org.apache.batik.ext.awt

Class RadialGradientPaint

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.

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

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

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

Constructs a RadialGradientPaint.

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

Constructs a RadialGradientPaint.

RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors, CycleMethodEnum cycleMethod, 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
PaintContextcreateContext(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.

Point2DgetCenterPoint()
Returns a copy of the center point of the radial gradient.
Point2DgetFocusPoint()
Returns a copy of the end point of the gradient axis.
floatgetRadius()
Returns the radius of the circle defining the radial gradient.

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, CycleMethodEnum cycleMethod, 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, CycleMethodEnum cycleMethod, 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 B) 2008 Apache Software Foundation. All Rights Reserved.