java.awt
class RadialGradientPaint

java.lang.Object java.awt.MultipleGradientPaint java.awt.RadialGradientPaint

All Implemented Interfaces:

Paint

public final class RadialGradientPaint
extends MultipleGradientPaint

The {@code RadialGradientPaint} 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 specify the circle controlling the gradient pattern, which is described by a center point and a radius. The user can also specify a separate focus point within that circle, which controls the location of the first color of the gradient. By default the focus is set to be the center of the circle.

This paint will map the first color of the gradient to the focus point, and the last color to the perimeter of the circle, interpolating smoothly for any in-between colors specified by the user. Any line drawn from the focus point to the circumference will thus span all the gradient colors.

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 perimeter of the circle.

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).

In the event that the user does not set the first keyframe value equal to 0 and/or 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}, {.3f, .7f}
 

     {Color.BLUE, Color.BLUE, Color.RED, Color.RED}, {0f, .3f, .7f, 1f}
 

The user may also select what action the {@code RadialGradientPaint} should take when filling color outside the bounds of the circle's radius. If no cycle method is specified, {@code NO_CYCLE} will be chosen by default, which means the the last keyframe color will be used to fill the remaining area.

The colorSpace parameter allows the user to specify in which colorspace the interpolation should be performed, default sRGB or linearized RGB.

The following code demonstrates typical usage of {@code RadialGradientPaint}, where the center and focus points are the same:

     Point2D center = new Point2D.Float(50, 50);
     float radius = 25;
     float[] dist = {0.0f, 0.2f, 1.0f};
     Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
     RadialGradientPaint p =
         new RadialGradientPaint(center, radius, dist, colors);
 

This image demonstrates the example code above, with default (centered) focus for each of the three cycle methods:

It is also possible to specify a non-centered focus point, as in the following code:

     Point2D center = new Point2D.Float(50, 50);
     float radius = 25;
     Point2D focus = new Point2D.Float(40, 40);
     float[] dist = {0.0f, 0.2f, 1.0f};
     Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
     RadialGradientPaint p =
         new RadialGradientPaint(center, radius, focus,
                                 dist, colors,
                                 CycleMethod.NO_CYCLE);
 

This image demonstrates the previous example code, with non-centered focus for each of the three cycle methods:

RadialGradientPaint

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

Constructs a {@code RadialGradientPaint} with a default {@code SRGB} color space.

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.

cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

RadialGradientPaint

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

Constructs a {@code RadialGradientPaint} with a default {@code NO_CYCLE} repeating method and {@code SRGB} color space, 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.

RadialGradientPaint

public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

Constructs a {@code RadialGradientPaint} with a default {@code SRGB} color space, 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.

cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

RadialGradientPaint

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

Constructs a {@code RadialGradientPaint} with a default {@code NO_CYCLE} repeating method and {@code SRGB} color space, 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.

RadialGradientPaint

public RadialGradientPaint(Point2D center,
                           float radius,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

Constructs a {@code RadialGradientPaint} with a default {@code SRGB} color space, 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.

cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

RadialGradientPaint

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

Constructs a {@code RadialGradientPaint} with a default {@code SRGB} color space.

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 {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

RadialGradientPaint

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

Constructs a {@code 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 {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

colorSpace - which color space to use for interpolation, either {@code SRGB} or {@code LINEAR_RGB}

gradientTransform - transform to apply to the gradient

RadialGradientPaint

public RadialGradientPaint(Rectangle2D gradientBounds,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

Constructs a {@code RadialGradientPaint} with a default {@code SRGB} color space. The gradient circle of the {@code RadialGradientPaint} is defined by the given bounding box.

This constructor is a more convenient way to express the following (equivalent) code:

     double gw = gradientBounds.getWidth();
     double gh = gradientBounds.getHeight();
     double cx = gradientBounds.getCenterX();
     double cy = gradientBounds.getCenterY();
     Point2D center = new Point2D.Double(cx, cy);

     AffineTransform gradientTransform = new AffineTransform();
     gradientTransform.translate(cx, cy);
     gradientTransform.scale(gw / 2, gh / 2);
     gradientTransform.translate(-cx, -cy);

     RadialGradientPaint gp =
         new RadialGradientPaint(center, 1.0f, center,
                                 fractions, colors,
                                 cycleMethod,
                                 ColorSpaceType.SRGB,
                                 gradientTransform);
 

Parameters:

gradientBounds - the bounding box, in user space, of the circle defining the 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.

cycleMethod - either {@code NO_CYCLE}, {@code REFLECT}, or {@code REPEAT}

createContext

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

{@inheritDoc}

Parameters:

cm

deviceBounds

userBounds

transform

hints

getCenterPoint

public Point2D getCenterPoint()

Returns a copy of the center point of the radial gradient.

Returns:

a {@code 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 {@code 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