Redrawing form
lazarus / 39-Graphics

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pascal111 · 2021-04-21 01:38

I'm trying in the next piece of code to delay the drawing of line of
pixels to see some motion, but I failed to make the form to redraw
itself again each determined time of "delay" procedure:


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormPaint(Sender: TObject);var   i:integer; begin     for i:=1
to 100 do  begin     canvas.Pixels[i,10]:=clblue;    self.update;   
delay(100);   end;     end;

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engkin · 2021-04-21 02:11

After delay call Application.ProcessMessages.

The correct way is to use a timer.

If you draw on the form, it will not retain the image when covered
with some other window.

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engkin · 2021-04-21 02:59

Check attached project

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pascal111 · 2021-04-21 11:25

I made some changes depending on attached project "simple", and it
works.


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  var 
Form1: TForm1;  x:integer;      procedure TForm1.FormPaint(Sender:
TObject); begin       canvas.Pixels[x,10]:=clblue;   end; procedure
TForm1.Timer1Timer(Sender: TObject);  begin   if x>=100 then  exit 
else    inc(x);     Invalidate;  end;             

With modifying "interval" property of the timer.