public final class RadialGradientPaint extends MultipleGradientPaint
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 inbetween 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 radius of the circle will cause the rings of the gradient pattern to be centered on the point just inside the edge of the circle in the direction of the focus point. The rendering will internally use this modified location as if it were the specified focus point.
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}this will be converted to a gradient with the following keyframes:
{Color.BLUE, Color.BLUE, Color.RED, Color.RED}, {0f, .3f, .7f, 1f}
The user may also select what action the RadialGradientPaint
object
takes when it is filling the space outside the circle's radius by
setting CycleMethod
to either REFLECTION
or REPEAT
.
The gradient color proportions are equal for any particular line drawn
from the focus point. The following figure shows that the distance AB
is equal to the distance BC, and the distance AD is equal to the distance DE.
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
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 noncentered 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 noncentered focus for each of the three cycle methods:
Paint
,
Graphics2D.setPaint(java.awt.Paint)
MultipleGradientPaint.ColorSpaceType, MultipleGradientPaint.CycleMethod
BITMASK, OPAQUE, TRANSLUCENT
Constructor and Description 

RadialGradientPaint(float cx,
float cy,
float radius,
float[] fractions,
Color[] colors)
Constructs a
RadialGradientPaint with a default
NO_CYCLE repeating method and SRGB color space,
using the center as the focus point. 
RadialGradientPaint(float cx,
float cy,
float radius,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod)
Constructs a
RadialGradientPaint with a default
SRGB color space, using the center as the focus point. 
RadialGradientPaint(float cx,
float cy,
float radius,
float fx,
float fy,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod)
Constructs a
RadialGradientPaint with a default
SRGB color space. 
RadialGradientPaint(Point2D center,
float radius,
float[] fractions,
Color[] colors)
Constructs a
RadialGradientPaint with a default
NO_CYCLE repeating method and SRGB color space,
using the center as the focus point. 
RadialGradientPaint(Point2D center,
float radius,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod)
Constructs a
RadialGradientPaint with a default
SRGB color space, using the center as the focus point. 
RadialGradientPaint(Point2D center,
float radius,
Point2D focus,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod)
Constructs a
RadialGradientPaint with a default
SRGB color space. 
RadialGradientPaint(Point2D center,
float radius,
Point2D focus,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod,
MultipleGradientPaint.ColorSpaceType colorSpace,
AffineTransform gradientTransform)
Constructs a
RadialGradientPaint . 
RadialGradientPaint(Rectangle2D gradientBounds,
float[] fractions,
Color[] colors,
MultipleGradientPaint.CycleMethod cycleMethod)
Constructs a
RadialGradientPaint with a default
SRGB color space. 
Modifier and Type  Method and Description 

PaintContext 
createContext(ColorModel cm,
Rectangle deviceBounds,
Rectangle2D userBounds,
AffineTransform transform,
RenderingHints hints)
Creates and returns a
PaintContext used to
generate a circular radial color gradient pattern. 
Point2D 
getCenterPoint()
Returns a copy of the center point of the radial gradient.

Point2D 
getFocusPoint()
Returns a copy of the focus point of the radial gradient.

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

getColors, getColorSpace, getCycleMethod, getFractions, getTransform, getTransparency
public RadialGradientPaint(float cx, float cy, float radius, float[] fractions, Color[] colors)
RadialGradientPaint
with a default
NO_CYCLE
repeating method and SRGB
color space,
using the center as the focus point.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 gradientfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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.NullPointerException
 if fractions
array is null,
or colors
array is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(Point2D center, float radius, float[] fractions, Color[] colors)
RadialGradientPaint
with a default
NO_CYCLE
repeating method and SRGB
color space,
using the center as the focus point.center
 the center point, in user space, of the circle defining
the gradientradius
 the radius of the circle defining the extents of the
color gradientfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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.NullPointerException
 if center
point is null,
or fractions
array is null,
or colors
array is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(float cx, float cy, float radius, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
RadialGradientPaint
with a default
SRGB
color space, using the center as the focus point.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 gradientfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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
NullPointerException
 if fractions
array is null,
or colors
array is null,
or cycleMethod
is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(Point2D center, float radius, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
RadialGradientPaint
with a default
SRGB
color space, using the center as the focus point.center
 the center point, in user space, of the circle defining
the gradientradius
 the radius of the circle defining the extents of the
color gradientfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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
NullPointerException
 if center
point is null,
or fractions
array is null,
or colors
array is null,
or cycleMethod
is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(float cx, float cy, float radius, float fx, float fy, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
RadialGradientPaint
with a default
SRGB
color space.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 gradientfx
 the X coordinate of the point in user space to which the
first color is mappedfy
 the Y coordinate of the point in user space to which the
first color is mappedfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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
NullPointerException
 if fractions
array is null,
or colors
array is null,
or cycleMethod
is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
RadialGradientPaint
with a default
SRGB
color space.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
gradientfocus
 the point in user space to which the first color is mappedfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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
NullPointerException
 if one of the points is null,
or fractions
array is null,
or colors
array is null,
or cycleMethod
is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing order@ConstructorProperties(value={"centerPoint","radius","focusPoint","fractions","colors","cycleMethod","colorSpace","transform"}) public RadialGradientPaint(Point2D center, float radius, Point2D focus, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod, MultipleGradientPaint.ColorSpaceType colorSpace, AffineTransform gradientTransform)
RadialGradientPaint
.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 gradientfocus
 the point in user space to which the first color is mappedfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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 color space to use for interpolation,
either SRGB
or LINEAR_RGB
gradientTransform
 transform to apply to the gradientNullPointerException
 if one of the points is null,
or fractions
array is null,
or colors
array is null,
or cycleMethod
is null,
or colorSpace
is null,
or gradientTransform
is nullIllegalArgumentException
 if radius
is nonpositive,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic RadialGradientPaint(Rectangle2D gradientBounds, float[] fractions, Color[] colors, MultipleGradientPaint.CycleMethod cycleMethod)
RadialGradientPaint
with a default
SRGB
color space.
The gradient circle of the 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);
gradientBounds
 the bounding box, in user space, of the circle
defining the outermost extent of the gradientfractions
 numbers ranging from 0.0 to 1.0 specifying the
distribution of colors along the gradientcolors
 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
NullPointerException
 if gradientBounds
is null,
or fractions
array is null,
or colors
array is null,
or cycleMethod
is nullIllegalArgumentException
 if gradientBounds
is empty,
or fractions.length != colors.length
,
or colors
is less than 2 in size,
or a fractions
value is less than 0.0 or greater than 1.0,
or the fractions
are not provided in strictly increasing orderpublic PaintContext createContext(ColorModel cm, Rectangle deviceBounds, Rectangle2D userBounds, AffineTransform transform, RenderingHints hints)
PaintContext
used to
generate a circular radial color gradient pattern.
See the description of the createContext
method
for information on null parameter handling.cm
 the preferred ColorModel
which represents the most convenient
format for the caller to receive the pixel data, or null
if there is no preference.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 set of hints that the context object can use to
choose between rendering alternatives.PaintContext
for
generating color patterns.Paint
,
PaintContext
,
ColorModel
,
Rectangle
,
Rectangle2D
,
AffineTransform
,
RenderingHints
public Point2D getCenterPoint()
Point2D
object that is a copy of the center pointpublic Point2D getFocusPoint()
Point2D
object that is a copy of the focus pointpublic float getRadius()
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For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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