[solved] drawing with layers
lazarus / 39-Graphics

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speter · 2022-06-05 06:29

G'Day Folks,

I have written a program to draw on a number of layers; the program
allows the user to show / hide layers and all that works okay.

What doesn't work is clearing the layer(s).

The layering is implemented by having multiple Timages with the
transparent colour set; this works fine - first time around - but
doesn't work when "erasing" the existing graphics...

I've attached the project and 2 images to show what I mean; in one
image you see a number of coloured polygons; in the other the previous
polygons are now black (the "transparent" colour).

Any help / suggestions would be very welcome!

cheers
S.

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paweld · 2022-06-05 06:54

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.Button1Click(Sender: TObject);var  a : byte;  b : TButton;  h,w
: integer;begin  b := TButton(sender);  if b.caption = 'Draw' then   
begin      for a := 1 to num_layers do        draw_layer(a);      
b.caption := 'Clear';    end  else    begin      w :=
image_layer1.Width;      h := image_layer1.Height;       for a := 1 to
num_layers do        layers[a].Picture.Clear; //<---------      
b.caption := 'Draw';    end;end;

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speter · 2022-06-05 06:59

Thanks very much @ paweld.

cheers
S.