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MVVM How bind MouseLeftButtonDown and MouseLeftButtonUp in Canvas

Im trying to add new child(circle) to my Canvas after user click on it. And i want to change position of circles while draging them.
I want to do it with MVVM but dont know how catch these events in ViewModel.
I need a MouseLeftButtonUp/Down
I've tried wih System.Windows.Interactivity but it didnt helped.
My only idea is to add invisible button and do easy binding Command="{Binding Method}", but it still wont solve my problem, and certainly its not a best option
This in my XAML code (part of it)
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
<Canvas x:Name="DrawableCanvas" HorizontalAlignment="Left" Height="{Binding ElementName=GridContainer, Path=ActualHeight}" VerticalAlignment="Top" Width="{Binding ElementName=GridContainer, Path=ActualWidth}" Background="{DynamicResource {x:Static SystemColors.ControlBrushKey}}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseLeftButtonDown">
<i:InvokeCommandAction Command="{Binding CanvasActionCommand}" x:Name="interactifityFix2">
</i:InvokeCommandAction>
</i:EventTrigger>
</i:Interaction.Triggers>
</Canvas>

Add this namespace in your XAML:
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
then you can add an interaction trigger wich will merge the event with an icommand in your viemodel like so:
<Ellipse>
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewMouseDown">
<i:InvokeCommandAction Command="{Binding MouseDownCommand}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</Ellipse>

Treeview selectedItem highlight on startup

I have a treeview in my xaml as below. I use the selected item by using interactivity and bind the event.
<DataTemplate x:Key="TreeTemplate">
<TreeView Name="TreeView" ItemsSource="{Binding ItemList}" ItemTemplate="{StaticResource ChildTemplate}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectedItemChanged">
<i:InvokeCommandAction
Command="{Binding SetSelectedItemCommand}"
CommandParameter="{Binding SelectedItem, ElementName=TreeView}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</TreeView>
</DataTemplate>
This all works very well except when by application loads for the first time. Even if SelectedItem property is set on startup, the treeview does not show the item highlighted unless a mouse event is fired which causes SelectedItemChanged event.
Any ideas as as to how can I do this?
My datacontext is in code behind of the xaml
myView = new MyViewModel();
this.DataContext = myView;
InitializeComponent();

This will work:
<DataTemplate x:Key="TreeTemplate">
<TreeView Name="TreeView" ItemsSource="{Binding ItemList}" ItemTemplate="{StaticResource ChildTemplate}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectedItemChanged">
<i:InvokeCommandAction
Command="{Binding SetSelectedItemCommand}"
CommandParameter="{Binding SelectedItem, ElementName=TreeView}"/>
<i:EventTrigger EventName="Loaded">
<i:InvokeCommandAction
Command="{Binding SetSelectedItemCommand}"
CommandParameter="{Binding SelectedItem, ElementName=TreeView}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</TreeView>
</DataTemplate>

Button inside the GridSplitter not working WPF MVVM

I put the button inside the gridsplitter. my intention is to make clickable gridsplitter as well as slideable. my problem is after putting button inside the grid splitter, totally cannot drag by mouse. how can i configure the grid splitter to clickable and slideable.
<GridSplitter BorderThickness="1" HorizontalAlignment="Stretch" Grid.Column="1" >
<GridSplitter.Template>
<ControlTemplate TargetType="{x:Type GridSplitter}">
<Grid>
<Button Name="btnSplit" Content="⁞" >
<i:Interaction.Triggers>
<i:EventTrigger EventName="Click">
<i:InvokeCommandAction Command="{Binding SplitterClickCommand}" CommandParameter="{Binding ElementName=btnSplit}" ></i:InvokeCommandAction>
</i:EventTrigger>
</i:Interaction.Triggers>
</Button>
</Grid>
</ControlTemplate>
</GridSplitter.Template>
</GridSplitter>
Best Rgds
df

Try to subscribe MouseDoubleClick event on GridSplitter:
<GridSplitter BorderThickness="1" HorizontalAlignment="Stretch" Grid.Column="1" >
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseDoubleClick">
<i:InvokeCommandAction Command="{Binding SplitterClickCommand}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</GridSplitter>
If MouseDoubleClick event is not suitable for you, you can try to subscribe to MouseDown or MouseLeftButtonDown.

RelativeSource binding can't find Frame ancestor

I'm trying to pass as a CommandParameter the actual Frame object to which I'm applying the Command
XAML
<Frame NavigationUIVisibility="Hidden" Source="{Binding TargetContentPage}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="ContentRendered">
<command:EventToCommand Command="{Binding ContentRendered}" CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=Frame}}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</Frame>
C#
public RelayCommand<Frame> ContentRendered
{
get
{
return new RelayCommand<Frame>(frame => frame.RemoveBackEntry());
}
}
When running, a NullReferenceException is raised saying frame is null.
What is possibly wrong in the code above ?

There is no ancestor/descendent relation between Frame and EventToCommand. Use an ElementName binding instead:
<Frame x:Name="frame" ...>
<i:Interaction.Triggers>
<i:EventTrigger EventName="ContentRendered">
<command:EventToCommand
Command="{Binding ContentRendered}"
CommandParameter="{Binding ElementName=frame}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</Frame>

Binding toggle button to two commands

I have a toggle button in my silverlight application as follows:
<ToggleButton Content="ToggleButton" Margin="0,30,0,0" Style="{StaticResource ChkToggleButton}" />
The toggle currently is changing visual states on toggle and nothing more.
However, I need to bind each of the toggle with a different command. For eg: On button press1, run command1 and on button press again, run command2.
How can this be done?

Use Triggers for such purposes:
<ToggleButton Content="ToggleButton" Margin="0,30,0,0" Style="{StaticResource ChkToggleButton}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Checked">
<i:InvokeCommandAction Command="{Binding FirstCommand}"
CommandParameter="{Binding SomeParameter}" />
</i:EventTrigger>
<i:EventTrigger EventName="Unchecked">
<i:InvokeCommandAction Command="{Binding SecondCommand}"
CommandParameter="{Binding AnotherParameter}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ToggleButton>
If you don't have Interactivity you can get it by installing Expression Blend SDK or as a NuGet package.

use a single command and also keep track of the toggle state.
Have a viewmodel (preferably, or some codebehind) and let it use these two inputs to decide what actually needs to be done.