Basic HTML version of Foils prepared Sept 21 1998

Foil 22 Flickering in Applets and its Solution

From Java Tutorial 98- 3: Graphics and the Abstract Windowing Toolkit NAVO Tutorial -- Sept 23 1998. by Geoffrey C. Fox, Nancy McCracken


Unless you are careful, dynamic applets will give flickering screens
This is due to cycle
  • repaint()
  • 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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