WP7: Dynamically adding UIElements to a LongListSelector item

Question

I'm trying to add UIElement s to a LongListSelector item programmatically. I've created templates for the header, footer, items etc.

Right now I'm doing something like this (the list item template):

<DataTemplate x:Key="listItemTemplate">
     <ContentPresenter Content="{Binding ItemContent}"></ContentPresenter>
</DataTemplate>

Inside the model, I assisgn the ItemContent to a Grid, on which I'm adding different UI elements. I don't really know if this is the way to do it or if this is even possible on the LongListSelector but when scrolling the list I get a "The parameter is incorrect." exception (at first, everything seems ok and all the elements added look fine). I tried different approaches but none worked and I feel that I'm just randomly trying solutions without a certain idea. Has anyone managed to do this by using a LongListSelector (any suggestions would be greatly appreciated)?

The call stack:

LongListSelectorPOC.dll!LongListSelectorPOC.App.Application_UnhandledException(object sender, System.Windows.ApplicationUnhandledExceptionEventArgs e) Line 102 + 0x5 bytes C# System.Windows.dll!MS.Internal.Error.CallApplicationUEHandler(System.Exception e) + 0x30 bytes
System.Windows.dll!MS.Internal.Error.GetXresultForUserException(System.Exception ex) + 0x4d bytes
System.Windows.dll!MS.Internal.FrameworkCallbacks.ManagedPeerTreeUpdate(System.IntPtr oldParentElement, System.IntPtr parentElement, System.IntPtr childElement, byte bIsParentAlive, byte bKeepReferenceToParent, byte bCanCreateParent) + 0x6b bytes
[External Code] System.Windows.dll!MS.Internal.XcpImports.MeasureOverrideNative(System.IntPtr element, float inWidth, float inHeight, out float outWidth, out float outHeight)
System.Windows.dll!MS.Internal.XcpImports.FrameworkElement_MeasureOverride(System.Windows.FrameworkElement element, System.Windows.Size availableSize) + 0x26 bytes System.Windows.dll!System.Windows.FrameworkElement.MeasureOverride(System.Windows.Size availableSize) + 0x7 bytes
System.Windows.dll!System.Windows.FrameworkElement.MeasureOverride(System.IntPtr nativeTarget, double inWidth, double inHeight, out double outWidth, out double outHeight) + 0x43 bytes [External Code] System.Windows.dll!MS.Internal.XcpImports.Measure_WithDesiredSizeNative(System.IntPtr element, float inWidth, float inHeight, out float outWidth, out float outHeight)
System.Windows.dll!MS.Internal.XcpImports.UIElement_Measure_WithDesiredSize(System.Windows.UIElement element, System.Windows.Size availableSize) + 0x26 bytes
System.Windows.dll!System.Windows.UIElement.Measure_WithDesiredSize(System.Windows.Size availableSize) + 0x39 bytes System.Windows.dll!System.Windows.Controls.VirtualizingStackPanel.MeasureChild(System.Windows.UIElement child, System.Windows.Size layoutSlotSize) + 0x42 bytes System.Windows.dll!System.Windows.Controls.VirtualizingStackPanel.GeneratePreviousChild(int childIndex, System.Windows.Size layoutSlotSize) + 0x6f bytes
System.Windows.dll!System.Windows.Controls.VirtualizingStackPanel.GeneratePreviousItems(ref double logicalVisibleSpace, ref System.Windows.Size stackDesiredSize, System.Windows.Size layoutSlotSize, bool isHorizontal, bool adjustPositions) + 0x138 bytes
System.Windows.dll!System.Windows.Controls.VirtualizingStackPanel.MeasureOverride(System.Windows.Size constraint) + 0x4e1 bytes System.Windows.dll!System.Windows.FrameworkElement.MeasureOverride(System.IntPtr nativeTarget, double inWidth, double inHeight, out double outWidth, out double outHeight) + 0x43 bytes [External Code]

Answer 1

You should use DataTemplateSelector approach.

Define, for example, enum ItemType with fields Grid , Border , StackPanel and then in DataTemplateSelector class choose template using that enum.

For DataTemplateSelector , please look at following article: http://www.windowsphonegeek.com/articles/Implementing-Windows-Phone-7-DataTemplateSelector-and-CustomDataTemplateSelector

Answer 2

将ObservableCollection用于ItemContent 。