What is the best way to check if the view is visible on the window?


What's the best way to check if the view is visible on the window?

I have a CustomView which is part of my SDK and anybody can add CustomView to their layouts. My CustomView is taking some actions when it is visible to the user periodically. So if view becomes invisible to the user then it needs to stop the timer and when it becomes visible again it should restart its course.

But unfortunately there is no certain way of checking if my CustomView becomes visible or invisible to the user. There are few things that I can check and listen to:

onVisibilityChange //it is for view's visibility change, and is introduced in new API 8 version so has backward compatibility issue
onWindowVisibilityChange //but my CustomView can be part of a ViewFlipper's Views so it can pose issues
onDetachedFromWindows //this not as useful
onWindowFocusChanged //Again my CustomView can be part of ViewFlipper's views.

So if anybody has faced this kind of issues please throw some light.

onDraw() is called each time the view needs to be drawn. When the view is off screen then onDraw() is never called. When a tiny bit of the view is becomes visible to the user then onDraw() is called. This is not ideal but I cannot see another call to use as I want to do the same thing. Remember to call the super.onDraw or the view won't get drawn. Be careful of changing anything in onDraw that causes the view to be invalidate as that will cause another call to onDraw.

If you are using a listview then getView can be used whenever your listview becomes shown to the user.

obviously the activity onPause() is called all your views are all covered up and are not visible to the user. perhaps calling invalidate() on the parent and if ondraw() is not called then it is not visible.