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 16 #ifdef SK_BUILD_FOR_ANDROID 17 #include "SkLanguage.h" 18 //For SkFontID 19 #include "SkTypeface.h" 20 #endif 21 22 struct SkGlyph; 23 class SkDescriptor; 24 class SkMaskFilter; 25 class SkPathEffect; 26 class SkRasterizer; 27 28 /* 29 * To allow this to be forward-declared, it must be its own typename, rather 30 * than a nested struct inside SkScalerContext (where it started). 31 */ 32 struct SkScalerContextRec { 33 uint32_t fOrigFontID; 34 uint32_t fFontID; 35 SkScalar fTextSize, fPreScaleX, fPreSkewX; 36 SkScalar fPost2x2[2][2]; 37 SkScalar fFrameWidth, fMiterLimit; 38 #ifdef SK_SUPPORT_HINTING_SCALE_FACTOR 39 SkScalar fHintingScaleFactor; 40 #endif 41 #ifdef SK_BUILD_FOR_ANDROID 42 SkLanguage fLanguage; 43 SkPaint::FontVariant fFontVariant; 44 #endif 45 46 //These describe the parameters to create (uniquely identify) the pre-blend. 47 uint32_t fLumBits; 48 uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 49 uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB 50 uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast 51 uint8_t fReservedAlign; 52 53 SkScalar getDeviceGamma() const { 54 return SkIntToScalar(fDeviceGamma) / (1 << 6); 55 } 56 void setDeviceGamma(SkScalar dg) { 57 SkASSERT(0 <= dg && dg < SkIntToScalar(4)); 58 fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6)); 59 } 60 61 SkScalar getPaintGamma() const { 62 return SkIntToScalar(fPaintGamma) / (1 << 6); 63 } 64 void setPaintGamma(SkScalar pg) { 65 SkASSERT(0 <= pg && pg < SkIntToScalar(4)); 66 fPaintGamma = SkScalarFloorToInt(pg * (1 << 6)); 67 } 68 69 SkScalar getContrast() const { 70 return SkIntToScalar(fContrast) / ((1 << 8) - 1); 71 } 72 void setContrast(SkScalar c) { 73 SkASSERT(0 <= c && c <= SK_Scalar1); 74 fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1)); 75 } 76 77 /** 78 * Causes the luminance color and contrast to be ignored, and the 79 * paint and device gamma to be effectively 1.0. 80 */ 81 void ignorePreBlend() { 82 setLuminanceColor(SK_ColorTRANSPARENT); 83 setPaintGamma(SK_Scalar1); 84 setDeviceGamma(SK_Scalar1); 85 setContrast(0); 86 } 87 88 uint8_t fMaskFormat; 89 uint8_t fStrokeJoin; 90 uint16_t fFlags; 91 // Warning: when adding members note that the size of this structure 92 // must be a multiple of 4. SkDescriptor requires that its arguments be 93 // multiples of four and this structure is put in an SkDescriptor in 94 // SkPaint::MakeRec. 95 96 void getMatrixFrom2x2(SkMatrix*) const; 97 void getLocalMatrix(SkMatrix*) const; 98 void getSingleMatrix(SkMatrix*) const; 99 100 inline SkPaint::Hinting getHinting() const; 101 inline void setHinting(SkPaint::Hinting); 102 103 SkMask::Format getFormat() const { 104 return static_cast<SkMask::Format>(fMaskFormat); 105 } 106 107 SkColor getLuminanceColor() const { 108 return fLumBits; 109 } 110 111 void setLuminanceColor(SkColor c) { 112 fLumBits = c; 113 } 114 }; 115 116 //The following typedef hides from the rest of the implementation the number of 117 //most significant bits to consider when creating mask gamma tables. Two bits 118 //per channel was chosen as a balance between fidelity (more bits) and cache 119 //sizes (fewer bits). Three bits per channel was chosen when #303942; (used by 120 //the Chrome UI) turned out too green. 121 typedef SkTMaskGamma<3, 3, 3> SkMaskGamma; 122 123 class SkScalerContext { 124 public: 125 typedef SkScalerContextRec Rec; 126 127 enum Flags { 128 kFrameAndFill_Flag = 0x0001, 129 kDevKernText_Flag = 0x0002, 130 kEmbeddedBitmapText_Flag = 0x0004, 131 kEmbolden_Flag = 0x0008, 132 kSubpixelPositioning_Flag = 0x0010, 133 kAutohinting_Flag = 0x0020, 134 kVertical_Flag = 0x0040, 135 136 // together, these two flags resulting in a two bit value which matches 137 // up with the SkPaint::Hinting enum. 138 kHinting_Shift = 7, // to shift into the other flags above 139 kHintingBit1_Flag = 0x0080, 140 kHintingBit2_Flag = 0x0100, 141 142 // these should only ever be set if fMaskFormat is LCD16 or LCD32 143 kLCD_Vertical_Flag = 0x0200, // else Horizontal 144 kLCD_BGROrder_Flag = 0x0400, // else RGB order 145 146 // Generate A8 from LCD source (for GDI), only meaningful if fMaskFormat is kA8 147 // Perhaps we can store this (instead) in fMaskFormat, in hight bit? 148 kGenA8FromLCD_Flag = 0x0800, 149 }; 150 151 // computed values 152 enum { 153 kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag, 154 }; 155 156 157 SkScalerContext(const SkDescriptor* desc); 158 virtual ~SkScalerContext(); 159 160 SkMask::Format getMaskFormat() const { 161 return (SkMask::Format)fRec.fMaskFormat; 162 } 163 164 bool isSubpixel() const { 165 return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag); 166 } 167 168 // remember our glyph offset/base 169 void setBaseGlyphCount(unsigned baseGlyphCount) { 170 fBaseGlyphCount = baseGlyphCount; 171 } 172 173 /** Return the corresponding glyph for the specified unichar. Since contexts 174 may be chained (under the hood), the glyphID that is returned may in 175 fact correspond to a different font/context. In that case, we use the 176 base-glyph-count to know how to translate back into local glyph space. 177 */ 178 uint16_t charToGlyphID(SkUnichar uni); 179 180 /** Map the glyphID to its glyph index, and then to its char code. Unmapped 181 glyphs return zero. 182 */ 183 SkUnichar glyphIDToChar(uint16_t glyphID); 184 185 unsigned getGlyphCount() { return this->generateGlyphCount(); } 186 void getAdvance(SkGlyph*); 187 void getMetrics(SkGlyph*); 188 void getImage(const SkGlyph&); 189 void getPath(const SkGlyph&, SkPath*); 190 void getFontMetrics(SkPaint::FontMetrics* mX, 191 SkPaint::FontMetrics* mY); 192 193 #ifdef SK_BUILD_FOR_ANDROID 194 unsigned getBaseGlyphCount(SkUnichar charCode); 195 196 // This function must be public for SkTypeface_android.h, but should not be 197 // called by other callers 198 SkFontID findTypefaceIdForChar(SkUnichar uni); 199 #endif 200 201 static inline void MakeRec(const SkPaint&, const SkDeviceProperties* deviceProperties, 202 const SkMatrix*, Rec* rec); 203 static inline void PostMakeRec(const SkPaint&, Rec*); 204 205 static SkScalerContext* Create(const SkDescriptor*); 206 static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec); 207 208 protected: 209 Rec fRec; 210 unsigned fBaseGlyphCount; 211 212 virtual unsigned generateGlyphCount() = 0; 213 virtual uint16_t generateCharToGlyph(SkUnichar) = 0; 214 virtual void generateAdvance(SkGlyph*) = 0; 215 virtual void generateMetrics(SkGlyph*) = 0; 216 virtual void generateImage(const SkGlyph&) = 0; 217 virtual void generatePath(const SkGlyph&, SkPath*) = 0; 218 virtual void generateFontMetrics(SkPaint::FontMetrics* mX, 219 SkPaint::FontMetrics* mY) = 0; 220 // default impl returns 0, indicating failure. 221 virtual SkUnichar generateGlyphToChar(uint16_t); 222 223 void forceGenerateImageFromPath() { fGenerateImageFromPath = true; } 224 225 private: 226 SkScalerContext* getContextFromChar(SkUnichar uni, unsigned& glyphID); 227 228 SkPathEffect* fPathEffect; 229 SkMaskFilter* fMaskFilter; 230 SkRasterizer* fRasterizer; 231 232 // if this is set, we draw the image from a path, rather than 233 // calling generateImage. 234 bool fGenerateImageFromPath; 235 236 void internalGetPath(const SkGlyph& glyph, SkPath* fillPath, 237 SkPath* devPath, SkMatrix* fillToDevMatrix); 238 239 // return the next context, treating fNextContext as a cache of the answer 240 SkScalerContext* getNextContext(); 241 242 // returns the right context from our link-list for this glyph. If no match 243 // is found, just returns the original context (this) 244 SkScalerContext* getGlyphContext(const SkGlyph& glyph); 245 246 // link-list of context, to handle missing chars. null-terminated. 247 SkScalerContext* fNextContext; 248 249 // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks. 250 protected: 251 // Visible to subclasses so that generateImage can apply the pre-blend directly. 252 const SkMaskGamma::PreBlend fPreBlend; 253 private: 254 // When there is a filter, previous steps must create a linear mask 255 // and the pre-blend applied as a final step. 256 const SkMaskGamma::PreBlend fPreBlendForFilter; 257 }; 258 259 #define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c') 260 #define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e') 261 #define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f') 262 #define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't') 263 264 /////////////////////////////////////////////////////////////////////////////// 265 266 enum SkAxisAlignment { 267 kNone_SkAxisAlignment, 268 kX_SkAxisAlignment, 269 kY_SkAxisAlignment 270 }; 271 272 /** 273 * Return the axis (if any) that the baseline for horizontal text will land on 274 * after running through the specified matrix. 275 * 276 * As an example, the identity matrix will return kX_SkAxisAlignment 277 */ 278 SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix); 279 280 /////////////////////////////////////////////////////////////////////////////// 281 282 SkPaint::Hinting SkScalerContextRec::getHinting() const { 283 unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >> 284 SkScalerContext::kHinting_Shift; 285 return static_cast<SkPaint::Hinting>(hint); 286 } 287 288 void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) { 289 fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) | 290 (hinting << SkScalerContext::kHinting_Shift); 291 } 292 293 294 #endif 295
