ScrollViewer and handling manipulation events on child elements

windows-8, windows-runtime, windows-store-apps, winrt-xaml

Solution

What I have done was I put a transparent rectangle on top of the ScrollViewer and handle manipulations there. When I find the manipulation should scroll the ScrollViewer - I scroll the ScrollViewer using the ScrollToHorizontal/VerticalOffset() methods. On ManipulationStarted I also use VisualTreeHelper.FindElementsInHostCoordinates to check which item I could manipulate too and then I can decide whether to manipulate that item or not depending on various conditions. It's quite a bit of custom code though. You would also need to update the RenderTransform of the ScrollContentPresenter in the ScrollViewer when the user tries to drag farther than minimum/maximum offset to immitate the ScrollViewer default behavior, handle mouse scrollwheel etc. Nothing YOU could not handle of course. I could not find a better way unfortunately and I am interested if someone finds one.

EDIT* Another solution I thought of when trying to answer another similar question was to use another ScrollViewer as a child item and use its ViewChanged events instead of manipulation events.

EDIT 2*

Also with Windows 8.1 you get `ManipulationModes.System` which combined with other modes should allow you to handle manipulations inside of a `ScrollViewer`. Then you can call `CancelDirectManipulations()` on the manipulated element once you want its parent `ScrollViewers` to stop processing manipulations for pan&zoom.

Problem

I have created a Windows 8 Store App using C# / XAML. My interface includes a scrollable list, which is rendered using an `ScrollViewer`. I would like to be able to handle manipulation events on the elements within the list, however, setting `ManipulationMode` to anything other than `None` on the list element causes my list to no longer scroll. Here is a simplified version of the UI: ``` <ScrollViewer> <Border/> <!-- these contain child content --> <Border/> <Border/> <!-- Set ManipulationMode on an element in order to receive manipulation events --> <!-- This causes the scroll viewer to stop working! --> <Border ManipulationMode="All" ManipulationDelta="..."/> <Border/> <Border/> </ScrollViewer> ``` I understand that the WinRT `ScrollViewer` uses a special `ManipulationMode` of `System` for performance reasons, but I would like to have a vertically scrolling list, containing elements that respond to horizontal manipulation / gestures. Can anyone think of a creative workaround that would make this possible?

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