org.jfree.chart.util

Class PaintAlpha

java.lang.Object

org.jfree.chart.util.PaintAlpha

public class PaintAlpha
extends java.lang.Object

This class contains static methods for the manipulation of objects of type Paint

The intention is to honour the alpha-channel in the process. PaintAlpha was originally conceived to improve the rendering of 3D Shapes with transparent colours and to allow invisible bars by making them completely transparent.

In, for example StackedBarRenderer3D, bars are rendered with 6 faces. The front face is rendered with the Paint requested. The other 5 faces are rendered darker to achieve the 3D effect.

Previously Color.darker() was used for this, which always returns an opaque colour.

Additionally there are methods to control the behaviour and in particular a cloneImage(..) method which is needed to darken objects of type TexturePaint.

Since:

1.0.15

Field Summary

Fields

Modifier and Type	Field and Description
private static double	FACTOR Multiplier for the darker Methods. (taken from Color.FACTOR)
private static boolean	legacyAlpha

Constructor Summary

Constructors

Constructor and Description
PaintAlpha()

Method Summary

Modifier and Type	Method and Description
static java.awt.image.BufferedImage	cloneImage(java.awt.image.BufferedImage image) Clone a BufferedImage.
private static java.awt.Color	darker(java.awt.Color paint) Similar to Color.darker().
private static java.awt.GradientPaint	darker(java.awt.GradientPaint paint) Create a new GradientPaint with its colors darkened.
static java.awt.Paint	darker(java.awt.Paint paint) Create a new (if possible, darker) Paint of the same Type.
private static java.awt.Paint	darkerLinearGradientPaint(java.awt.LinearGradientPaint paint) Create a new Gradient with its colours darkened.
private static java.awt.Paint	darkerRadialGradientPaint(java.awt.RadialGradientPaint paint) Create a new Gradient with its colours darkened.
private static java.awt.TexturePaint	darkerTexturePaint(java.awt.TexturePaint paint) Create a new TexturePaint with its colors darkened.
static boolean	setLegacyAlpha(boolean legacyAlpha) Per default PaintAlpha will try to honour alpha-channel information.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FACTOR

private static final double FACTOR

Multiplier for the darker Methods.
(taken from Color.FACTOR)

See Also:

Constant Field Values

legacyAlpha

private static boolean legacyAlpha

Constructor Detail

PaintAlpha

public PaintAlpha()

Method Detail

setLegacyAlpha

public static boolean setLegacyAlpha(boolean legacyAlpha)

Per default PaintAlpha will try to honour alpha-channel information. In the past this was not the case. If you wish legacy functionality for your application you can request this here.

Parameters:

legacyAlpha - boolean

Returns:

the previous setting

darker

public static java.awt.Paint darker(java.awt.Paint paint)

Create a new (if possible, darker) Paint of the same Type. If the Type is not supported, the original Paint is returned.

Parameters:

paint - a Paint implementation (e.g. Color, GradientPaint, TexturePaint,..)

Returns:

a (usually new, see above) Paint

darker

private static java.awt.Color darker(java.awt.Color paint)

Similar to Color.darker().

The essential difference is that this method maintains the alpha-channel unchanged

Parameters:

paint - a Color

Returns:

a darker version of the Color

darker

private static java.awt.GradientPaint darker(java.awt.GradientPaint paint)

Create a new GradientPaint with its colors darkened.

Parameters:

paint - the gradient paint (null not permitted).

Returns:

a darker version of the GradientPaint

darkerLinearGradientPaint

private static java.awt.Paint darkerLinearGradientPaint(java.awt.LinearGradientPaint paint)

Create a new Gradient with its colours darkened.

Parameters:

paint - a LinearGradientPaint

Returns:

a darker version of the LinearGradientPaint

darkerRadialGradientPaint

private static java.awt.Paint darkerRadialGradientPaint(java.awt.RadialGradientPaint paint)

Create a new Gradient with its colours darkened.

Parameters:

paint - a RadialGradientPaint

Returns:

a darker version of the RadialGradientPaint

darkerTexturePaint

private static java.awt.TexturePaint darkerTexturePaint(java.awt.TexturePaint paint)

Create a new TexturePaint with its colors darkened.

This entails cloning the underlying BufferedImage, then darkening each color-pixel individually!

Parameters:

paint - a TexturePaint

Returns:

a darker version of the TexturePaint

cloneImage

public static java.awt.image.BufferedImage cloneImage(java.awt.image.BufferedImage image)

Clone a BufferedImage.

Note: when constructing the clone, the original Color Model Object is reused.
That keeps things simple and should not be a problem, as all known Color Models
(IndexColorModel, DirectColorModel, ComponentColorModel) are immutable.

Parameters:

image - original BufferedImage to clone

Returns:

a new BufferedImage reusing the original's Color Model and containing a clone of its pixels