Home | History | Annotate | Download | only in fonts 
      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 #include "wtf/unicode/CharacterNames.h"
     38 
     39 namespace blink {
     40 
     41 FontFallbackList::FontFallbackList()
     42     : m_pageZero(0)
     43     , m_cachedPrimarySimpleFontData(0)
     44     , m_fontSelector(nullptr)
     45     , m_fontSelectorVersion(0)
     46     , m_familyIndex(0)
     47     , m_generation(FontCache::fontCache()->generation())
     48     , m_pitch(UnknownPitch)
     49     , m_hasLoadingFallback(false)
     50 {
     51 }
     52 
     53 void FontFallbackList::invalidate(PassRefPtrWillBeRawPtr<FontSelector> fontSelector)
     54 {
     55     releaseFontData();
     56     m_fontList.clear();
     57     m_pageZero = 0;
     58     m_pages.clear();
     59     m_cachedPrimarySimpleFontData = 0;
     60     m_familyIndex = 0;
     61     m_pitch = UnknownPitch;
     62     m_hasLoadingFallback = false;
     63     m_fontSelector = fontSelector;
     64     m_fontSelectorVersion = m_fontSelector ? m_fontSelector->version() : 0;
     65     m_generation = FontCache::fontCache()->generation();
     66     m_widthCache.clear();
     67 }
     68 
     69 void FontFallbackList::releaseFontData()
     70 {
     71     unsigned numFonts = m_fontList.size();
     72     for (unsigned i = 0; i < numFonts; ++i) {
     73         if (!m_fontList[i]->isCustomFont()) {
     74             ASSERT(!m_fontList[i]->isSegmented());
     75             FontCache::fontCache()->releaseFontData(toSimpleFontData(m_fontList[i]));
     76         }
     77     }
     78 }
     79 
     80 void FontFallbackList::determinePitch(const FontDescription& fontDescription) const
     81 {
     82     for (unsigned fontIndex = 0; ; ++fontIndex) {
     83         const FontData* fontData = fontDataAt(fontDescription, fontIndex);
     84         if (!fontData) {
     85             // All fonts are custom fonts and are loading. Fallback should be variable pitch.
     86             m_pitch = VariablePitch;
     87             break;
     88         }
     89 
     90         const SimpleFontData* simpleFontData;
     91         if (fontData->isSegmented()) {
     92             const SegmentedFontData* segmentedFontData = toSegmentedFontData(fontData);
     93             if (segmentedFontData->numRanges() != 1 || !segmentedFontData->rangeAt(0).isEntireRange()) {
     94                 m_pitch = VariablePitch;
     95                 break;
     96             }
     97             simpleFontData = segmentedFontData->rangeAt(0).fontData().get();
     98         } else {
     99             simpleFontData = toSimpleFontData(fontData);
    100         }
    101         if (!fontData->isLoadingFallback()) {
    102             m_pitch = simpleFontData->pitch();
    103             break;
    104         }
    105     }
    106 }
    107 
    108 bool FontFallbackList::loadingCustomFonts() const
    109 {
    110     if (!m_hasLoadingFallback)
    111         return false;
    112 
    113     unsigned numFonts = m_fontList.size();
    114     for (unsigned i = 0; i < numFonts; ++i) {
    115         if (m_fontList[i]->isLoading())
    116             return true;
    117     }
    118     return false;
    119 }
    120 
    121 bool FontFallbackList::shouldSkipDrawing() const
    122 {
    123     if (!m_hasLoadingFallback)
    124         return false;
    125 
    126     unsigned numFonts = m_fontList.size();
    127     for (unsigned i = 0; i < numFonts; ++i) {
    128         if (m_fontList[i]->shouldSkipDrawing())
    129             return true;
    130     }
    131     return false;
    132 }
    133 
    134 const SimpleFontData* FontFallbackList::determinePrimarySimpleFontData(const FontDescription& fontDescription) const
    135 {
    136     bool shouldLoadCustomFont = true;
    137 
    138     for (unsigned fontIndex = 0; ; ++fontIndex) {
    139         const FontData* fontData = fontDataAt(fontDescription, fontIndex);
    140         if (!fontData) {
    141             // All fonts are custom fonts and are loading. Return the first FontData.
    142             fontData = fontDataAt(fontDescription, 0);
    143             if (fontData)
    144                 return fontData->fontDataForCharacter(space);
    145 
    146             SimpleFontData* lastResortFallback = FontCache::fontCache()->getLastResortFallbackFont(fontDescription).get();
    147             ASSERT(lastResortFallback);
    148             return lastResortFallback;
    149         }
    150 
    151         if (fontData->isSegmented() && !toSegmentedFontData(fontData)->containsCharacter(space))
    152             continue;
    153 
    154         const SimpleFontData* fontDataForSpace = fontData->fontDataForCharacter(space);
    155         ASSERT(fontDataForSpace);
    156 
    157         // When a custom font is loading, we should use the correct fallback font to layout the text.
    158         // Here skip the temporary font for the loading custom font which may not act as the correct fallback font.
    159         if (!fontDataForSpace->isLoadingFallback())
    160             return fontDataForSpace;
    161 
    162         if (fontData->isSegmented()) {
    163             const SegmentedFontData* segmented = toSegmentedFontData(fontData);
    164             for (unsigned i = 0; i < segmented->numRanges(); i++) {
    165                 const SimpleFontData* rangeFontData = segmented->rangeAt(i).fontData().get();
    166                 if (!rangeFontData->isLoadingFallback())
    167                     return rangeFontData;
    168             }
    169             if (fontData->isLoading())
    170                 shouldLoadCustomFont = false;
    171         }
    172 
    173         // Begin to load the first custom font if needed.
    174         if (shouldLoadCustomFont) {
    175             shouldLoadCustomFont = false;
    176             fontDataForSpace->customFontData()->beginLoadIfNeeded();
    177         }
    178     }
    179 }
    180 
    181 PassRefPtr<FontData> FontFallbackList::getFontData(const FontDescription& fontDescription, int& familyIndex) const
    182 {
    183     RefPtr<FontData> result;
    184 
    185     int startIndex = familyIndex;
    186     const FontFamily* startFamily = &fontDescription.family();
    187     for (int i = 0; startFamily && i < startIndex; i++)
    188         startFamily = startFamily->next();
    189     const FontFamily* currFamily = startFamily;
    190     while (currFamily && !result) {
    191         familyIndex++;
    192         if (currFamily->family().length()) {
    193             if (m_fontSelector)
    194                 result = m_fontSelector->getFontData(fontDescription, currFamily->family());
    195 
    196             if (!result)
    197                 result = FontCache::fontCache()->getFontData(fontDescription, currFamily->family());
    198         }
    199         currFamily = currFamily->next();
    200     }
    201 
    202     if (!currFamily)
    203         familyIndex = cAllFamiliesScanned;
    204 
    205     if (result || startIndex)
    206         return result.release();
    207 
    208     // If it's the primary font that we couldn't find, we try the following. In all other cases, we will
    209     // just use per-character system fallback.
    210 
    211     if (m_fontSelector) {
    212         // Try the user's preferred standard font.
    213         if (RefPtr<FontData> data = m_fontSelector->getFontData(fontDescription, FontFamilyNames::webkit_standard))
    214             return data.release();
    215     }
    216 
    217     // Still no result. Hand back our last resort fallback font.
    218     return FontCache::fontCache()->getLastResortFallbackFont(fontDescription);
    219 }
    220 
    221 
    222 const FontData* FontFallbackList::fontDataAt(const FontDescription& fontDescription, unsigned realizedFontIndex) const
    223 {
    224     if (realizedFontIndex < m_fontList.size())
    225         return m_fontList[realizedFontIndex].get(); // This fallback font is already in our list.
    226 
    227     // Make sure we're not passing in some crazy value here.
    228     ASSERT(realizedFontIndex == m_fontList.size());
    229 
    230     if (m_familyIndex == cAllFamiliesScanned)
    231         return 0;
    232 
    233     // Ask the font cache for the font data.
    234     // We are obtaining this font for the first time.  We keep track of the families we've looked at before
    235     // in |m_familyIndex|, so that we never scan the same spot in the list twice.  getFontData will adjust our
    236     // |m_familyIndex| as it scans for the right font to make.
    237     ASSERT(FontCache::fontCache()->generation() == m_generation);
    238     RefPtr<FontData> result = getFontData(fontDescription, m_familyIndex);
    239     if (result) {
    240         m_fontList.append(result);
    241         if (result->isLoadingFallback())
    242             m_hasLoadingFallback = true;
    243     }
    244     return result.get();
    245 }
    246 
    247 } // namespace blink
    248