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      1 /*
      2  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include "config.h"
     30 #include "platform/fonts/FontFallbackList.h"
     31 
     32 #include "platform/FontFamilyNames.h"
     33 #include "platform/fonts/FontCache.h"
     34 #include "platform/fonts/FontDescription.h"
     35 #include "platform/fonts/FontFamily.h"
     36 #include "platform/fonts/SegmentedFontData.h"
     37 
     38 namespace WebCore {
     39 
     40 FontFallbackList::FontFallbackList()
     41     : m_pageZero(0)
     42     , m_cachedPrimarySimpleFontData(0)
     43     , m_fontSelector(nullptr)
     44     , m_fontSelectorVersion(0)
     45     , m_familyIndex(0)
     46     , m_generation(FontCache::fontCache()->generation())
     47     , m_pitch(UnknownPitch)
     48     , m_hasLoadingFallback(false)
     49 {
     50 }
     51 
     52 void FontFallbackList::invalidate(PassRefPtrWillBeRawPtr<FontSelector> fontSelector)
     53 {
     54     releaseFontData();
     55     m_fontList.clear();
     56     m_pageZero = 0;
     57     m_pages.clear();
     58     m_cachedPrimarySimpleFontData = 0;
     59     m_familyIndex = 0;
     60     m_pitch = UnknownPitch;
     61     m_hasLoadingFallback = false;
     62     m_fontSelector = fontSelector;
     63     m_fontSelectorVersion = m_fontSelector ? m_fontSelector->version() : 0;
     64     m_generation = FontCache::fontCache()->generation();
     65     m_widthCache.clear();
     66 }
     67 
     68 void FontFallbackList::releaseFontData()
     69 {
     70     unsigned numFonts = m_fontList.size();
     71     for (unsigned i = 0; i < numFonts; ++i) {
     72         if (!m_fontList[i]->isCustomFont()) {
     73             ASSERT(!m_fontList[i]->isSegmented());
     74             FontCache::fontCache()->releaseFontData(static_cast<const SimpleFontData*>(m_fontList[i].get()));
     75         }
     76     }
     77 }
     78 
     79 void FontFallbackList::determinePitch(const FontDescription& fontDescription) const
     80 {
     81     const FontData* fontData = primaryFontData(fontDescription);
     82     if (!fontData->isSegmented())
     83         m_pitch = static_cast<const SimpleFontData*>(fontData)->pitch();
     84     else {
     85         const SegmentedFontData* segmentedFontData = static_cast<const SegmentedFontData*>(fontData);
     86         unsigned numRanges = segmentedFontData->numRanges();
     87         if (numRanges == 1 && segmentedFontData->rangeAt(0).isEntireRange())
     88             m_pitch = segmentedFontData->rangeAt(0).fontData()->pitch();
     89         else
     90             m_pitch = VariablePitch;
     91     }
     92 }
     93 
     94 bool FontFallbackList::loadingCustomFonts() const
     95 {
     96     if (!m_hasLoadingFallback)
     97         return false;
     98 
     99     unsigned numFonts = m_fontList.size();
    100     for (unsigned i = 0; i < numFonts; ++i) {
    101         if (m_fontList[i]->isLoading())
    102             return true;
    103     }
    104     return false;
    105 }
    106 
    107 bool FontFallbackList::shouldSkipDrawing() const
    108 {
    109     if (!m_hasLoadingFallback)
    110         return false;
    111 
    112     unsigned numFonts = m_fontList.size();
    113     for (unsigned i = 0; i < numFonts; ++i) {
    114         if (m_fontList[i]->shouldSkipDrawing())
    115             return true;
    116     }
    117     return false;
    118 }
    119 
    120 const FontData* FontFallbackList::primaryFontData(const FontDescription& fontDescription) const
    121 {
    122     bool shouldLoadCustomFont = true;
    123 
    124     for (unsigned fontIndex = 0; ; ++fontIndex) {
    125         const FontData* fontData = fontDataAt(fontDescription, fontIndex);
    126         if (!fontData) {
    127             // All fonts are custom fonts and are loading. Return the first FontData.
    128             fontData = fontDataAt(fontDescription, 0);
    129             if (fontData)
    130                 return fontData->fontDataForCharacter(' ');
    131 
    132             SimpleFontData* lastResortFallback = FontCache::fontCache()->getLastResortFallbackFont(fontDescription).get();
    133             ASSERT(lastResortFallback);
    134             return lastResortFallback;
    135         }
    136 
    137         if (fontData->isSegmented() && !toSegmentedFontData(fontData)->containsCharacter(' '))
    138             continue;
    139 
    140         const SimpleFontData* simpleFontData = fontData->fontDataForCharacter(' ');
    141         ASSERT(simpleFontData);
    142 
    143         // When a custom font is loading, we should use the correct fallback font to layout the text.
    144         // Here skip the temporary font for the loading custom font which may not act as the correct fallback font.
    145         if (!simpleFontData->isLoadingFallback())
    146             return fontData;
    147 
    148         // Begin to load the first custom font if needed.
    149         if (shouldLoadCustomFont) {
    150             shouldLoadCustomFont = false;
    151             simpleFontData->customFontData()->beginLoadIfNeeded();
    152         }
    153     }
    154 }
    155 
    156 PassRefPtr<FontData> FontFallbackList::getFontData(const FontDescription& fontDescription, int& familyIndex) const
    157 {
    158     RefPtr<FontData> result;
    159 
    160     int startIndex = familyIndex;
    161     const FontFamily* startFamily = &fontDescription.family();
    162     for (int i = 0; startFamily && i < startIndex; i++)
    163         startFamily = startFamily->next();
    164     const FontFamily* currFamily = startFamily;
    165     while (currFamily && !result) {
    166         familyIndex++;
    167         if (currFamily->family().length()) {
    168             if (m_fontSelector)
    169                 result = m_fontSelector->getFontData(fontDescription, currFamily->family());
    170 
    171             if (!result)
    172                 result = FontCache::fontCache()->getFontData(fontDescription, currFamily->family());
    173         }
    174         currFamily = currFamily->next();
    175     }
    176 
    177     if (!currFamily)
    178         familyIndex = cAllFamiliesScanned;
    179 
    180     if (result || startIndex)
    181         return result.release();
    182 
    183     // If it's the primary font that we couldn't find, we try the following. In all other cases, we will
    184     // just use per-character system fallback.
    185 
    186     if (m_fontSelector) {
    187         // Try the user's preferred standard font.
    188         if (RefPtr<FontData> data = m_fontSelector->getFontData(fontDescription, FontFamilyNames::webkit_standard))
    189             return data.release();
    190     }
    191 
    192     // Still no result. Hand back our last resort fallback font.
    193     return FontCache::fontCache()->getLastResortFallbackFont(fontDescription);
    194 }
    195 
    196 
    197 const FontData* FontFallbackList::fontDataAt(const FontDescription& fontDescription, unsigned realizedFontIndex) const
    198 {
    199     if (realizedFontIndex < m_fontList.size())
    200         return m_fontList[realizedFontIndex].get(); // This fallback font is already in our list.
    201 
    202     // Make sure we're not passing in some crazy value here.
    203     ASSERT(realizedFontIndex == m_fontList.size());
    204 
    205     if (m_familyIndex == cAllFamiliesScanned)
    206         return 0;
    207 
    208     // Ask the font cache for the font data.
    209     // We are obtaining this font for the first time.  We keep track of the families we've looked at before
    210     // in |m_familyIndex|, so that we never scan the same spot in the list twice.  getFontData will adjust our
    211     // |m_familyIndex| as it scans for the right font to make.
    212     ASSERT(FontCache::fontCache()->generation() == m_generation);
    213     RefPtr<FontData> result = getFontData(fontDescription, m_familyIndex);
    214     if (result) {
    215         m_fontList.append(result);
    216         if (result->isLoadingFallback())
    217             m_hasLoadingFallback = true;
    218     }
    219     return result.get();
    220 }
    221 
    222 }
    223