src/gpu/effects/GrDistanceFieldTextureEffect.h

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrDistanceFieldTextureEffect_DEFINED
#define GrDistanceFieldTextureEffect_DEFINED

#include "GrProcessor.h"
#include "GrGeometryProcessor.h"

class GrGLDistanceFieldTextureEffect;
class GrGLDistanceFieldNoGammaTextureEffect;
class GrGLDistanceFieldLCDTextureEffect;
class GrInvariantOutput;

enum GrDistanceFieldEffectFlags {
    kSimilarity_DistanceFieldEffectFlag = 0x01,   // ctm is similarity matrix
    kRectToRect_DistanceFieldEffectFlag = 0x02,   // ctm maps rects to rects
    kUseLCD_DistanceFieldEffectFlag     = 0x04,   // use lcd text
    kBGR_DistanceFieldEffectFlag        = 0x08,   // lcd display has bgr order
    kPortrait_DistanceFieldEffectFlag   = 0x10,   // lcd display is in portrait mode (not used yet)
    kColorAttr_DistanceFieldEffectFlag  = 0x20,   // color vertex attribute

    kInvalid_DistanceFieldEffectFlag    = 0x80,   // invalid state (for initialization)
    
    kUniformScale_DistanceFieldEffectMask = kSimilarity_DistanceFieldEffectFlag |
                                            kRectToRect_DistanceFieldEffectFlag,
    // The subset of the flags relevant to GrDistanceFieldTextureEffect
    kNonLCD_DistanceFieldEffectMask       = kSimilarity_DistanceFieldEffectFlag |
                                            kColorAttr_DistanceFieldEffectFlag,
    // The subset of the flags relevant to GrDistanceFieldLCDTextureEffect
    kLCD_DistanceFieldEffectMask          = kSimilarity_DistanceFieldEffectFlag |
                                            kRectToRect_DistanceFieldEffectFlag |
                                            kUseLCD_DistanceFieldEffectFlag |
                                            kBGR_DistanceFieldEffectFlag,
};

/**
 * The output color of this effect is a modulation of the input color and a sample from a
 * distance field texture (using a smoothed step function near 0.5).
 * It allows explicit specification of the filtering and wrap modes (GrTextureParams). The input
 * coords are a custom attribute. Gamma correction is handled via a texture LUT.
 */
class GrDistanceFieldTextureEffect : public GrGeometryProcessor {
public:
#ifdef SK_GAMMA_APPLY_TO_A8
    static GrGeometryProcessor* Create(GrColor color, const SkMatrix& viewMatrix, GrTexture* tex,
                                       const GrTextureParams& params,
                                       float lum, uint32_t flags, bool opaqueVertexColors) {
       return SkNEW_ARGS(GrDistanceFieldTextureEffect, (color, viewMatrix, tex, params, lum,
                                                        flags, opaqueVertexColors));
    }
#else
    static GrGeometryProcessor* Create(GrColor color, const SkMatrix& viewMatrix, GrTexture* tex,
                                       const GrTextureParams& params,
                                       uint32_t flags, bool opaqueVertexColors) {
        return  SkNEW_ARGS(GrDistanceFieldTextureEffect, (color, viewMatrix, tex, params, flags,
                                                          opaqueVertexColors));
    }
#endif

    virtual ~GrDistanceFieldTextureEffect() {}

    const char* name() const override { return "DistanceFieldTexture"; }

    const Attribute* inPosition() const { return fInPosition; }
    const Attribute* inColor() const { return fInColor; }
    const Attribute* inTextureCoords() const { return fInTextureCoords; }
#ifdef SK_GAMMA_APPLY_TO_A8
    float getDistanceAdjust() const { return fDistanceAdjust; }
#endif
    uint32_t getFlags() const { return fFlags; }

    virtual void getGLProcessorKey(const GrBatchTracker& bt,
                                   const GrGLCaps& caps,
                                   GrProcessorKeyBuilder* b) const override;

    virtual GrGLPrimitiveProcessor* createGLInstance(const GrBatchTracker& bt,
                                                     const GrGLCaps&) const override;

    void initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const override;

    bool onCanMakeEqual(const GrBatchTracker&,
                        const GrGeometryProcessor&,
                        const GrBatchTracker&) const override;

private:
    GrDistanceFieldTextureEffect(GrColor, const SkMatrix& viewMatrix, GrTexture* texture,
                                 const GrTextureParams& params,
#ifdef SK_GAMMA_APPLY_TO_A8
                                 float distanceAdjust,
#endif
                                 uint32_t flags, bool opaqueVertexColors);

    bool onIsEqual(const GrGeometryProcessor& other) const override;

    void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const override;

    GrTextureAccess  fTextureAccess;
#ifdef SK_GAMMA_APPLY_TO_A8
    float            fDistanceAdjust;
#endif
    uint32_t         fFlags;
    const Attribute* fInPosition;
    const Attribute* fInColor;
    const Attribute* fInTextureCoords;

    GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

    typedef GrGeometryProcessor INHERITED;
};


/**
* The output color of this effect is a modulation of the input color and a sample from a
* distance field texture (using a smoothed step function near 0.5).
* It allows explicit specification of the filtering and wrap modes (GrTextureParams). The input
* coords are a custom attribute. No gamma correct blending is applied.
*/
class GrDistanceFieldNoGammaTextureEffect : public GrGeometryProcessor {
public:
    static GrGeometryProcessor* Create(GrColor color, const SkMatrix& viewMatrix, GrTexture* tex,
                                       const GrTextureParams& params,
                                       uint32_t flags, bool opaqueVertexColors) {
        return SkNEW_ARGS(GrDistanceFieldNoGammaTextureEffect, (color, viewMatrix, tex, params,
                                                                flags, opaqueVertexColors));
    }

    virtual ~GrDistanceFieldNoGammaTextureEffect() {}

    const char* name() const override { return "DistanceFieldTexture"; }

    const Attribute* inPosition() const { return fInPosition; }
    const Attribute* inColor() const { return fInColor; }
    const Attribute* inTextureCoords() const { return fInTextureCoords; }
    uint32_t getFlags() const { return fFlags; }

    virtual void getGLProcessorKey(const GrBatchTracker& bt,
                                   const GrGLCaps& caps,
                                   GrProcessorKeyBuilder* b) const override;

    virtual GrGLPrimitiveProcessor* createGLInstance(const GrBatchTracker& bt,
                                                     const GrGLCaps&) const override;

    void initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const override;

    bool onCanMakeEqual(const GrBatchTracker&,
                        const GrGeometryProcessor&,
                        const GrBatchTracker&) const override;

private:
    GrDistanceFieldNoGammaTextureEffect(GrColor, const SkMatrix& viewMatrix, GrTexture* texture,
                                        const GrTextureParams& params, uint32_t flags,
                                        bool opaqueVertexColors);

    bool onIsEqual(const GrGeometryProcessor& other) const override;

    void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const override;

    GrTextureAccess    fTextureAccess;
    uint32_t           fFlags;
    const Attribute* fInPosition;
    const Attribute* fInColor;
    const Attribute* fInTextureCoords;

    GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

    typedef GrGeometryProcessor INHERITED;
};

/**
 * The output color of this effect is a modulation of the input color and samples from a
 * distance field texture (using a smoothed step function near 0.5), adjusted for LCD displays.
 * It allows explicit specification of the filtering and wrap modes (GrTextureParams). The input
 * coords are a custom attribute. Gamma correction is handled via a texture LUT.
 */
class GrDistanceFieldLCDTextureEffect : public GrGeometryProcessor {
public:
    struct DistanceAdjust {
        SkScalar fR, fG, fB;
        static DistanceAdjust Make(SkScalar r, SkScalar g, SkScalar b) {
            DistanceAdjust result;
            result.fR = r; result.fG = g; result.fB = b;
            return result;
        }
        bool operator==(const DistanceAdjust& wa) const {
            return (fR == wa.fR && fG == wa.fG && fB == wa.fB);
        }
        bool operator!=(const DistanceAdjust& wa) const {
            return !(*this == wa);
        }
    };

    static GrGeometryProcessor* Create(GrColor color, const SkMatrix& viewMatrix, GrTexture* tex,
                                       const GrTextureParams& params, 
                                       DistanceAdjust distanceAdjust, uint32_t flags) {
        return SkNEW_ARGS(GrDistanceFieldLCDTextureEffect,
                          (color, viewMatrix, tex, params, distanceAdjust, flags));
    }

    virtual ~GrDistanceFieldLCDTextureEffect() {}

    const char* name() const override { return "DistanceFieldLCDTexture"; }

    const Attribute* inPosition() const { return fInPosition; }
    const Attribute* inTextureCoords() const { return fInTextureCoords; }
    DistanceAdjust getDistanceAdjust() const { return fDistanceAdjust; }
    uint32_t getFlags() const { return fFlags; }

    virtual void getGLProcessorKey(const GrBatchTracker& bt,
                                   const GrGLCaps& caps,
                                   GrProcessorKeyBuilder* b) const override;

    virtual GrGLPrimitiveProcessor* createGLInstance(const GrBatchTracker& bt,
                                                     const GrGLCaps&) const override;

    void initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const override;

    bool onCanMakeEqual(const GrBatchTracker&,
                        const GrGeometryProcessor&,
                        const GrBatchTracker&) const override;

private:
    GrDistanceFieldLCDTextureEffect(GrColor, const SkMatrix& viewMatrix, GrTexture* texture,
                                    const GrTextureParams& params,
                                    DistanceAdjust wa, uint32_t flags);

    bool onIsEqual(const GrGeometryProcessor& other) const override;

    void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const override;

    GrTextureAccess  fTextureAccess;
    DistanceAdjust   fDistanceAdjust;
    uint32_t         fFlags;
    const Attribute* fInPosition;
    const Attribute* fInTextureCoords;

    GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

    typedef GrGeometryProcessor INHERITED;
};

#endif