mirror of https://github.com/axmolengine/axmol.git
313 lines
13 KiB
C
313 lines
13 KiB
C
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/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkShader_DEFINED
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#define SkShader_DEFINED
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#include "SkBitmap.h"
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#include "SkFlattenable.h"
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#include "SkMask.h"
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#include "SkMatrix.h"
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#include "SkPaint.h"
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class SkPath;
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/** \class SkShader
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*
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* SkShader is the based class for objects that return horizontal spans of
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* colors during drawing. A subclass of SkShader is installed in a SkPaint
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* calling paint.setShader(shader). After that any object (other than a bitmap)
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* that is drawn with that paint will get its color(s) from the shader.
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*/
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class SK_API SkShader : public SkFlattenable {
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public:
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SkShader();
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virtual ~SkShader();
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/**
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* Return true if the shader has a non-identity local matrix.
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* @param localM Optional: If not null, return the shader's local matrix
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* @return true if the shader has a non-identity local matrix.
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*/
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bool getLocalMatrix(SkMatrix* localM) const;
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/**
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* Set the shader's local matrix.
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* @param localM The shader's new local matrix.
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*/
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void setLocalMatrix(const SkMatrix& localM);
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/**
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* Reset the shader's local matrix to identity.
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*/
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void resetLocalMatrix();
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enum TileMode {
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kClamp_TileMode, //!< replicate the edge color if the shader draws outside of its original bounds
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kRepeat_TileMode, //!< repeat the shader's image horizontally and vertically
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kMirror_TileMode, //!< repeat the shader's image horizontally and vertically, alternating mirror images so that adjacent images always seam
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kTileModeCount
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};
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// override these in your subclass
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enum Flags {
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//!< set if all of the colors will be opaque
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kOpaqueAlpha_Flag = 0x01,
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//! set if this shader's shadeSpan16() method can be called
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kHasSpan16_Flag = 0x02,
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/** Set this bit if the shader's native data type is instrinsically 16
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bit, meaning that calling the 32bit shadeSpan() entry point will
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mean the the impl has to up-sample 16bit data into 32bit. Used as a
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a means of clearing a dither request if the it will have no effect
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*/
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kIntrinsicly16_Flag = 0x04,
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/** set (after setContext) if the spans only vary in X (const in Y).
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e.g. an Nx1 bitmap that is being tiled in Y, or a linear-gradient
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that varies from left-to-right. This flag specifies this for
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shadeSpan().
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*/
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kConstInY32_Flag = 0x08,
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/** same as kConstInY32_Flag, but is set if this is true for shadeSpan16
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which may not always be the case, since shadeSpan16 may be
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predithered, which would mean it was not const in Y, even though
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the 32bit shadeSpan() would be const.
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*/
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kConstInY16_Flag = 0x10
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};
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/**
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* Called sometimes before drawing with this shader. Return the type of
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* alpha your shader will return. The default implementation returns 0.
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* Your subclass should override if it can (even sometimes) report a
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* non-zero value, since that will enable various blitters to perform
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* faster.
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*/
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virtual uint32_t getFlags() { return 0; }
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/**
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* Return the alpha associated with the data returned by shadeSpan16(). If
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* kHasSpan16_Flag is not set, this value is meaningless.
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*/
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virtual uint8_t getSpan16Alpha() const { return fPaintAlpha; }
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/**
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* Called once before drawing, with the current paint and device matrix.
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* Return true if your shader supports these parameters, or false if not.
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* If false is returned, nothing will be drawn.
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*/
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virtual bool setContext(const SkBitmap& device, const SkPaint& paint,
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const SkMatrix& matrix);
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/**
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* Called for each span of the object being drawn. Your subclass should
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* set the appropriate colors (with premultiplied alpha) that correspond
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* to the specified device coordinates.
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*/
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virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
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/**
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* Called only for 16bit devices when getFlags() returns
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* kOpaqueAlphaFlag | kHasSpan16_Flag
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*/
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virtual void shadeSpan16(int x, int y, uint16_t[], int count);
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/**
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* Similar to shadeSpan, but only returns the alpha-channel for a span.
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* The default implementation calls shadeSpan() and then extracts the alpha
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* values from the returned colors.
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*/
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virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count);
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/**
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* Helper function that returns true if this shader's shadeSpan16() method
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* can be called.
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*/
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bool canCallShadeSpan16() {
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return SkShader::CanCallShadeSpan16(this->getFlags());
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}
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/**
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* Helper to check the flags to know if it is legal to call shadeSpan16()
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*/
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static bool CanCallShadeSpan16(uint32_t flags) {
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return (flags & kHasSpan16_Flag) != 0;
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}
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/**
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* Called before a session using the shader begins. Some shaders override
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* this to defer some of their work (like calling bitmap.lockPixels()).
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* Must be balanced by a call to endSession.
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*/
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virtual void beginSession();
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virtual void endSession();
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/**
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Gives method bitmap should be read to implement a shader.
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Also determines number and interpretation of "extra" parameters returned
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by asABitmap
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*/
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enum BitmapType {
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kNone_BitmapType, //<! Shader is not represented as a bitmap
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kDefault_BitmapType,//<! Access bitmap using local coords transformed
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// by matrix. No extras
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kRadial_BitmapType, //<! Access bitmap by transforming local coordinates
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// by the matrix and taking the distance of result
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// from (0,0) as bitmap column. Bitmap is 1 pixel
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// tall. No extras
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kSweep_BitmapType, //<! Access bitmap by transforming local coordinates
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// by the matrix and taking the angle of result
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// to (0,0) as bitmap x coord, where angle = 0 is
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// bitmap left edge of bitmap = 2pi is the
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// right edge. Bitmap is 1 pixel tall. No extras
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kTwoPointRadial_BitmapType,
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//<! Matrix transforms to space where (0,0) is
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// the center of the starting circle. The second
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// circle will be centered (x, 0) where x may be
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// 0. The post-matrix space is normalized such
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// that 1 is the second radius - first radius.
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// Three extra parameters are returned:
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// 0: x-offset of second circle center
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// to first.
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// 1: radius of first circle in post-matrix
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// space
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// 2: the second radius minus the first radius
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// in pre-transformed space.
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kLast_BitmapType = kTwoPointRadial_BitmapType
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};
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/** Optional methods for shaders that can pretend to be a bitmap/texture
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to play along with opengl. Default just returns kNone_BitmapType and
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ignores the out parameters.
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@param outTexture if non-NULL will be the bitmap representing the shader
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after return.
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@param outMatrix if non-NULL will be the matrix to apply to vertices
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to access the bitmap after return.
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@param xy if non-NULL will be the tile modes that should be
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used to access the bitmap after return.
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@param twoPointRadialParams Two extra return values needed for two point
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radial bitmaps. The first is the x-offset of
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the second point and the second is the radius
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about the first point.
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*/
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virtual BitmapType asABitmap(SkBitmap* outTexture, SkMatrix* outMatrix,
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TileMode xy[2], SkScalar* twoPointRadialParams) const;
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/**
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* If the shader subclass can be represented as a gradient, asAGradient
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* returns the matching GradientType enum (or kNone_GradientType if it
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* cannot). Also, if info is not null, asAGradient populates info with
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* the relevant (see below) parameters for the gradient. fColorCount
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* is both an input and output parameter. On input, it indicates how
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* many entries in fColors and fColorOffsets can be used, if they are
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* non-NULL. After asAGradient has run, fColorCount indicates how
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* many color-offset pairs there are in the gradient. If there is
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* insufficient space to store all of the color-offset pairs, fColors
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* and fColorOffsets will not be altered. fColorOffsets specifies
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* where on the range of 0 to 1 to transition to the given color.
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* The meaning of fPoint and fRadius is dependant on the type of gradient.
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*
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* None:
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* info is ignored.
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* Color:
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* fColorOffsets[0] is meaningless.
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* Linear:
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* fPoint[0] and fPoint[1] are the end-points of the gradient
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* Radial:
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* fPoint[0] and fRadius[0] are the center and radius
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* Radial2:
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* fPoint[0] and fRadius[0] are the center and radius of the 1st circle
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* fPoint[1] and fRadius[1] are the center and radius of the 2nd circle
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* Sweep:
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* fPoint[0] is the center of the sweep.
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*/
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enum GradientType {
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kNone_GradientType,
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kColor_GradientType,
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kLinear_GradientType,
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kRadial_GradientType,
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kRadial2_GradientType,
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kSweep_GradientType,
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kLast_GradientType = kSweep_GradientType
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};
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struct GradientInfo {
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int fColorCount; //!< In-out parameter, specifies passed size
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// of fColors/fColorOffsets on input, and
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// actual number of colors/offsets on
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// output.
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SkColor* fColors; //!< The colors in the gradient.
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SkScalar* fColorOffsets; //!< The unit offset for color transitions.
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SkPoint fPoint[2]; //!< Type specific, see above.
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SkScalar fRadius[2]; //!< Type specific, see above.
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TileMode fTileMode; //!< The tile mode used.
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};
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virtual GradientType asAGradient(GradientInfo* info) const;
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//////////////////////////////////////////////////////////////////////////
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// Factory methods for stock shaders
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/** Call this to create a new shader that will draw with the specified bitmap.
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@param src The bitmap to use inside the shader
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@param tmx The tiling mode to use when sampling the bitmap in the x-direction.
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@param tmy The tiling mode to use when sampling the bitmap in the y-direction.
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@return Returns a new shader object. Note: this function never returns null.
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*/
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static SkShader* CreateBitmapShader(const SkBitmap& src,
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TileMode tmx, TileMode tmy);
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virtual void flatten(SkFlattenableWriteBuffer& );
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protected:
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enum MatrixClass {
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kLinear_MatrixClass, // no perspective
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kFixedStepInX_MatrixClass, // fast perspective, need to call fixedStepInX() each scanline
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kPerspective_MatrixClass // slow perspective, need to mappoints each pixel
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};
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static MatrixClass ComputeMatrixClass(const SkMatrix&);
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// These can be called by your subclass after setContext() has been called
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uint8_t getPaintAlpha() const { return fPaintAlpha; }
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SkBitmap::Config getDeviceConfig() const { return (SkBitmap::Config)fDeviceConfig; }
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const SkMatrix& getTotalInverse() const { return fTotalInverse; }
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MatrixClass getInverseClass() const { return (MatrixClass)fTotalInverseClass; }
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SkShader(SkFlattenableReadBuffer& );
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private:
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SkMatrix* fLocalMatrix;
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SkMatrix fTotalInverse;
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uint8_t fPaintAlpha;
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uint8_t fDeviceConfig;
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uint8_t fTotalInverseClass;
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SkDEBUGCODE(SkBool8 fInSession;)
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static SkShader* CreateBitmapShader(const SkBitmap& src,
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TileMode, TileMode,
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void* storage, size_t storageSize);
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friend class SkAutoBitmapShaderInstall;
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typedef SkFlattenable INHERITED;
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};
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#endif
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