Webmaster Forum / Flash / General Flash Topics / July 2008

Create a movie clip with a hit area shape, reduce it's opacity to 0. Place that
movie clip on the stage with instance name. When someone is dragging an object,
you can use hitTest to determine if it's in the correct spot (at least close
enough) when the mouse is let go. If so, you can assign the object to a defined
x and y coordinate.

Writing a simple snap to grid function is pretty easy, and may work well for
what you need. Essentially, you just test the _xmouse and _ymouse using mod,
if mousePos % snapSetting == 0, then you know you're on a grid point.

This should get you started:

var snapSpace = 10;
var myInterval:Number;

clipA.onPress = function(){
myInterval = setInterval(startDragging, 5, this);
}

clipA.onRelease = clipA.onReleaseOutside = function(){
clearInterval(myInterval);
}

function startDragging(clipRef:MovieClip){

if(_xmouse % snapSpace == 0){
 clipRef._x = _xmouse;
}
if(_ymouse % snapSpace == 0){
 clipRef._y = _ymouse;
}
}