97efada074
https://codereview.appspot.com/6244068/ git-svn-id: http://skia.googlecode.com/svn/trunk@4841 2bbb7eff-a529-9590-31e7-b0007b416f81
272 lines
9.2 KiB
C++
272 lines
9.2 KiB
C++
/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkScalerContext_DEFINED
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#define SkScalerContext_DEFINED
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#include "SkMask.h"
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#include "SkMaskGamma.h"
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#include "SkMatrix.h"
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#include "SkPaint.h"
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#ifdef SK_BUILD_FOR_ANDROID
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//For SkFontID
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#include "SkTypeface.h"
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#endif
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struct SkGlyph;
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class SkDescriptor;
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class SkMaskFilter;
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class SkPathEffect;
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class SkRasterizer;
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//The following typedef hides from the rest of the implementation the number of
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//most significant bits to consider when creating mask gamma tables. Two bits
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//per channel was chosen as a balance between fidelity (more bits) and cache
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//sizes (fewer bits).
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typedef SkTMaskGamma<2, 2, 2> SkMaskGamma;
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class SkScalerContext {
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public:
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enum Flags {
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kFrameAndFill_Flag = 0x0001,
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kDevKernText_Flag = 0x0002,
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kEmbeddedBitmapText_Flag = 0x0004,
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kEmbolden_Flag = 0x0008,
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kSubpixelPositioning_Flag = 0x0010,
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kAutohinting_Flag = 0x0020,
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kVertical_Flag = 0x0040,
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// together, these two flags resulting in a two bit value which matches
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// up with the SkPaint::Hinting enum.
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kHinting_Shift = 7, // to shift into the other flags above
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kHintingBit1_Flag = 0x0080,
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kHintingBit2_Flag = 0x0100,
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// these should only ever be set if fMaskFormat is LCD16 or LCD32
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kLCD_Vertical_Flag = 0x0200, // else Horizontal
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kLCD_BGROrder_Flag = 0x0400, // else RGB order
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// Generate A8 from LCD source (for GDI), only meaningful if fMaskFormat is kA8
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// Perhaps we can store this (instead) in fMaskFormat, in hight bit?
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kGenA8FromLCD_Flag = 0x0800,
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};
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// computed values
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enum {
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kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag,
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};
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struct Rec {
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uint32_t fOrigFontID;
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uint32_t fFontID;
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SkScalar fTextSize, fPreScaleX, fPreSkewX;
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SkScalar fPost2x2[2][2];
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SkScalar fFrameWidth, fMiterLimit;
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//These describe the parameters to create (uniquely identify) the pre-blend.
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uint32_t fLumBits;
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uint8_t fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB
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uint8_t fPaintGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB
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uint8_t fContrast; //0.8+1, [0.0, 1.0] artificial contrast
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uint8_t fReservedAlign;
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SkScalar getDeviceGamma() const {
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return SkIntToScalar(fDeviceGamma) / (1 << 6);
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}
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void setDeviceGamma(SkScalar dg) {
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SkASSERT(0 <= dg && dg < SkIntToScalar(4));
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fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6));
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}
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SkScalar getPaintGamma() const {
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return SkIntToScalar(fPaintGamma) / (1 << 6);
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}
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void setPaintGamma(SkScalar pg) {
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SkASSERT(0 <= pg && pg < SkIntToScalar(4));
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fPaintGamma = SkScalarFloorToInt(pg * (1 << 6));
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}
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SkScalar getContrast() const {
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return SkIntToScalar(fContrast) / ((1 << 8) - 1);
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}
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void setContrast(SkScalar c) {
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SkASSERT(0 <= c && c <= SK_Scalar1);
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fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1));
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}
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/**
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* Causes the luminance color and contrast to be ignored, and the
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* paint and device gamma to be effectively 1.0.
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*/
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void ignorePreBlend() {
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setLuminanceColor(0x00000000);
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setPaintGamma(SK_Scalar1);
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setDeviceGamma(SK_Scalar1);
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setContrast(0);
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}
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uint8_t fMaskFormat;
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uint8_t fStrokeJoin;
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uint16_t fFlags;
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// Warning: when adding members note that the size of this structure
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// must be a multiple of 4. SkDescriptor requires that its arguments be
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// multiples of four and this structure is put in an SkDescriptor in
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// SkPaint::MakeRec.
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void getMatrixFrom2x2(SkMatrix*) const;
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void getLocalMatrix(SkMatrix*) const;
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void getSingleMatrix(SkMatrix*) const;
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SkPaint::Hinting getHinting() const {
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unsigned hint = (fFlags & kHinting_Mask) >> kHinting_Shift;
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return static_cast<SkPaint::Hinting>(hint);
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}
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void setHinting(SkPaint::Hinting hinting) {
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fFlags = (fFlags & ~kHinting_Mask) | (hinting << kHinting_Shift);
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}
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SkMask::Format getFormat() const {
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return static_cast<SkMask::Format>(fMaskFormat);
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}
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SkColor getLuminanceColor() const {
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return fLumBits;
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}
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void setLuminanceColor(SkColor c) {
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fLumBits = c;
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}
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};
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SkScalerContext(const SkDescriptor* desc);
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virtual ~SkScalerContext();
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SkMask::Format getMaskFormat() const {
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return (SkMask::Format)fRec.fMaskFormat;
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}
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bool isSubpixel() const {
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return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
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}
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// remember our glyph offset/base
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void setBaseGlyphCount(unsigned baseGlyphCount) {
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fBaseGlyphCount = baseGlyphCount;
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}
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/** Return the corresponding glyph for the specified unichar. Since contexts
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may be chained (under the hood), the glyphID that is returned may in
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fact correspond to a different font/context. In that case, we use the
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base-glyph-count to know how to translate back into local glyph space.
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*/
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uint16_t charToGlyphID(SkUnichar uni);
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/** Map the glyphID to its glyph index, and then to its char code. Unmapped
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glyphs return zero.
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*/
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SkUnichar glyphIDToChar(uint16_t glyphID);
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unsigned getGlyphCount() { return this->generateGlyphCount(); }
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void getAdvance(SkGlyph*);
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void getMetrics(SkGlyph*);
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void getImage(const SkGlyph&);
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void getPath(const SkGlyph&, SkPath*);
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void getFontMetrics(SkPaint::FontMetrics* mX,
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SkPaint::FontMetrics* mY);
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#ifdef SK_BUILD_FOR_ANDROID
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unsigned getBaseGlyphCount(SkUnichar charCode);
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// This function must be public for SkTypeface_android.h, but should not be
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// called by other callers
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SkFontID findTypefaceIdForChar(SkUnichar uni) {
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SkScalerContext* ctx = this;
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while (NULL != ctx) {
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if (ctx->generateCharToGlyph(uni)) {
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return ctx->fRec.fFontID;
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}
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ctx = ctx->getNextContext();
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}
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return 0;
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}
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#endif
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static inline void MakeRec(const SkPaint&, const SkMatrix*, Rec* rec);
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static inline void PostMakeRec(const SkPaint&, Rec*);
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static SkScalerContext* Create(const SkDescriptor*);
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static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec);
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protected:
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Rec fRec;
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unsigned fBaseGlyphCount;
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virtual unsigned generateGlyphCount() = 0;
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virtual uint16_t generateCharToGlyph(SkUnichar) = 0;
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virtual void generateAdvance(SkGlyph*) = 0;
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virtual void generateMetrics(SkGlyph*) = 0;
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virtual void generateImage(const SkGlyph&, SkMaskGamma::PreBlend* maskPreBlend) = 0;
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virtual void generatePath(const SkGlyph&, SkPath*) = 0;
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virtual void generateFontMetrics(SkPaint::FontMetrics* mX,
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SkPaint::FontMetrics* mY) = 0;
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// default impl returns 0, indicating failure.
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virtual SkUnichar generateGlyphToChar(uint16_t);
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void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }
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private:
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SkPathEffect* fPathEffect;
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SkMaskFilter* fMaskFilter;
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SkRasterizer* fRasterizer;
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// if this is set, we draw the image from a path, rather than
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// calling generateImage.
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bool fGenerateImageFromPath;
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void internalGetPath(const SkGlyph& glyph, SkPath* fillPath,
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SkPath* devPath, SkMatrix* fillToDevMatrix);
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// return the next context, treating fNextContext as a cache of the answer
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SkScalerContext* getNextContext();
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// returns the right context from our link-list for this glyph. If no match
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// is found, just returns the original context (this)
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SkScalerContext* getGlyphContext(const SkGlyph& glyph);
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// link-list of context, to handle missing chars. null-terminated.
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SkScalerContext* fNextContext;
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// converts linear masks to gamma correcting masks.
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SkMaskGamma::PreBlend fMaskPreBlend;
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};
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#define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c')
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#define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e')
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#define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f')
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#define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't')
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///////////////////////////////////////////////////////////////////////////////
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enum SkAxisAlignment {
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kNone_SkAxisAlignment,
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kX_SkAxisAlignment,
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kY_SkAxisAlignment
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};
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/**
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* Return the axis (if any) that the baseline for horizontal text will land on
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* after running through the specified matrix.
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*
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* As an example, the identity matrix will return kX_SkAxisAlignment
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*/
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SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix);
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#endif
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