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problems on Invalidate()

Posted on 1998-08-20
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Last Modified: 2013-11-20
Hi,

  I have code structure like this in my program:

(inside a CView's subclass)

for(i=0;i<1000;i++) {
 do some calculations;
 Invalidate();
}

In my OnDraw() method, the drawing depends on some variable which will be changed by "do some calculations" part. So I expect to see my drawing being updated constantly. However, what I got is: First there was a long delay, then only my final results are drawn. It seems that WM_PAINT messages got blocked when there is intensive calculation, and they can only get to the destination after the calculations are finished. Am I right on this? Can anyone tell me what I should do in order to "force" the window to call OnDraw() BEFORE the next calculation is made?
  Thank you in advance.

sunjian
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Question by:sunjian061197
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trestan earned 200 total points
ID: 1321082
Yes. You are right. If you want to display the calculation results at each step, you can create a CClientDC then use text out to display the value on the screen. Or you can create another thread and pass the pDC to the thread to display. Any questions?
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Author Comment

by:sunjian061197
ID: 1321083
Hi trestan,
   Thanks for your answer. I used your first suggestion(create a CClientDC) and now the program works fine!

sunjian
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