diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/core/SkScalerContext.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gfx/skia/trunk/src/core/SkScalerContext.h Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,346 @@ +/* + * Copyright 2006 The Android Open Source Project + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#ifndef SkScalerContext_DEFINED +#define SkScalerContext_DEFINED + +#include "SkMask.h" +#include "SkMaskGamma.h" +#include "SkMatrix.h" +#include "SkPaint.h" +#include "SkTypeface.h" + +#ifdef SK_BUILD_FOR_ANDROID + #include "SkPaintOptionsAndroid.h" +#endif + +struct SkGlyph; +class SkDescriptor; +class SkMaskFilter; +class SkPathEffect; +class SkRasterizer; + +/* + * To allow this to be forward-declared, it must be its own typename, rather + * than a nested struct inside SkScalerContext (where it started). + */ +struct SkScalerContextRec { + uint32_t fOrigFontID; + uint32_t fFontID; + SkScalar fTextSize, fPreScaleX, fPreSkewX; + SkScalar fPost2x2[2][2]; + SkScalar fFrameWidth, fMiterLimit; + + //These describe the parameters to create (uniquely identify) the pre-blend. + uint32_t fLumBits; + uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB + uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB + uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast + uint8_t fReservedAlign; + + SkScalar getDeviceGamma() const { + return SkIntToScalar(fDeviceGamma) / (1 << 6); + } + void setDeviceGamma(SkScalar dg) { + SkASSERT(0 <= dg && dg < SkIntToScalar(4)); + fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6)); + } + + SkScalar getPaintGamma() const { + return SkIntToScalar(fPaintGamma) / (1 << 6); + } + void setPaintGamma(SkScalar pg) { + SkASSERT(0 <= pg && pg < SkIntToScalar(4)); + fPaintGamma = SkScalarFloorToInt(pg * (1 << 6)); + } + + SkScalar getContrast() const { + return SkIntToScalar(fContrast) / ((1 << 8) - 1); + } + void setContrast(SkScalar c) { + SkASSERT(0 <= c && c <= SK_Scalar1); + fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1)); + } + + /** + * Causes the luminance color and contrast to be ignored, and the + * paint and device gamma to be effectively 1.0. + */ + void ignorePreBlend() { + setLuminanceColor(SK_ColorTRANSPARENT); + setPaintGamma(SK_Scalar1); + setDeviceGamma(SK_Scalar1); + setContrast(0); + } + + uint8_t fMaskFormat; + uint8_t fStrokeJoin; + uint16_t fFlags; + // Warning: when adding members note that the size of this structure + // must be a multiple of 4. SkDescriptor requires that its arguments be + // multiples of four and this structure is put in an SkDescriptor in + // SkPaint::MakeRec. + + void getMatrixFrom2x2(SkMatrix*) const; + void getLocalMatrix(SkMatrix*) const; + void getSingleMatrix(SkMatrix*) const; + + inline SkPaint::Hinting getHinting() const; + inline void setHinting(SkPaint::Hinting); + + SkMask::Format getFormat() const { + return static_cast(fMaskFormat); + } + + SkColor getLuminanceColor() const { + return fLumBits; + } + + void setLuminanceColor(SkColor c) { + fLumBits = c; + } +}; + +//The following typedef hides from the rest of the implementation the number of +//most significant bits to consider when creating mask gamma tables. Two bits +//per channel was chosen as a balance between fidelity (more bits) and cache +//sizes (fewer bits). Three bits per channel was chosen when #303942; (used by +//the Chrome UI) turned out too green. +typedef SkTMaskGamma<3, 3, 3> SkMaskGamma; + +class SkScalerContext { +public: + typedef SkScalerContextRec Rec; + + enum Flags { + kFrameAndFill_Flag = 0x0001, + kDevKernText_Flag = 0x0002, + kEmbeddedBitmapText_Flag = 0x0004, + kEmbolden_Flag = 0x0008, + kSubpixelPositioning_Flag = 0x0010, + kForceAutohinting_Flag = 0x0020, // Use auto instead of bytcode hinting if hinting. + kVertical_Flag = 0x0040, + + // together, these two flags resulting in a two bit value which matches + // up with the SkPaint::Hinting enum. + kHinting_Shift = 7, // to shift into the other flags above + kHintingBit1_Flag = 0x0080, + kHintingBit2_Flag = 0x0100, + + // Pixel geometry information. + // only meaningful if fMaskFormat is LCD16 or LCD32 + kLCD_Vertical_Flag = 0x0200, // else Horizontal + kLCD_BGROrder_Flag = 0x0400, // else RGB order + + // Generate A8 from LCD source (for GDI and CoreGraphics). + // only meaningful if fMaskFormat is kA8 + kGenA8FromLCD_Flag = 0x0800, // could be 0x200 (bit meaning dependent on fMaskFormat) + }; + + // computed values + enum { + kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag, + }; + + + SkScalerContext(SkTypeface*, const SkDescriptor*); + virtual ~SkScalerContext(); + + SkTypeface* getTypeface() const { return fTypeface.get(); } + + SkMask::Format getMaskFormat() const { + return (SkMask::Format)fRec.fMaskFormat; + } + + bool isSubpixel() const { + return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag); + } + + // remember our glyph offset/base + void setBaseGlyphCount(unsigned baseGlyphCount) { + fBaseGlyphCount = baseGlyphCount; + } + + /** Return the corresponding glyph for the specified unichar. Since contexts + may be chained (under the hood), the glyphID that is returned may in + fact correspond to a different font/context. In that case, we use the + base-glyph-count to know how to translate back into local glyph space. + */ + uint16_t charToGlyphID(SkUnichar uni); + + /** Map the glyphID to its glyph index, and then to its char code. Unmapped + glyphs return zero. + */ + SkUnichar glyphIDToChar(uint16_t glyphID); + + unsigned getGlyphCount() { return this->generateGlyphCount(); } + void getAdvance(SkGlyph*); + void getMetrics(SkGlyph*); + void getImage(const SkGlyph&); + void getPath(const SkGlyph&, SkPath*); + void getFontMetrics(SkPaint::FontMetrics*); + +#ifdef SK_BUILD_FOR_ANDROID + unsigned getBaseGlyphCount(SkUnichar charCode); + + // This function must be public for SkTypeface_android.h, but should not be + // called by other callers + SkFontID findTypefaceIdForChar(SkUnichar uni); +#endif + + static inline void MakeRec(const SkPaint&, const SkDeviceProperties* deviceProperties, + const SkMatrix*, Rec* rec); + static inline void PostMakeRec(const SkPaint&, Rec*); + + static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec); + +protected: + Rec fRec; + unsigned fBaseGlyphCount; + + /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY. + * May call getMetrics if that would be just as fast. + */ + virtual void generateAdvance(SkGlyph* glyph) = 0; + + /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft, + * as well as fAdvanceX and fAdvanceY if not already set. + * + * TODO: fMaskFormat is set by getMetrics later; cannot be set here. + */ + virtual void generateMetrics(SkGlyph* glyph) = 0; + + /** Generates the contents of glyph.fImage. + * When called, glyph.fImage will be pointing to a pre-allocated, + * uninitialized region of memory of size glyph.computeImageSize(). + * This method may change glyph.fMaskFormat if the new image size is + * less than or equal to the old image size. + * + * Because glyph.computeImageSize() will determine the size of fImage, + * generateMetrics will be called before generateImage. + */ + virtual void generateImage(const SkGlyph& glyph) = 0; + + /** Sets the passed path to the glyph outline. + * If this cannot be done the path is set to empty; + * this is indistinguishable from a glyph with an empty path. + * This does not set glyph.fPath. + * + * TODO: path is always glyph.fPath, no reason to pass separately. + */ + virtual void generatePath(const SkGlyph& glyph, SkPath* path) = 0; + + /** Retrieves font metrics. + * TODO: there is now a vertical bit, no need for two parameters. + */ + virtual void generateFontMetrics(SkPaint::FontMetrics* mX, + SkPaint::FontMetrics* mY) = 0; + + /** Returns the number of glyphs in the font. */ + virtual unsigned generateGlyphCount() = 0; + + /** Returns the glyph id for the given unichar. + * If there is no 1:1 mapping from the unichar to a glyph id, returns 0. + */ + virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0; + + /** Returns the unichar for the given glyph id. + * If there is no 1:1 mapping from the glyph id to a unichar, returns 0. + * The default implementation always returns 0, indicating failure. + */ + virtual SkUnichar generateGlyphToChar(uint16_t glyphId); + + void forceGenerateImageFromPath() { fGenerateImageFromPath = true; } + +private: + // never null + SkAutoTUnref fTypeface; + +#ifdef SK_BUILD_FOR_ANDROID + SkPaintOptionsAndroid fPaintOptionsAndroid; +#endif + + // optional object, which may be null + SkPathEffect* fPathEffect; + SkMaskFilter* fMaskFilter; + SkRasterizer* fRasterizer; + + // if this is set, we draw the image from a path, rather than + // calling generateImage. + bool fGenerateImageFromPath; + + void internalGetPath(const SkGlyph& glyph, SkPath* fillPath, + SkPath* devPath, SkMatrix* fillToDevMatrix); + + // Return the context associated with the next logical typeface, or NULL if + // there are no more entries in the fallback chain. + SkScalerContext* allocNextContext() const; + + // return the next context, treating fNextContext as a cache of the answer + SkScalerContext* getNextContext(); + + // returns the right context from our link-list for this glyph. If no match + // is found, just returns the original context (this) + SkScalerContext* getGlyphContext(const SkGlyph& glyph); + + // returns the right context from our link-list for this char. If no match + // is found it returns NULL. If a match is found then the glyphID param is + // set to the glyphID that maps to the provided char. + SkScalerContext* getContextFromChar(SkUnichar uni, uint16_t* glyphID); + + // link-list of context, to handle missing chars. null-terminated. + SkScalerContext* fNextContext; + + // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks. +protected: + // Visible to subclasses so that generateImage can apply the pre-blend directly. + const SkMaskGamma::PreBlend fPreBlend; +private: + // When there is a filter, previous steps must create a linear mask + // and the pre-blend applied as a final step. + const SkMaskGamma::PreBlend fPreBlendForFilter; +}; + +#define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c') +#define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e') +#define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f') +#define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't') +#ifdef SK_BUILD_FOR_ANDROID +#define kAndroidOpts_SkDescriptorTag SkSetFourByteTag('a', 'n', 'd', 'r') +#endif + +/////////////////////////////////////////////////////////////////////////////// + +enum SkAxisAlignment { + kNone_SkAxisAlignment, + kX_SkAxisAlignment, + kY_SkAxisAlignment +}; + +/** + * Return the axis (if any) that the baseline for horizontal text will land on + * after running through the specified matrix. + * + * As an example, the identity matrix will return kX_SkAxisAlignment + */ +SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix); + +/////////////////////////////////////////////////////////////////////////////// + +SkPaint::Hinting SkScalerContextRec::getHinting() const { + unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >> + SkScalerContext::kHinting_Shift; + return static_cast(hint); +} + +void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) { + fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) | + (hinting << SkScalerContext::kHinting_Shift); +} + + +#endif