JAVA GRAPHICS

Graphics in Java is made relatively easy by many standard library calls that are not included in many languages. First and foremost, you should know that in Java graphics programming, one of the most important instantiated objects is the graphics context. This object is an instance of the java.awt.Graphics class, and it refers to an area of the screen such as an applet. A graphics context provides methods for all of the drawing operations on its area. It also holds "contextual" information about such things as the drawing area's clipping region, painting color, transfer mode, and text font.

Most often the graphics context is obtained from the Java window manager as a result of a painting request. This context is passed to your component's paint() or update() method. (Java also allows the user to obtain a graphics context for an offscreen image, which enables you to do double buffering. It is not necessary that you know what double buffering means, but you can find out from most any book on graphics and programming.)

The coordinate system is laid out with (0, 0) at the top left corner of the drawing area with the x's and y's increasing until they get to the applet's width and height. The coordinates are measured in pixels, with x increasing horizontal to the right and y increasing vertically down (not up!).