org.apache.batik.ext.awt
Class RadialGradientPaint

java.lang.Object
  extended by org.apache.batik.ext.awt.MultipleGradientPaint
      extended by org.apache.batik.ext.awt.RadialGradientPaint
All Implemented Interfaces:
Paint, Transparency

public final class RadialGradientPaint
extends MultipleGradientPaint

This class provides a way to fill a shape with a circular radial color gradient pattern. The user may specify 2 or more gradient colors, and this paint will provide an interpolation between each color.

The user must provide an array of floats specifying how to distribute the colors along the gradient. These values should range from 0.0 to 1.0 and act like keyframes along the gradient (they mark where the gradient should be exactly a particular color).

This paint will map the first color of the gradient to a focus point within the circle, and the last color to the perimeter of the circle, interpolating smoothly for any inbetween colors specified by the user. Any line drawn from the focus point to the circumference will span the all the gradient colors. By default the focus is set to be the center of the circle.

Specifying a focus point outside of the circle's radius will result in the focus being set to the intersection point of the focus-center line and the perimenter of the circle.

Specifying a cycle method allows the user to control the painting behavior outside of the bounds of the circle's radius. See LinearGradientPaint for more details.

The following code demonstrates typical usage of RadialGradientPaint:

Point2D center = new Point2D.Float(0, 0);
float radius = 20; float[] dist = {0.0, 0.2, 1.0};
Color[] colors = {Color.red, Color.white, Color.blue};
RadialGradientPaint p = new RadialGradientPaint(center, radius, dist, colors);

In the event that the user does not set the first keyframe value equal to 0 and the last keyframe value equal to 1, keyframes will be created at these positions and the first and last colors will be replicated there. So, if a user specifies the following arrays to construct a gradient:
{Color.blue, Color.red}, {.3, .7}
this will be converted to a gradient with the following keyframes: {Color.blue, Color.blue, Color.red, Color.red}, {0, .3, .7, 1}

This image demonstrates a radial gradient with NO_CYCLE and default focus.

This image demonstrates a radial gradient with NO_CYCLE and non-centered focus.

This image demonstrates a radial gradient with REFLECT and non-centered focus.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.batik.ext.awt.MultipleGradientPaint
MultipleGradientPaint.ColorSpaceEnum, MultipleGradientPaint.CycleMethodEnum
 
Field Summary
 
Fields inherited from class org.apache.batik.ext.awt.MultipleGradientPaint
colors, colorSpace, cycleMethod, fractions, gradientTransform, LINEAR_RGB, NO_CYCLE, REFLECT, REPEAT, SRGB, transparency
 
Fields inherited from interface java.awt.Transparency
BITMASK, OPAQUE, TRANSLUCENT
 
Constructor Summary
RadialGradientPaint(float cx, float cy, float radius, float[] fractions, Color[] colors)
           Constructs a RadialGradientPaint, using the center as the focus point.
RadialGradientPaint(float cx, float cy, float radius, float fx, float fy, float[] fractions, Color[] colors)
           Constructs a RadialGradientPaint.
RadialGradientPaint(Point2D center, float radius, float[] fractions, Color[] colors)
           Constructs a RadialGradientPaint, using the center as the focus point.
RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors)
           Constructs a RadialGradientPaint.
RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethodEnum cycleMethod, MultipleGradientPaint.ColorSpaceEnum colorSpace)
           Constructs a RadialGradientPaint.
RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethodEnum cycleMethod, MultipleGradientPaint.ColorSpaceEnum colorSpace, AffineTransform gradientTransform)
           Constructs a RadialGradientPaint.
RadialGradientPaint(Rectangle2D gradientBounds, float[] fractions, Color[] colors)
           Constructs a RadialGradientPaint, the gradient circle is defined by a bounding box.
 
Method Summary
 PaintContext createContext(ColorModel cm, Rectangle deviceBounds, Rectangle2D userBounds, AffineTransform transform, RenderingHints hints)
           Creates and returns a PaintContext used to generate the color pattern, for use by the internal rendering engine.
 Point2D getCenterPoint()
          Returns a copy of the center point of the radial gradient.
 Point2D getFocusPoint()
          Returns a copy of the end point of the gradient axis.
 float getRadius()
          Returns the radius of the circle defining the radial gradient.
 
Methods inherited from class org.apache.batik.ext.awt.MultipleGradientPaint
getColors, getColorSpace, getCycleMethod, getFractions, getTransform, getTransparency
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

RadialGradientPaint

public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float[] fractions,
                           Color[] colors)

Constructs a RadialGradientPaint, using the center as the focus point.

Parameters:
cx - the x coordinate in user space of the center point of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
cy - the y coordinate in user space of the center point of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
radius - the radius of the circle defining the extents of the color gradient
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
Throws:
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(Point2D center,
                           float radius,
                           float[] fractions,
                           Color[] colors)

Constructs a RadialGradientPaint, using the center as the focus point.

Parameters:
center - the center point, in user space, of the circle defining the gradient
radius - the radius of the circle defining the extents of the color gradient
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
Throws:
NullPointerException - if center point is null
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float fx,
                           float fy,
                           float[] fractions,
                           Color[] colors)

Constructs a RadialGradientPaint.

Parameters:
cx - the x coordinate in user space of the center point of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
cy - the y coordinate in user space of the center point of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
radius - the radius of the circle defining the extents of the color gradient
fx - the x coordinate of the point in user space to which the first color is mapped
fy - the y coordinate of the point in user space to which the first color is mapped
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
Throws:
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(Point2D center,
                           float radius,
                           Point2D focus,
                           float[] fractions,
                           Color[] colors)

Constructs a RadialGradientPaint.

Parameters:
center - the center point, in user space, of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
radius - the radius of the circle defining the extents of the color gradient
focus - the point, in user space, to which the first color is mapped
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
Throws:
NullPointerException - if one of the points is null
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(Point2D center,
                           float radius,
                           Point2D focus,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethodEnum cycleMethod,
                           MultipleGradientPaint.ColorSpaceEnum colorSpace)

Constructs a RadialGradientPaint.

Parameters:
center - the center point in user space of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
radius - the radius of the circle defining the extents of the color gradient
focus - the point in user space to which the first color is mapped
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
cycleMethod - either NO_CYCLE, REFLECT, or REPEAT
colorSpace - which colorspace to use for interpolation, either SRGB or LINEAR_RGB
Throws:
NullPointerException - if one of the points is null
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(Point2D center,
                           float radius,
                           Point2D focus,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethodEnum cycleMethod,
                           MultipleGradientPaint.ColorSpaceEnum colorSpace,
                           AffineTransform gradientTransform)

Constructs a RadialGradientPaint.

Parameters:
center - the center point in user space of the circle defining the gradient. The last color of the gradient is mapped to the perimeter of this circle
radius - the radius of the circle defining the extents of the color gradient.
focus - the point in user space to which the first color is mapped
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
cycleMethod - either NO_CYCLE, REFLECT, or REPEAT
colorSpace - which colorspace to use for interpolation, either SRGB or LINEAR_RGB
gradientTransform - transform to apply to the gradient
Throws:
NullPointerException - if one of the points is null, or gradientTransform is null
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0

RadialGradientPaint

public RadialGradientPaint(Rectangle2D gradientBounds,
                           float[] fractions,
                           Color[] colors)

Constructs a RadialGradientPaint, the gradient circle is defined by a bounding box.

Parameters:
gradientBounds - the bounding box, in user space, of the circle defining outermost extent of the gradient.
fractions - numbers ranging from 0.0 to 1.0 specifying the distribution of colors along the gradient
colors - array of colors to use in the gradient. The first color is used at the focus point, the last color around the perimeter of the circle.
Throws:
NullPointerException - if the gradientBounds is null
IllegalArgumentException - if fractions.length != colors.length, or if colors is less than 2 in size, or if radius < 0
Method Detail

createContext

public PaintContext createContext(ColorModel cm,
                                  Rectangle deviceBounds,
                                  Rectangle2D userBounds,
                                  AffineTransform transform,
                                  RenderingHints hints)

Creates and returns a PaintContext used to generate the color pattern, for use by the internal rendering engine.

Parameters:
cm - ColorModel that receives the Paint data. This is used only as a hint.
deviceBounds - the device space bounding box of the graphics primitive being rendered
userBounds - the user space bounding box of the graphics primitive being rendered
transform - the AffineTransform from user space into device space
hints - the hints that the context object uses to choose between rendering alternatives
Returns:
the PaintContext that generates color patterns.
Throws:
IllegalArgumentException - if the transform is not invertible
See Also:
PaintContext

getCenterPoint

public Point2D getCenterPoint()
Returns a copy of the center point of the radial gradient.

Returns:
a Point2D object that is a copy of the center point

getFocusPoint

public Point2D getFocusPoint()
Returns a copy of the end point of the gradient axis.

Returns:
a Point2D object that is a copy of the focus point

getRadius

public float getRadius()
Returns the radius of the circle defining the radial gradient.

Returns:
the radius of the circle defining the radial gradient


Copyright © 2008 Apache Software Foundation. All Rights Reserved.