I'm having a problem getting mouse wheel scrolling to work in the following XAML, which I have simplified for clarity:
<ScrollViewer
HorizontalScrollBarVisibility="Visible"
VerticalScrollBarVisibility="Visible"
CanContentScroll="False"
>
<Grid
MouseDown="Editor_MouseDown"
MouseUp="Editor_MouseUp"
MouseMove="Editor_MouseMove"
Focusable="False"
>
<Grid.Resources>
<DataTemplate
DataType="{x:Type local:DataFieldModel}"
>
<Grid
Margin="0,2,2,2"
>
<TextBox
Cursor="IBeam"
MouseDown="TextBox_MouseDown"
MouseUp="TextBox_MouseUp"
MouseMove="TextBox_MouseMove"
/>
</Grid>
</DataTemplate>
</Grid.Resources>
<ListBox
x:Name="DataFieldListBox"
ItemsSource="{Binding GetDataFields}"
SelectionMode="Extended"
Background="Transparent"
Focusable="False"
>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemContainerStyle>
<Style
TargetType="ListBoxItem"
>
<Setter
Property="Canvas.Left"
Value="{Binding dfX}"
/>
<Setter
Property="Canvas.Top"
Value="{Binding dfY}"
/>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
</Grid>
</ScrollViewer>
Visually, the result is an area of some known size where DataField
s read from a collection can be represented with TextBox
es which have arbitrary position, size, et cetera. In cases where the ListBox
's styled "area" is too large to display all at once, horizontal and vertical scrolling is possible, but only with the scroll bars.
For better ergonomics and sanity, mouse wheel scrolling should be possible, and normally ScrollViewer
would handle it automatically, but the ListBox
appears to be handing those events such that the parent ScrollViewer
never sees them. So far I have only been able to get wheel scrolling working be setting IsHitTestVisible=False
for either the ListBox
or the parent Grid
, but of course none of the child element's mouse events work after that.
What can I do to ensure the ScrollViewer
sees mouse wheel events while preserving others for child elements?
Edit: I just learned that ListBox
has a built-in ScrollViewer
which is probably stealing wheel events from the parent ScrollViewer
and that specifying a control template can disable it. I'll update this question if that resolves the problem.
Specifying a ControlTemplate
for the Listbox
which doesn't include a ScrollViewer
solves the problem. See this answer and these two MSDN pages for more information: