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* 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/SkBlendMode.h"
#include "include/core/SkColor.h"
#include "include/core/SkFilterQuality.h"
#include "include/core/SkFlattenable.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkTileMode.h"
class SkArenaAlloc;
class SkBitmap;
class SkColorFilter;
class SkColorSpace;
class SkImage;
class SkPath;
class SkPicture;
class SkRasterPipeline;
class GrContext;
class GrFragmentProcessor;
/** \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 {
* 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;
* If the shader subclass can be represented as a gradient, asAGradient
* returns the matching GradientType enum (or kNone_GradientType if it
* cannot). Also, if info is not null, asAGradient 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 asAGradient 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 dependant 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.
enum GradientType {
kLast_GradientType = kConical_GradientType,
struct GradientInfo {
int fColorCount; //!< In-out parameter, specifies passed size
// of fColors/fColorOffsets on input, and
// actual number of colors/offsets on
// output.
SkColor* fColors; //!< The colors in the gradient.
SkScalar* fColorOffsets; //!< 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; //!< see SkGradientShader::Flags
virtual GradientType asAGradient(GradientInfo* info) const;
// 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;
SkShader() = default;
friend class SkShaderBase;
typedef SkFlattenable INHERITED;
class SK_API SkShaders {
static sk_sp<SkShader> Empty();
static sk_sp<SkShader> Color(SkColor);
static sk_sp<SkShader> Color(const SkColor4f&, sk_sp<SkColorSpace>);
static sk_sp<SkShader> Blend(SkBlendMode mode, sk_sp<SkShader> dst, sk_sp<SkShader> src);
static sk_sp<SkShader> Lerp(float t, sk_sp<SkShader> dst, sk_sp<SkShader> src);
SkShaders() = delete;