Solved

How to distinglish causes of Repaint events

Posted on 1998-01-02
1
412 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

On Demand Webinar - Networking for the Cloud Era

This webinar discusses:
-Common barriers companies experience when moving to the cloud
-How SD-WAN changes the way we look at networks
-Best practices customers should employ moving forward with cloud migration
-What happens behind the scenes of SteelConnect’s one-click button

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Way to decrease size of apk file 9 109
how to debug htl and js pages 8 57
How to configure empty element in XML Document parser? 15 44
Coding for the first time 9 69
Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
Viewers learn about the “while” loop and how to utilize it correctly in Java. Additionally, viewers begin exploring how to include conditional statements within a while loop and avoid an endless loop. Define While Loop: Basic Example: Explanatio…
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…

733 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