3 * Copyright 2011 Google Inc.
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
10 #ifndef GrPaint_DEFINED
11 #define GrPaint_DEFINED
14 #include "GrProcessorStage.h"
16 #include "SkXfermode.h"
19 * The paint describes how color and coverage are computed at each pixel by GrContext draw
20 * functions and the how color is blended with the destination pixel.
22 * The paint allows installation of custom color and coverage stages. New types of stages are
23 * created by subclassing GrProcessor.
25 * The primitive color computation starts with the color specified by setColor(). This color is the
26 * input to the first color stage. Each color stage feeds its output to the next color stage. The
27 * final color stage's output color is input to the color filter specified by
28 * setXfermodeColorFilter which produces the final source color, S.
30 * Fractional pixel coverage follows a similar flow. The coverage is initially the value specified
31 * by setCoverage(). This is input to the first coverage stage. Coverage stages are chained
32 * together in the same manner as color stages. The output of the last stage is modulated by any
33 * fractional coverage produced by anti-aliasing. This last step produces the final coverage, C.
35 * setBlendFunc() specifies blending coefficients for S (described above) and D, the initial value
36 * of the destination pixel, labeled Bs and Bd respectively. The final value of the destination
37 * pixel is then D' = (1-C)*D + C*(Bd*D + Bs*S).
39 * Note that the coverage is applied after the blend. This is why they are computed as distinct
42 * TODO: Encapsulate setXfermodeColorFilter in a GrProcessor and remove from GrPaint.
46 GrPaint() { this->reset(); }
48 GrPaint(const GrPaint& paint) { *this = paint; }
53 * Sets the blending coefficients to use to blend the final primitive color with the
54 * destination color. Defaults to kOne for src and kZero for dst (i.e. src mode).
56 void setBlendFunc(GrBlendCoeff srcCoeff, GrBlendCoeff dstCoeff) {
57 fSrcBlendCoeff = srcCoeff;
58 fDstBlendCoeff = dstCoeff;
60 GrBlendCoeff getSrcBlendCoeff() const { return fSrcBlendCoeff; }
61 GrBlendCoeff getDstBlendCoeff() const { return fDstBlendCoeff; }
64 * The initial color of the drawn primitive. Defaults to solid white.
66 void setColor(GrColor color) { fColor = color; }
67 GrColor getColor() const { return fColor; }
70 * Applies fractional coverage to the entire drawn primitive. Defaults to 0xff.
72 void setCoverage(uint8_t coverage) { fCoverage = coverage; }
73 uint8_t getCoverage() const { return fCoverage; }
76 * Should primitives be anti-aliased or not. Defaults to false.
78 void setAntiAlias(bool aa) { fAntiAlias = aa; }
79 bool isAntiAlias() const { return fAntiAlias; }
82 * Should dithering be applied. Defaults to false.
84 void setDither(bool dither) { fDither = dither; }
85 bool isDither() const { return fDither; }
88 * Appends an additional color processor to the color computation.
90 const GrFragmentProcessor* addColorProcessor(const GrFragmentProcessor* fp) {
92 SkNEW_APPEND_TO_TARRAY(&fColorStages, GrFragmentStage, (fp));
97 * Appends an additional coverage processor to the coverage computation.
99 const GrFragmentProcessor* addCoverageProcessor(const GrFragmentProcessor* fp) {
101 SkNEW_APPEND_TO_TARRAY(&fCoverageStages, GrFragmentStage, (fp));
106 * Helpers for adding color or coverage effects that sample a texture. The matrix is applied
107 * to the src space position to compute texture coordinates.
109 void addColorTextureProcessor(GrTexture*, const SkMatrix&);
110 void addCoverageTextureProcessor(GrTexture*, const SkMatrix&);
111 void addColorTextureProcessor(GrTexture*, const SkMatrix&, const GrTextureParams&);
112 void addCoverageTextureProcessor(GrTexture*, const SkMatrix&, const GrTextureParams&);
114 int numColorStages() const { return fColorStages.count(); }
115 int numCoverageStages() const { return fCoverageStages.count(); }
116 int numTotalStages() const { return this->numColorStages() + this->numCoverageStages(); }
118 const GrFragmentStage& getColorStage(int s) const { return fColorStages[s]; }
119 const GrFragmentStage& getCoverageStage(int s) const { return fCoverageStages[s]; }
121 GrPaint& operator=(const GrPaint& paint) {
122 fSrcBlendCoeff = paint.fSrcBlendCoeff;
123 fDstBlendCoeff = paint.fDstBlendCoeff;
124 fAntiAlias = paint.fAntiAlias;
125 fDither = paint.fDither;
127 fColor = paint.fColor;
128 fCoverage = paint.fCoverage;
130 fColorStages = paint.fColorStages;
131 fCoverageStages = paint.fCoverageStages;
137 * Resets the paint to the defaults.
141 this->resetOptions();
143 this->resetCoverage();
148 * Determines whether the drawing with this paint is opaque with respect to both color blending
149 * and fractional coverage. It does not consider whether AA has been enabled on the paint or
150 * not. Depending upon whether multisampling or coverage-based AA is in use, AA may make the
151 * result only apply to the interior of primitives.
154 bool isOpaque() const;
157 * Returns true if isOpaque would return true and the paint represents a solid constant color
158 * draw. If the result is true, constantColor will be updated to contain the constant color.
160 bool isOpaqueAndConstantColor(GrColor* constantColor) const;
165 * Helper for isOpaque and isOpaqueAndConstantColor.
167 bool getOpaqueAndKnownColor(GrColor* solidColor, uint32_t* solidColorKnownComponents) const;
170 * Called when the source coord system from which geometry is rendered changes. It ensures that
171 * the local coordinates seen by effects remains unchanged. oldToNew gives the transformation
172 * from the previous coord system to the new coord system.
174 void localCoordChange(const SkMatrix& oldToNew) {
175 for (int i = 0; i < fColorStages.count(); ++i) {
176 fColorStages[i].localCoordChange(oldToNew);
178 for (int i = 0; i < fCoverageStages.count(); ++i) {
179 fCoverageStages[i].localCoordChange(oldToNew);
183 bool localCoordChangeInverse(const SkMatrix& newToOld) {
185 bool computed = false;
186 for (int i = 0; i < fColorStages.count(); ++i) {
187 if (!computed && !newToOld.invert(&oldToNew)) {
192 fColorStages[i].localCoordChange(oldToNew);
194 for (int i = 0; i < fCoverageStages.count(); ++i) {
195 if (!computed && !newToOld.invert(&oldToNew)) {
200 fCoverageStages[i].localCoordChange(oldToNew);
205 friend class GrContext; // To access above two functions
206 friend class GrStencilAndCoverTextContext; // To access above two functions
208 SkSTArray<4, GrFragmentStage> fColorStages;
209 SkSTArray<2, GrFragmentStage> fCoverageStages;
211 GrBlendCoeff fSrcBlendCoeff;
212 GrBlendCoeff fDstBlendCoeff;
220 fSrcBlendCoeff = kOne_GrBlendCoeff;
221 fDstBlendCoeff = kZero_GrBlendCoeff;
224 void resetOptions() {
230 fColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff);
233 void resetCoverage() {
238 fColorStages.reset();
239 fCoverageStages.reset();