/*

 * Copyright 2006 The Android Open Source Project

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#ifndef SkShader_DEFINED

#define SkShader_DEFINED

#include "include/core/SkColor.h"

#include "include/core/SkFlattenable.h"

#include "include/core/SkRefCnt.h"

#include "include/private/base/SkAPI.h"

class SkBlender;

class SkColorFilter;

class SkColorSpace;

class SkImage;

class SkMatrix;

enum class SkBlendMode;

enum class SkTileMode;

struct SkRect;

struct SkSamplingOptions;

/** \class SkShader

 *

 *  Shaders specify the source color(s) for what is being drawn. If a paint

 *  has no shader, then the paint's color is used. If the paint has a

 *  shader, then the shader's color(s) are use instead, but they are

 *  modulated by the paint's alpha. This makes it easy to create a shader

 *  once (e.g. bitmap tiling or gradient) and then change its transparency

 *  w/o having to modify the original shader... only the paint's alpha needs

 *  to be modified.

 */

class SK_API SkShader : public SkFlattenable {

public:

    /**

     *  Returns true if the shader is guaranteed to produce only opaque

     *  colors, subject to the SkPaint using the shader to apply an opaque

     *  alpha value. Subclasses should override this to allow some

     *  optimizations.

     */

    virtual bool isOpaque() const { return false; }

    /**

     *  Iff this shader is backed by a single SkImage, return its ptr (the caller must ref this

     *  if they want to keep it longer than the lifetime of the shader). If not, return nullptr.

     */

    SkImage* isAImage(SkMatrix* localMatrix, SkTileMode xy[2]) const;

    bool isAImage() const {

        return this->isAImage(nullptr, (SkTileMode*)nullptr) != nullptr;

    }

    //////////////////////////////////////////////////////////////////////////

    //  Methods to create combinations or variants of shaders

    /**

     *  Return a shader that will apply the specified localMatrix to this shader.

     *  The specified matrix will be applied before any matrix associated with this shader.

     */

    sk_sp<SkShader> makeWithLocalMatrix(const SkMatrix&) const;

    /**

     *  Create a new shader that produces the same colors as invoking this shader and then applying

     *  the colorfilter.

     */

    sk_sp<SkShader> makeWithColorFilter(sk_sp<SkColorFilter>) const;

    /**

     *  Return a shader that will compute this shader in a specific color space.

     *  By default, all shaders operate in the destination (surface) color space.

     *  The results of a shader are still always converted to the destination - this

     *  API has no impact on simple shaders or images. Primarily, it impacts shaders

     *  that perform mathematical operations, like Blend shaders, or runtime shaders.

     */

    sk_sp<SkShader> makeWithWorkingColorSpace(sk_sp<SkColorSpace>) const;

private:

    SkShader() = default;

    friend class SkShaderBase;

    using INHERITED = SkFlattenable;

};

namespace SkShaders {

SK_API sk_sp<SkShader> Empty();

SK_API sk_sp<SkShader> Color(SkColor);

SK_API sk_sp<SkShader> Color(const SkColor4f&, sk_sp<SkColorSpace>);

SK_API sk_sp<SkShader> Blend(SkBlendMode mode, sk_sp<SkShader> dst, sk_sp<SkShader> src);

SK_API sk_sp<SkShader> Blend(sk_sp<SkBlender>, sk_sp<SkShader> dst, sk_sp<SkShader> src);

SK_API sk_sp<SkShader> CoordClamp(sk_sp<SkShader>, const SkRect& subset);

/*

 * Create an SkShader that will sample the 'image'. This is equivalent to SkImage::makeShader.

 */

SK_API sk_sp<SkShader> Image(sk_sp<SkImage> image,

                             SkTileMode tmx, SkTileMode tmy,

                             const SkSamplingOptions& options,

                             const SkMatrix* localMatrix = nullptr);

/*

 * Create an SkShader that will sample 'image' with minimal processing. This is equivalent to

 * SkImage::makeRawShader.

 */

SK_API sk_sp<SkShader> RawImage(sk_sp<SkImage> image,

                                SkTileMode tmx, SkTileMode tmy,

                                const SkSamplingOptions& options,

                                const SkMatrix* localMatrix = nullptr);

}

#endif