Anyway, to calculate the size of the extent (to enable scrolling) the panel should know the total number of the items (realized and virtualized).

Any help?

Right, the panel will keep consuming memory until you’ve loaded all your items into it. I admit it’s not the ideal way to do things, yet at the time of this article, the items I were loading were from disk, and wanted to avoid having to constantly read from the hard drive from loading and unloading the items. After I wrote the article, I was assigned to other areas of my project not having to do with WPF, so it’s with regret that I haven’t had the chance to explore a possible better solution.

Fortunately, we had a major release last week, so I now have some free time. Thanks for asking, I will try to explore better solutions and get them posted if I find any

Jerry

I’m trying to implement such a panel using your advices.

I have a question:
*If you do not clean the items after you scroll, then the more your scroll the more memory to consume ? Isn’t it ?

Thanks
Jonathan

Thanks for writing this! This is a really good article and will help me implement what I need. I need to create a StackPanel (could be a wrap panel) that will implement scrolling in a different way than normal. Our designer thought it would be a good idea if our program didn’t have any scroll bars. Luckily we don’t have lots of data that needs to be shown in any given stack panel … Just more controls.

Stack panels that have more content than can fit into the scroll viewer will have buttons at the top and bottom. If the user wishes to scroll down, they hit a “Page Down” button. This will cause all the elements in the current view that are visible to fade out, then the elements that are under the last fully visible element will slide up into view. The opposite will occur if the user tries to page up.

I don’t need to worry about virtualizing visuals since the number of child controls in my panel will be always be small (under 10). The one concern I have is that I will be able to perform two different Animations in the ArrangeOverride function. Maybe I just need to fade the visible items out in the IScrollInfo.PageDown function and then translate the items into view in the ArrangeOverride function.

My biggest concern is being able to determine what child controls are visible in the scrollviewer and which are not. Is there an easy way to determine this?

Thanks,
Louis