Media: Graphics, Audio,Video - Java - page 466

Painting with a Graphics Object

Problem

You want to draw something on the screen.

Solution

Write a Component subclass; in your paint() method, use the provided Graphics object's
drawing methods:

public public class class PaintDemo PaintDemo extends extends Component {

private private static static final final long long serialVersionUID = - 5595189404659801913L ;

int int rectX = 20 , rectY = 30 ;

int int rectWidth = 50 , rectHeight = 50 ;

/**
* Component subclasses can override paint(), but
* JComponent subclasses should normally use paintComponent()
* instead, to avoid clobbering border painting and the like.
*/
@Override
public

public void void paint ( Graphics g ) {

g . setColor ( Color . red );
g . fillRect ( rectX , rectY , rectWidth , rectHeight );

}

@Override
public public Dimension getPreferredSize () {

return

return new new Dimension ( 100 , 100 );

}

}

Discussion

The Graphics class has a large set of drawing primitives. Each shape— Rect (angle), Arc ,
Ellipse , and Polygon —has a draw method (draws just the outline) and a fill method (fills
inside the outline). You don't need both, unless you want the outline and the interior (fill) of
a shape to be different colors. The method drawString() and its relatives let you print text