1
2/*
3 * Copyright 2006 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10#ifndef SkScalerContext_DEFINED
11#define SkScalerContext_DEFINED
12
13#include "SkMask.h"
14#include "SkMatrix.h"
15#include "SkPaint.h"
16#include "SkPath.h"
17#include "SkPoint.h"
18#include "SkTypeface.h"
19
20#ifdef SK_BUILD_FOR_ANDROID
21#include "SkLanguage.h"
22#endif
23
24//#define SK_USE_COLOR_LUMINANCE
25
26class SkDescriptor;
27class SkMaskFilter;
28class SkPathEffect;
29class SkRasterizer;
30
31// needs to be != to any valid SkMask::Format
32#define MASK_FORMAT_UNKNOWN         (0xFF)
33#define MASK_FORMAT_JUST_ADVANCE    MASK_FORMAT_UNKNOWN
34
35#define kMaxGlyphWidth (1<<13)
36
37struct SkGlyph {
38    void*       fImage;
39    SkPath*     fPath;
40    SkFixed     fAdvanceX, fAdvanceY;
41
42    uint32_t    fID;
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
49    void init(uint32_t id) {
50        fID             = id;
51        fImage          = NULL;
52        fPath           = NULL;
53        fMaskFormat     = MASK_FORMAT_UNKNOWN;
54    }
55
56    /**
57     *  Compute the rowbytes for the specified width and mask-format.
58     */
59    static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
60        unsigned rb = width;
61        if (SkMask::kBW_Format == format) {
62            rb = (rb + 7) >> 3;
63		} else if (SkMask::kARGB32_Format == format ||
64                   SkMask::kLCD32_Format == format)
65        {
66			rb <<= 2;
67		} else if (SkMask::kLCD16_Format == format) {
68			rb = SkAlign4(rb << 1);
69        } else {
70            rb = SkAlign4(rb);
71        }
72        return rb;
73    }
74
75    unsigned rowBytes() const {
76        return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
77    }
78
79    bool isJustAdvance() const {
80        return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
81    }
82
83    bool isFullMetrics() const {
84        return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
85    }
86
87    uint16_t getGlyphID() const {
88        return ID2Code(fID);
89    }
90
91    unsigned getGlyphID(unsigned baseGlyphCount) const {
92        unsigned code = ID2Code(fID);
93        SkASSERT(code >= baseGlyphCount);
94        return code - baseGlyphCount;
95    }
96
97    unsigned getSubX() const {
98        return ID2SubX(fID);
99    }
100
101    SkFixed getSubXFixed() const {
102        return SubToFixed(ID2SubX(fID));
103    }
104
105    SkFixed getSubYFixed() const {
106        return SubToFixed(ID2SubY(fID));
107    }
108
109    size_t computeImageSize() const;
110
111    /** Call this to set all of the metrics fields to 0 (e.g. if the scaler
112        encounters an error measuring a glyph). Note: this does not alter the
113        fImage, fPath, fID, fMaskFormat fields.
114     */
115    void zeroMetrics();
116
117    enum {
118        kSubBits = 2,
119        kSubMask = ((1 << kSubBits) - 1),
120        kSubShift = 24, // must be large enough for glyphs and unichars
121        kCodeMask = ((1 << kSubShift) - 1),
122        // relative offsets for X and Y subpixel bits
123        kSubShiftX = kSubBits,
124        kSubShiftY = 0
125    };
126
127    static unsigned ID2Code(uint32_t id) {
128        return id & kCodeMask;
129    }
130
131    static unsigned ID2SubX(uint32_t id) {
132        return id >> (kSubShift + kSubShiftX);
133    }
134
135    static unsigned ID2SubY(uint32_t id) {
136        return (id >> (kSubShift + kSubShiftY)) & kSubMask;
137    }
138
139    static unsigned FixedToSub(SkFixed n) {
140        return (n >> (16 - kSubBits)) & kSubMask;
141    }
142
143    static SkFixed SubToFixed(unsigned sub) {
144        SkASSERT(sub <= kSubMask);
145        return sub << (16 - kSubBits);
146    }
147
148    static uint32_t MakeID(unsigned code) {
149        return code;
150    }
151
152    static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
153        SkASSERT(code <= kCodeMask);
154        x = FixedToSub(x);
155        y = FixedToSub(y);
156        return (x << (kSubShift + kSubShiftX)) |
157               (y << (kSubShift + kSubShiftY)) |
158               code;
159    }
160
161    void toMask(SkMask* mask) const;
162};
163
164class SkScalerContext {
165public:
166    enum Flags {
167        kFrameAndFill_Flag        = 0x0001,
168        kDevKernText_Flag         = 0x0002,
169        kEmbeddedBitmapText_Flag  = 0x0004,
170        kEmbolden_Flag            = 0x0008,
171        kSubpixelPositioning_Flag = 0x0010,
172        kAutohinting_Flag         = 0x0020,
173        kVertical_Flag            = 0x0040,
174
175        // together, these two flags resulting in a two bit value which matches
176        // up with the SkPaint::Hinting enum.
177        kHinting_Shift            = 7, // to shift into the other flags above
178        kHintingBit1_Flag         = 0x0080,
179        kHintingBit2_Flag         = 0x0100,
180
181        // these should only ever be set if fMaskFormat is LCD16 or LCD32
182        kLCD_Vertical_Flag        = 0x0200,    // else Horizontal
183        kLCD_BGROrder_Flag        = 0x0400,    // else RGB order
184
185        // Generate A8 from LCD source (for GDI), only meaningful if fMaskFormat is kA8
186        // Perhaps we can store this (instead) in fMaskFormat, in hight bit?
187        kGenA8FromLCD_Flag        = 0x0800,
188
189#ifdef SK_USE_COLOR_LUMINANCE
190        kLuminance_Bits           = 3,
191#else
192        // luminance : 0 for black text, kLuminance_Max for white text
193        kLuminance_Shift          = 13, // shift to land in the high 3-bits of Flags
194        kLuminance_Bits           = 3,  // ensure Flags doesn't exceed 16bits
195#endif
196    };
197
198    // computed values
199    enum {
200        kHinting_Mask   = kHintingBit1_Flag | kHintingBit2_Flag,
201#ifdef SK_USE_COLOR_LUMINANCE
202#else
203        kLuminance_Max  = (1 << kLuminance_Bits) - 1,
204        kLuminance_Mask = kLuminance_Max << kLuminance_Shift,
205#endif
206    };
207
208    struct Rec {
209        uint32_t    fOrigFontID;
210        uint32_t    fFontID;
211        SkScalar    fTextSize, fPreScaleX, fPreSkewX;
212        SkScalar    fPost2x2[2][2];
213        SkScalar    fFrameWidth, fMiterLimit;
214#ifdef SK_USE_COLOR_LUMINANCE
215        uint32_t    fLumBits;
216#endif
217#ifdef SK_BUILD_FOR_ANDROID
218        SkLanguage fLanguage;
219        SkPaint::FontVariant fFontVariant;
220#endif
221        uint8_t     fMaskFormat;
222        uint8_t     fStrokeJoin;
223        uint16_t    fFlags;
224        // Warning: when adding members note that the size of this structure
225        // must be a multiple of 4. SkDescriptor requires that its arguments be
226        // multiples of four and this structure is put in an SkDescriptor in
227        // SkPaint::MakeRec.
228
229        void    getMatrixFrom2x2(SkMatrix*) const;
230        void    getLocalMatrix(SkMatrix*) const;
231        void    getSingleMatrix(SkMatrix*) const;
232
233        SkPaint::Hinting getHinting() const {
234            unsigned hint = (fFlags & kHinting_Mask) >> kHinting_Shift;
235            return static_cast<SkPaint::Hinting>(hint);
236        }
237
238        void setHinting(SkPaint::Hinting hinting) {
239            fFlags = (fFlags & ~kHinting_Mask) | (hinting << kHinting_Shift);
240        }
241
242        SkMask::Format getFormat() const {
243            return static_cast<SkMask::Format>(fMaskFormat);
244        }
245#ifdef SK_USE_COLOR_LUMINANCE
246        SkColor getLuminanceColor() const {
247            return fLumBits;
248        }
249
250        void setLuminanceColor(SkColor c) {
251            fLumBits = c;
252        }
253#else
254        unsigned getLuminanceBits() const {
255            return (fFlags & kLuminance_Mask) >> kLuminance_Shift;
256        }
257
258        void setLuminanceBits(unsigned lum) {
259            SkASSERT(lum <= kLuminance_Max);
260            fFlags = (fFlags & ~kLuminance_Mask) | (lum << kLuminance_Shift);
261        }
262
263        U8CPU getLuminanceByte() const {
264            SkASSERT(3 == kLuminance_Bits);
265            unsigned lum = this->getLuminanceBits();
266            lum |= (lum << kLuminance_Bits);
267            lum |= (lum << kLuminance_Bits*2);
268            return lum >> (4*kLuminance_Bits - 8);
269        }
270#endif
271    };
272
273    SkScalerContext(const SkDescriptor* desc);
274    virtual ~SkScalerContext();
275
276    SkMask::Format getMaskFormat() const {
277        return (SkMask::Format)fRec.fMaskFormat;
278    }
279
280    bool isSubpixel() const {
281        return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
282    }
283
284    // remember our glyph offset/base
285    void setBaseGlyphCount(unsigned baseGlyphCount) {
286        fBaseGlyphCount = baseGlyphCount;
287    }
288
289    /** Return the corresponding glyph for the specified unichar. Since contexts
290        may be chained (under the hood), the glyphID that is returned may in
291        fact correspond to a different font/context. In that case, we use the
292        base-glyph-count to know how to translate back into local glyph space.
293     */
294    uint16_t charToGlyphID(SkUnichar uni);
295
296    /** Map the glyphID to its glyph index, and then to its char code. Unmapped
297        glyphs return zero.
298    */
299    SkUnichar glyphIDToChar(uint16_t glyphID);
300
301    unsigned    getGlyphCount() { return this->generateGlyphCount(); }
302    void        getAdvance(SkGlyph*);
303    void        getMetrics(SkGlyph*);
304    void        getImage(const SkGlyph&);
305    void        getPath(const SkGlyph&, SkPath*);
306    void        getFontMetrics(SkPaint::FontMetrics* mX,
307                               SkPaint::FontMetrics* mY);
308
309#ifdef SK_BUILD_FOR_ANDROID
310    // This function must be public for SkTypeface_android.h, but should not be
311    // called by other callers
312    SkFontID findTypefaceIdForChar(SkUnichar uni);
313
314    unsigned getBaseGlyphCount(SkUnichar charCode);
315#endif
316
317    static inline void MakeRec(const SkPaint&, const SkMatrix*, Rec* rec);
318    static inline void PostMakeRec(Rec*);
319
320    static SkScalerContext* Create(const SkDescriptor*);
321
322protected:
323    Rec         fRec;
324    unsigned    fBaseGlyphCount;
325
326    virtual unsigned generateGlyphCount() = 0;
327    virtual uint16_t generateCharToGlyph(SkUnichar) = 0;
328    virtual void generateAdvance(SkGlyph*) = 0;
329    virtual void generateMetrics(SkGlyph*) = 0;
330    virtual void generateImage(const SkGlyph&) = 0;
331    virtual void generatePath(const SkGlyph&, SkPath*) = 0;
332    virtual void generateFontMetrics(SkPaint::FontMetrics* mX,
333                                     SkPaint::FontMetrics* mY) = 0;
334    // default impl returns 0, indicating failure.
335    virtual SkUnichar generateGlyphToChar(uint16_t);
336
337    void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }
338
339private:
340    SkScalerContext* getContextFromChar(SkUnichar uni, unsigned& glyphID);
341
342    SkPathEffect*   fPathEffect;
343    SkMaskFilter*   fMaskFilter;
344    SkRasterizer*   fRasterizer;
345    SkScalar        fDevFrameWidth;
346
347    // if this is set, we draw the image from a path, rather than
348    // calling generateImage.
349    bool fGenerateImageFromPath;
350
351    void internalGetPath(const SkGlyph& glyph, SkPath* fillPath,
352                         SkPath* devPath, SkMatrix* fillToDevMatrix);
353
354    // return the next context, treating fNextContext as a cache of the answer
355    SkScalerContext* getNextContext();
356
357    // returns the right context from our link-list for this glyph. If no match
358    // is found, just returns the original context (this)
359    SkScalerContext* getGlyphContext(const SkGlyph& glyph);
360
361    // link-list of context, to handle missing chars. null-terminated.
362    SkScalerContext* fNextContext;
363};
364
365#define kRec_SkDescriptorTag            SkSetFourByteTag('s', 'r', 'e', 'c')
366#define kPathEffect_SkDescriptorTag     SkSetFourByteTag('p', 't', 'h', 'e')
367#define kMaskFilter_SkDescriptorTag     SkSetFourByteTag('m', 's', 'k', 'f')
368#define kRasterizer_SkDescriptorTag     SkSetFourByteTag('r', 'a', 's', 't')
369
370///////////////////////////////////////////////////////////////////////////////
371
372enum SkAxisAlignment {
373    kNone_SkAxisAlignment,
374    kX_SkAxisAlignment,
375    kY_SkAxisAlignment
376};
377
378/**
379 *  Return the axis (if any) that the baseline for horizontal text will land on
380 *  after running through the specified matrix.
381 *
382 *  As an example, the identity matrix will return kX_SkAxisAlignment
383 */
384SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix);
385
386#endif
387
388