Line data Source code
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 SkScalerContext_DEFINED
9 : #define SkScalerContext_DEFINED
10 :
11 : #include "SkGlyph.h"
12 : #include "SkMask.h"
13 : #include "SkMaskGamma.h"
14 : #include "SkMatrix.h"
15 : #include "SkPaint.h"
16 : #include "SkTypeface.h"
17 :
18 : class SkDescriptor;
19 : class SkMaskFilter;
20 : class SkPathEffect;
21 : class SkRasterizer;
22 :
23 : struct SkScalerContextEffects {
24 0 : SkScalerContextEffects() : fPathEffect(nullptr), fMaskFilter(nullptr), fRasterizer(nullptr) {}
25 21 : SkScalerContextEffects(SkPathEffect* pe, SkMaskFilter* mf, SkRasterizer* ra)
26 21 : : fPathEffect(pe), fMaskFilter(mf), fRasterizer(ra) {}
27 :
28 : SkPathEffect* fPathEffect;
29 : SkMaskFilter* fMaskFilter;
30 : SkRasterizer* fRasterizer;
31 : };
32 :
33 : enum SkAxisAlignment {
34 : kNone_SkAxisAlignment,
35 : kX_SkAxisAlignment,
36 : kY_SkAxisAlignment
37 : };
38 :
39 : /*
40 : * To allow this to be forward-declared, it must be its own typename, rather
41 : * than a nested struct inside SkScalerContext (where it started).
42 : */
43 : struct SkScalerContextRec {
44 : uint32_t fFontID;
45 : SkScalar fTextSize, fPreScaleX, fPreSkewX;
46 : SkScalar fPost2x2[2][2];
47 : SkScalar fFrameWidth, fMiterLimit;
48 :
49 : //These describe the parameters to create (uniquely identify) the pre-blend.
50 : uint32_t fLumBits;
51 : uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB
52 : uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB
53 : uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast
54 : uint8_t fReservedAlign;
55 :
56 2 : SkScalar getDeviceGamma() const {
57 2 : return SkIntToScalar(fDeviceGamma) / (1 << 6);
58 : }
59 42 : void setDeviceGamma(SkScalar dg) {
60 42 : SkASSERT(0 <= dg && dg < SkIntToScalar(4));
61 42 : fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6));
62 42 : }
63 :
64 2 : SkScalar getPaintGamma() const {
65 2 : return SkIntToScalar(fPaintGamma) / (1 << 6);
66 : }
67 42 : void setPaintGamma(SkScalar pg) {
68 42 : SkASSERT(0 <= pg && pg < SkIntToScalar(4));
69 42 : fPaintGamma = SkScalarFloorToInt(pg * (1 << 6));
70 42 : }
71 :
72 2 : SkScalar getContrast() const {
73 2 : return SkIntToScalar(fContrast) / ((1 << 8) - 1);
74 : }
75 42 : void setContrast(SkScalar c) {
76 42 : SkASSERT(0 <= c && c <= SK_Scalar1);
77 42 : fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1));
78 42 : }
79 :
80 : /**
81 : * Causes the luminance color to be ignored, and the paint and device
82 : * gamma to be effectively 1.0
83 : */
84 21 : void ignoreGamma() {
85 21 : setLuminanceColor(SK_ColorTRANSPARENT);
86 21 : setPaintGamma(SK_Scalar1);
87 21 : setDeviceGamma(SK_Scalar1);
88 21 : }
89 :
90 : /**
91 : * Causes the luminance color and contrast to be ignored, and the
92 : * paint and device gamma to be effectively 1.0.
93 : */
94 21 : void ignorePreBlend() {
95 21 : ignoreGamma();
96 21 : setContrast(0);
97 21 : }
98 :
99 : uint8_t fMaskFormat;
100 : uint8_t fStrokeJoin : 4;
101 : uint8_t fStrokeCap : 4;
102 : uint16_t fFlags;
103 : // Warning: when adding members note that the size of this structure
104 : // must be a multiple of 4. SkDescriptor requires that its arguments be
105 : // multiples of four and this structure is put in an SkDescriptor in
106 : // SkPaint::MakeRec.
107 :
108 : void getMatrixFrom2x2(SkMatrix*) const;
109 : void getLocalMatrix(SkMatrix*) const;
110 : void getSingleMatrix(SkMatrix*) const;
111 :
112 : /** The kind of scale which will be applied by the underlying port (pre-matrix). */
113 : enum PreMatrixScale {
114 : kFull_PreMatrixScale, // The underlying port can apply both x and y scale.
115 : kVertical_PreMatrixScale, // The underlying port can only apply a y scale.
116 : kVerticalInteger_PreMatrixScale // The underlying port can only apply an integer y scale.
117 : };
118 : /**
119 : * Compute useful matrices for use with sizing in underlying libraries.
120 : *
121 : * There are two kinds of text size, a 'requested/logical size' which is like asking for size
122 : * '12' and a 'real' size which is the size after the matrix is applied. The matrices produced
123 : * by this method are based on the 'real' size. This method effectively finds the total device
124 : * matrix and decomposes it in various ways.
125 : *
126 : * The most useful decomposition is into 'scale' and 'remaining'. The 'scale' is applied first
127 : * and then the 'remaining' to fully apply the total matrix. This decomposition is useful when
128 : * the text size ('scale') may have meaning apart from the total matrix. This is true when
129 : * hinting, and sometimes true for other properties as well.
130 : *
131 : * The second (optional) decomposition is of 'remaining' into a non-rotational part
132 : * 'remainingWithoutRotation' and a rotational part 'remainingRotation'. The 'scale' is applied
133 : * first, then 'remainingWithoutRotation', then 'remainingRotation' to fully apply the total
134 : * matrix. This decomposition is helpful when only horizontal metrics can be trusted, so the
135 : * 'scale' and 'remainingWithoutRotation' will be handled by the underlying library, but
136 : * the final rotation 'remainingRotation' will be handled manually.
137 : *
138 : * The 'total' matrix is also (optionally) available. This is useful in cases where the
139 : * underlying library will not be used, often when working directly with font data.
140 : *
141 : * The parameters 'scale' and 'remaining' are required, the other pointers may be nullptr.
142 : *
143 : * @param preMatrixScale the kind of scale to extract from the total matrix.
144 : * @param scale the scale extracted from the total matrix (both values positive).
145 : * @param remaining apply after scale to apply the total matrix.
146 : * @param remainingWithoutRotation apply after scale to apply the total matrix sans rotation.
147 : * @param remainingRotation apply after remainingWithoutRotation to apply the total matrix.
148 : * @param total the total matrix.
149 : * @return false if the matrix was singular. The output will be valid but not invertible.
150 : */
151 : bool computeMatrices(PreMatrixScale preMatrixScale,
152 : SkVector* scale, SkMatrix* remaining,
153 : SkMatrix* remainingWithoutRotation = nullptr,
154 : SkMatrix* remainingRotation = nullptr,
155 : SkMatrix* total = nullptr);
156 :
157 : inline SkPaint::Hinting getHinting() const;
158 : inline void setHinting(SkPaint::Hinting);
159 :
160 : SkMask::Format getFormat() const {
161 : return static_cast<SkMask::Format>(fMaskFormat);
162 : }
163 :
164 23 : SkColor getLuminanceColor() const {
165 23 : return fLumBits;
166 : }
167 :
168 63 : void setLuminanceColor(SkColor c) {
169 63 : fLumBits = c;
170 63 : }
171 : };
172 :
173 : //The following typedef hides from the rest of the implementation the number of
174 : //most significant bits to consider when creating mask gamma tables. Two bits
175 : //per channel was chosen as a balance between fidelity (more bits) and cache
176 : //sizes (fewer bits). Three bits per channel was chosen when #303942; (used by
177 : //the Chrome UI) turned out too green.
178 : typedef SkTMaskGamma<3, 3, 3> SkMaskGamma;
179 :
180 : class SkScalerContext {
181 : public:
182 : typedef SkScalerContextRec Rec;
183 :
184 : enum Flags {
185 : kFrameAndFill_Flag = 0x0001,
186 : kDevKernText_Flag = 0x0002,
187 : kEmbeddedBitmapText_Flag = 0x0004,
188 : kEmbolden_Flag = 0x0008,
189 : kSubpixelPositioning_Flag = 0x0010,
190 : kForceAutohinting_Flag = 0x0020, // Use auto instead of bytcode hinting if hinting.
191 : kVertical_Flag = 0x0040,
192 :
193 : // together, these two flags resulting in a two bit value which matches
194 : // up with the SkPaint::Hinting enum.
195 : kHinting_Shift = 7, // to shift into the other flags above
196 : kHintingBit1_Flag = 0x0080,
197 : kHintingBit2_Flag = 0x0100,
198 :
199 : // Pixel geometry information.
200 : // only meaningful if fMaskFormat is kLCD16
201 : kLCD_Vertical_Flag = 0x0200, // else Horizontal
202 : kLCD_BGROrder_Flag = 0x0400, // else RGB order
203 :
204 : // Generate A8 from LCD source (for GDI and CoreGraphics).
205 : // only meaningful if fMaskFormat is kA8
206 : kGenA8FromLCD_Flag = 0x0800, // could be 0x200 (bit meaning dependent on fMaskFormat)
207 : };
208 :
209 : // computed values
210 : enum {
211 : kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag,
212 : };
213 :
214 : SkScalerContext(sk_sp<SkTypeface>, const SkScalerContextEffects&, const SkDescriptor*);
215 : virtual ~SkScalerContext();
216 :
217 0 : SkTypeface* getTypeface() const { return fTypeface.get(); }
218 :
219 : SkMask::Format getMaskFormat() const {
220 : return (SkMask::Format)fRec.fMaskFormat;
221 : }
222 :
223 21 : bool isSubpixel() const {
224 21 : return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
225 : }
226 :
227 : bool isVertical() const {
228 : return SkToBool(fRec.fFlags & kVertical_Flag);
229 : }
230 :
231 : /** Return the corresponding glyph for the specified unichar. Since contexts
232 : may be chained (under the hood), the glyphID that is returned may in
233 : fact correspond to a different font/context. In that case, we use the
234 : base-glyph-count to know how to translate back into local glyph space.
235 : */
236 0 : uint16_t charToGlyphID(SkUnichar uni) {
237 0 : return generateCharToGlyph(uni);
238 : }
239 :
240 : /** Map the glyphID to its glyph index, and then to its char code. Unmapped
241 : glyphs return zero.
242 : */
243 0 : SkUnichar glyphIDToChar(uint16_t glyphID) {
244 0 : return (glyphID < getGlyphCount()) ? generateGlyphToChar(glyphID) : 0;
245 : }
246 :
247 0 : unsigned getGlyphCount() { return this->generateGlyphCount(); }
248 : void getAdvance(SkGlyph*);
249 : void getMetrics(SkGlyph*);
250 : void getImage(const SkGlyph&);
251 : void getPath(SkPackedGlyphID, SkPath*);
252 : void getFontMetrics(SkPaint::FontMetrics*);
253 :
254 : /** Return the size in bytes of the associated gamma lookup table
255 : */
256 : static size_t GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
257 : int* width, int* height);
258 :
259 : /** Get the associated gamma lookup table. The 'data' pointer must point to pre-allocated
260 : memory, with size in bytes greater than or equal to the return value of getGammaLUTSize().
261 : */
262 : static void GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
263 : void* data);
264 :
265 : static void MakeRec(const SkPaint&, const SkSurfaceProps* surfaceProps,
266 : const SkMatrix*, Rec* rec);
267 : static inline void PostMakeRec(const SkPaint&, Rec*);
268 :
269 : static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec);
270 :
271 0 : const Rec& getRec() const { return fRec; }
272 :
273 0 : SkScalerContextEffects getEffects() const {
274 0 : return { fPathEffect.get(), fMaskFilter.get(), fRasterizer.get() };
275 : }
276 :
277 : /**
278 : * Return the axis (if any) that the baseline for horizontal text should land on.
279 : * As an example, the identity matrix will return kX_SkAxisAlignment
280 : */
281 : SkAxisAlignment computeAxisAlignmentForHText();
282 :
283 : protected:
284 : Rec fRec;
285 :
286 : /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY.
287 : * May call getMetrics if that would be just as fast.
288 : */
289 : virtual void generateAdvance(SkGlyph* glyph) = 0;
290 :
291 : /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft,
292 : * as well as fAdvanceX and fAdvanceY if not already set.
293 : *
294 : * TODO: fMaskFormat is set by getMetrics later; cannot be set here.
295 : */
296 : virtual void generateMetrics(SkGlyph* glyph) = 0;
297 :
298 : /** Generates the contents of glyph.fImage.
299 : * When called, glyph.fImage will be pointing to a pre-allocated,
300 : * uninitialized region of memory of size glyph.computeImageSize().
301 : * This method may change glyph.fMaskFormat if the new image size is
302 : * less than or equal to the old image size.
303 : *
304 : * Because glyph.computeImageSize() will determine the size of fImage,
305 : * generateMetrics will be called before generateImage.
306 : */
307 : virtual void generateImage(const SkGlyph& glyph) = 0;
308 :
309 : /** Sets the passed path to the glyph outline.
310 : * If this cannot be done the path is set to empty;
311 : * this is indistinguishable from a glyph with an empty path.
312 : */
313 : virtual void generatePath(SkGlyphID glyphId, SkPath* path) = 0;
314 :
315 : /** Retrieves font metrics. */
316 : virtual void generateFontMetrics(SkPaint::FontMetrics*) = 0;
317 :
318 : /** Returns the number of glyphs in the font. */
319 : virtual unsigned generateGlyphCount() = 0;
320 :
321 : /** Returns the glyph id for the given unichar.
322 : * If there is no 1:1 mapping from the unichar to a glyph id, returns 0.
323 : */
324 : virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0;
325 :
326 : /** Returns the unichar for the given glyph id.
327 : * If there is no 1:1 mapping from the glyph id to a unichar, returns 0.
328 : * The default implementation always returns 0, indicating failure.
329 : */
330 : virtual SkUnichar generateGlyphToChar(uint16_t glyphId);
331 :
332 : void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }
333 : void forceOffGenerateImageFromPath() { fGenerateImageFromPath = false; }
334 :
335 : private:
336 : friend class SkRandomScalerContext; // For debug purposes
337 :
338 : // never null
339 : sk_sp<SkTypeface> fTypeface;
340 :
341 : // optional objects, which may be null
342 : sk_sp<SkPathEffect> fPathEffect;
343 : sk_sp<SkMaskFilter> fMaskFilter;
344 : sk_sp<SkRasterizer> fRasterizer;
345 :
346 : // if this is set, we draw the image from a path, rather than
347 : // calling generateImage.
348 : bool fGenerateImageFromPath;
349 :
350 : void internalGetPath(SkPackedGlyphID id, SkPath* fillPath,
351 : SkPath* devPath, SkMatrix* fillToDevMatrix);
352 :
353 : // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks.
354 : protected:
355 : // Visible to subclasses so that generateImage can apply the pre-blend directly.
356 : const SkMaskGamma::PreBlend fPreBlend;
357 : private:
358 : // When there is a filter, previous steps must create a linear mask
359 : // and the pre-blend applied as a final step.
360 : const SkMaskGamma::PreBlend fPreBlendForFilter;
361 : };
362 :
363 : #define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c')
364 : #define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e')
365 : #define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f')
366 : #define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't')
367 :
368 : ///////////////////////////////////////////////////////////////////////////////
369 :
370 4 : SkPaint::Hinting SkScalerContextRec::getHinting() const {
371 4 : unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >>
372 4 : SkScalerContext::kHinting_Shift;
373 4 : return static_cast<SkPaint::Hinting>(hint);
374 : }
375 :
376 23 : void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) {
377 46 : fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) |
378 23 : (hinting << SkScalerContext::kHinting_Shift);
379 23 : }
380 :
381 :
382 : #endif
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