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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 SkGradientShader_DEFINED
#define SkGradientShader_DEFINED
#include "SkShader.h"
class SkUnitMapper;
/** \class SkGradientShader
SkGradientShader hosts factories for creating subclasses of SkShader that
render linear and radial gradients.
*/
class SK_API SkGradientShader {
public:
enum Flags {
/** By default gradients will interpolate their colors in unpremul space
* and then premultiply each of the results. By setting this flag, the
* gradients will premultiply their colors first, and then interpolate
* between them.
*/
kInterpolateColorsInPremul_Flag = 1 << 0,
};
/** Returns a shader that generates a linear gradient between the two
specified points.
<p />
CreateLinear returns a shader with a reference count of 1.
The caller should decrement the shader's reference count when done with the shader.
It is an error for count to be < 2.
@param pts The start and end points for the gradient.
@param colors The array[count] of colors, to be distributed between the two points
@param pos May be NULL. array[count] of SkScalars, or NULL, of the relative position of
each corresponding color in the colors array. If this is NULL,
the the colors are distributed evenly between the start and end point.
If this is not null, the values must begin with 0, end with 1.0, and
intermediate values must be strictly increasing.
@param count Must be >=2. The number of colors (and pos if not NULL) entries.
@param mode The tiling mode
@param mapper May be NULL. Callback to modify the spread of the colors.
*/
static SkShader* CreateLinear(const SkPoint pts[2],
const SkColor colors[], const SkScalar pos[], int count,
SkShader::TileMode mode,
SkUnitMapper* mapper = NULL,
uint32_t flags = 0);
/** Returns a shader that generates a radial gradient given the center and radius.
<p />
CreateRadial returns a shader with a reference count of 1.
The caller should decrement the shader's reference count when done with the shader.
It is an error for colorCount to be < 2, or for radius to be <= 0.
@param center The center of the circle for this gradient
@param radius Must be positive. The radius of the circle for this gradient
@param colors The array[count] of colors, to be distributed between the center and edge of the circle
@param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
each corresponding color in the colors array. If this is NULL,
the the colors are distributed evenly between the center and edge of the circle.
If this is not null, the values must begin with 0, end with 1.0, and
intermediate values must be strictly increasing.
@param count Must be >= 2. The number of colors (and pos if not NULL) entries
@param mode The tiling mode
@param mapper May be NULL. Callback to modify the spread of the colors.
*/
static SkShader* CreateRadial(const SkPoint& center, SkScalar radius,
const SkColor colors[], const SkScalar pos[], int count,
SkShader::TileMode mode,
SkUnitMapper* mapper = NULL,
uint32_t flags = 0);
/** Returns a shader that generates a radial gradient given the start position, start radius, end position and end radius.
<p />
CreateTwoPointRadial returns a shader with a reference count of 1.
The caller should decrement the shader's reference count when done with the shader.
It is an error for colorCount to be < 2, for startRadius or endRadius to be < 0, or for
startRadius to be equal to endRadius.
@param start The center of the start circle for this gradient
@param startRadius Must be positive. The radius of the start circle for this gradient.
@param end The center of the end circle for this gradient
@param endRadius Must be positive. The radius of the end circle for this gradient.
@param colors The array[count] of colors, to be distributed between the center and edge of the circle
@param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
each corresponding color in the colors array. If this is NULL,
the the colors are distributed evenly between the center and edge of the circle.
If this is not null, the values must begin with 0, end with 1.0, and
intermediate values must be strictly increasing.
@param count Must be >= 2. The number of colors (and pos if not NULL) entries
@param mode The tiling mode
@param mapper May be NULL. Callback to modify the spread of the colors.
*/
static SkShader* CreateTwoPointRadial(const SkPoint& start,
SkScalar startRadius,
const SkPoint& end,
SkScalar endRadius,
const SkColor colors[],
const SkScalar pos[], int count,
SkShader::TileMode mode,
SkUnitMapper* mapper = NULL,
uint32_t flags = 0);
/**
* Returns a shader that generates a conical gradient given two circles, or
* returns NULL if the inputs are invalid. The gradient interprets the
* two circles according to the following HTML spec.
* http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient
*/
static SkShader* CreateTwoPointConical(const SkPoint& start,
SkScalar startRadius,
const SkPoint& end,
SkScalar endRadius,
const SkColor colors[],
const SkScalar pos[], int count,
SkShader::TileMode mode,
SkUnitMapper* mapper = NULL,
uint32_t flags = 0);
/** Returns a shader that generates a sweep gradient given a center.
<p />
CreateSweep returns a shader with a reference count of 1.
The caller should decrement the shader's reference count when done with the shader.
It is an error for colorCount to be < 2.
@param cx The X coordinate of the center of the sweep
@param cx The Y coordinate of the center of the sweep
@param colors The array[count] of colors, to be distributed around the center.
@param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
each corresponding color in the colors array. If this is NULL,
the the colors are distributed evenly between the center and edge of the circle.
If this is not null, the values must begin with 0, end with 1.0, and
intermediate values must be strictly increasing.
@param count Must be >= 2. The number of colors (and pos if not NULL) entries
@param mapper May be NULL. Callback to modify the spread of the colors.
*/
static SkShader* CreateSweep(SkScalar cx, SkScalar cy,
const SkColor colors[], const SkScalar pos[],
int count, SkUnitMapper* mapper = NULL,
uint32_t flags = 0);
SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
};
#endif
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