Solved

How to distinglish causes of Repaint events

Posted on 1998-01-02
1
414 Views
Last Modified: 2010-05-18
Does anybody know within the callback method
"paint(Graphics)", how can we distinglish between whether it
is ...
a) Caused by component movement (e.g. when I drag a
   component over other components)
OR
b) Caused by window exposure (e.g. when I drag another
   window over my applet)

For yr background information, I need to distinglish
them and handle in a different way in order to support drag
& drop of components in my applet.

In the moving component in case (a), I need to erase the
current location before I draw and on a new location.  I
also use myGraphics.setXORMode(..) to ensure it doesn't
erase its path.

In case (b), I just erase the whole applet and redraw it.

Best regards,
Ricky
0
Comment
Question by:hori
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 4

Accepted Solution

by:
russgold earned 50 total points
ID: 1231923
The AWT does not support any way to tell why paint is being called; generally, if you are trying to minimize repainting, you keep an offscreen bitmap and just copy it to the screen during paint.

The best that you can do is to keep track of your own invalidations and recompute those areas only.  For an example of how this might work, check:

http://www.netaxs.com/~russgold/java_samples/dragTest.html

which includes a JDK 1.02-compatible drag-and-drop demo that I wrote a while ago.
0

Featured Post

PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Java functions are among the best things for programmers to work with as Java sites can be very easy to read and prepare. Java especially simplifies many processes in the coding industry as it helps integrate many forms of technology and different d…
In this post we will learn different types of Android Layout and some basics of an Android App.
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
This tutorial covers a practical example of lazy loading technique and early loading technique in a Singleton Design Pattern.

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question