Constraining 'grab'

[Geoff Canyon]

At 2:06 PM -0800 3/4/02, Ken Norris (dialup) wrote:
>If it's unwise to use 'the mouse' repeats to do it, then...How do I
>constrain 'grab' to a rect (or any other) boundary?
>
>Know what I mean? I don't want the user to drag the object out of bounds. I
>looked through the docs and couldn't find an example.

local tDragging

on mouseDown
    put true into tDragging
end mouseDown

on mouseMove mouseX,mouseY
    if tDragging then
-- Do bounds checking here --
        set the loc of me to (mouseX,mouseY)
    end if
end mouseMove

on mouseUp
    stopDragging
end mouseUp

on mouseRelease
    stopDragging
end mouseRelease

on stopDragging
    put false into tDragging
end stopDragging

Note that you will likely want to get the offset of the mouse from the loc of the object in the mouseDown in order to maintain that offset while dragging. Otherwise the object will snap to the mouseLoc at mouseDown.

regards,

Geoff