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29 #ifndef GlyphPageTreeNode_h
30 #define GlyphPageTreeNode_h
32 #include "GlyphPage.h"
34 #include <wtf/HashMap.h>
35 #include <wtf/PassRefPtr.h>
36 #include <wtf/RefCounted.h>
37 #include <wtf/unicode/Unicode.h>
40 void showGlyphPageTrees();
41 void showGlyphPageTree(unsigned pageNumber);
49 // The glyph page tree is a data structure that maps (FontData, glyph page number)
50 // to a GlyphPage. Level 0 (the "root") is special. There is one root
51 // GlyphPageTreeNode for each glyph page number. The roots do not have a
52 // GlyphPage associated with them, and their initializePage() function is never
53 // called to fill the glyphs.
55 // Each root node maps a FontData pointer to another GlyphPageTreeNode at
56 // level 1 (the "root child") that stores the actual glyphs for a specific font data.
57 // These nodes will only have a GlyphPage if they have glyphs for that range.
59 // Levels greater than one correspond to subsequent levels of the fallback list
60 // for that font. These levels override their parent's page of glyphs by
61 // filling in holes with the new font (thus making a more complete page).
63 // A NULL FontData pointer corresponds to the system fallback
64 // font. It is tracked separately from the regular pages and overrides so that
65 // the glyph pages do not get polluted with these last-resort glyphs. The
66 // system fallback page is not populated at construction like the other pages,
67 // but on demand for each glyph, because the system may need to use different
68 // fallback fonts for each. This lazy population is done by the Font.
69 class GlyphPageTreeNode {
74 , m_isSystemFallback(false)
75 , m_customFontCount(0)
76 , m_systemFallbackChild(0)
85 static HashMap<int, GlyphPageTreeNode*>* roots;
86 static GlyphPageTreeNode* pageZeroRoot;
88 static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber)
90 return getRoot(pageNumber)->getChild(fontData, pageNumber);
93 static void pruneTreeCustomFontData(const FontData*);
94 static void pruneTreeFontData(const SimpleFontData*);
96 void pruneCustomFontData(const FontData*);
97 void pruneFontData(const SimpleFontData*, unsigned level = 0);
99 GlyphPageTreeNode* parent() const { return m_parent; }
100 GlyphPageTreeNode* getChild(const FontData*, unsigned pageNumber);
102 // Returns a page of glyphs (or NULL if there are no glyphs in this page's character range).
103 GlyphPage* page() const { return m_page.get(); }
105 // Returns the level of this node. See class-level comment.
106 unsigned level() const { return m_level; }
108 // The system fallback font has special rules (see above).
109 bool isSystemFallback() const { return m_isSystemFallback; }
111 static size_t treeGlyphPageCount();
112 size_t pageCount() const;
115 static GlyphPageTreeNode* getRoot(unsigned pageNumber);
116 void initializePage(const FontData*, unsigned pageNumber);
122 GlyphPageTreeNode* m_parent;
123 RefPtr<GlyphPage> m_page;
124 unsigned m_level : 31;
125 bool m_isSystemFallback : 1;
126 unsigned m_customFontCount;
127 HashMap<const FontData*, GlyphPageTreeNode*> m_children;
128 GlyphPageTreeNode* m_systemFallbackChild;
131 unsigned m_pageNumber;
133 friend void ::showGlyphPageTree(unsigned pageNumber);
137 } // namespace WebCore
139 #endif // GlyphPageTreeNode_h