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 "SkChecksum.h"
12#include "SkTypes.h"
13#include "SkFixed.h"
14#include "SkMask.h"
15
16class SkPath;
17class SkGlyphCache;
18
19// needs to be != to any valid SkMask::Format
20#define MASK_FORMAT_UNKNOWN         (0xFF)
21#define MASK_FORMAT_JUST_ADVANCE    MASK_FORMAT_UNKNOWN
22
23#define kMaxGlyphWidth (1<<13)
24
25SK_BEGIN_REQUIRE_DENSE
26class SkGlyph {
27    enum {
28        kSubBits = 2,
29        kSubMask = ((1 << kSubBits) - 1),
30        kSubShift = 24, // must be large enough for glyphs and unichars
31        kCodeMask = ((1 << kSubShift) - 1),
32        // relative offsets for X and Y subpixel bits
33        kSubShiftX = kSubBits,
34        kSubShiftY = 0
35    };
36
37    // Support horizontal and vertical skipping strike-through / underlines.
38    // The caller walks the linked list looking for a match. For a horizontal underline,
39    // the fBounds contains the top and bottom of the underline. The fInterval pair contains the
40    // beginning and end of of the intersection of the bounds and the glyph's path.
41    // If interval[0] >= interval[1], no intesection was found.
42    struct Intercept {
43        Intercept* fNext;
44        SkScalar   fBounds[2];    // for horz underlines, the boundaries in Y
45        SkScalar   fInterval[2];  // the outside intersections of the axis and the glyph
46    };
47
48    struct PathData {
49        Intercept* fIntercept;
50        SkPath*    fPath;
51    };
52
53public:
54    static const SkFixed kSubpixelRound = SK_FixedHalf >> SkGlyph::kSubBits;
55    // A value that can never be generated by MakeID.
56    static const uint32_t kImpossibleID = ~0;
57    void*       fImage;
58    PathData*   fPathData;
59    SkFixed     fAdvanceX, fAdvanceY;
60
61    uint16_t    fWidth, fHeight;
62    int16_t     fTop, fLeft;
63
64    uint8_t     fMaskFormat;
65    int8_t      fRsbDelta, fLsbDelta;  // used by auto-kerning
66    int8_t      fForceBW;
67
68    void initWithGlyphID(uint32_t glyph_id) {
69        this->initCommon(MakeID(glyph_id));
70    }
71
72    void initGlyphIdFrom(const SkGlyph& glyph) {
73        this->initCommon(glyph.fID);
74    }
75
76    void initGlyphFromCombinedID(uint32_t combined_id) {
77      this->initCommon(combined_id);
78    }
79
80    /**
81     *  Compute the rowbytes for the specified width and mask-format.
82     */
83    static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
84        unsigned rb = width;
85        if (SkMask::kBW_Format == format) {
86            rb = (rb + 7) >> 3;
87        } else if (SkMask::kARGB32_Format == format) {
88            rb <<= 2;
89        } else if (SkMask::kLCD16_Format == format) {
90            rb = SkAlign4(rb << 1);
91        } else {
92            rb = SkAlign4(rb);
93        }
94        return rb;
95    }
96
97    unsigned rowBytes() const {
98        return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
99    }
100
101    bool isJustAdvance() const {
102        return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
103    }
104
105    bool isFullMetrics() const {
106        return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
107    }
108
109    uint16_t getGlyphID() const {
110        return ID2Code(fID);
111    }
112
113    unsigned getSubX() const {
114        return ID2SubX(fID);
115    }
116
117    SkFixed getSubXFixed() const {
118        return SubToFixed(ID2SubX(fID));
119    }
120
121    SkFixed getSubYFixed() const {
122        return SubToFixed(ID2SubY(fID));
123    }
124
125    size_t computeImageSize() const;
126
127    /** Call this to set all of the metrics fields to 0 (e.g. if the scaler
128        encounters an error measuring a glyph). Note: this does not alter the
129        fImage, fPath, fID, fMaskFormat fields.
130     */
131    void zeroMetrics();
132
133    void toMask(SkMask* mask) const;
134
135    class HashTraits {
136    public:
137        static uint32_t GetKey(const SkGlyph& glyph) {
138            return glyph.fID;
139        }
140        static uint32_t Hash(uint32_t glyphId) {
141            return SkChecksum::CheapMix(glyphId);
142        }
143    };
144
145 private:
146    // TODO(herb) remove friend statement after SkGlyphCache cleanup.
147    friend class SkGlyphCache;
148
149    void initCommon(uint32_t id) {
150        fID             = id;
151        fImage          = nullptr;
152        fPathData       = nullptr;
153        fMaskFormat     = MASK_FORMAT_UNKNOWN;
154        fForceBW        = 0;
155    }
156
157    static unsigned ID2Code(uint32_t id) {
158        return id & kCodeMask;
159    }
160
161    static unsigned ID2SubX(uint32_t id) {
162        return id >> (kSubShift + kSubShiftX);
163    }
164
165    static unsigned ID2SubY(uint32_t id) {
166        return (id >> (kSubShift + kSubShiftY)) & kSubMask;
167    }
168
169    static unsigned FixedToSub(SkFixed n) {
170        return (n >> (16 - kSubBits)) & kSubMask;
171    }
172
173    static SkFixed SubToFixed(unsigned sub) {
174        SkASSERT(sub <= kSubMask);
175        return sub << (16 - kSubBits);
176    }
177
178    static uint32_t MakeID(unsigned code) {
179        SkASSERT(code <= kCodeMask);
180        SkASSERT(code != kImpossibleID);
181        return code;
182    }
183
184    static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
185        SkASSERT(code <= kCodeMask);
186        x = FixedToSub(x);
187        y = FixedToSub(y);
188        uint32_t ID = (x << (kSubShift + kSubShiftX)) |
189                      (y << (kSubShift + kSubShiftY)) |
190                      code;
191        SkASSERT(ID != kImpossibleID);
192        return ID;
193    }
194
195    // FIXME - This is needed because the Android frame work directly
196  // accesses fID. Remove when fID accesses are cleaned up.
197#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
198  public:
199#endif
200    uint32_t    fID;
201};
202SK_END_REQUIRE_DENSE
203
204#endif
205