2 * Copyright 2006 The Android Open Source Project
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
8 #ifndef SkScalerContext_DEFINED
9 #define SkScalerContext_DEFINED
12 #include "SkMaskGamma.h"
15 #include "SkTypeface.h"
17 #ifdef SK_BUILD_FOR_ANDROID
18 #include "SkPaintOptionsAndroid.h"
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).
31 struct SkScalerContextRec {
34 SkScalar fTextSize, fPreScaleX, fPreSkewX;
35 SkScalar fPost2x2[2][2];
36 SkScalar fFrameWidth, fMiterLimit;
38 //These describe the parameters to create (uniquely identify) the pre-blend.
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;
45 SkScalar getDeviceGamma() const {
46 return SkIntToScalar(fDeviceGamma) / (1 << 6);
48 void setDeviceGamma(SkScalar dg) {
49 SkASSERT(0 <= dg && dg < SkIntToScalar(4));
50 fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6));
53 SkScalar getPaintGamma() const {
54 return SkIntToScalar(fPaintGamma) / (1 << 6);
56 void setPaintGamma(SkScalar pg) {
57 SkASSERT(0 <= pg && pg < SkIntToScalar(4));
58 fPaintGamma = SkScalarFloorToInt(pg * (1 << 6));
61 SkScalar getContrast() const {
62 return SkIntToScalar(fContrast) / ((1 << 8) - 1);
64 void setContrast(SkScalar c) {
65 SkASSERT(0 <= c && c <= SK_Scalar1);
66 fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1));
70 * Causes the luminance color and contrast to be ignored, and the
71 * paint and device gamma to be effectively 1.0.
73 void ignorePreBlend() {
74 setLuminanceColor(SK_ColorTRANSPARENT);
75 setPaintGamma(SK_Scalar1);
76 setDeviceGamma(SK_Scalar1);
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
88 void getMatrixFrom2x2(SkMatrix*) const;
89 void getLocalMatrix(SkMatrix*) const;
90 void getSingleMatrix(SkMatrix*) const;
92 inline SkPaint::Hinting getHinting() const;
93 inline void setHinting(SkPaint::Hinting);
95 SkMask::Format getFormat() const {
96 return static_cast<SkMask::Format>(fMaskFormat);
99 SkColor getLuminanceColor() const {
103 void setLuminanceColor(SkColor c) {
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.
113 typedef SkTMaskGamma<3, 3, 3> SkMaskGamma;
115 class SkScalerContext {
117 typedef SkScalerContextRec Rec;
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,
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,
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
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)
146 kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag,
150 SkScalerContext(SkTypeface*, const SkDescriptor*);
151 virtual ~SkScalerContext();
153 SkTypeface* getTypeface() const { return fTypeface.get(); }
155 SkMask::Format getMaskFormat() const {
156 return (SkMask::Format)fRec.fMaskFormat;
159 bool isSubpixel() const {
160 return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
163 // remember our glyph offset/base
164 void setBaseGlyphCount(unsigned baseGlyphCount) {
165 fBaseGlyphCount = baseGlyphCount;
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.
173 uint16_t charToGlyphID(SkUnichar uni);
175 /** Map the glyphID to its glyph index, and then to its char code. Unmapped
178 SkUnichar glyphIDToChar(uint16_t glyphID);
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*);
187 #ifdef SK_BUILD_FOR_ANDROID
188 unsigned getBaseGlyphCount(SkUnichar charCode);
190 // This function must be public for SkTypeface_android.h, but should not be
191 // called by other callers
192 SkFontID findTypefaceIdForChar(SkUnichar uni);
195 static void MakeRec(const SkPaint&, const SkDeviceProperties* deviceProperties,
196 const SkMatrix*, Rec* rec);
197 static inline void PostMakeRec(const SkPaint&, Rec*);
199 static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec);
203 unsigned fBaseGlyphCount;
205 /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY.
206 * May call getMetrics if that would be just as fast.
208 virtual void generateAdvance(SkGlyph* glyph) = 0;
210 /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft,
211 * as well as fAdvanceX and fAdvanceY if not already set.
213 * TODO: fMaskFormat is set by getMetrics later; cannot be set here.
215 virtual void generateMetrics(SkGlyph* glyph) = 0;
217 /** Generates the contents of glyph.fImage.
218 * When called, glyph.fImage will be pointing to a pre-allocated,
219 * uninitialized region of memory of size glyph.computeImageSize().
220 * This method may change glyph.fMaskFormat if the new image size is
221 * less than or equal to the old image size.
223 * Because glyph.computeImageSize() will determine the size of fImage,
224 * generateMetrics will be called before generateImage.
226 virtual void generateImage(const SkGlyph& glyph) = 0;
228 /** Sets the passed path to the glyph outline.
229 * If this cannot be done the path is set to empty;
230 * this is indistinguishable from a glyph with an empty path.
231 * This does not set glyph.fPath.
233 * TODO: path is always glyph.fPath, no reason to pass separately.
235 virtual void generatePath(const SkGlyph& glyph, SkPath* path) = 0;
237 /** Retrieves font metrics.
238 * TODO: there is now a vertical bit, no need for two parameters.
240 virtual void generateFontMetrics(SkPaint::FontMetrics* mX,
241 SkPaint::FontMetrics* mY) = 0;
243 /** Returns the number of glyphs in the font. */
244 virtual unsigned generateGlyphCount() = 0;
246 /** Returns the glyph id for the given unichar.
247 * If there is no 1:1 mapping from the unichar to a glyph id, returns 0.
249 virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0;
251 /** Returns the unichar for the given glyph id.
252 * If there is no 1:1 mapping from the glyph id to a unichar, returns 0.
253 * The default implementation always returns 0, indicating failure.
255 virtual SkUnichar generateGlyphToChar(uint16_t glyphId);
257 void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }
261 SkAutoTUnref<SkTypeface> fTypeface;
263 #ifdef SK_BUILD_FOR_ANDROID
264 SkPaintOptionsAndroid fPaintOptionsAndroid;
267 // optional object, which may be null
268 SkPathEffect* fPathEffect;
269 SkMaskFilter* fMaskFilter;
270 SkRasterizer* fRasterizer;
272 // if this is set, we draw the image from a path, rather than
273 // calling generateImage.
274 bool fGenerateImageFromPath;
276 void internalGetPath(const SkGlyph& glyph, SkPath* fillPath,
277 SkPath* devPath, SkMatrix* fillToDevMatrix);
279 // Return the context associated with the next logical typeface, or NULL if
280 // there are no more entries in the fallback chain.
281 SkScalerContext* allocNextContext() const;
283 // return the next context, treating fNextContext as a cache of the answer
284 SkScalerContext* getNextContext();
286 // returns the right context from our link-list for this glyph. If no match
287 // is found, just returns the original context (this)
288 SkScalerContext* getGlyphContext(const SkGlyph& glyph);
290 // returns the right context from our link-list for this char. If no match
291 // is found it returns NULL. If a match is found then the glyphID param is
292 // set to the glyphID that maps to the provided char.
293 SkScalerContext* getContextFromChar(SkUnichar uni, uint16_t* glyphID);
295 // link-list of context, to handle missing chars. null-terminated.
296 SkScalerContext* fNextContext;
298 // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks.
300 // Visible to subclasses so that generateImage can apply the pre-blend directly.
301 const SkMaskGamma::PreBlend fPreBlend;
303 // When there is a filter, previous steps must create a linear mask
304 // and the pre-blend applied as a final step.
305 const SkMaskGamma::PreBlend fPreBlendForFilter;
308 #define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c')
309 #define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e')
310 #define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f')
311 #define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't')
312 #ifdef SK_BUILD_FOR_ANDROID
313 #define kAndroidOpts_SkDescriptorTag SkSetFourByteTag('a', 'n', 'd', 'r')
316 ///////////////////////////////////////////////////////////////////////////////
318 enum SkAxisAlignment {
319 kNone_SkAxisAlignment,
325 * Return the axis (if any) that the baseline for horizontal text will land on
326 * after running through the specified matrix.
328 * As an example, the identity matrix will return kX_SkAxisAlignment
330 SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix);
332 ///////////////////////////////////////////////////////////////////////////////
334 SkPaint::Hinting SkScalerContextRec::getHinting() const {
335 unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >>
336 SkScalerContext::kHinting_Shift;
337 return static_cast<SkPaint::Hinting>(hint);
340 void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) {
341 fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) |
342 (hinting << SkScalerContext::kHinting_Shift);