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gnu.java.awt

Class BitwiseXORComposite

Implemented Interfaces:
Composite
public class BitwiseXORComposite
extends Object
implements Composite
A composite for emulating traditional bitwise XOR of pixel values. Please note that this composite does not implement the Porter-Duff XOR operator, but an exclusive or of overlapping subpixel regions.

A screen shot of BitwiseXORComposite in action

The above screen shot shows the result of applying six different BitwiseXORComposites. They were constructed with the colors white, blue, black, orange, green, and brown, respectively. Each composite was used to paint a fully white rectangle on top of the blue bar in the background.

The purpose of this composite is to support the Graphics.setXORMode(Color) method in composite-aware graphics implementations. Applications typically would use setXORMode for drawing “highlights” such as text selections or cursors by inverting colors temporarily and then inverting them back.

A concrete Graphics implementation may contain the following code: 

 public void setXORMode(Color xorColor)
 {
   setComposite(new gnu.java.awt.BitwiseXORComposite(xorColor));
 }

 public void setPaintMode()
 {
   setComposite(java.awt.AlphaComposite.SrcOver);
 }

Field Summary

protected Color
xorColor
The color whose RGB value is xor-ed with the values of each pixel.

Constructor Summary

BitwiseXORComposite(Color xorColor)
Constructs a new composite for xor-ing the pixel value.

Method Summary

CompositeContext
createContext(ColorModel srcColorModel, ColorModel dstColorModel, RenderingHints hints)
Creates a context object for performing the compositing operation.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

xorColor

protected Color xorColor
The color whose RGB value is xor-ed with the values of each pixel.

Constructor Details

BitwiseXORComposite

public BitwiseXORComposite(Color xorColor)
Constructs a new composite for xor-ing the pixel value.
Parameters:
xorColor - the color whose pixel value will be bitwise xor-ed with the source and destination pixels.

Method Details

createContext

public CompositeContext createContext(ColorModel srcColorModel,
                                      ColorModel dstColorModel,
                                      RenderingHints hints)
Creates a context object for performing the compositing operation. Several contexts may co-exist for one composite; each context may simultaneously be called from concurrent threads.
Specified by:
createContext in interface Composite
Parameters:
srcColorModel - the color model of the source.
dstColorModel - the color model of the destination.
hints - hints for choosing between rendering alternatives.
BitwiseXORComposite.java -- Composite for emulating old-style XOR. Copyright (C) 2003, 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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