gpu/include/GrPaint.h

/*
 * 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 "GrTexture.h"
#include "GrColor.h"
#include "GrSamplerState.h"

#include "SkXfermode.h"

/**
 * The paint describes how pixels are colored when the context draws to
 * them. TODO: Make this a "real" class with getters and setters, default
 * values, and documentation.
 */
class GrPaint {
public:
    enum {
        kMaxTextures = 1,
        kMaxMasks    = 1,
    };

    // All the paint fields are public except textures/samplers
    GrBlendCoeff                fSrcBlendCoeff;
    GrBlendCoeff                fDstBlendCoeff;
    bool                        fAntiAlias;
    bool                        fDither;

    GrColor                     fColor;

    GrColor                     fColorFilterColor;
    SkXfermode::Mode            fColorFilterXfermode;

    void setTexture(int i, GrTexture* texture) {
        GrAssert((unsigned)i < kMaxTextures);
        GrSafeRef(texture);
        GrSafeUnref(fTextures[i]);
        fTextures[i] = texture;
    }

    GrTexture* getTexture(int i) const { 
        GrAssert((unsigned)i < kMaxTextures);
        return fTextures[i]; 
    }

    GrSamplerState* getTextureSampler(int i) {
        GrAssert((unsigned)i < kMaxTextures);
        return fTextureSamplers + i;
    }

    const GrSamplerState* getTextureSampler(int i) const {
        GrAssert((unsigned)i < kMaxTextures);
        return fTextureSamplers + i;
    }

    // The mask can be alpha-only or per channel. It is applied
    // after the colorfilter
    void setMask(int i, GrTexture* mask) {
        GrAssert((unsigned)i < kMaxMasks);
        GrSafeRef(mask);
        GrSafeUnref(fMaskTextures[i]);
        fMaskTextures[i] = mask;
    }

    GrTexture* getMask(int i) const { 
        GrAssert((unsigned)i < kMaxMasks);
        return fMaskTextures[i]; 
    }

    // mask's sampler matrix is always applied to the positions
    // (i.e. no explicit texture coordinates)
    GrSamplerState* getMaskSampler(int i) {
        GrAssert((unsigned)i < kMaxMasks);
        return fMaskSamplers + i;
    }

    const GrSamplerState* getMaskSampler(int i) const {
        GrAssert((unsigned)i < kMaxMasks);
        return fMaskSamplers + i;
    }

    // pre-concats sampler matrices for non-NULL textures and masks
    void preConcatActiveSamplerMatrices(const GrMatrix& matrix) {
        for (int i = 0; i < kMaxTextures; ++i) {
            fTextureSamplers[i].preConcatMatrix(matrix);
        }
        for (int i = 0; i < kMaxMasks; ++i) {
            fMaskSamplers[i].preConcatMatrix(matrix);
        }
    }

    // uninitialized
    GrPaint() {
        for (int i = 0; i < kMaxTextures; ++i) {
            fTextures[i] = NULL;
        }
        for (int i = 0; i < kMaxMasks; ++i) {
            fMaskTextures[i] = NULL;
        }
    }

    GrPaint(const GrPaint& paint) {
        fSrcBlendCoeff = paint.fSrcBlendCoeff;
        fDstBlendCoeff = paint.fDstBlendCoeff;
        fAntiAlias = paint.fAntiAlias;
        fDither = paint.fDither;

        fColor = paint.fColor;

        fColorFilterColor = paint.fColorFilterColor;
        fColorFilterXfermode = paint.fColorFilterXfermode;

        for (int i = 0; i < kMaxTextures; ++i) {
            fTextureSamplers[i] = paint.fTextureSamplers[i];
            fTextures[i] = paint.fTextures[i];
            GrSafeRef(fTextures[i]);
        }
        for (int i = 0; i < kMaxMasks; ++i) {
            fMaskSamplers[i] = paint.fMaskSamplers[i];
            fMaskTextures[i] = paint.fMaskTextures[i];
            GrSafeRef(fMaskTextures[i]);
        }
    }

    ~GrPaint() {
        for (int i = 0; i < kMaxTextures; ++i) {
            GrSafeUnref(fTextures[i]);
        }
        for (int i = 0; i < kMaxMasks; ++i) {
            GrSafeUnref(fMaskTextures[i]);
        }
    }

    // sets paint to src-over, solid white, no texture, no mask
    void reset() {
        this->resetBlend();
        this->resetOptions();
        this->resetColor();
        this->resetTextures();
        this->resetColorFilter();
        this->resetMasks();
    }

    void resetColorFilter() {
        fColorFilterXfermode = SkXfermode::kDst_Mode;
        fColorFilterColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff);
    }

    bool hasTexture() const {
        return 0 != this->getActiveTextureStageMask();
    }

    bool hasMask() const {
        return 0 != this->getActiveMaskStageMask();
    }

    bool hasTextureOrMask() const {
        return this->hasTexture() || this->hasMask();
    }

    // helpers for GrContext, GrTextContext
    int getActiveTextureStageMask() const {
        int mask = 0;
        for (int i = 0; i < kMaxTextures; ++i) {
            if (NULL != fTextures[i]) {
                mask |= 1 << (i + kFirstTextureStage);
            }
        }
        return mask;
    }

    int getActiveMaskStageMask() const {
        int mask = 0;
        for (int i = 0; i < kMaxMasks; ++i) {
            if (NULL != fMaskTextures[i]) {
                mask |= 1 << (i + kFirstMaskStage);
            }
        }
        return mask;
    }
    
    int getActiveStageMask() const {
        return this->getActiveTextureStageMask() |
                this->getActiveMaskStageMask();
    }

    // internal use
    // GrPaint's textures and masks map to the first N stages
    // of GrDrawTarget in that order (textures followed by masks)
    enum {
        kFirstTextureStage = 0,
        kFirstMaskStage = kMaxTextures,
        kTotalStages = kMaxTextures + kMaxMasks,
    };

private:

    GrSamplerState              fTextureSamplers[kMaxTextures];
    GrSamplerState              fMaskSamplers[kMaxMasks];

    GrTexture*      fTextures[kMaxTextures];
    GrTexture*      fMaskTextures[kMaxMasks];

    void resetBlend() {
        fSrcBlendCoeff = kOne_BlendCoeff;
        fDstBlendCoeff = kZero_BlendCoeff;
    }

    void resetOptions() {
        fAntiAlias = false;
        fDither = false;
    }

    void resetColor() {
        fColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff);
    }

    void resetTextures() {
        for (int i = 0; i < kMaxTextures; ++i) {
            this->setTexture(i, NULL);
            fTextureSamplers[i].setClampNoFilter();
        }
    }

    void resetMasks() {
        for (int i = 0; i < kMaxMasks; ++i) {
            this->setMask(i, NULL);
            fMaskSamplers[i].setClampNoFilter();
        }
    }
};

#endif