1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkGlyph_DEFINED
9#define SkGlyph_DEFINED
10
11#include "SkTypes.h"
12#include "SkFixed.h"
13#include "SkMask.h"
14
15class SkPath;
16class SkGlyphCache;
17
18// needs to be != to any valid SkMask::Format
19#define MASK_FORMAT_UNKNOWN         (0xFF)
20#define MASK_FORMAT_JUST_ADVANCE    MASK_FORMAT_UNKNOWN
21
22#define kMaxGlyphWidth (1<<13)
23
24class SkGlyph {
25    enum {
26        kSubBits = 2,
27        kSubMask = ((1 << kSubBits) - 1),
28        kSubShift = 24, // must be large enough for glyphs and unichars
29        kCodeMask = ((1 << kSubShift) - 1),
30        // relative offsets for X and Y subpixel bits
31        kSubShiftX = kSubBits,
32        kSubShiftY = 0
33    };
34
35 public:
36    static const SkFixed kSubpixelRound = SK_FixedHalf >> SkGlyph::kSubBits;
37    // A value that can never be generated by MakeID.
38    static const uint32_t kImpossibleID = ~0;
39    void*       fImage;
40    SkPath*     fPath;
41    SkFixed     fAdvanceX, fAdvanceY;
42
43    uint16_t    fWidth, fHeight;
44    int16_t     fTop, fLeft;
45
46    uint8_t     fMaskFormat;
47    int8_t      fRsbDelta, fLsbDelta;  // used by auto-kerning
48    int8_t      fForceBW;
49
50    void initWithGlyphID(uint32_t glyph_id) {
51        this->initCommon(MakeID(glyph_id));
52    }
53
54    void initGlyphIdFrom(const SkGlyph& glyph) {
55        this->initCommon(glyph.fID);
56    }
57
58    void initGlyphFromCombinedID(uint32_t combined_id) {
59      this->initCommon(combined_id);
60    }
61
62    /**
63     *  Compute the rowbytes for the specified width and mask-format.
64     */
65    static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
66        unsigned rb = width;
67        if (SkMask::kBW_Format == format) {
68            rb = (rb + 7) >> 3;
69        } else if (SkMask::kARGB32_Format == format) {
70            rb <<= 2;
71        } else if (SkMask::kLCD16_Format == format) {
72            rb = SkAlign4(rb << 1);
73        } else {
74            rb = SkAlign4(rb);
75        }
76        return rb;
77    }
78
79    unsigned rowBytes() const {
80        return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
81    }
82
83    bool isJustAdvance() const {
84        return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
85    }
86
87    bool isFullMetrics() const {
88        return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
89    }
90
91    uint16_t getGlyphID() const {
92        return ID2Code(fID);
93    }
94
95    unsigned getSubX() const {
96        return ID2SubX(fID);
97    }
98
99    SkFixed getSubXFixed() const {
100        return SubToFixed(ID2SubX(fID));
101    }
102
103    SkFixed getSubYFixed() const {
104        return SubToFixed(ID2SubY(fID));
105    }
106
107    size_t computeImageSize() const;
108
109    /** Call this to set all of the metrics fields to 0 (e.g. if the scaler
110        encounters an error measuring a glyph). Note: this does not alter the
111        fImage, fPath, fID, fMaskFormat fields.
112     */
113    void zeroMetrics();
114
115    void toMask(SkMask* mask) const;
116
117 private:
118    // TODO(herb) remove friend statement after SkGlyphCache cleanup.
119    friend class SkGlyphCache;
120
121    void initCommon(uint32_t id) {
122        fID             = id;
123        fImage          = NULL;
124        fPath           = NULL;
125        fMaskFormat     = MASK_FORMAT_UNKNOWN;
126        fForceBW        = 0;
127    }
128
129    static unsigned ID2Code(uint32_t id) {
130        return id & kCodeMask;
131    }
132
133    static unsigned ID2SubX(uint32_t id) {
134        return id >> (kSubShift + kSubShiftX);
135    }
136
137    static unsigned ID2SubY(uint32_t id) {
138        return (id >> (kSubShift + kSubShiftY)) & kSubMask;
139    }
140
141    static unsigned FixedToSub(SkFixed n) {
142        return (n >> (16 - kSubBits)) & kSubMask;
143    }
144
145    static SkFixed SubToFixed(unsigned sub) {
146        SkASSERT(sub <= kSubMask);
147        return sub << (16 - kSubBits);
148    }
149
150    static uint32_t MakeID(unsigned code) {
151        SkASSERT(code <= kCodeMask);
152        SkASSERT(code != kImpossibleID);
153        return code;
154    }
155
156    static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
157        SkASSERT(code <= kCodeMask);
158        x = FixedToSub(x);
159        y = FixedToSub(y);
160        uint32_t ID = (x << (kSubShift + kSubShiftX)) |
161                      (y << (kSubShift + kSubShiftY)) |
162                      code;
163        SkASSERT(ID != kImpossibleID);
164        return ID;
165    }
166
167  // FIXME - This is needed because the Android frame work directly
168  // accesses fID. Remove when fID accesses are cleaned up.
169#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
170  public:
171#endif
172    uint32_t    fID;
173};
174
175#endif
176