[fpc-pascal] interactively draw an ellipse

[duilio foschi]

Hi!

this code

procedure TForm1.DrawBtnClick(Sender: TObject);
{Draw some ellipses on the canvas - random size and color}
var
  i:integer;
  cx,cy:integer;
begin
  with image1, canvas do
  begin
    for i:= 1 to 10 do
    begin
      cx:=random(width);
      cy:=random(height);
      brush.color:=random(256*256*256);
      ellipse(cx,cy,cx+random(100), cy+random(100));
    end;
  end;
end;

will draw 10 ellipses on Image1.

However, I want to do it interactively, like it is done in Photo-Paint.

The ellipse should be contained in a rectangle R whose upper-left
corner is given by the original position of the mouse on screen.

And the bottom-right corner of R will be the final position of the mouse.

During dragging, a temporary ellipse should be shown on screen and the
mouse will be cross-shaped.

Any idea re how to do it ?

An unexpensive well debugged 3th-party library would be the ideal
solution (as I don't plan to work in graphics in the future).

Thank you

Duilio