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 "SkArenaAlloc.h"
12#include "SkChecksum.h"
13#include "SkFixed.h"
14#include "SkMask.h"
15#include "SkTypes.h"
16
17
18class SkPath;
19class SkGlyphCache;
20
21// needs to be != to any valid SkMask::Format
22#define MASK_FORMAT_UNKNOWN         (0xFF)
23#define MASK_FORMAT_JUST_ADVANCE    MASK_FORMAT_UNKNOWN
24
25#define kMaxGlyphWidth (1<<13)
26
27/** (glyph-index or unicode-point) + subpixel-pos */
28struct SkPackedID {
29    static constexpr uint32_t kImpossibleID = ~0;
30    enum {
31        kSubBits = 2,
32        kSubMask = ((1 << kSubBits) - 1),
33        kSubShift = 24, // must be large enough for glyphs and unichars
34        kCodeMask = ((1 << kSubShift) - 1),
35        // relative offsets for X and Y subpixel bits
36        kSubShiftX = kSubBits,
37        kSubShiftY = 0
38    };
39
40    SkPackedID(uint32_t code) {
41        SkASSERT(code <= kCodeMask);
42        SkASSERT(code != kImpossibleID);
43        fID = code;
44    }
45
46    SkPackedID(uint32_t code, SkFixed x, SkFixed y) {
47        SkASSERT(code <= kCodeMask);
48        x = FixedToSub(x);
49        y = FixedToSub(y);
50        uint32_t ID = (x << (kSubShift + kSubShiftX)) |
51                      (y << (kSubShift + kSubShiftY)) |
52                      code;
53        SkASSERT(ID != kImpossibleID);
54        fID = ID;
55    }
56
57    constexpr SkPackedID() : fID(kImpossibleID) {}
58
59    bool operator==(const SkPackedID& that) const {
60        return fID == that.fID;
61    }
62    bool operator!=(const SkPackedID& that) const {
63        return !(*this == that);
64    }
65
66    uint32_t code() const {
67        return fID & kCodeMask;
68    }
69
70    SkFixed getSubXFixed() const {
71        return SubToFixed(ID2SubX(fID));
72    }
73
74    SkFixed getSubYFixed() const {
75        return SubToFixed(ID2SubY(fID));
76    }
77
78    uint32_t hash() const {
79        return SkChecksum::CheapMix(fID);
80    }
81
82// FIXME - This is needed because the Android framework directly accesses fID.
83// Remove when fID accesses are cleaned up.
84#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
85    operator uint32_t() const { return fID; }
86#endif
87
88private:
89    static unsigned ID2SubX(uint32_t id) {
90        return id >> (kSubShift + kSubShiftX);
91    }
92
93    static unsigned ID2SubY(uint32_t id) {
94        return (id >> (kSubShift + kSubShiftY)) & kSubMask;
95    }
96
97    static unsigned FixedToSub(SkFixed n) {
98        return (n >> (16 - kSubBits)) & kSubMask;
99    }
100
101    static SkFixed SubToFixed(unsigned sub) {
102        SkASSERT(sub <= kSubMask);
103        return sub << (16 - kSubBits);
104    }
105
106    uint32_t fID;
107};
108
109struct SkPackedGlyphID : public SkPackedID {
110    SkPackedGlyphID(SkGlyphID code) : SkPackedID(code) { }
111    SkPackedGlyphID(SkGlyphID code, SkFixed x, SkFixed y) : SkPackedID(code, x, y) { }
112    SkPackedGlyphID() : SkPackedID() { }
113    SkGlyphID code() const {
114        return SkTo<SkGlyphID>(SkPackedID::code());
115    }
116};
117
118struct SkPackedUnicharID : public SkPackedID {
119    SkPackedUnicharID(SkUnichar code) : SkPackedID(code) { }
120    SkPackedUnicharID(SkUnichar code, SkFixed x, SkFixed y) : SkPackedID(code, x, y) { }
121    SkPackedUnicharID() : SkPackedID() { }
122    SkUnichar code() const {
123        return SkTo<SkUnichar>(SkPackedID::code());
124    }
125};
126
127SK_BEGIN_REQUIRE_DENSE
128class SkGlyph {
129    // Support horizontal and vertical skipping strike-through / underlines.
130    // The caller walks the linked list looking for a match. For a horizontal underline,
131    // the fBounds contains the top and bottom of the underline. The fInterval pair contains the
132    // beginning and end of of the intersection of the bounds and the glyph's path.
133    // If interval[0] >= interval[1], no intesection was found.
134    struct Intercept {
135        Intercept* fNext;
136        SkScalar   fBounds[2];    // for horz underlines, the boundaries in Y
137        SkScalar   fInterval[2];  // the outside intersections of the axis and the glyph
138    };
139
140    struct PathData {
141        Intercept* fIntercept;
142        SkPath*    fPath;
143    };
144
145public:
146    static const SkFixed kSubpixelRound = SK_FixedHalf >> SkPackedID::kSubBits;
147    void*       fImage;
148    PathData*   fPathData;
149    float       fAdvanceX, fAdvanceY;
150
151    uint16_t    fWidth, fHeight;
152    int16_t     fTop, fLeft;
153
154    uint8_t     fMaskFormat;
155    int8_t      fRsbDelta, fLsbDelta;  // used by auto-kerning
156    int8_t      fForceBW;
157
158    void initWithGlyphID(SkPackedGlyphID glyph_id) {
159        fID             = glyph_id;
160        fImage          = nullptr;
161        fPathData       = nullptr;
162        fMaskFormat     = MASK_FORMAT_UNKNOWN;
163        fForceBW        = 0;
164    }
165
166    static size_t BitsToBytes(size_t bits) {
167        return (bits + 7) >> 3;
168    }
169
170    /**
171     *  Compute the rowbytes for the specified width and mask-format.
172     */
173    static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
174        unsigned rb = width;
175        if (SkMask::kBW_Format == format) {
176            rb = BitsToBytes(rb);
177        } else if (SkMask::kARGB32_Format == format) {
178            rb <<= 2;
179        } else if (SkMask::kLCD16_Format == format) {
180            rb = SkAlign4(rb << 1);
181        } else {
182            rb = SkAlign4(rb);
183        }
184        return rb;
185    }
186
187    size_t allocImage(SkArenaAlloc* alloc) {
188        size_t allocSize;
189        if (SkMask::kBW_Format == fMaskFormat) {
190            allocSize = BitsToBytes(fWidth) * fHeight;
191            fImage = alloc->makeArrayDefault<char>(allocSize);
192        } else if (SkMask::kARGB32_Format == fMaskFormat) {
193            allocSize = fWidth * fHeight;
194            fImage = alloc->makeArrayDefault<uint32_t>(fWidth * fHeight);
195            allocSize *= sizeof(uint32_t);
196        } else if (SkMask::kLCD16_Format == fMaskFormat) {
197            allocSize = SkAlign2(fWidth) * fHeight;
198            fImage = alloc->makeArrayDefault<uint16_t>(allocSize);
199            allocSize *= sizeof(uint16_t);
200        } else {
201            allocSize = SkAlign4(fWidth) * fHeight;
202            fImage = alloc->makeArrayDefault<char>(allocSize);
203        }
204        return allocSize;
205    }
206
207    unsigned rowBytes() const {
208        return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
209    }
210
211    bool isJustAdvance() const {
212        return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
213    }
214
215    bool isFullMetrics() const {
216        return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
217    }
218
219    SkGlyphID getGlyphID() const {
220        return fID.code();
221    }
222
223    SkPackedGlyphID getPackedID() const {
224        return fID;
225    }
226
227    SkFixed getSubXFixed() const {
228        return fID.getSubXFixed();
229    }
230
231    SkFixed getSubYFixed() const {
232        return fID.getSubYFixed();
233    }
234
235    size_t computeImageSize() const;
236
237    /** Call this to set all of the metrics fields to 0 (e.g. if the scaler
238        encounters an error measuring a glyph). Note: this does not alter the
239        fImage, fPath, fID, fMaskFormat fields.
240     */
241    void zeroMetrics();
242
243    void toMask(SkMask* mask) const;
244
245    class HashTraits {
246    public:
247        static SkPackedGlyphID GetKey(const SkGlyph& glyph) {
248            return glyph.fID;
249        }
250        static uint32_t Hash(SkPackedGlyphID glyphId) {
251            return glyphId.hash();
252        }
253    };
254
255 private:
256    // TODO(herb) remove friend statement after SkGlyphCache cleanup.
257    friend class SkGlyphCache;
258
259// FIXME - This is needed because the Android frame work directly accesses fID.
260// Remove when fID accesses are cleaned up.
261#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
262  public:
263#endif
264    SkPackedGlyphID fID;
265};
266SK_END_REQUIRE_DENSE
267
268#endif
269