SkLocalMatrixShader.h

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/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef SkLocalMatrixShader_DEFINED
#define SkLocalMatrixShader_DEFINED
 
#include "include/core/SkFlattenable.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkShader.h"
#include "include/core/SkTypes.h"
#include "src/shaders/SkShaderBase.h"
 
#include <type_traits>
#include <utility>
 
class SkArenaAlloc;
class SkImage;
class SkReadBuffer;
class SkWriteBuffer;
enum class SkTileMode;
struct SkStageRec;
 
class SkLocalMatrixShader final : public SkShaderBase {
public:
    template <typename T, typename... Args>
    static std::enable_if_t<std::is_base_of_v<SkShader, T>, sk_sp<SkShader>>
    MakeWrapped(const SkMatrix* localMatrix, Args&&... args) {
        auto t = sk_make_sp<T>(std::forward<Args>(args)...);
        if (localMatrix) {
            return t->makeWithLocalMatrix(*localMatrix);
        }
        return t;
    }
 
    SkLocalMatrixShader(sk_sp<SkShader> wrapped, const SkMatrix& localMatrix)
            : fLocalMatrix(localMatrix), fWrappedShader(std::move(wrapped)) {}
 
    bool isOpaque() const override { return as_SB(fWrappedShader)->isOpaque(); }
 
    bool isConstant() const override;
    GradientType asGradient(GradientInfo* info, SkMatrix* localMatrix) const override;
    ShaderType type() const override { return ShaderType::kLocalMatrix; }
 
    sk_sp<SkShader> makeAsALocalMatrixShader(SkMatrix* localMatrix) const override {
        if (localMatrix) {
            *localMatrix = fLocalMatrix;
        }
        return fWrappedShader;
    }
 
    const SkMatrix& localMatrix() const { return fLocalMatrix; }
    sk_sp<SkShader> wrappedShader() const { return fWrappedShader; }
 
protected:
    void flatten(SkWriteBuffer&) const override;
 
#ifdef SK_ENABLE_LEGACY_SHADERCONTEXT
    Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const override;
#endif
 
    SkImage* onIsAImage(SkMatrix* matrix, SkTileMode* mode) const override;
 
    bool appendStages(const SkStageRec&, const SkShaders::MatrixRec&) const override;
 
private:
    SK_FLATTENABLE_HOOKS(SkLocalMatrixShader)
 
    SkMatrix fLocalMatrix;
    sk_sp<SkShader> fWrappedShader;
};
 
/**
 *  Replaces the CTM when used. Created to support clipShaders, which have to be evaluated
 *  using the CTM that was present at the time they were specified (which may be different
 *  from the CTM at the time something is drawn through the clip.
 */
class SkCTMShader final : public SkShaderBase {
public:
    SkCTMShader(sk_sp<SkShader> proxy, const SkMatrix& ctm);
 
    bool isOpaque() const override { return fProxyShader->isOpaque(); }
 
    bool isConstant() const override;
    GradientType asGradient(GradientInfo* info, SkMatrix* localMatrix) const override;
 
    ShaderType type() const override { return ShaderType::kCTM; }
 
    const SkMatrix& ctm() const { return fCTM; }
    sk_sp<SkShader> proxyShader() const { return fProxyShader; }
 
protected:
    void flatten(SkWriteBuffer&) const override { SkASSERT(false); }
 
    bool appendStages(const SkStageRec& rec, const SkShaders::MatrixRec&) const override;
 
private:
    SK_FLATTENABLE_HOOKS(SkCTMShader)
 
    sk_sp<SkShader> fProxyShader;
    SkMatrix fCTM;
};
 
#endif