Painter<JComponent>
public abstract class AbstractRegionPainter extends Object implements Painter<JComponent>
Modifier and Type | Class | Description |
---|---|---|
protected static class |
AbstractRegionPainter.PaintContext |
A class encapsulating state useful when painting. |
Modifier | Constructor | Description |
---|---|---|
protected |
Create a new AbstractRegionPainter |
Modifier and Type | Method | Description |
---|---|---|
protected void |
configureGraphics |
Configures the given Graphics2D. |
protected final float |
decodeAnchorX |
Decodes and returns a float value representing the actual pixel location for the anchor point given the encoded X value of the control point, and the offset distance to the anchor from that control point. |
protected final float |
decodeAnchorY |
Decodes and returns a float value representing the actual pixel location for the anchor point given the encoded Y value of the control point, and the offset distance to the anchor from that control point. |
protected final Color |
decodeColor |
Decodes and returns a color, which is derived from a offset between two other colors. |
protected final Color |
decodeColor |
Decodes and returns a color, which is derived from a base color in UI defaults. |
protected final LinearGradientPaint |
decodeGradient |
Given parameters for creating a LinearGradientPaint, this method will create and return a linear gradient paint. |
protected final RadialGradientPaint |
decodeRadialGradient |
Given parameters for creating a RadialGradientPaint, this method will create and return a radial gradient paint. |
protected final float |
decodeX |
Decodes and returns a float value representing the actual pixel location for the given encoded X value. |
protected final float |
decodeY |
Decodes and returns a float value representing the actual pixel location for the given encoded y value. |
protected abstract void |
doPaint |
Actually performs the painting operation. |
protected final Color |
getComponentColor |
Get a color property from the given JComponent. |
protected Object[] |
getExtendedCacheKeys |
Get any extra attributes which the painter implementation would like to include in the image cache lookups. |
protected abstract AbstractRegionPainter.PaintContext |
getPaintContext() |
Gets the PaintContext for this painting operation. |
final void |
paint |
Renders to the given Graphics2D object. |
protected AbstractRegionPainter()
public final void paint(Graphics2D g, JComponent c, int w, int h)
Renders to the given Graphics2D
object. Implementations of this method may modify state on the Graphics2D
, and are not required to restore that state upon completion. In most cases, it is recommended that the caller pass in a scratch graphics object. The Graphics2D
must never be null.
State on the graphics object may be honored by the paint
method, but may not be. For instance, setting the antialiasing rendering hint on the graphics may or may not be respected by the Painter
implementation.
The supplied object parameter acts as an optional configuration argument. For example, it could be of type Component
. A Painter
that expected it could then read state from that Component
and use the state for painting. For example, an implementation may read the backgroundColor and use that.
Generally, to enhance reusability, most standard Painter
s ignore this parameter. They can thus be reused in any context. The object
may be null. Implementations must not throw a NullPointerException if the object parameter is null.
Finally, the width
and height
arguments specify the width and height that the Painter
should paint into. More specifically, the specified width and height instruct the painter that it should paint fully within this width and height. Any specified clip on the g
param will further constrain the region.
For example, suppose I have a Painter
implementation that draws a gradient. The gradient goes from white to black. It "stretches" to fill the painted region. Thus, if I use this Painter
to paint a 500 x 500 region, the far left would be black, the far right would be white, and a smooth gradient would be painted between. I could then, without modification, reuse the Painter
to paint a region that is 20x20 in size. This region would also be black on the left, white on the right, and a smooth gradient painted between.
paint
in interface Painter<JComponent>
g
- The Graphics2D to render to. This must not be null.c
- an optional configuration parameter. This may be null.w
- width of the area to paint.h
- height of the area to paint.protected Object[] getExtendedCacheKeys(JComponent c)
c
- The component on the current paint callprotected abstract AbstractRegionPainter.PaintContext getPaintContext()
Gets the PaintContext for this painting operation. This method is called on every paint, and so should be fast and produce no garbage. The PaintContext contains information such as cache hints. It also contains data necessary for decoding points at runtime, such as the stretching insets, the canvas size at which the encoded points were defined, and whether the stretching insets are inverted.
This method allows for subclasses to package the painting of different states with possibly different canvas sizes, etc, into one AbstractRegionPainter implementation.
protected void configureGraphics(Graphics2D g)
Configures the given Graphics2D. Often, rendering hints or compositing rules are applied to a Graphics2D object prior to painting, which should affect all of the subsequent painting operations. This method provides a convenient hook for configuring the Graphics object prior to rendering, regardless of whether the render operation is performed to an intermediate buffer or directly to the display.
g
- The Graphics2D object to configure. Will not be null.protected abstract void doPaint(Graphics2D g, JComponent c, int width, int height, Object[] extendedCacheKeys)
width
and a height of height
. For performance reasons, you may want to read the clip from the Graphics2D object and only render within that space.g
- The Graphics2D surface to paint toc
- The JComponent related to the drawing event. For example, if the region being rendered is Button, then c
will be a JButton. If the region being drawn is ScrollBarSlider, then the component will be JScrollBar. This value may be null.width
- The width of the region to paint. Note that in the case of painting the foreground, this value may differ from c.getWidth().height
- The height of the region to paint. Note that in the case of painting the foreground, this value may differ from c.getHeight().extendedCacheKeys
- The result of the call to getExtendedCacheKeys()protected final float decodeX(float x)
x
- an encoded x value (0...1, or 1...2, or 2...3)IllegalArgumentException
- if x < 0
or x > 3
protected final float decodeY(float y)
y
- an encoded y value (0...1, or 1...2, or 2...3)IllegalArgumentException
- if y < 0
or y > 3
protected final float decodeAnchorX(float x, float dx)
x
- an encoded x value of the bezier control point (0...1, or 1...2, or 2...3)dx
- the offset distance to the anchor from the control point xIllegalArgumentException
- if x < 0
or x > 3
protected final float decodeAnchorY(float y, float dy)
y
- an encoded y value of the bezier control point (0...1, or 1...2, or 2...3)dy
- the offset distance to the anchor from the control point yIllegalArgumentException
- if y < 0
or y > 3
protected final Color decodeColor(String key, float hOffset, float sOffset, float bOffset, int aOffset)
key
- A key corresponding to the value in the UI Defaults table of UIManager where the base color is definedhOffset
- The hue offset used for derivation.sOffset
- The saturation offset used for derivation.bOffset
- The brightness offset used for derivation.aOffset
- The alpha offset used for derivation. Between 0...255protected final Color decodeColor(Color color1, Color color2, float midPoint)
color1
- The first colorcolor2
- The second colormidPoint
- The offset between color 1 and color 2, a value of 0.0 is color 1 and 1.0 is color 2;protected final LinearGradientPaint decodeGradient(float x1, float y1, float x2, float y2, float[] midpoints, Color[] colors)
x1
- x1y1
- y1x2
- x2y2
- y2midpoints
- the midpointscolors
- the colorsNullPointerException
- if midpoints
array is null, or colors
array is null,IllegalArgumentException
- if start and end points are the same points, or midpoints.length != colors.length
, or colors
is less than 2 in size, or a midpoints
value is less than 0.0 or greater than 1.0, or the midpoints
are not provided in strictly increasing orderprotected final RadialGradientPaint decodeRadialGradient(float x, float y, float r, float[] midpoints, Color[] colors)
x
- x-coordinatey
- y-coordinater
- radiusmidpoints
- the midpointscolors
- the colorsNullPointerException
- if midpoints
array is null, or colors
array is nullIllegalArgumentException
- if r
is non-positive, or midpoints.length != colors.length
, or colors
is less than 2 in size, or a midpoints
value is less than 0.0 or greater than 1.0, or the midpoints
are not provided in strictly increasing orderprotected final Color getComponentColor(JComponent c, String property, Color defaultColor, float saturationOffset, float brightnessOffset, int alphaOffset)
getXXX()
method and if that fails checks for a client property with key property
. If that still fails to return a Color then defaultColor
is returned.c
- The component to get the color property fromproperty
- The name of a bean style property or client propertydefaultColor
- The color to return if no color was obtained from the component.saturationOffset
- additively modifies the HSB saturation component of the color returned (ignored if default color is returned).brightnessOffset
- additively modifies the HSB brightness component of the color returned (ignored if default color is returned).alphaOffset
- additively modifies the ARGB alpha component of the color returned (ignored if default color is returned).
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