1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/include/gpu/GrPaint.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,253 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2011 Google Inc.
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#ifndef GrPaint_DEFINED
1.14 +#define GrPaint_DEFINED
1.15 +
1.16 +#include "GrColor.h"
1.17 +#include "GrEffectStage.h"
1.18 +
1.19 +#include "SkXfermode.h"
1.20 +
1.21 +/**
1.22 + * The paint describes how color and coverage are computed at each pixel by GrContext draw
1.23 + * functions and the how color is blended with the destination pixel.
1.24 + *
1.25 + * The paint allows installation of custom color and coverage stages. New types of stages are
1.26 + * created by subclassing GrEffect.
1.27 + *
1.28 + * The primitive color computation starts with the color specified by setColor(). This color is the
1.29 + * input to the first color stage. Each color stage feeds its output to the next color stage. The
1.30 + * final color stage's output color is input to the color filter specified by
1.31 + * setXfermodeColorFilter which produces the final source color, S.
1.32 + *
1.33 + * Fractional pixel coverage follows a similar flow. The coverage is initially the value specified
1.34 + * by setCoverage(). This is input to the first coverage stage. Coverage stages are chained
1.35 + * together in the same manner as color stages. The output of the last stage is modulated by any
1.36 + * fractional coverage produced by anti-aliasing. This last step produces the final coverage, C.
1.37 + *
1.38 + * setBlendFunc() specifies blending coefficients for S (described above) and D, the initial value
1.39 + * of the destination pixel, labeled Bs and Bd respectively. The final value of the destination
1.40 + * pixel is then D' = (1-C)*D + C*(Bd*D + Bs*S).
1.41 + *
1.42 + * Note that the coverage is applied after the blend. This is why they are computed as distinct
1.43 + * values.
1.44 + *
1.45 + * TODO: Encapsulate setXfermodeColorFilter in a GrEffect and remove from GrPaint.
1.46 + */
1.47 +class GrPaint {
1.48 +public:
1.49 + GrPaint() { this->reset(); }
1.50 +
1.51 + GrPaint(const GrPaint& paint) { *this = paint; }
1.52 +
1.53 + ~GrPaint() {}
1.54 +
1.55 + /**
1.56 + * Sets the blending coefficients to use to blend the final primitive color with the
1.57 + * destination color. Defaults to kOne for src and kZero for dst (i.e. src mode).
1.58 + */
1.59 + void setBlendFunc(GrBlendCoeff srcCoeff, GrBlendCoeff dstCoeff) {
1.60 + fSrcBlendCoeff = srcCoeff;
1.61 + fDstBlendCoeff = dstCoeff;
1.62 + }
1.63 + GrBlendCoeff getSrcBlendCoeff() const { return fSrcBlendCoeff; }
1.64 + GrBlendCoeff getDstBlendCoeff() const { return fDstBlendCoeff; }
1.65 +
1.66 + /**
1.67 + * The initial color of the drawn primitive. Defaults to solid white.
1.68 + */
1.69 + void setColor(GrColor color) { fColor = color; }
1.70 + GrColor getColor() const { return fColor; }
1.71 +
1.72 + /**
1.73 + * Applies fractional coverage to the entire drawn primitive. Defaults to 0xff.
1.74 + */
1.75 + void setCoverage(uint8_t coverage) { fCoverage = coverage; }
1.76 + uint8_t getCoverage() const { return fCoverage; }
1.77 +
1.78 + /**
1.79 + * Should primitives be anti-aliased or not. Defaults to false.
1.80 + */
1.81 + void setAntiAlias(bool aa) { fAntiAlias = aa; }
1.82 + bool isAntiAlias() const { return fAntiAlias; }
1.83 +
1.84 + /**
1.85 + * Should dithering be applied. Defaults to false.
1.86 + */
1.87 + void setDither(bool dither) { fDither = dither; }
1.88 + bool isDither() const { return fDither; }
1.89 +
1.90 + /**
1.91 + * Appends an additional color effect to the color computation.
1.92 + */
1.93 + const GrEffectRef* addColorEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) {
1.94 + SkASSERT(NULL != effect);
1.95 + if (!(*effect)->willUseInputColor()) {
1.96 + fColorStages.reset();
1.97 + }
1.98 + SkNEW_APPEND_TO_TARRAY(&fColorStages, GrEffectStage, (effect, attr0, attr1));
1.99 + return effect;
1.100 + }
1.101 +
1.102 + /**
1.103 + * Appends an additional coverage effect to the coverage computation.
1.104 + */
1.105 + const GrEffectRef* addCoverageEffect(const GrEffectRef* effect, int attr0 = -1, int attr1 = -1) {
1.106 + SkASSERT(NULL != effect);
1.107 + if (!(*effect)->willUseInputColor()) {
1.108 + fCoverageStages.reset();
1.109 + }
1.110 + SkNEW_APPEND_TO_TARRAY(&fCoverageStages, GrEffectStage, (effect, attr0, attr1));
1.111 + return effect;
1.112 + }
1.113 +
1.114 + /**
1.115 + * Helpers for adding color or coverage effects that sample a texture. The matrix is applied
1.116 + * to the src space position to compute texture coordinates.
1.117 + */
1.118 + void addColorTextureEffect(GrTexture* texture, const SkMatrix& matrix);
1.119 + void addCoverageTextureEffect(GrTexture* texture, const SkMatrix& matrix);
1.120 +
1.121 + void addColorTextureEffect(GrTexture* texture,
1.122 + const SkMatrix& matrix,
1.123 + const GrTextureParams& params);
1.124 + void addCoverageTextureEffect(GrTexture* texture,
1.125 + const SkMatrix& matrix,
1.126 + const GrTextureParams& params);
1.127 +
1.128 + int numColorStages() const { return fColorStages.count(); }
1.129 + int numCoverageStages() const { return fCoverageStages.count(); }
1.130 + int numTotalStages() const { return this->numColorStages() + this->numCoverageStages(); }
1.131 +
1.132 + const GrEffectStage& getColorStage(int s) const { return fColorStages[s]; }
1.133 + const GrEffectStage& getCoverageStage(int s) const { return fCoverageStages[s]; }
1.134 +
1.135 + GrPaint& operator=(const GrPaint& paint) {
1.136 + fSrcBlendCoeff = paint.fSrcBlendCoeff;
1.137 + fDstBlendCoeff = paint.fDstBlendCoeff;
1.138 + fAntiAlias = paint.fAntiAlias;
1.139 + fDither = paint.fDither;
1.140 +
1.141 + fColor = paint.fColor;
1.142 + fCoverage = paint.fCoverage;
1.143 +
1.144 + fColorStages = paint.fColorStages;
1.145 + fCoverageStages = paint.fCoverageStages;
1.146 +
1.147 + return *this;
1.148 + }
1.149 +
1.150 + /**
1.151 + * Resets the paint to the defaults.
1.152 + */
1.153 + void reset() {
1.154 + this->resetBlend();
1.155 + this->resetOptions();
1.156 + this->resetColor();
1.157 + this->resetCoverage();
1.158 + this->resetStages();
1.159 + }
1.160 +
1.161 + /**
1.162 + * Determines whether the drawing with this paint is opaque with respect to both color blending
1.163 + * and fractional coverage. It does not consider whether AA has been enabled on the paint or
1.164 + * not. Depending upon whether multisampling or coverage-based AA is in use, AA may make the
1.165 + * result only apply to the interior of primitives.
1.166 + *
1.167 + */
1.168 + bool isOpaque() const;
1.169 +
1.170 + /**
1.171 + * Returns true if isOpaque would return true and the paint represents a solid constant color
1.172 + * draw. If the result is true, constantColor will be updated to contain the constant color.
1.173 + */
1.174 + bool isOpaqueAndConstantColor(GrColor* constantColor) const;
1.175 +
1.176 +private:
1.177 +
1.178 + /**
1.179 + * Helper for isOpaque and isOpaqueAndConstantColor.
1.180 + */
1.181 + bool getOpaqueAndKnownColor(GrColor* solidColor, uint32_t* solidColorKnownComponents) const;
1.182 +
1.183 + /**
1.184 + * Called when the source coord system from which geometry is rendered changes. It ensures that
1.185 + * the local coordinates seen by effects remains unchanged. oldToNew gives the transformation
1.186 + * from the previous coord system to the new coord system.
1.187 + */
1.188 + void localCoordChange(const SkMatrix& oldToNew) {
1.189 + for (int i = 0; i < fColorStages.count(); ++i) {
1.190 + fColorStages[i].localCoordChange(oldToNew);
1.191 + }
1.192 + for (int i = 0; i < fCoverageStages.count(); ++i) {
1.193 + fCoverageStages[i].localCoordChange(oldToNew);
1.194 + }
1.195 + }
1.196 +
1.197 + bool localCoordChangeInverse(const SkMatrix& newToOld) {
1.198 + SkMatrix oldToNew;
1.199 + bool computed = false;
1.200 + for (int i = 0; i < fColorStages.count(); ++i) {
1.201 + if (!computed && !newToOld.invert(&oldToNew)) {
1.202 + return false;
1.203 + } else {
1.204 + computed = true;
1.205 + }
1.206 + fColorStages[i].localCoordChange(oldToNew);
1.207 + }
1.208 + for (int i = 0; i < fCoverageStages.count(); ++i) {
1.209 + if (!computed && !newToOld.invert(&oldToNew)) {
1.210 + return false;
1.211 + } else {
1.212 + computed = true;
1.213 + }
1.214 + fCoverageStages[i].localCoordChange(oldToNew);
1.215 + }
1.216 + return true;
1.217 + }
1.218 +
1.219 + friend class GrContext; // To access above two functions
1.220 +
1.221 + SkSTArray<4, GrEffectStage> fColorStages;
1.222 + SkSTArray<2, GrEffectStage> fCoverageStages;
1.223 +
1.224 + GrBlendCoeff fSrcBlendCoeff;
1.225 + GrBlendCoeff fDstBlendCoeff;
1.226 + bool fAntiAlias;
1.227 + bool fDither;
1.228 +
1.229 + GrColor fColor;
1.230 + uint8_t fCoverage;
1.231 +
1.232 + void resetBlend() {
1.233 + fSrcBlendCoeff = kOne_GrBlendCoeff;
1.234 + fDstBlendCoeff = kZero_GrBlendCoeff;
1.235 + }
1.236 +
1.237 + void resetOptions() {
1.238 + fAntiAlias = false;
1.239 + fDither = false;
1.240 + }
1.241 +
1.242 + void resetColor() {
1.243 + fColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff);
1.244 + }
1.245 +
1.246 + void resetCoverage() {
1.247 + fCoverage = 0xff;
1.248 + }
1.249 +
1.250 + void resetStages() {
1.251 + fColorStages.reset();
1.252 + fCoverageStages.reset();
1.253 + }
1.254 +};
1.255 +
1.256 +#endif
