Write a short note on lavatron applet?

Answer 1

Lavatron is a sports arena lightbulb display.Lavatron is able to present an interesting image onscreen because of a small trick that it employs, and its side effect allows the applet to load very quickly. The reason it loads so quickly is that there isn't much data transmitted over the Net. The source image is a JPEG image that is 64 times smaller than the displayed image. Each pixel in the source image is scaled up to an 8×8-pixel square. Here is the trick that Lavatron uses to produce the lightbulb effect. An 8×8-pixel image of a transparent circle surrounded by a black bezel, with a white highlight for a dash of style, is painted over the scaled-up color pixel. As an optimization, the bulbs are preassembled into an image that can be painted once for each column.

Lavatron paints so fast because it doesn't have to repaint what it has already drawn.

The technique of copying the area of the screen that's good and painting just the portion

that's new is used in many common operations involving scrolling.