diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/include/gpu/GrPaint.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gfx/skia/trunk/include/gpu/GrPaint.h Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,253 @@ + +/* + * Copyright 2011 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + + +#ifndef GrPaint_DEFINED +#define GrPaint_DEFINED + +#include "GrColor.h" +#include "GrEffectStage.h" + +#include "SkXfermode.h" + +/** + * The paint describes how color and coverage are computed at each pixel by GrContext draw + * functions and the how color is blended with the destination pixel. + * + * The paint allows installation of custom color and coverage stages. New types of stages are + * created by subclassing GrEffect. + * + * The primitive color computation starts with the color specified by setColor(). This color is the + * input to the first color stage. Each color stage feeds its output to the next color stage. The + * final color stage's output color is input to the color filter specified by + * setXfermodeColorFilter which produces the final source color, S. + * + * Fractional pixel coverage follows a similar flow. The coverage is initially the value specified + * by setCoverage(). This is input to the first coverage stage. Coverage stages are chained + * together in the same manner as color stages. The output of the last stage is modulated by any + * fractional coverage produced by anti-aliasing. This last step produces the final coverage, C. + * + * setBlendFunc() specifies blending coefficients for S (described above) and D, the initial value + * of the destination pixel, labeled Bs and Bd respectively. The final value of the destination + * pixel is then D' = (1-C)*D + C*(Bd*D + Bs*S). + * + * Note that the coverage is applied after the blend. This is why they are computed as distinct + * values. + * + * TODO: Encapsulate setXfermodeColorFilter in a GrEffect and remove from GrPaint. + */ +class GrPaint { +public: + GrPaint() { this->reset(); } + + GrPaint(const GrPaint& paint) { *this = paint; } + + ~GrPaint() {} + + /** + * Sets the blending coefficients to use to blend the final primitive color with the + * destination color. Defaults to kOne for src and kZero for dst (i.e. src mode). + */ + void setBlendFunc(GrBlendCoeff srcCoeff, GrBlendCoeff dstCoeff) { + fSrcBlendCoeff = srcCoeff; + fDstBlendCoeff = dstCoeff; + } + GrBlendCoeff getSrcBlendCoeff() const { return fSrcBlendCoeff; } + GrBlendCoeff getDstBlendCoeff() const { return fDstBlendCoeff; } + + /** + * The initial color of the drawn primitive. Defaults to solid white. + */ + void setColor(GrColor color) { fColor = color; } + GrColor getColor() const { return fColor; } + + /** + * Applies fractional coverage to the entire drawn primitive. Defaults to 0xff. + */ + void setCoverage(uint8_t coverage) { fCoverage = coverage; } + uint8_t getCoverage() const { return fCoverage; } + + /** + * Should primitives be anti-aliased or not. Defaults to false. + */ + void setAntiAlias(bool aa) { fAntiAlias = aa; } + bool isAntiAlias() const { return fAntiAlias; } + + /** + * Should dithering be applied. Defaults to false. + */ + void setDither(bool dither) { fDither = dither; } + bool isDither() const { return fDither; } + + /** + * Appends an additional color effect to the color computation. + */ + const GrEffectRef* addColorEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) { + SkASSERT(NULL != effect); + if (!(*effect)->willUseInputColor()) { + fColorStages.reset(); + } + SkNEW_APPEND_TO_TARRAY(&fColorStages, GrEffectStage, (effect, attr0, attr1)); + return effect; + } + + /** + * Appends an additional coverage effect to the coverage computation. + */ + const GrEffectRef* addCoverageEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) { + SkASSERT(NULL != effect); + if (!(*effect)->willUseInputColor()) { + fCoverageStages.reset(); + } + SkNEW_APPEND_TO_TARRAY(&fCoverageStages, GrEffectStage, (effect, attr0, attr1)); + return effect; + } + + /** + * Helpers for adding color or coverage effects that sample a texture. The matrix is applied + * to the src space position to compute texture coordinates. + */ + void addColorTextureEffect(GrTexture* texture, const SkMatrix& matrix); + void addCoverageTextureEffect(GrTexture* texture, const SkMatrix& matrix); + + void addColorTextureEffect(GrTexture* texture, + const SkMatrix& matrix, + const GrTextureParams& params); + void addCoverageTextureEffect(GrTexture* texture, + const SkMatrix& matrix, + const GrTextureParams& params); + + int numColorStages() const { return fColorStages.count(); } + int numCoverageStages() const { return fCoverageStages.count(); } + int numTotalStages() const { return this->numColorStages() + this->numCoverageStages(); } + + const GrEffectStage& getColorStage(int s) const { return fColorStages[s]; } + const GrEffectStage& getCoverageStage(int s) const { return fCoverageStages[s]; } + + GrPaint& operator=(const GrPaint& paint) { + fSrcBlendCoeff = paint.fSrcBlendCoeff; + fDstBlendCoeff = paint.fDstBlendCoeff; + fAntiAlias = paint.fAntiAlias; + fDither = paint.fDither; + + fColor = paint.fColor; + fCoverage = paint.fCoverage; + + fColorStages = paint.fColorStages; + fCoverageStages = paint.fCoverageStages; + + return *this; + } + + /** + * Resets the paint to the defaults. + */ + void reset() { + this->resetBlend(); + this->resetOptions(); + this->resetColor(); + this->resetCoverage(); + this->resetStages(); + } + + /** + * Determines whether the drawing with this paint is opaque with respect to both color blending + * and fractional coverage. It does not consider whether AA has been enabled on the paint or + * not. Depending upon whether multisampling or coverage-based AA is in use, AA may make the + * result only apply to the interior of primitives. + * + */ + bool isOpaque() const; + + /** + * Returns true if isOpaque would return true and the paint represents a solid constant color + * draw. If the result is true, constantColor will be updated to contain the constant color. + */ + bool isOpaqueAndConstantColor(GrColor* constantColor) const; + +private: + + /** + * Helper for isOpaque and isOpaqueAndConstantColor. + */ + bool getOpaqueAndKnownColor(GrColor* solidColor, uint32_t* solidColorKnownComponents) const; + + /** + * Called when the source coord system from which geometry is rendered changes. It ensures that + * the local coordinates seen by effects remains unchanged. oldToNew gives the transformation + * from the previous coord system to the new coord system. + */ + void localCoordChange(const SkMatrix& oldToNew) { + for (int i = 0; i < fColorStages.count(); ++i) { + fColorStages[i].localCoordChange(oldToNew); + } + for (int i = 0; i < fCoverageStages.count(); ++i) { + fCoverageStages[i].localCoordChange(oldToNew); + } + } + + bool localCoordChangeInverse(const SkMatrix& newToOld) { + SkMatrix oldToNew; + bool computed = false; + for (int i = 0; i < fColorStages.count(); ++i) { + if (!computed && !newToOld.invert(&oldToNew)) { + return false; + } else { + computed = true; + } + fColorStages[i].localCoordChange(oldToNew); + } + for (int i = 0; i < fCoverageStages.count(); ++i) { + if (!computed && !newToOld.invert(&oldToNew)) { + return false; + } else { + computed = true; + } + fCoverageStages[i].localCoordChange(oldToNew); + } + return true; + } + + friend class GrContext; // To access above two functions + + SkSTArray<4, GrEffectStage> fColorStages; + SkSTArray<2, GrEffectStage> fCoverageStages; + + GrBlendCoeff fSrcBlendCoeff; + GrBlendCoeff fDstBlendCoeff; + bool fAntiAlias; + bool fDither; + + GrColor fColor; + uint8_t fCoverage; + + void resetBlend() { + fSrcBlendCoeff = kOne_GrBlendCoeff; + fDstBlendCoeff = kZero_GrBlendCoeff; + } + + void resetOptions() { + fAntiAlias = false; + fDither = false; + } + + void resetColor() { + fColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff); + } + + void resetCoverage() { + fCoverage = 0xff; + } + + void resetStages() { + fColorStages.reset(); + fCoverageStages.reset(); + } +}; + +#endif