When I right click on an item in the ListView the event CommandBinding_CanExecute is getting called and Context Menu is displayed. But when I do the same in the empty space of the ListView the event is not fired and Context Menu is displayed but disabled.
Why is CanExecute not called in the second case and is there any workaround to raise this event when clicked in empty space of ListView.
<Window.Resources>
<RoutedUICommand x:Key="NewItemCommand" />
</Window.Resources>
<Window.CommandBindings>
<CommandBinding Command="{StaticResource NewItemCommand}" CanExecute="CommandBinding_OnCanExecute" Executed="CommandBinding_OnExecuted" />
</Window.CommandBindings>
<Grid>
<ListView Background="AntiqueWhite" Name="lst">
<ListView.ContextMenu>
<ContextMenu>
<MenuItem Header="New Item" Command="{StaticResource NewItemCommand}" />
</ContextMenu>
</ListView.ContextMenu>
</ListView>
</Grid>
Related
I have a UserControl with Button inside which opens a ContextMenu when left clicked. I'm trying to pass UserControl's parent Window as a parameter to ContextMenu item's command to close that window, but with no avail. I've tried everything with RelativeSource and PlacementTarget, but parameter is always null. I'm aware that ContextMenu is not part of parent window's VisualTree. I'm currently stuck with this approach, but it is not working.
<Grid x:Name="LayoutRoot">
<Button
HorizontalAlignment="Left"
Margin="0"
Style="{DynamicResource ButtonStyle1}"
VerticalAlignment="Top"
Width="120"
Height="25"
Content="Dashboard Menu"
TextElement.FontWeight="Bold"
Foreground="AliceBlue"
>
<!--Tag="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={ x:Type Window}}}"-->
<Button.ContextMenu>
<ContextMenu DataContext="{Binding PlacementTarget, RelativeSource={RelativeSource Self}}" >
<MenuItem Header="Open Log Viewer" Command="{StaticResource openLogViewer}" />
<Separator />
<MenuItem Header="Exit" Command="{StaticResource exit}" CommandParameter="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource AncestorType=Window}}"/>
</ContextMenu>
</Button.ContextMenu>
</Button>
</Grid>
Command is a Referenced command defined in UserControl.Resources:
<my:CommandReference x:Key="exit" Command="{Binding Exit}" />
and it's Execute part is triggered but parameter is always null. So, my question is, what is the right way to bind parent window as CommandParameter of MenuItem. Any help is appreciated, because this thing is bothering me for almost two days.
Right way here is to not pass parent Window to the VM as CommandParameter. If this is MVVM you should be using a Messenger(MVVM Light) / EventAggregator(Prism) approach to send a Message to the Window's code-behind when the command is triggered to Close it.
Referencing Window in the VM is just plain wrong.
Just for reference, what your trying to do "can be done"
something like:
<Grid x:Name="LayoutRoot">
<Button HorizontalAlignment="Left"
Margin="0"
Style="{DynamicResource ButtonStyle1}"
VerticalAlignment="Top"
Width="120"
Height="25"
Content="Dashboard Menu"
TextElement.FontWeight="Bold"
Foreground="AliceBlue"
Tag="{Binding RelativeSource={RelativeSource FindAncestor,
AncestorType={x:Type Window}}}">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Open Log Viewer" Command="{StaticResource openLogViewer}" />
<Separator />
<MenuItem Command="{StaticResource exit}"
CommandParameter="{Binding PlacementTarget.Tag,
RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"
Header="Exit" />
...
Update:
Download Link
When executing the "Exit" command from the ContextMenu you should see Sender Object: MvvmLight16.MainWindow in your Output Window. This output is sent from the VM.
I have a ListView which displays a list of string values. I want to add a context menu entry for each item in the list to remove the selected item. My XAML looks like this:
<ListView x:Name="itemsListView" ItemsSource="{Binding MyItems}">
<ListView.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove"
Command="{Binding RemoveItem}"
CommandParameter="{Binding ElementName=itemsListView, Path=SelectedItem}" />
</ContextMenu>
</ListView.ContextMenu>
</ListView>
The problem is that the CommandParameter value is always null. I've added an additional button to remove the selected item to check if my command works. The button has exactly the same binding and removing items via the button works. The button looks like this:
<Button Content="Remove selected item"
Command="{Binding RemoveItem}"
CommandParameter="{Binding ElementName=itemsListView, Path=SelectedItem}"/>
The command looks like this:
private ICommand _removeItem;
public ICommand RemoveItem
{
get { return _removeItem ?? (_removeItem = new RelayCommand(p => RemoveItemCommand((string)p))); }
}
private void RemoveItemCommand(string item)
{
if(!string.IsNullOrEmpty(item))
MyItems.Remove(item);
}
Any ideas why the selected item is null when opening the context menu? Maybe a focus problem of the listview?
H.B. is right. but you can also use RelativeSource Binding
<ListView x:Name="itemsListView" ItemsSource="{Binding MyItems}">
<ListView.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove"
Command="{Binding RemoveItem}"
CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.SelectedItem}" />
</ContextMenu>
</ListView.ContextMenu>
</ListView>
ContextMenus are disconnected, you cannot use ElementName bindings. One workaround would be using Binding.Source and x:Reference which requires you to extract parts that use it to be in the resources (due to cyclical dependency errors). You can just put the whole context menu there.
An example:
<ListBox Name="lb" Height="200">
<ListBox.Resources>
<ContextMenu x:Key="cm">
<MenuItem Header="{Binding ActualHeight, Source={x:Reference lb}}" />
</ContextMenu>
</ListBox.Resources>
<ListBox.ContextMenu>
<StaticResource ResourceKey="cm" />
</ListBox.ContextMenu>
</ListBox>
This work for me CommandParameter="{Binding}"
I want to bind a command in my ViewModel to a menuItem which is in DataTemplate. I can do that with using Tag. Is there any method which can do the same task but without using tag.
<Window.Resources>
<DataTemplate x:Key="StudentListBoxItemTemplate">
<StackPanel Tag="{Binding DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}}">
<TextBlock Text="{Binding Name}"/>
<StackPanel.ContextMenu>
<ContextMenu>
<MenuItem Header="Trigger" Command="{Binding PlacementTarget.Tag.TriggerCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
</ContextMenu>
</StackPanel.ContextMenu>
</StackPanel>
</DataTemplate>
</Window.Resources>
<StackPanel>
<ListBox
ItemsSource="{Binding StudentList}"
ItemTemplate="{StaticResource StudentListBoxItemTemplate}">
</ListBox>
</StackPanel>
My ViewModel
public class MainViewModel {
public ICommand TriggerCommand { ... }
public ObservableList<Student> StudentList { ... }
}
With your current design, you need to get from the ContextMenu through the StackPanel and back to the DataContext of the containing ListBox. What makes this awkward is that the DataContext of the StackPanel is already narrowed down to a particular student.
There are at least two ways to make this easier:
Provide a TriggerCommand property in Student so the command is right there where you need it
Provide a Parent property in the Student to escape the narrowed scope
You can try to add click event to the menuItem like following
<Menu Style="{StaticResource bellRingersFontStyle}" Height="23" Name="menu1" Width="Auto" DockPanel.Dock="Top" VerticalAlignment="Top">
<MenuItem Header="_File">
<MenuItem Header="_New Member" Name="newMember" Click="newMember_Click" >
<MenuItem.Icon>
<Image Source="Face.bmp" />
</MenuItem.Icon>
</MenuItem>
<MenuItem Header="_Save Member Details" Name="saveMember" IsEnabled="False" Click="saveMember_Click">
<MenuItem.Icon>
<Image Source="Note.bmp" />
</MenuItem.Icon>
</MenuItem>
<Separator />
<MenuItem Header="E_xit" Name="exit" Click="exit_Click" />
</MenuItem>
<MenuItem Header="_Help">
<MenuItem Header="_About Middleshire Bell Ringers" Name="about" Click="about_Click" >
<MenuItem.Icon>
<Image Source="Ring.bmp" />
</MenuItem.Icon>
</MenuItem>
</MenuItem>
</Menu>
Try binding the command to Click. My VS is down so can't check at this moment.
One way would be to get the context menu collection presentation defined in your viewmodel, which will contain the header string and command action (maybe with predicate).
The viewmodel creates an observable collection of the contextmenu items and the view binds that to ContextMenu itemssource and sets the displaymember path to header string.
I have made my application multilingual. It changes it's language when you click the corresponding menuitem. This works fine but my problem comes when my parent window doesn't change it's language (menu is in parent window). All child windows change their language. Is there any way to force window to load again? I have done my application with resx-files and also checked that Thread.CurrentThread.CurrentCulture and Thread.CurrentThread.CurrentUICulture are changed when menuitem is clicked.
Edit:
I have made my own class to do the multilingual part and it is an adaptation from this article's approach: WPF Runtime Localization, it works. Here is a part of my XAML code to show the databindings:
<Window x:Class="Multilingual.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:properties="clr-namespace:Multilingual.Properties"
Height="350" Width="300" Name="mainWindow" ResizeMode="CanMinimize" SizeToContent="Manual" Closing="mainWindow_Closing" KeyDown="mainWindow_KeyDown">
and
<Menu Height="22" Name="menu" Width="{Binding ElementName=mainWindow, Path=Width}" HorizontalAlignment="Left" VerticalAlignment="Top" Background="Snow" BorderThickness="2">
<Menu.BitmapEffect>
<DropShadowBitmapEffect />
</Menu.BitmapEffect>
<MenuItem Header="{x:Static properties:Resources.Menu}">
<MenuItem Header="{x:Static properties:Resources.Language}" >
<MenuItem Header="{x:Static properties:Resources.Deutsch}" Name="itemDeutsch" Click="menuItem_Click" />
<MenuItem Header="{x:Static properties:Resources.English}" Name="itemEnglish" Click="menuItem_Click" />
</MenuItem>
<MenuItem Header="{x:Static properties:Resources.Exit}" Click="itemExit_Click"/>
</MenuItem>
</Menu>
So I think it would be enough if I would be able to update the window somehow.
WPF: How to change the CurrentUICulture at runtime
I found a solution. I changed my databindings to look like this:
<MenuItem Header="{Binding Path=Menu, Source={StaticResource Resources}}">
Where "Menu" corresponds the MenuItem's name in resx-file.
What is the best way to add "copy to clipboard" functionality to a ListView control in WPF?
I tried adding an ApplicationCommands.Copy to either the ListView ContextMenu or the ListViewItem ContextMenu, but the command remains disabled.
Thanks,
Peter
Here is an xaml sample of one of my attempts...
<Window.Resources>
<ContextMenu x:Key="SharedInstanceContextMenu" x:Shared="True">
<MenuItem Header="Copy" Command="ApplicationCommands.Copy"/>
</ContextMenu>
</Window.Resources>
<ListBox Margin="12,233,225,68" Name="listBox1" >
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=UpToSourceCategoryByCategoryId.Category}" ContextMenu="{DynamicResource ResourceKey=SharedInstanceContextMenu}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
How should I set the CommandTarget in this case?
Thanks,Peter
It looks like you need a CommandBinding.
Here is how I would probably go about doing what you trying to do.
<Window.CommandBindings>
<CommandBinding
Command="ApplicationCommands.Copy"
Executed="CopyCommandHandler"
CanExecute="CanCopyExecuteHandler" />
</Window.CommandBindings>
<Window.Resources>
<ContextMenu x:Key="SharedInstanceContextMenu">
<MenuItem Header="Copy" Command="ApplicationCommands.Copy"/>
</ContextMenu>
<Style x:Key="MyItemContainerStyle" TargetType="{x:Type ListBoxItem}">
<Setter Property="ContextMenu" Value="{StaticResource SharedInstanceContextMenu}" />
</Style>
</Window.Resources>
<ListBox ItemContainerStyle="{StaticResource MyItemContainerStyle}">
<ListBoxItem>One</ListBoxItem>
<ListBoxItem>Two</ListBoxItem>
<ListBoxItem>Three</ListBoxItem>
<ListBoxItem>Four</ListBoxItem>
</ListBox>
It is also possible to achieve this functionality via an attached property, as I described it on my blog. The idea is to register the ApplicationCommands.Copy command with the ListView and, when the command is executed, read the values from the data bindings.
You'll find a downloadable sample on the blog entry, too.