% 7. Write a procedure called follow that allows the user to use the mouse to
% click on the screen. When they click on the screen it draws a circle with
% radius 10, and a line to the last spot clicked (no line if its the first
% click).When the user clicks for the fourth time the procedure will erase
% the first circle and line. From then on, whenever a new circle and line are
% drawn the oldest one will be erased. The procedure will end when the user
% clicks on both buttons at once. The colour of all the drawing is supplied
% by a single integer parameter. Save as array7.t
View.Set ("graphics:max,max")
proc follow (x, y : array 1 .. 4 of int)
var count : int := 0
var mx, my, mb : int
loop
for i : 1 .. upper (x)
mousewhere (mx, my, mb)
if mb = 1 then
drawfilloval (mx - 5, my - 5, 10, 10, black)
count += 1
exit when count = 4
end if
end for
delay (100)
end loop
end follow
var x, y : array 1 .. 4 of int
follow (x, y)