Java Foundation Classes in a Nutshell

Her e’s an example of creating and using a GradientPaint:

Graphics2D g; // Initialized elsewhere

Paint p = new GradientPaint(0, 0, Color.red, 100, 100, Color.pink, true);

g.setPaint(p);

g.fillRect(0, 0, 300, 300);

Both TexturePaint and GradientPaint objects are immutable: they have no set()

methods that allow their attributes to be changed. This is important because it

means that a

Graphics2D object can use a Paint object without worrying about its

attributes being changed concurrently (i.e., the

Graphics2D object does not have to

make a private copy of its

Paint attribute).

Blending Colors with AlphaComposite

Although a Paint object is used to generate the colors used when drawing and fill-

ing with Java 2D, these colors are not always the final colors that end up displayed

on the screen. Another Java 2D attribute, the

Composite object, controls the way in

which the colors being drawn combine with the colors that are alr eady visible on

the drawing surface.

A compositing operation combines the pixels of your drawing (the source pixels)

with the pixels of the drawing surface (the destination pixels) to produce a new,

composite set of pixels. Prior to Java 2D, you could use the

setXORMode() method

of a

Graphics object to produce a simple and very specialized kind of compositing

operation. Java 2D supports generalized compositing through the

java.awt.Com-

posite inter face and its implementation, java.awt.AlphaComposite ...