Flex: Determine if a component is showing

Question

What is the best way to determine if a component in Flex/Flash is showing on the user\'s screen? I\'m looking for an analog to Java\'s Component.isShowing() method.

The

Answer 1

I was trying to obtain the same in a reusable manner.. I almost found out a way using getObjectsUnderPoint() - this returns the object under a particolar point, z-ordered (even if they are not siblings, e.g. ViewStack, Popups, ecc.).

Basically, I get the topmost display object on under a particular point of the stage, then go up un the display object hierarchy to find the tested object. If I find it, the object is visible (not visible objects in the hierarchy should be already filtered out by the getObjectsUnderPoint call).

The problem here is that you must use a non-transparent point of your object (in my case, I used an offset of 5 pixel due to rounder borders), otherwise it will not be picked up by this function.

Any ideas to improve it?

Cosma

public static function isVisible(object:DisplayObject):Boolean  {
    var point:Point = object.localToGlobal(new Point(5, 5));
    var objects:Array = object.stage.getObjectsUnderPoint(point);
    if (objects.length > 0) {
        if (isDescendantOf(object, objects[objects.length - 1] as DisplayObject)) {
            return true;
        }
    }
    return false;
}

public static function isDescendantOf(parent:DisplayObject, child:DisplayObject):Boolean  {
    while (child.parent != null) {
        if (child.parent === parent) {
            return true;
        } else {
            child = child.parent;
        }
    }
    return false;
}