OpenEuphoria

Re: Silly Scribble Program

• Posted by "Cuny, David" <David.Cuny at DSS.CA.GOV> Nov 16, 1998
• 567 views

I just got around to looking at Hawke's version of TruScribble, and noticed
that he made many of the mistakes that I documented in my prior post.
Specifically:

    - not using and_bits to test the mouse state
    - making the tests mutually exclusive

As a result, the code ignores certain mouse events (such as MOVE+LEFT_UP)
and continues to draw lines after the mouse has been released. Of course, he
could always rewrite TruMouse to return the mouse events as *seperate*
events, like I did in the WinLib library I wrote for my version of Scribble.

Here's the code with the errors:

-- BEGIN SNIPPET OF HAWKE'S CODE --
    if event = MOVE then
       if draw then
          x = mouse[2]  y = mouse[3]
          drawline(oldx,oldy,x,y)
          oldx = x      oldy = y
       end if
    elsif event = LEFT_DOWN then
       oldx = mouse[2]  oldy = mouse[3]
       draw = TRUE
    elsif event = LEFT_UP then
       x    = mouse[2]  y    = mouse[3]
       draw = FALSE
    end if
-- END SNIPPET OF HAWKE'S CODE --

The corrected version might look something like:

-- BEGIN FIXED SNIPPET OF HAWKE'S CODE --
    if and_bits( event, MOVE ) then
       if draw then
          x = mouse[2]  y = mouse[3]
          drawline(oldx,oldy,x,y)
          oldx = x      oldy = y
       end if
    end if

    if and_bits( event, LEFT_DOWN ) then
       oldx = mouse[2]  oldy = mouse[3]
       draw = TRUE
    end if

    if and_bits( event = LEFT_UP ) then
       x    = mouse[2]  y    = mouse[3]
       drawline(oldx,oldy,x,y)
       draw = FALSE
    end if
-- END FIXED SNIPPET OF HAWKE'S CODE --

-- David Cuny