Drawing Lines

To draw a straight line on a canvas, use the LineTo method of the canvas.

LineTo draws a line from the current pen position to the point you specify and makes the endpoint of the line the current position. The canvas draws the line using its pen.

For example, the following method draws crossed diagonal lines across a form whenever the form is painted:

Copy Code

procedure TForm1.FormPaint(Sender: TObject);
begin
with Canvas do
begin
MoveTo(0, 0);
LineTo(ClientWidth, ClientHeight);
MoveTo(0, ClientHeight);
LineTo(ClientWidth, 0);
end;
end;

Copy Code

void __fastcall TForm1::FormPaint(TObject *Sender)
{
  Canvas->MoveTo(0,0);
  Canvas->LineTo(ClientWidth, ClientHeight);
  Canvas->MoveTo(0, ClientHeight);
  Canvas->LineTo(ClientWidth, 0);
}