fetching FontDatas (platform fonts).
struct FontDescriptionFontDataCacheKey {
    explicit FontDescriptionFontDataCacheKey(unsigned size = 0)
        : size(size)
        , weight(0)
        , flags(0)
    { }
    FontDescriptionFontDataCacheKey(const FontDescription& description)
        : size(description.computedPixelSize())
        , weight(description.weight())
        , flags(makeFlagKey(description))
    { }
    static unsigned makeFlagKey(const FontDescription& description)
    {
        return static_cast<unsigned>(description.widthVariant()) << 4
            | static_cast<unsigned>(description.orientation()) << 3
            | static_cast<unsigned>(description.italic()) << 2
            | static_cast<unsigned>(description.usePrinterFont()) << 1
            | static_cast<unsigned>(description.renderingMode());
    }
    bool operator==(const FontDescriptionFontDataCacheKey& other) const
    {
        return size == other.size && weight == other.weight && flags == other.flags;
    }
    bool operator!=(const FontDescriptionFontDataCacheKey& other) const
    {
        return !(*this == other);
    }
    inline unsigned computeHash() const
    {
        return StringHasher::hashMemory<sizeof(FontDescriptionFontDataCacheKey)>(this);
    }
    unsigned size;
    unsigned weight;
    unsigned flags;
};

class FontCache {
    friend class FontCachePurgePreventer;

    WTF_MAKE_NONCOPYABLE(FontCache); WTF_MAKE_FAST_ALLOCATED;
public:
    friend FontCache* fontCache();

    enum ShouldRetain { Retain, DoNotRetain };

    PassRefPtr<FontData> getFontData(const FontDescription&, int& familyIndex, FontSelector*);
    void releaseFontData(const SimpleFontData*);

    // This method is implemented by the platform.
    PassRefPtr<SimpleFontData> systemFallbackForCharacters(const FontDescription&, const SimpleFontData* originalFontData, bool isPlatformFont, const UChar* characters, int length);

    // Also implemented by the platform.
    void platformInit();

#if PLATFORM(WIN)
    IMLangFontLinkType* getFontLinkInterface();
    static void comInitialize();
    static void comUninitialize();
    static IMultiLanguage* getMultiLanguageInterface();
#endif

    void getTraitsInFamily(const AtomicString&, Vector<unsigned>&);

    PassRefPtr<SimpleFontData> getCachedFontData(const FontDescription&, const AtomicString&, bool checkingAlternateName = false, ShouldRetain = Retain);
    PassRefPtr<SimpleFontData> getLastResortFallbackFont(const FontDescription&, ShouldRetain = Retain);
    SimpleFontData* getNonRetainedLastResortFallbackFont(const FontDescription&);

    void addClient(FontSelector*);
    void removeClient(FontSelector*);

    unsigned short generation();
    void invalidate();

    size_t fontDataCount();
    size_t inactiveFontDataCount();
    void purgeInactiveFontData(int count = INT_MAX);

#if PLATFORM(WIN)
    PassRefPtr<SimpleFontData> fontDataFromDescriptionAndLogFont(const FontDescription&, ShouldRetain, const LOGFONT&, AtomicString& outFontFamilyName);
#endif

#if ENABLE(OPENTYPE_VERTICAL)
    typedef AtomicString FontFileKey;
    PassRefPtr<OpenTypeVerticalData> getVerticalData(const FontFileKey&, const FontPlatformData&);
#endif

    struct SimpleFontFamily {
        String name;
        bool isBold;
        bool isItalic;
    };
#if PLATFORM(BLACKBERRY)
    static void getFontFamilyForCharacters(const UChar* characters, size_t numCharacters, const char* preferredLocale, const FontDescription&, SimpleFontFamily*);
#else
    static void getFontFamilyForCharacters(const UChar* characters, size_t numCharacters, const char* preferredLocale, SimpleFontFamily*);
#endif

private:
    FontCache();
    ~FontCache();

    void disablePurging() { m_purgePreventCount++; }
    void enablePurging()
    {
        ASSERT(m_purgePreventCount);
        if (!--m_purgePreventCount)
            purgeInactiveFontDataIfNeeded();
    }

    void purgeInactiveFontDataIfNeeded();

    // FIXME: This method should eventually be removed.
    FontPlatformData* getCachedFontPlatformData(const FontDescription&, const AtomicString& family, bool checkingAlternateName = false);

    // These methods are implemented by each platform.
    PassOwnPtr<FontPlatformData> createFontPlatformData(const FontDescription&, const AtomicString& family);
#if PLATFORM(MAC)
    PassRefPtr<SimpleFontData> similarFontPlatformData(const FontDescription&);
#endif

    PassRefPtr<SimpleFontData> getCachedFontData(const FontPlatformData*, ShouldRetain = Retain);

    // Don't purge if this count is > 0;
    int m_purgePreventCount;

#if PLATFORM(MAC)
    friend class ComplexTextController;
#endif
    friend class SimpleFontData; // For getCachedFontData(const FontPlatformData*)
    friend class FontGlyphs;
};

// Get the global fontCache.
FontCache* fontCache();

class FontCachePurgePreventer {
public:
    FontCachePurgePreventer() { fontCache()->disablePurging(); }
    ~FontCachePurgePreventer() { fontCache()->enablePurging(); }
};

}

#endif