How to draw a rectangle, and then delete it
lazarus / 39-Graphics

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BlueIcaro · 2011-04-05 19:09

Hello, I use this code to draw a rectangule, over a canvas

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  
Canvas.Brush.Style := bsClear;  Canvas.Pen.Mode := pmCopy; 
Canvas.Rectangle(100,100,200,200); 
When I want to delete it, I use:
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  
 Canvas.Brush.Style := bsClear;  Canvas.Pen.Mode := pmNotCopy; 
Canvas.Rectangle(100,100,200,200);         
But This code, makes a rectangle with a white border.

Any help?

/BlueIcaro

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typo · 2011-04-05 19:20

Because clWhite is the inverse color of clBlack.

In order to restore the background correctly, you need to save it
previously.

To save and draw:
Code: [Select]var
  r, r2 :trect;
begin
  r.Top := 100;
  r.Left := 100;
  r.Right := 200;
  r.Bottom := 200;
  r2.Top := 0;
  r2.Left := 0;
  r2.Right := 100;
  r2.Bottom := 100;
  Image2.Canvas.Copyrect(r2, canvas, r);
  Canvas.Brush.Color := clBlack;
  Canvas.Pen.Color := clBlack;
  Canvas.Rectangle(100,100,200,200);
end;                    

To restore:
Code: [Select]var
  r, r2 :trect;
begin
  r.Top := 100;
  r.Left := 100;
  r.Right := 200;
  r.Bottom := 200;
  r2.Top := 0;
  r2.Left := 0;
  r2.Right := 100;
  r2.Bottom := 100;
  Canvas.Copyrect(r, image2.canvas, r2);
end;

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BlueIcaro · 2011-04-05 20:27

Thnak you!!, it's works!!!

/BlueIcaro