fontcache.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Nicholas Shanks <[e-mail]>
 *
 * 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 "config.h"
#include "FontCache.h"

#include "Font.h"
#include "FontFallbackList.h"
#include "FontPlatformData.h"
#include "FontSelector.h"
#include "StringHash.h"
#include <wtf/HashMap.h>
#include <wtf/ListHashSet.h>
#include <wtf/StdLibExtras.h>

using namespace WTF;

namespace WebCore {

FontCache* fontCache()
{
    DEFINE_STATIC_LOCAL(FontCache, globalFontCache, ());
    return &globalFontCache;
}

FontCache::FontCache()
{
}

struct FontPlatformDataCacheKey {
    FontPlatformDataCacheKey(const AtomicString& family = AtomicString(), unsigned size = 0, unsigned weight = 0, bool italic = false,
                             bool isPrinterFont = false, FontRenderingMode renderingMode = NormalRenderingMode)
        : m_family(family)
        , m_size(size)
        , m_weight(weight)
        , m_italic(italic)
        , m_printerFont(isPrinterFont)
        , m_renderingMode(renderingMode)
    {
    }

    FontPlatformDataCacheKey(HashTableDeletedValueType) : m_size(hashTableDeletedSize()) { }
    bool isHashTableDeletedValue() const { return m_size == hashTableDeletedSize(); }

    bool operator==(const FontPlatformDataCacheKey& other) const
    {
        return equalIgnoringCase(m_family, other.m_family) && m_size == other.m_size && 
               m_weight == other.m_weight && m_italic == other.m_italic && m_printerFont == other.m_printerFont &&
               m_renderingMode == other.m_renderingMode;
    }

    AtomicString m_family;
    unsigned m_size;
    unsigned m_weight;
    bool m_italic;
    bool m_printerFont;
    FontRenderingMode m_renderingMode;

private:
    static unsigned hashTableDeletedSize() { return 0xFFFFFFFFU; }
};

inline unsigned computeHash(const FontPlatformDataCacheKey& fontKey)
{
    unsigned hashCodes[4] = {
        CaseFoldingHash::hash(fontKey.m_family),
        fontKey.m_size,
        fontKey.m_weight,
        static_cast<unsigned>(fontKey.m_italic) << 2 | static_cast<unsigned>(fontKey.m_printerFont) << 1 | static_cast<unsigned>(fontKey.m_renderingMode)
    };
    return StringImpl::computeHash(reinterpret_cast<UChar*>(hashCodes), sizeof(hashCodes) / sizeof(UChar));
}

struct FontPlatformDataCacheKeyHash {
    static unsigned hash(const FontPlatformDataCacheKey& font)
    {
        return computeHash(font);
    }
         
    static bool equal(const FontPlatformDataCacheKey& a, const FontPlatformDataCacheKey& b)
    {
        return a == b;
    }

    static const bool safeToCompareToEmptyOrDeleted = true;
};

struct FontPlatformDataCacheKeyTraits : WTF::GenericHashTraits<FontPlatformDataCacheKey> {
    static const bool emptyValueIsZero = true;
    static const FontPlatformDataCacheKey& emptyValue()
    {
        DEFINE_STATIC_LOCAL(FontPlatformDataCacheKey, key, (nullAtom));
        return key;
    }
    static void constructDeletedValue(FontPlatformDataCacheKey& slot)
    {
        new (&slot) FontPlatformDataCacheKey(HashTableDeletedValue);
    }
    static bool isDeletedValue(const FontPlatformDataCacheKey& value)
    {
        return value.isHashTableDeletedValue();
    }
};

typedef HashMap<FontPlatformDataCacheKey, FontPlatformData*, FontPlatformDataCacheKeyHash, FontPlatformDataCacheKeyTraits> FontPlatformDataCache;

static FontPlatformDataCache* gFontPlatformDataCache = 0;

static const AtomicString& alternateFamilyName(const AtomicString& familyName)
{
    // Alias Courier <-> Courier New
    DEFINE_STATIC_LOCAL(AtomicString, courier, ("Courier"));
    DEFINE_STATIC_LOCAL(AtomicString, courierNew, ("Courier New"));
    if (equalIgnoringCase(familyName, courier))
        return courierNew;
#if !PLATFORM(WIN_OS)
    // On Windows, Courier New (truetype font) is always present and
    // Courier is a bitmap font. So, we don't want to map Courier New to
    // Courier.
    if (equalIgnoringCase(familyName, courierNew))
        return courier;
#endif

    // Alias Times and Times New Roman.
    DEFINE_STATIC_LOCAL(AtomicString, times, ("Times"));
    DEFINE_STATIC_LOCAL(AtomicString, timesNewRoman, ("Times New Roman"));
    if (equalIgnoringCase(familyName, times))
        return timesNewRoman;
    if (equalIgnoringCase(familyName, timesNewRoman))
        return times;
    
    // Alias Arial and Helvetica
    DEFINE_STATIC_LOCAL(AtomicString, arial, ("Arial"));
    DEFINE_STATIC_LOCAL(AtomicString, helvetica, ("Helvetica"));
    if (equalIgnoringCase(familyName, arial))
        return helvetica;
    if (equalIgnoringCase(familyName, helvetica))
        return arial;

#if PLATFORM(WIN_OS)
    // On Windows, bitmap fonts are blocked altogether so that we have to 
    // alias MS Sans Serif (bitmap font) -> Microsoft Sans Serif (truetype font)
    DEFINE_STATIC_LOCAL(AtomicString, msSans, ("MS Sans Serif"));
    DEFINE_STATIC_LOCAL(AtomicString, microsoftSans, ("Microsoft Sans Serif"));
    if (equalIgnoringCase(familyName, msSans))
        return microsoftSans;

    // Alias MS Serif (bitmap) -> Times New Roman (truetype font). There's no 
    // 'Microsoft Sans Serif-equivalent' for Serif. 
    static AtomicString msSerif("MS Serif");
    if (equalIgnoringCase(familyName, msSerif))
        return timesNewRoman;
#endif

    return emptyAtom;
}

FontPlatformData* FontCache::getCachedFontPlatformData(const FontDescription& fontDescription, 
                                                       const AtomicString& familyName,
                                                       bool checkingAlternateName)
{
    if (!gFontPlatformDataCache) {
        gFontPlatformDataCache = new FontPlatformDataCache;
        platformInit();
    }

    FontPlatformDataCacheKey key(familyName, fontDescription.computedPixelSize(), fontDescription.weight(), fontDescription.italic(),
                                 fontDescription.usePrinterFont(), fontDescription.renderingMode());
    FontPlatformData* result = 0;
    bool foundResult;
    FontPlatformDataCache::iterator it = gFontPlatformDataCache->find(key);
    if (it == gFontPlatformDataCache->end()) {
        result = createFontPlatformData(fontDescription, familyName);
        gFontPlatformDataCache->set(key, result);
        foundResult = result;
    } else {
        result = it->second;
        foundResult = true;
    }

    if (!foundResult && !checkingAlternateName) {
        // We were unable to find a font.  We have a small set of fonts that we alias to other names, 
        // e.g., Arial/Helvetica, Courier/Courier New, etc.  Try looking up the font under the aliased name.
        const AtomicString& alternateName = alternateFamilyName(familyName);
        if (!alternateName.isEmpty())
            result = getCachedFontPlatformData(fontDescription, alternateName, true);
        if (result)
            gFontPlatformDataCache->set(key, new FontPlatformData(*result)); // Cache the result under the old name.
    }

    return result;
}

struct FontDataCacheKeyHash {
    static unsigned hash(const FontPlatformData& platformData)
    {
        return platformData.hash();
    }
         
    static bool equal(const FontPlatformData& a, const FontPlatformData& b)
    {
        return a == b;
    }