Scrollbars not visible + Events not thrown - wpf

Question

I would like to implement a userControl which is able to scroll and zoom with provided mouse input.
Therefore, I implemented following user Control. (If its working I am going to move the Events directly to the Model)
ScrollDragZoomControl.xaml
<UserControl x:Class="MinimalMonitoringClient.Controls.ScrollDragZoomControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:models="clr-namespace:MinimalMonitoringClient.Controls.Models"
Background="Transparent">
<UserControl.DataContext>
<models:ScrollDragZoomViewModel />
</UserControl.DataContext>
<ScrollViewer x:Name="scrollViewer"
MouseLeftButtonUp="scrollViewer_MouseLeftButtonUp"
PreviewMouseLeftButtonUp="scrollViewer_PreviewMouseLeftButtonUp"
PreviewMouseWheel="scrollViewer_PreviewMouseWheel"
PreviewMouseLeftButtonDown="scrollViewer_PreviewMouseLeftButtonDown"
MouseMove="scrollViewer_MouseMove"
VerticalScrollBarVisibility="{Binding VerticalScrollBarVisibility}"
HorizontalScrollBarVisibility="{Binding HorizontalScrollBarVisibility}">
<Grid RenderTransformOrigin="0.5,0.5">
<Grid.LayoutTransform>
<TransformGroup>
<ScaleTransform />
</TransformGroup>
</Grid.LayoutTransform>
<Viewbox>
<!-- Present the actual stuff the user wants to display -->
<ContentPresenter />
</Viewbox>
</Grid>
</ScrollViewer>
In another UserControl I would like to use this UserControl so show Content which could be bigger than the current UserControl's width and height. For Testing I set Width and Height to something huge.
<UserControl x:Class="MinimalMonitoringClient.Panels.HierarchicalView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:panels="clr-namespace:MinimalMonitoringClient.Models.Panels"
xmlns:controls="clr-namespace:MinimalMonitoringClient.Controls">
<UserControl.DataContext>
<panels:HierarchicalViewModel />
</UserControl.DataContext>
<controls:ScrollDragZoomControl>
<Image Source="/Images/Information.png" Width="2000" Height="2000" IsHitTestVisible="False" />
</controls:ScrollDragZoomControl>
No Events are called in the ScrollDragZoomControl. I set the
Background to transparent. Also played with IsHitTestVisible.
The Scrollbars are not visible.

Answer 1

When you set the Content property of the UserControl to an Image element you effectively "override" any content that you have defined in ScrollDragZoomControl.xaml.
You probably want the ScrollViewer and the rest of the stuff you have defined in ScrollDragZoomControl.xaml to be part of the UserControl's template:
<UserControl x:Class="MinimalMonitoringClient.Controls.ScrollDragZoomControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:models="clr-namespace:MinimalMonitoringClient.Controls.Models"
Background="Transparent">
<UserControl.DataContext>
<panels:HierarchicalViewModel />
</UserControl.DataContext>
<UserControl.Template>
<ControlTemplate TargetType="UserControl">
<ScrollViewer x:Name="scrollViewer"
MouseLeftButtonUp="scrollViewer_MouseLeftButtonUp"
PreviewMouseLeftButtonUp="scrollViewer_PreviewMouseLeftButtonUp"
PreviewMouseWheel="scrollViewer_PreviewMouseWheel"
PreviewMouseLeftButtonDown="scrollViewer_PreviewMouseLeftButtonDown"
MouseMove="scrollViewer_MouseMove"
VerticalScrollBarVisibility="{Binding VerticalScrollBarVisibility}"
HorizontalScrollBarVisibility="{Binding HorizontalScrollBarVisibility}">
<Grid RenderTransformOrigin="0.5,0.5">
<Grid.LayoutTransform>
<TransformGroup>
<ScaleTransform />
</TransformGroup>
</Grid.LayoutTransform>
<Viewbox>
<!-- Present the actual stuff the user wants to display -->
<ContentPresenter />
</Viewbox>
</Grid>
</ScrollViewer>
</ControlTemplate>
</UserControl.Template>
</UserControl>