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

UIComponent.visible is not necessarily valid for children of an object where visible=false. From the docs:

"In either case the children of the object will not emit a show or hide event unless the object has specifically written an implementation to do so."

I wrote a sample application that confirms this to be true. What you can do is walk up the display list checking for visible to be false on a parent. Basically "visible" gives false positives but shouldn't give false negatives. Here is a quick utility I put together:

package
{
    import flash.display.DisplayObject;

    import mx.core.Application;

    public class VisibilityUtils
    {
        public static function isDisplayObjectVisible(obj : DisplayObject) : Boolean {
            if (!obj.visible) return false;
            return checkDisplayObjectVisible(obj);
        }

        private static function checkDisplayObjectVisible(obj : DisplayObject) : Boolean {
            if (!obj.parent.visible) return false;
            if (obj.parent != null && !(obj.parent is Application))
                return checkDisplayObjectVisible(obj.parent);
            else
                return true;
        }
    }
}

I haven't done anything more than trivial tests on this but it should get you started.