Creating and Enriching Graphical User Interfaces - Beginning Java 7 - page 662

ated AlphaComposite instanceconstantsnamed Clear , Dst , DstAtop , DstIn ,
DstOut , DstOver , Src , SrcAtop , SrcIn , SrcOut , SrcOver , and Xor .
Thedifferencebetweenthesetwosetsofconstantshastodowithalphavalues.The
precreated AlphaComposite instances are wired to an alpha value of 1.0 (opaque).
The integer constants and specific floating-point alpha values can be passed to
AlphaComposite 's AlphaComposite getInstance(int rule, float
alpha) class method. This alpha value is used to modify the opacity or coverage of
everysourcepixelbeforeit'susedintheblendingequationsdescribedin AlphaCom-
posite 's Java documentation.
Figure 7-22 shows the results of applying these rules.
Figure 7-22. Select Composite Rule from the Demo menu to view the composite rule
demonstration.
Figure 7-22 shows you the rules with an alpha value of 1.0. However, you can also
vary the alpha value by using getInstance(int rule, float alpha) . I