Flex/QNX scrolling gallery

I was hoping someone could give me some guidance on building an image gallery which loads images dynamically for a Play开发者_如何学JAVABook application.I've uploaded a quick mockup of what I am trying to achieve, I want to dynamically load images into a QNX TileList or Flex equivalent and as the user scrolls through the list I want to call another 'page' of images dynamically. I have already produced an example which uses a custom cell renderer to dynamically load images but I am having problems when I attempt to identify when the user has reached the end of the list.

I have tried using the lastVisibleItem property of the list while the user is scrolling to identify if the last item visible in the list is also last in the DataProvider (so I know when I need to call for more images) but when I add images to the DataProvider it takes me back to the start of the list, can anyone tell me the reason for this?

Any advice on a different approach or how to modify the TileList would be greatly appreciated.

The scrollPosition automatically gets reset to 0 when you update the dataProvider. I've done workarounds that store the current scrollPosition before updating the dataProvider and then re-set it after the update to the dataProvider has completed. Let me know if you need some code sample and I'll see if I can dig something up.

Another option would be to use dataPaging. Here is a good example of how to do that:

http://www.jamesward.com/2010/10/11/data-paging-in-flex-4/