What event is fired after all views are fully drawn?

I need to capture the absolute positions of some ImageViews to use as drop targets. I can't seem to find what event I need to put my code in to read the screen and get the Left(), Top() .. positions. I do not want monitor the inflation of each individual view. There must be some sort of onScreenFinsihed type of event, but I can't find it. onMeasure and onDraw seem to fire at the start of their work, I need to know when they are done. TIA.