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* Copyright (C) 2006, 2007, 2008 Apple 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
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*/
#ifndef GlyphPageTreeNode_h
#define GlyphPageTreeNode_h
#include "platform/fonts/GlyphPage.h"
#include <string.h>
#include "wtf/HashMap.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/unicode/Unicode.h"
#ifndef NDEBUG
void PLATFORM_EXPORT showGlyphPageTrees();
void PLATFORM_EXPORT showGlyphPageTree(unsigned pageNumber);
#endif
namespace WebCore {
class FontData;
class SimpleFontData;
// 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 PLATFORM_EXPORT GlyphPageTreeNode {
WTF_MAKE_FAST_ALLOCATED; WTF_MAKE_NONCOPYABLE(GlyphPageTreeNode);
public:
static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber)
{
return getRoot(pageNumber)->getChild(fontData, pageNumber);
}
static void pruneTreeCustomFontData(const FontData*);
static void pruneTreeFontData(const SimpleFontData*);
void pruneCustomFontData(const FontData*);
void pruneFontData(const SimpleFontData*, unsigned level = 0);
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; }
static size_t treeGlyphPageCount();
size_t pageCount() const;
private:
GlyphPageTreeNode()
: m_parent(0)
, m_level(0)
, m_isSystemFallback(false)
, m_customFontCount(0)
#ifndef NDEBUG
, m_pageNumber(0)
#endif
{
}
static GlyphPageTreeNode* getRoot(unsigned pageNumber);
void initializePage(const FontData*, unsigned pageNumber);
#ifndef NDEBUG
void showSubtree();
#endif
static HashMap<int, GlyphPageTreeNode*>* roots;
static GlyphPageTreeNode* pageZeroRoot;
typedef HashMap<const FontData*, OwnPtr<GlyphPageTreeNode> > GlyphPageTreeNodeMap;
GlyphPageTreeNodeMap m_children;
GlyphPageTreeNode* m_parent;
RefPtr<GlyphPage> m_page;
unsigned m_level : 31;
bool m_isSystemFallback : 1;
unsigned m_customFontCount;
OwnPtr<GlyphPageTreeNode> m_systemFallbackChild;
#ifndef NDEBUG
unsigned m_pageNumber;
friend void ::showGlyphPageTrees();
friend void ::showGlyphPageTree(unsigned pageNumber);
#endif
};
} // namespace WebCore
#endif // GlyphPageTreeNode_h