LinearGradientPaintpublic final class LinearGradientPaint extends MultipleGradientPaint | The {@code LinearGradientPaint} class provides a way to fill
a {@link java.awt.Shape} with a linear color gradient pattern. The user
may specify two or more gradient colors, and this paint will provide an
interpolation between each color. The user also specifies start and end
points which define where in user space the color gradient should begin
and end.
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 {@code LinearGradientPaint}
should take when filling color outside the start and end points.
If no cycle method is specified, {@code NO_CYCLE} will be chosen by
default, which means the endpoint colors 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 LinearGradientPaint}:
Point2D start = new Point2D.Float(0, 0);
Point2D end = new Point2D.Float(50, 50);
float[] dist = {0.0f, 0.2f, 1.0f};
Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
LinearGradientPaint p =
new LinearGradientPaint(start, end, dist, colors);
This code will create a {@code LinearGradientPaint} which interpolates
between red and white for the first 20% of the gradient and between white
and blue for the remaining 80%.
This image demonstrates the example code above for each
of the three cycle methods:
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| Fields Summary |
|---|
| private final Point2D | startGradient start and end points. | | private final Point2D | end |
| Constructors Summary |
|---|
public LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors)Constructs a {@code LinearGradientPaint} with a default
{@code NO_CYCLE} repeating method and {@code SRGB} color space.
this(new Point2D.Float(startX, startY),
new Point2D.Float(endX, endY),
fractions,
colors,
CycleMethod.NO_CYCLE);
| public LinearGradientPaint(float startX, float startY, float endX, float endY, float[] fractions, Color[] colors, CycleMethod cycleMethod)Constructs a {@code LinearGradientPaint} with a default {@code SRGB}
color space.
this(new Point2D.Float(startX, startY),
new Point2D.Float(endX, endY),
fractions,
colors,
cycleMethod);
| public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors)Constructs a {@code LinearGradientPaint} with a default
{@code NO_CYCLE} repeating method and {@code SRGB} color space.
this(start, end,
fractions, colors,
CycleMethod.NO_CYCLE);
| public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, CycleMethod cycleMethod)Constructs a {@code LinearGradientPaint} with a default {@code SRGB}
color space.
this(start, end,
fractions, colors,
cycleMethod,
ColorSpaceType.SRGB,
new AffineTransform());
| public LinearGradientPaint(Point2D start, Point2D end, float[] fractions, Color[] colors, CycleMethod cycleMethod, ColorSpaceType colorSpace, AffineTransform gradientTransform)Constructs a {@code LinearGradientPaint}.
super(fractions, colors, cycleMethod, colorSpace, gradientTransform);
// check input parameters
if (start == null || end == null) {
throw new NullPointerException("Start and end points must be" +
"non-null");
}
if (start.equals(end)) {
throw new IllegalArgumentException("Start point cannot equal" +
"endpoint");
}
// copy the points...
this.start = new Point2D.Double(start.getX(), start.getY());
this.end = new Point2D.Double(end.getX(), end.getY());
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| Methods Summary |
|---|
| public java.awt.PaintContext | createContext(java.awt.image.ColorModel cm, java.awt.Rectangle deviceBounds, java.awt.geom.Rectangle2D userBounds, java.awt.geom.AffineTransform transform, java.awt.RenderingHints hints){@inheritDoc}
// avoid modifying the user's transform...
transform = new AffineTransform(transform);
// incorporate the gradient transform
transform.concatenate(gradientTransform);
if ((fractions.length == 2) &&
(cycleMethod != CycleMethod.REPEAT) &&
(colorSpace == ColorSpaceType.SRGB))
{
// faster to use the basic GradientPaintContext for this
// common case
boolean cyclic = (cycleMethod != CycleMethod.NO_CYCLE);
return new GradientPaintContext(cm, start, end,
transform,
colors[0], colors[1],
cyclic);
} else {
return new LinearGradientPaintContext(this, cm,
deviceBounds, userBounds,
transform, hints,
start, end,
fractions, colors,
cycleMethod, colorSpace);
}
| | public java.awt.geom.Point2D | getEndPoint()Returns a copy of the end point of the gradient axis.
return new Point2D.Double(end.getX(), end.getY());
| | public java.awt.geom.Point2D | getStartPoint()Returns a copy of the start point of the gradient axis.
return new Point2D.Double(start.getX(), start.getY());
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