SkScalerContext.h revision 2d2a68c51b4a71bd60760510bf2b2e58bc9890b2
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#ifdef SK_BUILD_FOR_ANDROID 18 #include "SkPaintOptionsAndroid.h" 19#endif 20 21struct SkGlyph; 22class SkDescriptor; 23class SkMaskFilter; 24class SkPathEffect; 25class SkRasterizer; 26 27/* 28 * To allow this to be forward-declared, it must be its own typename, rather 29 * than a nested struct inside SkScalerContext (where it started). 30 */ 31struct SkScalerContextRec { 32 uint32_t fOrigFontID; 33 uint32_t fFontID; 34 SkScalar fTextSize, fPreScaleX, fPreSkewX; 35 SkScalar fPost2x2[2][2]; 36 SkScalar fFrameWidth, fMiterLimit; 37 38 //These describe the parameters to create (uniquely identify) the pre-blend. 39 uint32_t fLumBits; 40 uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 41 uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 42 uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast 43 uint8_t fReservedAlign; 44 45 SkScalar getDeviceGamma() const { 46 return SkIntToScalar(fDeviceGamma) / (1 << 6); 47 } 48 void setDeviceGamma(SkScalar dg) { 49 SkASSERT(0 <= dg && dg < SkIntToScalar(4)); 50 fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6)); 51 } 52 53 SkScalar getPaintGamma() const { 54 return SkIntToScalar(fPaintGamma) / (1 << 6); 55 } 56 void setPaintGamma(SkScalar pg) { 57 SkASSERT(0 <= pg && pg < SkIntToScalar(4)); 58 fPaintGamma = SkScalarFloorToInt(pg * (1 << 6)); 59 } 60 61 SkScalar getContrast() const { 62 return SkIntToScalar(fContrast) / ((1 << 8) - 1); 63 } 64 void setContrast(SkScalar c) { 65 SkASSERT(0 <= c && c <= SK_Scalar1); 66 fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1)); 67 } 68 69 /** 70 * Causes the luminance color and contrast to be ignored, and the 71 * paint and device gamma to be effectively 1.0. 72 */ 73 void ignorePreBlend() { 74 setLuminanceColor(SK_ColorTRANSPARENT); 75 setPaintGamma(SK_Scalar1); 76 setDeviceGamma(SK_Scalar1); 77 setContrast(0); 78 } 79 80 uint8_t fMaskFormat; 81 uint8_t fStrokeJoin; 82 uint16_t fFlags; 83 // Warning: when adding members note that the size of this structure 84 // must be a multiple of 4. SkDescriptor requires that its arguments be 85 // multiples of four and this structure is put in an SkDescriptor in 86 // SkPaint::MakeRec. 87 88 void getMatrixFrom2x2(SkMatrix*) const; 89 void getLocalMatrix(SkMatrix*) const; 90 void getSingleMatrix(SkMatrix*) const; 91 92 inline SkPaint::Hinting getHinting() const; 93 inline void setHinting(SkPaint::Hinting); 94 95 SkMask::Format getFormat() const { 96 return static_cast<SkMask::Format>(fMaskFormat); 97 } 98 99 SkColor getLuminanceColor() const { 100 return fLumBits; 101 } 102 103 void setLuminanceColor(SkColor c) { 104 fLumBits = c; 105 } 106}; 107 108//The following typedef hides from the rest of the implementation the number of 109//most significant bits to consider when creating mask gamma tables. Two bits 110//per channel was chosen as a balance between fidelity (more bits) and cache 111//sizes (fewer bits). Three bits per channel was chosen when #303942; (used by 112//the Chrome UI) turned out too green. 113typedef SkTMaskGamma<3, 3, 3> SkMaskGamma; 114 115class SkScalerContext { 116public: 117 typedef SkScalerContextRec Rec; 118 119 enum Flags { 120 kFrameAndFill_Flag = 0x0001, 121 kDevKernText_Flag = 0x0002, 122 kEmbeddedBitmapText_Flag = 0x0004, 123 kEmbolden_Flag = 0x0008, 124 kSubpixelPositioning_Flag = 0x0010, 125 kForceAutohinting_Flag = 0x0020, // Use auto instead of bytcode hinting if hinting. 126 kVertical_Flag = 0x0040, 127 128 // together, these two flags resulting in a two bit value which matches 129 // up with the SkPaint::Hinting enum. 130 kHinting_Shift = 7, // to shift into the other flags above 131 kHintingBit1_Flag = 0x0080, 132 kHintingBit2_Flag = 0x0100, 133 134 // Pixel geometry information. 135 // only meaningful if fMaskFormat is LCD16 or LCD32 136 kLCD_Vertical_Flag = 0x0200, // else Horizontal 137 kLCD_BGROrder_Flag = 0x0400, // else RGB order 138 139 // Generate A8 from LCD source (for GDI and CoreGraphics). 140 // only meaningful if fMaskFormat is kA8 141 kGenA8FromLCD_Flag = 0x0800, // could be 0x200 (bit meaning dependent on fMaskFormat) 142 }; 143 144 // computed values 145 enum { 146 kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag, 147 }; 148 149 150 SkScalerContext(SkTypeface*, const SkDescriptor*); 151 virtual ~SkScalerContext(); 152 153 SkTypeface* getTypeface() const { return fTypeface.get(); } 154 155 SkMask::Format getMaskFormat() const { 156 return (SkMask::Format)fRec.fMaskFormat; 157 } 158 159 bool isSubpixel() const { 160 return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag); 161 } 162 163 // remember our glyph offset/base 164 void setBaseGlyphCount(unsigned baseGlyphCount) { 165 fBaseGlyphCount = baseGlyphCount; 166 } 167 168 /** Return the corresponding glyph for the specified unichar. Since contexts 169 may be chained (under the hood), the glyphID that is returned may in 170 fact correspond to a different font/context. In that case, we use the 171 base-glyph-count to know how to translate back into local glyph space. 172 */ 173 uint16_t charToGlyphID(SkUnichar uni); 174 175 /** Map the glyphID to its glyph index, and then to its char code. Unmapped 176 glyphs return zero. 177 */ 178 SkUnichar glyphIDToChar(uint16_t glyphID); 179 180 unsigned getGlyphCount() { return this->generateGlyphCount(); } 181 void getAdvance(SkGlyph*); 182 void getMetrics(SkGlyph*); 183 void getImage(const SkGlyph&); 184 void getPath(const SkGlyph&, SkPath*); 185 void getFontMetrics(SkPaint::FontMetrics*); 186 187 /** Return the size in bytes of the associated gamma lookup table 188 */ 189 static size_t GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma, 190 int* width, int* height); 191 192 /** Get the associated gamma lookup table. The 'data' pointer must point to pre-allocated 193 memory, with size in bytes greater than or equal to the return value of getGammaLUTSize(). 194 */ 195 static void GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma, 196 void* data); 197 198#ifdef SK_BUILD_FOR_ANDROID 199 unsigned getBaseGlyphCount(SkUnichar charCode); 200 201 // This function must be public for SkTypeface_android.h, but should not be 202 // called by other callers 203 SkFontID findTypefaceIdForChar(SkUnichar uni); 204#endif 205 206 static void MakeRec(const SkPaint&, const SkDeviceProperties* deviceProperties, 207 const SkMatrix*, Rec* rec); 208 static inline void PostMakeRec(const SkPaint&, Rec*); 209 210 static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec); 211 212protected: 213 Rec fRec; 214 unsigned fBaseGlyphCount; 215 216 /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY. 217 * May call getMetrics if that would be just as fast. 218 */ 219 virtual void generateAdvance(SkGlyph* glyph) = 0; 220 221 /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft, 222 * as well as fAdvanceX and fAdvanceY if not already set. 223 * 224 * TODO: fMaskFormat is set by getMetrics later; cannot be set here. 225 */ 226 virtual void generateMetrics(SkGlyph* glyph) = 0; 227 228 /** Generates the contents of glyph.fImage. 229 * When called, glyph.fImage will be pointing to a pre-allocated, 230 * uninitialized region of memory of size glyph.computeImageSize(). 231 * This method may change glyph.fMaskFormat if the new image size is 232 * less than or equal to the old image size. 233 * 234 * Because glyph.computeImageSize() will determine the size of fImage, 235 * generateMetrics will be called before generateImage. 236 */ 237 virtual void generateImage(const SkGlyph& glyph) = 0; 238 239 /** Sets the passed path to the glyph outline. 240 * If this cannot be done the path is set to empty; 241 * this is indistinguishable from a glyph with an empty path. 242 * This does not set glyph.fPath. 243 * 244 * TODO: path is always glyph.fPath, no reason to pass separately. 245 */ 246 virtual void generatePath(const SkGlyph& glyph, SkPath* path) = 0; 247 248 /** Retrieves font metrics. 249 * TODO: there is now a vertical bit, no need for two parameters. 250 */ 251 virtual void generateFontMetrics(SkPaint::FontMetrics* mX, 252 SkPaint::FontMetrics* mY) = 0; 253 254 /** Returns the number of glyphs in the font. */ 255 virtual unsigned generateGlyphCount() = 0; 256 257 /** Returns the glyph id for the given unichar. 258 * If there is no 1:1 mapping from the unichar to a glyph id, returns 0. 259 */ 260 virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0; 261 262 /** Returns the unichar for the given glyph id. 263 * If there is no 1:1 mapping from the glyph id to a unichar, returns 0. 264 * The default implementation always returns 0, indicating failure. 265 */ 266 virtual SkUnichar generateGlyphToChar(uint16_t glyphId); 267 268 void forceGenerateImageFromPath() { fGenerateImageFromPath = true; } 269 270private: 271 // never null 272 SkAutoTUnref<SkTypeface> fTypeface; 273 274#ifdef SK_BUILD_FOR_ANDROID 275 SkPaintOptionsAndroid fPaintOptionsAndroid; 276#endif 277 278 // optional object, which may be null 279 SkPathEffect* fPathEffect; 280 SkMaskFilter* fMaskFilter; 281 SkRasterizer* fRasterizer; 282 283 // if this is set, we draw the image from a path, rather than 284 // calling generateImage. 285 bool fGenerateImageFromPath; 286 287 void internalGetPath(const SkGlyph& glyph, SkPath* fillPath, 288 SkPath* devPath, SkMatrix* fillToDevMatrix); 289 290 // Return the context associated with the next logical typeface, or NULL if 291 // there are no more entries in the fallback chain. 292 SkScalerContext* allocNextContext() const; 293 294 // return the next context, treating fNextContext as a cache of the answer 295 SkScalerContext* getNextContext(); 296 297 // returns the right context from our link-list for this glyph. If no match 298 // is found, just returns the original context (this) 299 SkScalerContext* getGlyphContext(const SkGlyph& glyph); 300 301 // returns the right context from our link-list for this char. If no match 302 // is found it returns NULL. If a match is found then the glyphID param is 303 // set to the glyphID that maps to the provided char. 304 SkScalerContext* getContextFromChar(SkUnichar uni, uint16_t* glyphID); 305 306 // link-list of context, to handle missing chars. null-terminated. 307 SkScalerContext* fNextContext; 308 309 // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks. 310protected: 311 // Visible to subclasses so that generateImage can apply the pre-blend directly. 312 const SkMaskGamma::PreBlend fPreBlend; 313private: 314 // When there is a filter, previous steps must create a linear mask 315 // and the pre-blend applied as a final step. 316 const SkMaskGamma::PreBlend fPreBlendForFilter; 317}; 318 319#define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c') 320#define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e') 321#define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f') 322#define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't') 323#ifdef SK_BUILD_FOR_ANDROID 324#define kAndroidOpts_SkDescriptorTag SkSetFourByteTag('a', 'n', 'd', 'r') 325#endif 326 327/////////////////////////////////////////////////////////////////////////////// 328 329enum SkAxisAlignment { 330 kNone_SkAxisAlignment, 331 kX_SkAxisAlignment, 332 kY_SkAxisAlignment 333}; 334 335/** 336 * Return the axis (if any) that the baseline for horizontal text will land on 337 * after running through the specified matrix. 338 * 339 * As an example, the identity matrix will return kX_SkAxisAlignment 340 */ 341SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix); 342 343/////////////////////////////////////////////////////////////////////////////// 344 345SkPaint::Hinting SkScalerContextRec::getHinting() const { 346 unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >> 347 SkScalerContext::kHinting_Shift; 348 return static_cast<SkPaint::Hinting>(hint); 349} 350 351void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) { 352 fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) | 353 (hinting << SkScalerContext::kHinting_Shift); 354} 355 356 357#endif 358