| /* |
| * 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 "SkBitmap.h" |
| #include "SkFlattenable.h" |
| #include "SkImageInfo.h" |
| #include "SkMask.h" |
| #include "SkMatrix.h" |
| #include "SkPaint.h" |
| #include "../gpu/GrColor.h" |
| |
| class SkColorFilter; |
| class SkPath; |
| class SkPicture; |
| class SkXfermode; |
| 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 { |
| public: |
| SkShader(const SkMatrix* localMatrix = NULL); |
| virtual ~SkShader(); |
| |
| /** |
| * Returns the local matrix. |
| * |
| * FIXME: This can be incorrect for a Shader with its own local matrix |
| * that is also wrapped via CreateLocalMatrixShader. |
| */ |
| const SkMatrix& getLocalMatrix() const { return fLocalMatrix; } |
| |
| enum TileMode { |
| /** replicate the edge color if the shader draws outside of its |
| * original bounds |
| */ |
| kClamp_TileMode, |
| |
| /** repeat the shader's image horizontally and vertically */ |
| kRepeat_TileMode, |
| |
| /** repeat the shader's image horizontally and vertically, alternating |
| * mirror images so that adjacent images always seam |
| */ |
| kMirror_TileMode, |
| |
| #if 0 |
| /** only draw within the original domain, return 0 everywhere else */ |
| kDecal_TileMode, |
| #endif |
| }; |
| |
| enum { |
| kTileModeCount = kMirror_TileMode + 1 |
| }; |
| |
| // override these in your subclass |
| |
| enum Flags { |
| //!< set if all of the colors will be opaque |
| kOpaqueAlpha_Flag = 1 << 0, |
| |
| /** set if the spans only vary in X (const in Y). |
| e.g. an Nx1 bitmap that is being tiled in Y, or a linear-gradient |
| that varies from left-to-right. This flag specifies this for |
| shadeSpan(). |
| */ |
| kConstInY32_Flag = 1 << 1, |
| |
| /** hint for the blitter that 4f is the preferred shading mode. |
| */ |
| kPrefers4f_Flag = 1 << 2, |
| }; |
| |
| /** |
| * 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; } |
| |
| /** |
| * ContextRec acts as a parameter bundle for creating Contexts. |
| */ |
| struct ContextRec { |
| enum DstType { |
| kPMColor_DstType, // clients prefer shading into PMColor dest |
| kPM4f_DstType, // clients prefer shading into PM4f dest |
| }; |
| |
| ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM, |
| DstType dstType) |
| : fPaint(&paint) |
| , fMatrix(&matrix) |
| , fLocalMatrix(localM) |
| , fPreferredDstType(dstType) {} |
| |
| const SkPaint* fPaint; // the current paint associated with the draw |
| const SkMatrix* fMatrix; // the current matrix in the canvas |
| const SkMatrix* fLocalMatrix; // optional local matrix |
| const DstType fPreferredDstType; // the "natural" client dest type |
| }; |
| |
| class Context : public ::SkNoncopyable { |
| public: |
| Context(const SkShader& 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; |
| |
| virtual void shadeSpan4f(int x, int y, SkPM4f[], int count); |
| |
| /** |
| * The const void* ctx is only const because all the implementations are const. |
| * This can be changed to non-const if a new shade proc needs to change the ctx. |
| */ |
| typedef void (*ShadeProc)(const void* ctx, int x, int y, SkPMColor[], int count); |
| virtual ShadeProc asAShadeProc(void** ctx); |
| |
| /** |
| * Similar to shadeSpan, but only returns the alpha-channel for a span. |
| * The default implementation calls shadeSpan() and then extracts the alpha |
| * values from the returned colors. |
| */ |
| virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count); |
| |
| // Notification from blitter::blitMask in case we need to see the non-alpha channels |
| virtual void set3DMask(const SkMask*) {} |
| |
| protected: |
| // Reference to shader, so we don't have to dupe information. |
| const SkShader& fShader; |
| |
| enum MatrixClass { |
| kLinear_MatrixClass, // no perspective |
| kFixedStepInX_MatrixClass, // fast perspective, need to call fixedStepInX() each |
| // scanline |
| kPerspective_MatrixClass // slow perspective, need to mappoints each pixel |
| }; |
| static MatrixClass ComputeMatrixClass(const SkMatrix&); |
| |
| uint8_t getPaintAlpha() const { return fPaintAlpha; } |
| const SkMatrix& getTotalInverse() const { return fTotalInverse; } |
| MatrixClass getInverseClass() const { return (MatrixClass)fTotalInverseClass; } |
| const SkMatrix& getCTM() const { return fCTM; } |
| private: |
| SkMatrix fCTM; |
| SkMatrix fTotalInverse; |
| uint8_t fPaintAlpha; |
| uint8_t fTotalInverseClass; |
| |
| typedef SkNoncopyable INHERITED; |
| }; |
| |
| /** |
| * Create the actual object that does the shading. |
| * Size of storage must be >= contextSize. |
| */ |
| Context* createContext(const ContextRec&, void* storage) const; |
| |
| /** |
| * Return the size of a Context returned by createContext. |
| * |
| * Override this if your subclass overrides createContext, to return the correct size of |
| * your subclass' context. |
| */ |
| virtual size_t contextSize(const ContextRec&) const; |
| |
| /** |
| * Returns true if this shader is just a bitmap, and if not null, returns the bitmap, |
| * localMatrix, and tilemodes. If this is not a bitmap, returns false and ignores the |
| * out-parameters. |
| */ |
| bool isABitmap(SkBitmap* outTexture, SkMatrix* outMatrix, TileMode xy[2]) const { |
| return this->onIsABitmap(outTexture, outMatrix, xy); |
| } |
| |
| bool isABitmap() const { |
| return this->isABitmap(nullptr, 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 { |
| kNone_GradientType, |
| kColor_GradientType, |
| kLinear_GradientType, |
| kRadial_GradientType, |
| kSweep_GradientType, |
| kConical_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. |
| TileMode fTileMode; //!< The tile mode used. |
| uint32_t fGradientFlags; //!< see SkGradientShader::Flags |
| }; |
| |
| virtual GradientType asAGradient(GradientInfo* info) const; |
| |
| /** |
| * If the shader subclass is composed of two shaders, return true, and if rec is not NULL, |
| * fill it out with info about the shader. |
| * |
| * These are bare pointers; the ownership and reference count are unchanged. |
| */ |
| |
| struct ComposeRec { |
| const SkShader* fShaderA; |
| const SkShader* fShaderB; |
| const SkXfermode* fMode; |
| }; |
| |
| virtual bool asACompose(ComposeRec*) const { return false; } |
| |
| |
| /** |
| * Returns a GrFragmentProcessor that implements the shader for the GPU backend. NULL is |
| * returned if there is no GPU implementation. |
| * |
| * The GPU device does not call SkShader::createContext(), instead we pass the view matrix, |
| * local matrix, and filter quality directly. |
| * |
| * The GrContext may be used by the to create textures that are required by the returned |
| * processor. |
| * |
| * The returned GrFragmentProcessor should expect an unpremultiplied input color and |
| * produce a premultiplied output. |
| */ |
| virtual const GrFragmentProcessor* asFragmentProcessor(GrContext*, |
| const SkMatrix& viewMatrix, |
| const SkMatrix* localMatrix, |
| SkFilterQuality) 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(SkColor*) const; |
| |
| #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK |
| /** |
| * If the shader is a custom shader which has data the caller might want, call this function |
| * to get that data. |
| */ |
| virtual bool asACustomShader(void** /* customData */) const { return false; } |
| #endif |
| |
| ////////////////////////////////////////////////////////////////////////// |
| // 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. |
| */ |
| SkShader* newWithLocalMatrix(const SkMatrix&) const; |
| |
| /** |
| * Create a new shader that produces the same colors as invoking this shader and then applying |
| * the colorfilter. |
| */ |
| SkShader* newWithColorFilter(SkColorFilter*) const; |
| |
| ////////////////////////////////////////////////////////////////////////// |
| // Factory methods for stock shaders |
| |
| /** |
| * Call this to create a new "empty" shader, that will not draw anything. |
| */ |
| static SkShader* CreateEmptyShader(); |
| |
| /** |
| * Call this to create a new shader that just draws the specified color. This should always |
| * draw the same as a paint with this color (and no shader). |
| */ |
| static SkShader* CreateColorShader(SkColor); |
| |
| static SkShader* CreateComposeShader(SkShader* dst, SkShader* src, SkXfermode::Mode); |
| |
| /** |
| * Create a new compose shader, given shaders dst, src, and a combining xfermode mode. |
| * The xfermode is called with the output of the two shaders, and its output is returned. |
| * If xfer is null, SkXfermode::kSrcOver_Mode is assumed. |
| * |
| * Ownership of the shaders, and the xfermode if not null, is not transfered, so the caller |
| * is still responsible for managing its reference-count for those objects. |
| */ |
| static SkShader* CreateComposeShader(SkShader* dst, SkShader* src, SkXfermode* xfer); |
| |
| /** Call this to create a new shader that will draw with the specified bitmap. |
| * |
| * If the bitmap cannot be used (e.g. has no pixels, or its dimensions |
| * exceed implementation limits (currently at 64K - 1)) then SkEmptyShader |
| * may be returned. |
| * |
| * If the src is kA8_Config then that mask will be colorized using the color on |
| * the paint. |
| * |
| * @param src The bitmap to use inside the shader |
| * @param tmx The tiling mode to use when sampling the bitmap in the x-direction. |
| * @param tmy The tiling mode to use when sampling the bitmap in the y-direction. |
| * @return Returns a new shader object. Note: this function never returns null. |
| */ |
| static SkShader* CreateBitmapShader(const SkBitmap& src, |
| TileMode tmx, TileMode tmy, |
| const SkMatrix* localMatrix = NULL); |
| |
| // NOTE: You can create an SkImage Shader with SkImage::newShader(). |
| |
| /** Call this to create a new shader that will draw with the specified picture. |
| * |
| * @param src The picture to use inside the shader (if not NULL, its ref count |
| * is incremented). The SkPicture must not be changed after |
| * successfully creating a picture shader. |
| * @param tmx The tiling mode to use when sampling the bitmap in the x-direction. |
| * @param tmy The tiling mode to use when sampling the bitmap in the y-direction. |
| * @param tile The tile rectangle in picture coordinates: this represents the subset |
| * (or superset) of the picture used when building a tile. It is not |
| * affected by localMatrix and does not imply scaling (only translation |
| * and cropping). If null, the tile rect is considered equal to the picture |
| * bounds. |
| * @return Returns a new shader object. Note: this function never returns null. |
| */ |
| static SkShader* CreatePictureShader(const SkPicture* src, |
| TileMode tmx, TileMode tmy, |
| const SkMatrix* localMatrix, |
| const SkRect* tile); |
| |
| /** |
| * If this shader can be represented by another shader + a localMatrix, return that shader |
| * and, if not NULL, the localMatrix. If not, return NULL and ignore the localMatrix parameter. |
| * |
| * Note: the returned shader (if not NULL) will have been ref'd, and it is the responsibility |
| * of the caller to balance that with unref() when they are done. |
| */ |
| virtual SkShader* refAsALocalMatrixShader(SkMatrix* localMatrix) const; |
| |
| SK_TO_STRING_VIRT() |
| SK_DEFINE_FLATTENABLE_TYPE(SkShader) |
| |
| protected: |
| void flatten(SkWriteBuffer&) const override; |
| |
| bool computeTotalInverse(const ContextRec&, SkMatrix* totalInverse) const; |
| |
| /** |
| * Your subclass must also override contextSize() if it overrides onCreateContext(). |
| * Base class impl returns NULL. |
| */ |
| virtual Context* onCreateContext(const ContextRec&, void* storage) const; |
| |
| virtual bool onAsLuminanceColor(SkColor*) const { |
| return false; |
| } |
| |
| virtual bool onIsABitmap(SkBitmap*, SkMatrix*, TileMode[2]) const { |
| return false; |
| } |
| |
| private: |
| // This is essentially const, but not officially so it can be modified in |
| // constructors. |
| SkMatrix fLocalMatrix; |
| |
| // So the SkLocalMatrixShader can whack fLocalMatrix in its SkReadBuffer constructor. |
| friend class SkLocalMatrixShader; |
| friend class SkBitmapProcShader; // for computeTotalInverse() |
| |
| typedef SkFlattenable INHERITED; |
| }; |
| |
| #endif |
