src/gpu/GrTextureAdjuster.h

/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrTextureAdjuster_DEFINED
#define GrTextureAdjuster_DEFINED

#include "GrTextureProducer.h"
#include "GrTextureProxy.h"
#include "SkTLazy.h"

/**
 * Base class for sources that start out as textures. Optionally allows for a content area subrect.
 * The intent is not to use content area for subrect rendering. Rather, the pixels outside the
 * content area have undefined values and shouldn't be read *regardless* of filtering mode or
 * the SkCanvas::SrcRectConstraint used for subrect draws.
 */
class GrTextureAdjuster : public GrTextureProducer {
public:
    /** Makes the subset of the texture safe to use with the given texture parameters. If the copy's
        size does not match subset's dimensions then the contents are scaled to fit the copy.*/
    sk_sp<GrTextureProxy> refTextureProxySafeForParams(const GrSamplerState&,
                                                       SkScalar scaleAdjust[2]);

    std::unique_ptr<GrFragmentProcessor> createFragmentProcessor(
            const SkMatrix& textureMatrix,
            const SkRect& constraintRect,
            FilterConstraint,
            bool coordsLimitedToConstraintRect,
            const GrSamplerState::Filter* filterOrNullForBicubic,
            SkColorSpace* dstColorSpace) override;

    // We do not ref the texture nor the colorspace, so the caller must keep them in scope while
    // this Adjuster is alive.
    GrTextureAdjuster(GrContext*, sk_sp<GrTextureProxy>, SkAlphaType, uint32_t uniqueID,
                      SkColorSpace*);

protected:
    SkAlphaType alphaType() const override { return fAlphaType; }
    void makeCopyKey(const CopyParams& params, GrUniqueKey* copyKey,
                     SkColorSpace* dstColorSpace) override;
    void didCacheCopy(const GrUniqueKey& copyKey) override;

    GrTextureProxy* originalProxy() const { return fOriginal.get(); }
    sk_sp<GrTextureProxy> originalProxyRef() const { return fOriginal; }

private:
    GrContext*            fContext;
    sk_sp<GrTextureProxy> fOriginal;
    SkAlphaType           fAlphaType;
    SkColorSpace*         fColorSpace;
    uint32_t              fUniqueID;

    sk_sp<GrTextureProxy> refTextureProxyCopy(const CopyParams &copyParams, bool willBeMipped);

    typedef GrTextureProducer INHERITED;
};

#endif