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