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29 #ifndef GlyphPageTreeNode_h
30 #define GlyphPageTreeNode_h
32 #include "platform/fonts/GlyphPage.h"
34 #include "wtf/HashMap.h"
35 #include "wtf/OwnPtr.h"
36 #include "wtf/PassRefPtr.h"
37 #include "wtf/RefCounted.h"
38 #include "wtf/unicode/Unicode.h"
45 // The glyph page tree is a data structure that maps (FontData, glyph page number)
46 // to a GlyphPage. Level 0 (the "root") is special. There is one root
47 // GlyphPageTreeNode for each glyph page number. The roots do not have a
48 // GlyphPage associated with them, and their initializePage() function is never
49 // called to fill the glyphs.
51 // Each root node maps a FontData pointer to another GlyphPageTreeNode at
52 // level 1 (the "root child") that stores the actual glyphs for a specific font data.
53 // These nodes will only have a GlyphPage if they have glyphs for that range.
55 // Levels greater than one correspond to subsequent levels of the fallback list
56 // for that font. These levels override their parent's page of glyphs by
57 // filling in holes with the new font (thus making a more complete page).
59 // A NULL FontData pointer corresponds to the system fallback
60 // font. It is tracked separately from the regular pages and overrides so that
61 // the glyph pages do not get polluted with these last-resort glyphs. The
62 // system fallback page is not populated at construction like the other pages,
63 // but on demand for each glyph, because the system may need to use different
64 // fallback fonts for each. This lazy population is done by the Font.
65 class PLATFORM_EXPORT GlyphPageTreeNode {
66 WTF_MAKE_FAST_ALLOCATED; WTF_MAKE_NONCOPYABLE(GlyphPageTreeNode);
68 static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber)
70 return getRoot(pageNumber)->getChild(fontData, pageNumber);
73 static void pruneTreeCustomFontData(const FontData*);
74 static void pruneTreeFontData(const SimpleFontData*);
76 void pruneCustomFontData(const FontData*);
77 void pruneFontData(const SimpleFontData*, unsigned level = 0);
79 GlyphPageTreeNode* parent() const { return m_parent; }
80 GlyphPageTreeNode* getChild(const FontData*, unsigned pageNumber);
82 // Returns a page of glyphs (or NULL if there are no glyphs in this page's character range).
83 GlyphPage* page() const { return m_page.get(); }
85 // Returns the level of this node. See class-level comment.
86 unsigned level() const { return m_level; }
88 // The system fallback font has special rules (see above).
89 bool isSystemFallback() const { return m_isSystemFallback; }
91 static size_t treeGlyphPageCount();
92 size_t pageCount() const;
98 , m_isSystemFallback(false)
99 , m_customFontCount(0)
106 static GlyphPageTreeNode* getRoot(unsigned pageNumber);
107 void initializePage(const FontData*, unsigned pageNumber);
113 static HashMap<int, GlyphPageTreeNode*>* roots;
114 static GlyphPageTreeNode* pageZeroRoot;
116 typedef HashMap<const FontData*, OwnPtr<GlyphPageTreeNode> > GlyphPageTreeNodeMap;
118 GlyphPageTreeNodeMap m_children;
119 GlyphPageTreeNode* m_parent;
120 RefPtr<GlyphPage> m_page;
121 unsigned m_level : 31;
122 bool m_isSystemFallback : 1;
123 unsigned m_customFontCount;
124 OwnPtr<GlyphPageTreeNode> m_systemFallbackChild;
127 unsigned m_pageNumber;
133 #endif // GlyphPageTreeNode_h