% A small program to demonstrate how the mouse works.



% This procedure draws crosshairs centred at (x,y) in a particular colour.
procedure drawCrossHairs(x, y : int, colour : int)
	const delta := 5
	drawline(max(1,x-delta), y, min(maxx, x+delta), y, colour)
	drawline(x, max(1,y-delta), x, min(maxy, y+delta), colour)
end drawCrossHairs



var oldx, oldy : int
var x, y, buttonNum, buttonUpDown : int
var firstTime : boolean := true

% Initialize the mouse.
buttonchoose("onebutton")

loop
	% Wait for a button click.
	buttonwait("downup", x, y, buttonNum, buttonUpDown)

	% Erase old crosshairs, if present.
	if not firstTime then
		% Erase old crosshairs
		drawCrossHairs(oldx, oldy, White)
	end if
	firstTime := false

	% Draw crosshairs at new position and record the position.
	drawCrossHairs(x, y, Black)
	oldx := x
	oldy := y
end loop