Preventing TImage from flickering
lazarus / 7-LCL

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Leledumbo · 2007-11-16 12:18

I try to make a 2D game with only LCL. I'm using TImage as the sprite,
and in order to have the same FPS limit on every machine, I use TTimer
to draw the form (and the game objects). But as expected (well, in
sprite example the image flickers, too), the sprite flickers and it's
really bad. Setting DoubleBuffered property of the form doesn't help.
Is there anyway to solve this? Some painting code:
Code: [Select]
...
procedure TMainForm.FormPaint(Sender: TObject);
begin
  // Sprite: TImage;
  Canvas.Draw(Sprite.Picture.Graphic);
end;
...
// GameTimer: TTimer;
procedure TMainForm.GameTimerTimer(Sender: TObject);
begin
  FormPaint(nil);
end;
...

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antonio · 2007-11-16 12:33

You could have a look at my Banner Example,
http://br.geocities.com/antoniog123456/ , where I draw a sprite
directly on canvas. It does not flick.

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Leledumbo · 2007-11-16 12:57

Kinda weird, I use the same code (I guess, I'm not at home so I can't
see it now), except a call to Canvas.Rectangle. I prefer using
Canvas.Clear, could it be the problem?

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antonio · 2007-11-16 13:09

Quote from: "Leledumbo"I prefer using Canvas.Clear, could it be the
problem?

I don't think so. I tested with Canvas.Clear and it is not better, but
does not flick.

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Leledumbo · 2007-11-16 13:15

Well, I guess I have to go home and see it first. I'll be back on
monday.

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theo · 2007-11-16 13:57

If you want really flicker - free, do it like this:
http://wiki.lazarus.freepascal.org/Developing_with_Graphics#Create_a_c
ustom_control_which_draws_itself
(Custom control with buffer)