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;
16
17// needs to be != to any valid SkMask::Format
18#define MASK_FORMAT_UNKNOWN         (0xFF)
19#define MASK_FORMAT_JUST_ADVANCE    MASK_FORMAT_UNKNOWN
20
21#define kMaxGlyphWidth (1<<13)
22
23struct SkGlyph {
24    void*       fImage;
25    SkPath*     fPath;
26    SkFixed     fAdvanceX, fAdvanceY;
27
28    uint32_t    fID;
29    uint16_t    fWidth, fHeight;
30    int16_t     fTop, fLeft;
31
32    void*       fDistanceField;
33    uint8_t     fMaskFormat;
34    int8_t      fRsbDelta, fLsbDelta;  // used by auto-kerning
35
36    void init(uint32_t id) {
37        fID             = id;
38        fImage          = NULL;
39        fPath           = NULL;
40        fDistanceField  = NULL;
41        fMaskFormat     = MASK_FORMAT_UNKNOWN;
42    }
43
44    /**
45     *  Compute the rowbytes for the specified width and mask-format.
46     */
47    static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
48        unsigned rb = width;
49        if (SkMask::kBW_Format == format) {
50            rb = (rb + 7) >> 3;
51        } else if (SkMask::kARGB32_Format == format ||
52                   SkMask::kLCD32_Format == format)
53        {
54            rb <<= 2;
55        } else if (SkMask::kLCD16_Format == format) {
56            rb = SkAlign4(rb << 1);
57        } else {
58            rb = SkAlign4(rb);
59        }
60        return rb;
61    }
62
63    unsigned rowBytes() const {
64        return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
65    }
66
67    bool isJustAdvance() const {
68        return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
69    }
70
71    bool isFullMetrics() const {
72        return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
73    }
74
75    uint16_t getGlyphID() const {
76        return ID2Code(fID);
77    }
78
79    unsigned getGlyphID(unsigned baseGlyphCount) const {
80        unsigned code = ID2Code(fID);
81        SkASSERT(code >= baseGlyphCount);
82        return code - baseGlyphCount;
83    }
84
85    unsigned getSubX() const {
86        return ID2SubX(fID);
87    }
88
89    SkFixed getSubXFixed() const {
90        return SubToFixed(ID2SubX(fID));
91    }
92
93    SkFixed getSubYFixed() const {
94        return SubToFixed(ID2SubY(fID));
95    }
96
97    size_t computeImageSize() const;
98
99    /** Call this to set all of the metrics fields to 0 (e.g. if the scaler
100        encounters an error measuring a glyph). Note: this does not alter the
101        fImage, fPath, fID, fMaskFormat fields.
102     */
103    void zeroMetrics();
104
105    enum {
106        kSubBits = 2,
107        kSubMask = ((1 << kSubBits) - 1),
108        kSubShift = 24, // must be large enough for glyphs and unichars
109        kCodeMask = ((1 << kSubShift) - 1),
110        // relative offsets for X and Y subpixel bits
111        kSubShiftX = kSubBits,
112        kSubShiftY = 0
113    };
114
115    static unsigned ID2Code(uint32_t id) {
116        return id & kCodeMask;
117    }
118
119    static unsigned ID2SubX(uint32_t id) {
120        return id >> (kSubShift + kSubShiftX);
121    }
122
123    static unsigned ID2SubY(uint32_t id) {
124        return (id >> (kSubShift + kSubShiftY)) & kSubMask;
125    }
126
127    static unsigned FixedToSub(SkFixed n) {
128        return (n >> (16 - kSubBits)) & kSubMask;
129    }
130
131    static SkFixed SubToFixed(unsigned sub) {
132        SkASSERT(sub <= kSubMask);
133        return sub << (16 - kSubBits);
134    }
135
136    static uint32_t MakeID(unsigned code) {
137        return code;
138    }
139
140    static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
141        SkASSERT(code <= kCodeMask);
142        x = FixedToSub(x);
143        y = FixedToSub(y);
144        return (x << (kSubShift + kSubShiftX)) |
145               (y << (kSubShift + kSubShiftY)) |
146               code;
147    }
148
149    void toMask(SkMask* mask) const;
150};
151
152#endif
153