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Disable window update

Posted on 2002-05-10
6
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Last Modified: 2011-09-20
hi,
is it possible to disable update of a control? it is a very slow process to insert lines to a tmemo control while the visual update in effect.
thanks
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Question by:omavideniz
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6 Comments
 
LVL 27

Accepted Solution

by:
kretzschmar earned 200 total points
ID: 7001624
memo1.lines.beginupdate;

don't forget

memo1.lines.endupdate;

after your insert action

meikl ;-)
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LVL 10

Expert Comment

by:Jacco
ID: 7001644
Hi all,

I agree with meikl. I just wanted to say thay I always put the BeginUpdate/EndUpdate in a try/finally structure:

Memo1.Lines.BeginUpdate;
try
  .. code adding lines ..
finally
  Memo1.Lines.BeginUpdate;
end;

Regards Jacco
0
 
LVL 10

Expert Comment

by:Jacco
ID: 7001646
Oops (cut and past is not always very good)

Memo1.Lines.BeginUpdate;
try
 .. code adding lines ..
finally
 Memo1.Lines.EndUpdate;
end;
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LVL 3

Expert Comment

by:SteveWaite
ID: 7002140
 LockWindowUpdate(Memo1.Handle);
  // do your stuff
  // ..
  LockWindowUpdate(0);

Regards,
Steve
0
 
LVL 2

Expert Comment

by:mikepj
ID: 7002792
When I've needed something with a bit more strength, this is what is use:

with mywincontrol do
 begin
  Perform( WM_SETREDRAW, 0, 0 );
  try
    ...
  finally
    Perform( WM_SETREDRAW, 1, 0 );
    Invalidate;
  end;
 end;

0
 
LVL 2

Expert Comment

by:Hagen040798
ID: 7004339
All above methods don't speedup real, because the painting code is indeed executed, but with one exception. Any response to get a "visible" DeviceContext to the Screen retruns a invalid or virtual DC. This avoid that the following Paintingcode paints on the screen, but don't avoid this Paintingcode itself.
Ok, the System detect this state by every call to functions like Invalidate() or RedrawWindow() and avoid now some addtional code.
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