SkShaderBase.h File Reference

#include "include/core/SkColor.h"
#include "include/core/SkFlattenable.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkSurfaceProps.h"
#include "include/core/SkTypes.h"
#include "include/private/base/SkNoncopyable.h"
#include <cstddef>
#include <cstdint>
#include <optional>
#include <tuple>

Go to the source code of this file.

Classes
class	SkShaders::MatrixRec
class	SkShaderBase
struct	SkShaderBase::GradientInfo
struct	SkShaderBase::ContextRec
class	SkShaderBase::Context

Namespaces
namespace	SkShaders

Macros
#define	SK_ALL_SHADERS(M)
#define	SK_ALL_GRADIENTS(M)
#define	M(type)   k##type,
#define	M(type)   k##type,

Functions
SkShaderBase *	as_SB (SkShader *shader)
const SkShaderBase *	as_SB (const SkShader *shader)
const SkShaderBase *	as_SB (const sk_sp< SkShader > &shader)
void	SkRegisterBlendShaderFlattenable ()
void	SkRegisterColor4ShaderFlattenable ()
void	SkRegisterColorShaderFlattenable ()
void	SkRegisterCoordClampShaderFlattenable ()
void	SkRegisterEmptyShaderFlattenable ()
void	SkRegisterPerlinNoiseShaderFlattenable ()
void	SkRegisterWorkingColorSpaceShaderFlattenable ()

Macro Definition Documentation

M [1/2]

#define M

(

type

)

k##type,

Definition at line 200 of file SkShaderBase.h.

M [2/2]

#define M

(

type

)

k##type,

Definition at line 200 of file SkShaderBase.h.

SK_ALL_GRADIENTS

#define SK_ALL_GRADIENTS

(

M

)

Value:

    M(Conical)              \
    M(Linear)               \
    M(Radial)               \
    M(Sweep)

Definition at line 180 of file SkShaderBase.h.

                   : public SkShader {
public:
    ~SkShaderBase() override;
 
    sk_sp<SkShader> makeInvertAlpha() const;
    sk_sp<SkShader> makeWithCTM(const SkMatrix&) const;  // owns its own ctm
 
    /**
     *  Returns true if the shader is guaranteed to produce only a single color.
     *  Subclasses can override this to allow loop-hoisting optimization.
     */
    virtual bool isConstant() const { return false; }
 
    enum class ShaderType {
#define M(type) k##type,
        SK_ALL_SHADERS(M)
#undef M
    };
 
    virtual ShaderType type() const = 0;
 
    enum class GradientType {
        kNone,
#define M(type) k##type,
        SK_ALL_GRADIENTS(M)
#undef M
    };
 
    /**
     *  If the shader subclass can be represented as a gradient, asGradient
     *  returns the matching GradientType enum (or GradientType::kNone if it
     *  cannot). Also, if info is not null, asGradient populates info with
     *  the relevant (see below) parameters for the gradient.  fColorCount
     *  is both an input and output parameter.  On input, it indicates how
     *  many entries in fColors and fColorOffsets can be used, if they are
     *  non-NULL.  After asGradient has run, fColorCount indicates how
     *  many color-offset pairs there are in the gradient.  If there is
     *  insufficient space to store all of the color-offset pairs, fColors
     *  and fColorOffsets will not be altered.  fColorOffsets specifies
     *  where on the range of 0 to 1 to transition to the given color.
     *  The meaning of fPoint and fRadius is dependent on the type of gradient.
     *
     *  None:
     *      info is ignored.
     *  Color:
     *      fColorOffsets[0] is meaningless.
     *  Linear:
     *      fPoint[0] and fPoint[1] are the end-points of the gradient
     *  Radial:
     *      fPoint[0] and fRadius[0] are the center and radius
     *  Conical:
     *      fPoint[0] and fRadius[0] are the center and radius of the 1st circle
     *      fPoint[1] and fRadius[1] are the center and radius of the 2nd circle
     *  Sweep:
     *      fPoint[0] is the center of the sweep.
     */
    struct GradientInfo {
        int         fColorCount    = 0;        //!< In-out parameter, specifies passed size
                                               //   of fColors/fColorOffsets on input, and
                                               //   actual number of colors/offsets on
                                               //   output.
        SkColor*    fColors        = nullptr;  //!< The colors in the gradient.
        SkScalar*   fColorOffsets  = nullptr;  //!< The unit offset for color transitions.
        SkPoint     fPoint[2];                 //!< Type specific, see above.
        SkScalar    fRadius[2];                //!< Type specific, see above.
        SkTileMode  fTileMode;
        uint32_t    fGradientFlags = 0;        //!< see SkGradientShader::Flags
    };
 
    virtual GradientType asGradient(GradientInfo* info    = nullptr,
                                    SkMatrix* localMatrix = nullptr) const {
        return GradientType::kNone;
    }
 
    enum Flags {
        //!< set if all of the colors will be opaque
        kOpaqueAlpha_Flag = 1 << 0,
    };
 
    /**
     *  ContextRec acts as a parameter bundle for creating Contexts.
     */
    struct ContextRec {
        ContextRec(SkAlpha paintAlpha,
                   const SkShaders::MatrixRec& matrixRec,
                   SkColorType dstColorType,
                   SkColorSpace* dstColorSpace,
                   const SkSurfaceProps& props)
                : fMatrixRec(matrixRec)
                , fDstColorType(dstColorType)
                , fDstColorSpace(dstColorSpace)
                , fProps(props)
                , fPaintAlpha(paintAlpha) {}
 
        static ContextRec Concat(const ContextRec& parentRec, const SkMatrix& localM) {
            return {parentRec.fPaintAlpha,
                    parentRec.fMatrixRec.concat(localM),
                    parentRec.fDstColorType,
                    parentRec.fDstColorSpace,
                    parentRec.fProps};
        }
 
        const SkShaders::MatrixRec fMatrixRec;
        SkColorType                fDstColorType;   // the color type of the dest surface
        SkColorSpace*              fDstColorSpace;  // the color space of the dest surface (if any)
        SkSurfaceProps             fProps;          // props of the dest surface
        SkAlpha                    fPaintAlpha;
 
        bool isLegacyCompatible(SkColorSpace* shadersColorSpace) const;
    };
 
    class Context : public ::SkNoncopyable {
    public:
        Context(const SkShaderBase& shader, const ContextRec&);
 
        virtual ~Context();
 
        /**
         *  Called sometimes before drawing with this shader. Return the type of
         *  alpha your shader will return. The default implementation returns 0.
         *  Your subclass should override if it can (even sometimes) report a
         *  non-zero value, since that will enable various blitters to perform
         *  faster.
         */
        virtual uint32_t getFlags() const { return 0; }
 
        /**
         *  Called for each span of the object being drawn. Your subclass should
         *  set the appropriate colors (with premultiplied alpha) that correspond
         *  to the specified device coordinates.
         */
        virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
 
    protected:
        // Reference to shader, so we don't have to dupe information.
        const SkShaderBase& fShader;
 
        uint8_t         getPaintAlpha() const { return fPaintAlpha; }
        const SkMatrix& getTotalInverse() const { return fTotalInverse; }
 
    private:
        SkMatrix    fTotalInverse;
        uint8_t     fPaintAlpha;
    };
 
    /**
     * Make a context using the memory provided by the arena.
     *
     * @return pointer to context or nullptr if can't be created
     */
    Context* makeContext(const ContextRec&, SkArenaAlloc*) const;
 
    /**
     *  If the shader can represent its "average" luminance in a single color, return true and
     *  if color is not NULL, return that color. If it cannot, return false and ignore the color
     *  parameter.
     *
     *  Note: if this returns true, the returned color will always be opaque, as only the RGB
     *  components are used to compute luminance.
     */
    bool asLuminanceColor(SkColor4f*) const;
 
    /**
     * If this returns false, then we draw nothing (do not fall back to shader context). This should
     * only be called on a root-level effect. It assumes that the initial device coordinates have
     * not yet been seeded.
     */
    [[nodiscard]] bool appendRootStages(const SkStageRec& rec, const SkMatrix& ctm) const;
 
    /**
     * Adds stages to implement this shader. To ensure that the correct input coords are present
     * in r,g MatrixRec::apply() must be called (unless the shader doesn't require it's input
     * coords). The default impl creates shadercontext and calls that (not very efficient).
     */
    virtual bool appendStages(const SkStageRec&, const SkShaders::MatrixRec&) const = 0;
 
    virtual SkImage* onIsAImage(SkMatrix*, SkTileMode[2]) const {
        return nullptr;
    }
 
    virtual SkRuntimeEffect* asRuntimeEffect() const { return nullptr; }
 
    static Type GetFlattenableType() { return kSkShader_Type; }
    Type getFlattenableType() const override { return GetFlattenableType(); }
 
    static sk_sp<SkShaderBase> Deserialize(const void* data, size_t size,
                                             const SkDeserialProcs* procs = nullptr) {
        return sk_sp<SkShaderBase>(static_cast<SkShaderBase*>(
                SkFlattenable::Deserialize(GetFlattenableType(), data, size, procs).release()));
    }
    static void RegisterFlattenables();
 
    /** DEPRECATED. skbug.com/8941
     *  If this shader can be represented by another shader + a localMatrix, return that shader and
     *  the localMatrix. If not, return nullptr and ignore the localMatrix parameter.
     */
    virtual sk_sp<SkShader> makeAsALocalMatrixShader(SkMatrix* localMatrix) const;
 
    static SkMatrix ConcatLocalMatrices(const SkMatrix& parentLM, const SkMatrix& childLM) {
#if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK)  // b/256873449
        return SkMatrix::Concat(childLM, parentLM);
#endif
        return SkMatrix::Concat(parentLM, childLM);
    }
 
protected:
    SkShaderBase();
 
    void flatten(SkWriteBuffer&) const override;
 
#ifdef SK_ENABLE_LEGACY_SHADERCONTEXT
    /**
     * Specialize creating a SkShader context using the supplied allocator.
     * @return pointer to context owned by the arena allocator.
     */
    virtual Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const {
        return nullptr;
    }
#endif
 
    virtual bool onAsLuminanceColor(SkColor4f*) const {
        return false;
    }
 
    friend class SkShaders::MatrixRec;
};
inline SkShaderBase* as_SB(SkShader* shader) {
    return static_cast<SkShaderBase*>(shader);
}
 
inline const SkShaderBase* as_SB(const SkShader* shader) {
    return static_cast<const SkShaderBase*>(shader);
}
 
inline const SkShaderBase* as_SB(const sk_sp<SkShader>& shader) {
    return static_cast<SkShaderBase*>(shader.get());
}
 
void SkRegisterBlendShaderFlattenable();
void SkRegisterColor4ShaderFlattenable();
void SkRegisterColorShaderFlattenable();
void SkRegisterCoordClampShaderFlattenable();
void SkRegisterEmptyShaderFlattenable();
void SkRegisterPerlinNoiseShaderFlattenable();
void SkRegisterWorkingColorSpaceShaderFlattenable();
 
#endif // SkShaderBase_DEFINED

SK_ALL_SHADERS

#define SK_ALL_SHADERS

(

M

)

Value:

    M(Blend)              \
    M(CTM)                \
    M(Color)              \
    M(Color4)             \
    M(ColorFilter)        \
    M(CoordClamp)         \
    M(Empty)              \
    M(GradientBase)       \
    M(Image)              \
    M(LocalMatrix)        \
    M(PerlinNoise)        \
    M(Picture)            \
    M(Runtime)            \
    M(Transform)          \
    M(TriColor)           \
    M(WorkingColorSpace)

Definition at line 162 of file SkShaderBase.h.

Function Documentation

as_SB() [1/3]

const SkShaderBase * as_SB ( const sk_sp< SkShader > &  shader )

inline

Definition at line 420 of file SkShaderBase.h.

                                                                {
    return static_cast<SkShaderBase*>(shader.get());
}

as_SB() [2/3]

const SkShaderBase * as_SB ( const SkShader *  shader )

inline

Definition at line 416 of file SkShaderBase.h.

                                                         {
    return static_cast<const SkShaderBase*>(shader);
}

as_SB() [3/3]

SkShaderBase * as_SB ( SkShader *  shader )

inline

Definition at line 412 of file SkShaderBase.h.

                                             {
    return static_cast<SkShaderBase*>(shader);
}

SkRegisterBlendShaderFlattenable()

void SkRegisterBlendShaderFlattenable

(

)

Definition at line 139 of file SkBlendShader.cpp.

                                        {
    SK_REGISTER_FLATTENABLE(SkBlendShader);
    // Previous name
    SkFlattenable::Register("SkShader_Blend", SkBlendShader::CreateProc);
}

SkRegisterColor4ShaderFlattenable()

void SkRegisterColor4ShaderFlattenable

(

)

Definition at line 94 of file SkColorShader.cpp.

                                         {
    SK_REGISTER_FLATTENABLE(SkColor4Shader);
}

SkRegisterColorShaderFlattenable()

void SkRegisterColorShaderFlattenable

(

)

Definition at line 98 of file SkColorShader.cpp.

                                        {
    SK_REGISTER_FLATTENABLE(SkColorShader);
}

SkRegisterCoordClampShaderFlattenable()

void SkRegisterCoordClampShaderFlattenable

(

)

Definition at line 52 of file SkCoordClampShader.cpp.

                                             {
    SK_REGISTER_FLATTENABLE(SkCoordClampShader);
 
    // Previous name
    SkFlattenable::Register("SkShader_CoordClamp", SkCoordClampShader::CreateProc);
}

SkRegisterEmptyShaderFlattenable()

void SkRegisterEmptyShaderFlattenable

(

)

Definition at line 22 of file SkEmptyShader.cpp.

                                        {
    SK_REGISTER_FLATTENABLE(SkEmptyShader);
}

SkRegisterPerlinNoiseShaderFlattenable()

void SkRegisterPerlinNoiseShaderFlattenable

(

)

Definition at line 277 of file SkPerlinNoiseShaderImpl.cpp.

                                              {
    SK_REGISTER_FLATTENABLE(SkPerlinNoiseShader);
    // Previous name
    SkFlattenable::Register("SkPerlinNoiseShaderImpl", SkPerlinNoiseShader::CreateProc);
}

SkRegisterWorkingColorSpaceShaderFlattenable()

void SkRegisterWorkingColorSpaceShaderFlattenable

(

)

Definition at line 75 of file SkWorkingColorSpaceShader.cpp.

                                                    {
    SK_REGISTER_FLATTENABLE(SkWorkingColorSpaceShader);
}