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 <memory> 12 13 #include "SkGlyph.h" 14 #include "SkMask.h" 15 #include "SkMaskFilter.h" 16 #include "SkMaskGamma.h" 17 #include "SkMatrix.h" 18 #include "SkPaint.h" 19 #include "SkTypeface.h" 20 #include "SkWriteBuffer.h" 21 22 class SkAutoDescriptor; 23 class SkDescriptor; 24 class SkMaskFilter; 25 class SkPathEffect; 26 27 enum SkScalerContextFlags : uint32_t { 28 kNone = 0, 29 kFakeGamma = 1 << 0, 30 kBoostContrast = 1 << 1, 31 kFakeGammaAndBoostContrast = kFakeGamma | kBoostContrast, 32 }; 33 34 struct SkScalerContextEffects { 35 SkScalerContextEffects() : fPathEffect(nullptr), fMaskFilter(nullptr) {} 36 SkScalerContextEffects(SkPathEffect* pe, SkMaskFilter* mf) 37 : fPathEffect(pe), fMaskFilter(mf) {} 38 explicit SkScalerContextEffects(const SkPaint& paint) 39 : fPathEffect(paint.getPathEffect()) 40 , fMaskFilter(paint.getMaskFilter()) {} 41 42 SkPathEffect* fPathEffect; 43 SkMaskFilter* fMaskFilter; 44 }; 45 46 enum SkAxisAlignment { 47 kNone_SkAxisAlignment, 48 kX_SkAxisAlignment, 49 kY_SkAxisAlignment 50 }; 51 52 /* 53 * To allow this to be forward-declared, it must be its own typename, rather 54 * than a nested struct inside SkScalerContext (where it started). 55 */ 56 struct SkScalerContextRec { 57 uint32_t fFontID; 58 SkScalar fTextSize, fPreScaleX, fPreSkewX; 59 SkScalar fPost2x2[2][2]; 60 SkScalar fFrameWidth, fMiterLimit; 61 62 //These describe the parameters to create (uniquely identify) the pre-blend. 63 uint32_t fLumBits; 64 uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 65 uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 66 uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast 67 uint8_t fReservedAlign; 68 69 SkScalar getDeviceGamma() const { 70 return SkIntToScalar(fDeviceGamma) / (1 << 6); 71 } 72 void setDeviceGamma(SkScalar dg) { 73 SkASSERT(0 <= dg && dg < SkIntToScalar(4)); 74 fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6)); 75 } 76 77 SkScalar getPaintGamma() const { 78 return SkIntToScalar(fPaintGamma) / (1 << 6); 79 } 80 void setPaintGamma(SkScalar pg) { 81 SkASSERT(0 <= pg && pg < SkIntToScalar(4)); 82 fPaintGamma = SkScalarFloorToInt(pg * (1 << 6)); 83 } 84 85 SkScalar getContrast() const { 86 return SkIntToScalar(fContrast) / ((1 << 8) - 1); 87 } 88 void setContrast(SkScalar c) { 89 SkASSERT(0 <= c && c <= SK_Scalar1); 90 fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1)); 91 } 92 93 /** 94 * Causes the luminance color to be ignored, and the paint and device 95 * gamma to be effectively 1.0 96 */ 97 void ignoreGamma() { 98 setLuminanceColor(SK_ColorTRANSPARENT); 99 setPaintGamma(SK_Scalar1); 100 setDeviceGamma(SK_Scalar1); 101 } 102 103 /** 104 * Causes the luminance color and contrast to be ignored, and the 105 * paint and device gamma to be effectively 1.0. 106 */ 107 void ignorePreBlend() { 108 ignoreGamma(); 109 setContrast(0); 110 } 111 112 uint8_t fMaskFormat; 113 uint8_t fStrokeJoin : 4; 114 uint8_t fStrokeCap : 4; 115 uint16_t fFlags; 116 // Warning: when adding members note that the size of this structure 117 // must be a multiple of 4. SkDescriptor requires that its arguments be 118 // multiples of four and this structure is put in an SkDescriptor in 119 // SkPaint::MakeRecAndEffects. 120 121 void getMatrixFrom2x2(SkMatrix*) const; 122 void getLocalMatrix(SkMatrix*) const; 123 void getSingleMatrix(SkMatrix*) const; 124 125 /** The kind of scale which will be applied by the underlying port (pre-matrix). */ 126 enum PreMatrixScale { 127 kFull_PreMatrixScale, // The underlying port can apply both x and y scale. 128 kVertical_PreMatrixScale, // The underlying port can only apply a y scale. 129 kVerticalInteger_PreMatrixScale // The underlying port can only apply an integer y scale. 130 }; 131 /** 132 * Compute useful matrices for use with sizing in underlying libraries. 133 * 134 * There are two kinds of text size, a 'requested/logical size' which is like asking for size 135 * '12' and a 'real' size which is the size after the matrix is applied. The matrices produced 136 * by this method are based on the 'real' size. This method effectively finds the total device 137 * matrix and decomposes it in various ways. 138 * 139 * The most useful decomposition is into 'scale' and 'remaining'. The 'scale' is applied first 140 * and then the 'remaining' to fully apply the total matrix. This decomposition is useful when 141 * the text size ('scale') may have meaning apart from the total matrix. This is true when 142 * hinting, and sometimes true for other properties as well. 143 * 144 * The second (optional) decomposition is of 'remaining' into a non-rotational part 145 * 'remainingWithoutRotation' and a rotational part 'remainingRotation'. The 'scale' is applied 146 * first, then 'remainingWithoutRotation', then 'remainingRotation' to fully apply the total 147 * matrix. This decomposition is helpful when only horizontal metrics can be trusted, so the 148 * 'scale' and 'remainingWithoutRotation' will be handled by the underlying library, but 149 * the final rotation 'remainingRotation' will be handled manually. 150 * 151 * The 'total' matrix is also (optionally) available. This is useful in cases where the 152 * underlying library will not be used, often when working directly with font data. 153 * 154 * The parameters 'scale' and 'remaining' are required, the other pointers may be nullptr. 155 * 156 * @param preMatrixScale the kind of scale to extract from the total matrix. 157 * @param scale the scale extracted from the total matrix (both values positive). 158 * @param remaining apply after scale to apply the total matrix. 159 * @param remainingWithoutRotation apply after scale to apply the total matrix sans rotation. 160 * @param remainingRotation apply after remainingWithoutRotation to apply the total matrix. 161 * @param total the total matrix. 162 * @return false if the matrix was singular. The output will be valid but not invertible. 163 */ 164 bool computeMatrices(PreMatrixScale preMatrixScale, 165 SkVector* scale, SkMatrix* remaining, 166 SkMatrix* remainingWithoutRotation = nullptr, 167 SkMatrix* remainingRotation = nullptr, 168 SkMatrix* total = nullptr); 169 170 inline SkPaint::Hinting getHinting() const; 171 inline void setHinting(SkPaint::Hinting); 172 173 SkMask::Format getFormat() const { 174 return static_cast<SkMask::Format>(fMaskFormat); 175 } 176 177 SkColor getLuminanceColor() const { 178 return fLumBits; 179 } 180 181 void setLuminanceColor(SkColor c) { 182 fLumBits = c; 183 } 184 }; 185 186 //The following typedef hides from the rest of the implementation the number of 187 //most significant bits to consider when creating mask gamma tables. Two bits 188 //per channel was chosen as a balance between fidelity (more bits) and cache 189 //sizes (fewer bits). Three bits per channel was chosen when #303942; (used by 190 //the Chrome UI) turned out too green. 191 typedef SkTMaskGamma<3, 3, 3> SkMaskGamma; 192 193 class SkScalerContext { 194 public: 195 enum Flags { 196 kFrameAndFill_Flag = 0x0001, 197 kDevKernText_Flag = 0x0002, 198 kEmbeddedBitmapText_Flag = 0x0004, 199 kEmbolden_Flag = 0x0008, 200 kSubpixelPositioning_Flag = 0x0010, 201 kForceAutohinting_Flag = 0x0020, // Use auto instead of bytcode hinting if hinting. 202 kVertical_Flag = 0x0040, 203 204 // together, these two flags resulting in a two bit value which matches 205 // up with the SkPaint::Hinting enum. 206 kHinting_Shift = 7, // to shift into the other flags above 207 kHintingBit1_Flag = 0x0080, 208 kHintingBit2_Flag = 0x0100, 209 210 // Pixel geometry information. 211 // only meaningful if fMaskFormat is kLCD16 212 kLCD_Vertical_Flag = 0x0200, // else Horizontal 213 kLCD_BGROrder_Flag = 0x0400, // else RGB order 214 215 // Generate A8 from LCD source (for GDI and CoreGraphics). 216 // only meaningful if fMaskFormat is kA8 217 kGenA8FromLCD_Flag = 0x0800, // could be 0x200 (bit meaning dependent on fMaskFormat) 218 }; 219 220 // computed values 221 enum { 222 kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag, 223 }; 224 225 SkScalerContext(sk_sp<SkTypeface>, const SkScalerContextEffects&, const SkDescriptor*); 226 virtual ~SkScalerContext(); 227 228 SkTypeface* getTypeface() const { return fTypeface.get(); } 229 230 SkMask::Format getMaskFormat() const { 231 return (SkMask::Format)fRec.fMaskFormat; 232 } 233 234 bool isSubpixel() const { 235 return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag); 236 } 237 238 bool isVertical() const { 239 return SkToBool(fRec.fFlags & kVertical_Flag); 240 } 241 242 /** Return the corresponding glyph for the specified unichar. Since contexts 243 may be chained (under the hood), the glyphID that is returned may in 244 fact correspond to a different font/context. In that case, we use the 245 base-glyph-count to know how to translate back into local glyph space. 246 */ 247 uint16_t charToGlyphID(SkUnichar uni) { 248 return generateCharToGlyph(uni); 249 } 250 251 /** Map the glyphID to its glyph index, and then to its char code. Unmapped 252 glyphs return zero. 253 */ 254 SkUnichar glyphIDToChar(uint16_t glyphID) { 255 return (glyphID < getGlyphCount()) ? generateGlyphToChar(glyphID) : 0; 256 } 257 258 unsigned getGlyphCount() { return this->generateGlyphCount(); } 259 void getAdvance(SkGlyph*); 260 void getMetrics(SkGlyph*); 261 void getImage(const SkGlyph&); 262 void getPath(SkPackedGlyphID, SkPath*); 263 void getFontMetrics(SkPaint::FontMetrics*); 264 265 /** Return the size in bytes of the associated gamma lookup table 266 */ 267 static size_t GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma, 268 int* width, int* height); 269 270 /** Get the associated gamma lookup table. The 'data' pointer must point to pre-allocated 271 * memory, with size in bytes greater than or equal to the return value of getGammaLUTSize(). 272 * 273 * If the lookup table hasn't been initialized (e.g., it's linear), this will return false. 274 */ 275 static bool GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma, 276 uint8_t* data); 277 278 static void MakeRecAndEffects(const SkPaint& paint, 279 const SkSurfaceProps* surfaceProps, 280 const SkMatrix* deviceMatrix, 281 SkScalerContextFlags scalerContextFlags, 282 SkScalerContextRec* rec, 283 SkScalerContextEffects* effects); 284 285 static SkDescriptor* AutoDescriptorGivenRecAndEffects( 286 const SkScalerContextRec& rec, 287 const SkScalerContextEffects& effects, 288 SkAutoDescriptor* ad); 289 290 static std::unique_ptr<SkDescriptor> DescriptorGivenRecAndEffects( 291 const SkScalerContextRec& rec, 292 const SkScalerContextEffects& effects); 293 294 static void DescriptorBufferGiveRec(const SkScalerContextRec& rec, void* buffer); 295 static bool CheckBufferSizeForRec(const SkScalerContextRec& rec, 296 const SkScalerContextEffects& effects, 297 size_t size); 298 299 static SkMaskGamma::PreBlend GetMaskPreBlend(const SkScalerContextRec& rec); 300 301 const SkScalerContextRec& getRec() const { return fRec; } 302 303 SkScalerContextEffects getEffects() const { 304 return { fPathEffect.get(), fMaskFilter.get() }; 305 } 306 307 /** 308 * Return the axis (if any) that the baseline for horizontal text should land on. 309 * As an example, the identity matrix will return kX_SkAxisAlignment 310 */ 311 SkAxisAlignment computeAxisAlignmentForHText(); 312 313 static SkDescriptor* CreateDescriptorAndEffectsUsingPaint( 314 const SkPaint& paint, const SkSurfaceProps* surfaceProps, 315 SkScalerContextFlags scalerContextFlags, 316 const SkMatrix* deviceMatrix, SkAutoDescriptor* ad, 317 SkScalerContextEffects* effects); 318 319 protected: 320 SkScalerContextRec fRec; 321 322 /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY. 323 * May call getMetrics if that would be just as fast. 324 */ 325 virtual void generateAdvance(SkGlyph* glyph) = 0; 326 327 /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft, 328 * as well as fAdvanceX and fAdvanceY if not already set. 329 * 330 * TODO: fMaskFormat is set by getMetrics later; cannot be set here. 331 */ 332 virtual void generateMetrics(SkGlyph* glyph) = 0; 333 334 /** Generates the contents of glyph.fImage. 335 * When called, glyph.fImage will be pointing to a pre-allocated, 336 * uninitialized region of memory of size glyph.computeImageSize(). 337 * This method may change glyph.fMaskFormat if the new image size is 338 * less than or equal to the old image size. 339 * 340 * Because glyph.computeImageSize() will determine the size of fImage, 341 * generateMetrics will be called before generateImage. 342 */ 343 virtual void generateImage(const SkGlyph& glyph) = 0; 344 345 /** Sets the passed path to the glyph outline. 346 * If this cannot be done the path is set to empty; 347 * this is indistinguishable from a glyph with an empty path. 348 */ 349 virtual void generatePath(SkGlyphID glyphId, SkPath* path) = 0; 350 351 /** Retrieves font metrics. */ 352 virtual void generateFontMetrics(SkPaint::FontMetrics*) = 0; 353 354 /** Returns the number of glyphs in the font. */ 355 virtual unsigned generateGlyphCount() = 0; 356 357 /** Returns the glyph id for the given unichar. 358 * If there is no 1:1 mapping from the unichar to a glyph id, returns 0. 359 */ 360 virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0; 361 362 /** Returns the unichar for the given glyph id. 363 * If there is no 1:1 mapping from the glyph id to a unichar, returns 0. 364 * The default implementation always returns 0, indicating failure. 365 */ 366 virtual SkUnichar generateGlyphToChar(uint16_t glyphId); 367 368 void forceGenerateImageFromPath() { fGenerateImageFromPath = true; } 369 void forceOffGenerateImageFromPath() { fGenerateImageFromPath = false; } 370 371 private: 372 friend class SkRandomScalerContext; // For debug purposes 373 374 // never null 375 sk_sp<SkTypeface> fTypeface; 376 377 // optional objects, which may be null 378 sk_sp<SkPathEffect> fPathEffect; 379 sk_sp<SkMaskFilter> fMaskFilter; 380 381 // if this is set, we draw the image from a path, rather than 382 // calling generateImage. 383 bool fGenerateImageFromPath; 384 385 void internalGetPath(SkPackedGlyphID id, SkPath* fillPath, 386 SkPath* devPath, SkMatrix* fillToDevMatrix); 387 388 // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks. 389 protected: 390 // Visible to subclasses so that generateImage can apply the pre-blend directly. 391 const SkMaskGamma::PreBlend fPreBlend; 392 private: 393 // When there is a filter, previous steps must create a linear mask 394 // and the pre-blend applied as a final step. 395 const SkMaskGamma::PreBlend fPreBlendForFilter; 396 }; 397 398 #define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c') 399 #define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e') 400 #define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f') 401 402 /////////////////////////////////////////////////////////////////////////////// 403 404 SkPaint::Hinting SkScalerContextRec::getHinting() const { 405 unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >> 406 SkScalerContext::kHinting_Shift; 407 return static_cast<SkPaint::Hinting>(hint); 408 } 409 410 void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) { 411 fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) | 412 (hinting << SkScalerContext::kHinting_Shift); 413 } 414 415 416 #endif 417
