/* * Copyright (C) 2006, 2007, 2008 Apple Computer, 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. * 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 GlyphPageTreeNode_h #define GlyphPageTreeNode_h #include <wtf/RefCounted.h> #include <wtf/unicode/Unicode.h> #include <wtf/HashMap.h> namespace WebCore { class FontData; class GlyphPageTreeNode; class SimpleFontData; typedef unsigned short Glyph; // Holds the glyph index and the corresponding SimpleFontData information for a given // character. struct GlyphData { Glyph glyph; const SimpleFontData* fontData; }; // A GlyphPage contains a fixed-size set of GlyphData mappings for a contiguous // range of characters in the Unicode code space. GlyphPages are indexed // starting from 0 and incrementing for each 256 glyphs. // // One page may actually include glyphs from other fonts if the characters are // missing in the parimary font. It is owned by exactly one GlyphPageTreeNode, // although multiple nodes may reference it as their "page" if they are supposed // to be overriding the parent's node, but provide no additional information. struct GlyphPage : public RefCounted<GlyphPage> { GlyphPage() : m_owner(0) { } GlyphPage(GlyphPageTreeNode* owner) : m_owner(owner) { } static const size_t size = 256; // Covers Latin-1 in a single page. GlyphData m_glyphs[size]; GlyphPageTreeNode* m_owner; const GlyphData& glyphDataForCharacter(UChar32 c) const { return m_glyphs[c % size]; } void setGlyphDataForCharacter(UChar32 c, Glyph g, const SimpleFontData* f) { setGlyphDataForIndex(c % size, g, f); } void setGlyphDataForIndex(unsigned index, Glyph g, const SimpleFontData* f) { ASSERT(index < size); m_glyphs[index].glyph = g; m_glyphs[index].fontData = f; } GlyphPageTreeNode* owner() const { return m_owner; } // Implemented by the platform. bool fill(unsigned offset, unsigned length, UChar* characterBuffer, unsigned bufferLength, const SimpleFontData* fontData); }; // The glyph page tree is a data structure that maps (FontData, glyph page number) // to a GlyphPage. Level 0 (the "root") is special. There is one root // GlyphPageTreeNode for each glyph page number. The roots do not have a // GlyphPage associated with them, and their initializePage() function is never // called to fill the glyphs. // // Each root node maps a FontData pointer to another GlyphPageTreeNode at // level 1 (the "root child") that stores the actual glyphs for a specific font data. // These nodes will only have a GlyphPage if they have glyphs for that range. // // Levels greater than one correspond to subsequent levels of the fallback list // for that font. These levels override their parent's page of glyphs by // filling in holes with the new font (thus making a more complete page). // // A NULL FontData pointer corresponds to the system fallback // font. It is tracked separately from the regular pages and overrides so that // the glyph pages do not get polluted with these last-resort glyphs. The // system fallback page is not populated at construction like the other pages, // but on demand for each glyph, because the system may need to use different // fallback fonts for each. This lazy population is done by the Font. class GlyphPageTreeNode { public: GlyphPageTreeNode() : m_parent(0) , m_level(0) , m_isSystemFallback(false) , m_systemFallbackChild(0) , m_customFontCount(0) #ifndef NDEBUG , m_pageNumber(0) #endif { } ~GlyphPageTreeNode(); static HashMap<int, GlyphPageTreeNode*>* roots; static GlyphPageTreeNode* pageZeroRoot; static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber) { return getRoot(pageNumber)->getChild(fontData, pageNumber); } static void pruneTreeCustomFontData(const FontData*); void pruneCustomFontData(const FontData*); GlyphPageTreeNode* parent() const { return m_parent; } GlyphPageTreeNode* getChild(const FontData*, unsigned pageNumber); // Returns a page of glyphs (or NULL if there are no glyphs in this page's character range). GlyphPage* page() const { return m_page.get(); } // Returns the level of this node. See class-level comment. unsigned level() const { return m_level; } // The system fallback font has special rules (see above). bool isSystemFallback() const { return m_isSystemFallback; } private: static GlyphPageTreeNode* getRoot(unsigned pageNumber); void initializePage(const FontData*, unsigned pageNumber); GlyphPageTreeNode* m_parent; RefPtr<GlyphPage> m_page; unsigned m_level; bool m_isSystemFallback; HashMap<const FontData*, GlyphPageTreeNode*> m_children; GlyphPageTreeNode* m_systemFallbackChild; unsigned m_customFontCount; #ifndef NDEBUG unsigned m_pageNumber; #endif }; } // namespace WebCore #endif // GlyphPageTreeNode_h