1/*
2 * Copyright (C) 2006, 2009 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 Computer, 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 GlyphMetricsMap_h
30#define GlyphMetricsMap_h
31
32#include <wtf/FixedArray.h>
33#include <wtf/HashMap.h>
34#include <wtf/OwnPtr.h>
35#include <wtf/unicode/Unicode.h>
36
37namespace WebCore {
38
39typedef unsigned short Glyph;
40
41const float cGlyphSizeUnknown = -1;
42
43template<class T> class GlyphMetricsMap {
44    WTF_MAKE_NONCOPYABLE(GlyphMetricsMap);
45public:
46    GlyphMetricsMap() : m_filledPrimaryPage(false) { }
47    ~GlyphMetricsMap()
48    {
49        if (m_pages)
50            deleteAllValues(*m_pages);
51    }
52
53    T metricsForGlyph(Glyph glyph)
54    {
55        return locatePage(glyph / GlyphMetricsPage::size)->metricsForGlyph(glyph);
56    }
57
58    void setMetricsForGlyph(Glyph glyph, const T& metrics)
59    {
60        locatePage(glyph / GlyphMetricsPage::size)->setMetricsForGlyph(glyph, metrics);
61    }
62
63private:
64    struct GlyphMetricsPage {
65        static const size_t size = 256; // Usually covers Latin-1 in a single page.
66        FixedArray<T, size> m_metrics;
67
68        T metricsForGlyph(Glyph glyph) const { return m_metrics[glyph % size]; }
69        void setMetricsForGlyph(Glyph glyph, const T& metrics)
70        {
71            setMetricsForIndex(glyph % size, metrics);
72        }
73        void setMetricsForIndex(unsigned index, const T& metrics)
74        {
75            m_metrics[index] = metrics;
76        }
77    };
78
79    GlyphMetricsPage* locatePage(unsigned pageNumber)
80    {
81        if (!pageNumber && m_filledPrimaryPage)
82            return &m_primaryPage;
83        return locatePageSlowCase(pageNumber);
84    }
85
86    GlyphMetricsPage* locatePageSlowCase(unsigned pageNumber);
87
88    static T unknownMetrics();
89
90    bool m_filledPrimaryPage;
91    GlyphMetricsPage m_primaryPage; // We optimize for the page that contains glyph indices 0-255.
92    OwnPtr<HashMap<int, GlyphMetricsPage*> > m_pages;
93};
94
95template<> inline float GlyphMetricsMap<float>::unknownMetrics()
96{
97    return cGlyphSizeUnknown;
98}
99
100template<> inline FloatRect GlyphMetricsMap<FloatRect>::unknownMetrics()
101{
102    return FloatRect(0, 0, cGlyphSizeUnknown, cGlyphSizeUnknown);
103}
104
105template<class T> typename GlyphMetricsMap<T>::GlyphMetricsPage* GlyphMetricsMap<T>::locatePageSlowCase(unsigned pageNumber)
106{
107    GlyphMetricsPage* page;
108    if (!pageNumber) {
109        ASSERT(!m_filledPrimaryPage);
110        page = &m_primaryPage;
111        m_filledPrimaryPage = true;
112    } else {
113        if (m_pages) {
114            if ((page = m_pages->get(pageNumber)))
115                return page;
116        } else
117            m_pages = adoptPtr(new HashMap<int, GlyphMetricsPage*>);
118        page = new GlyphMetricsPage;
119        m_pages->set(pageNumber, page);
120    }
121
122    // Fill in the whole page with the unknown glyph information.
123    for (unsigned i = 0; i < GlyphMetricsPage::size; i++)
124        page->setMetricsForIndex(i, unknownMetrics());
125
126    return page;
127}
128
129} // namespace WebCore
130
131#endif
132