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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrTextureDomainEffect_DEFINED
#define GrTextureDomainEffect_DEFINED
#include "GrSingleTextureEffect.h"
class GrGLTextureDomainEffect;
struct SkRect;
/**
* Limits a texture's lookup coordinates to a domain. Samples outside the domain are either clamped
* the edge of the domain or result in a vec4 of zeros. The domain is clipped to normalized texture
* coords ([0,1]x[0,1] square). Bilinear filtering can cause texels outside the domain to affect the
* read value unless the caller considers this when calculating the domain. TODO: This should be a
* helper that can assist an effect rather than effect unto itself.
*/
class GrTextureDomainEffect : public GrSingleTextureEffect {
public:
/**
* If SkShader::kDecal_TileMode sticks then this enum could be replaced by SkShader::TileMode.
* We could also consider replacing/augmenting Decal mode with Border mode where the color
* outside of the domain is user-specifiable. Decal mode currently has a hard (non-lerped)
* transition between the border and the interior.
*/
enum WrapMode {
kClamp_WrapMode,
kDecal_WrapMode,
};
static GrEffectRef* Create(GrTexture*,
const SkMatrix&,
const SkRect& domain,
WrapMode,
bool bilerp,
CoordsType = kLocal_CoordsType);
virtual ~GrTextureDomainEffect();
static const char* Name() { return "TextureDomain"; }
typedef GrGLTextureDomainEffect GLEffect;
virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
const SkRect& domain() const { return fTextureDomain; }
WrapMode wrapMode() const { return fWrapMode; }
/* Computes a domain that bounds all the texels in texelRect. Note that with bilerp enabled
texels neighboring the domain may be read. */
static const SkRect MakeTexelDomain(const GrTexture* texture, const SkIRect& texelRect) {
SkScalar wInv = SK_Scalar1 / texture->width();
SkScalar hInv = SK_Scalar1 / texture->height();
SkRect result = {
texelRect.fLeft * wInv,
texelRect.fTop * hInv,
texelRect.fRight * wInv,
texelRect.fBottom * hInv
};
return result;
}
protected:
WrapMode fWrapMode;
SkRect fTextureDomain;
private:
GrTextureDomainEffect(GrTexture*,
const SkMatrix&,
const SkRect& domain,
WrapMode,
bool bilerp,
CoordsType type);
virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
GR_DECLARE_EFFECT_TEST;
typedef GrSingleTextureEffect INHERITED;
};
#endif
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