1/*
2 * Copyright (C) 2006, 2007, 2008 Apple 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 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#ifndef GlyphPageTreeNode_h
30#define GlyphPageTreeNode_h
31
32#include "GlyphPage.h"
33#include <string.h>
34#include <wtf/HashMap.h>
35#include <wtf/OwnPtr.h>
36#include <wtf/PassRefPtr.h>
37#include <wtf/RefCounted.h>
38
39#ifndef NDEBUG
40void showGlyphPageTrees();
41void showGlyphPageTree(unsigned pageNumber);
42#endif
43
44namespace WebCore {
45
46class FontData;
47class SimpleFontData;
48
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.
54//
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.
58//
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).
62//
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.
69class GlyphPageTreeNode {
70    WTF_MAKE_FAST_ALLOCATED;
71public:
72    static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber)
73    {
74        return getRoot(pageNumber)->getChild(fontData, pageNumber);
75    }
76
77    static void pruneTreeCustomFontData(const FontData*);
78    static void pruneTreeFontData(const SimpleFontData*);
79
80    void pruneCustomFontData(const FontData*);
81    void pruneFontData(const SimpleFontData*, unsigned level = 0);
82
83    GlyphPageTreeNode* parent() const { return m_parent; }
84    GlyphPageTreeNode* getChild(const FontData*, unsigned pageNumber);
85
86    // Returns a page of glyphs (or NULL if there are no glyphs in this page's character range).
87    GlyphPage* page() const { return m_page.get(); }
88
89    // Returns the level of this node. See class-level comment.
90    unsigned level() const { return m_level; }
91
92    // The system fallback font has special rules (see above).
93    bool isSystemFallback() const { return m_isSystemFallback; }
94
95    static size_t treeGlyphPageCount();
96    size_t pageCount() const;
97
98private:
99    GlyphPageTreeNode()
100        : m_parent(0)
101        , m_level(0)
102        , m_isSystemFallback(false)
103        , m_customFontCount(0)
104#ifndef NDEBUG
105        , m_pageNumber(0)
106#endif
107    {
108    }
109
110    static GlyphPageTreeNode* getRoot(unsigned pageNumber);
111    void initializePage(const FontData*, unsigned pageNumber);
112
113#ifndef NDEBUG
114    void showSubtree();
115#endif
116
117    static HashMap<int, GlyphPageTreeNode*>* roots;
118    static GlyphPageTreeNode* pageZeroRoot;
119
120    typedef HashMap<const FontData*, OwnPtr<GlyphPageTreeNode>> GlyphPageTreeNodeMap;
121
122    GlyphPageTreeNodeMap m_children;
123    GlyphPageTreeNode* m_parent;
124    RefPtr<GlyphPage> m_page;
125    unsigned m_level : 31;
126    bool m_isSystemFallback : 1;
127    unsigned m_customFontCount;
128    OwnPtr<GlyphPageTreeNode> m_systemFallbackChild;
129
130#ifndef NDEBUG
131    unsigned m_pageNumber;
132
133    friend void ::showGlyphPageTrees();
134    friend void ::showGlyphPageTree(unsigned pageNumber);
135#endif
136};
137
138} // namespace WebCore
139
140#endif // GlyphPageTreeNode_h
141