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