HELP! * GREY=local LOCAL HTML version of Foils prepared July 10 1996

Foil 147 Flickering in Applets and its Solution

From Basic Lectures on Java Language Applets Graphics Networking Trip to China and Icase Tutorial -- July 12-28 and June 10-13 96. by Geoffrey C. Fox * See also color IMAGE

Unless you are careful, dynamic applets will give flickering screens
This is due to cycle
paint(g)
update(g) clearing screen
paint(g) drawing new screen .....
where flicker caused by rapid clear-paint cycle.
There are two ways to solve this problem which involve changing update in different ways
  • 1: Change update() either not to clear screen at all (because you know paint() will write over parts that are to be changed) or to just clear the parts of the screen that are changed
  • or 2:Double Buffering



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