I'm having this code where I would like to update the image in my main window when the property in a usercontrol changes. But somehow I can't get the trigger working.
Some of the XAML code
<StatusBar MinHeight="10" MaxHeight="20" VerticalAlignment="Bottom" Grid.Row="2">
<Image x:Name="SomeNameHere">
<Image.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=pingable}" Value="false">
<Setter Property="Image.Source" Value="Icons/MainWindow/StatusOffline_stop_32x.png"/>
</DataTrigger>
<DataTrigger Binding="{Binding Path=pingable}" Value="true">
<Setter Property="Image.Source" Value="Icons/MainWindow/StatusOK_32x.png"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Image.Style>
</Image>
</StatusBar>
The part where the property comes from
public bool pingable { get; set; }
public MainWindow()
{
InitializeComponent();
pingable = PingHost("some random IP");
}
public bool PingHost(string nameOrAddress)
{
pingable = false;
Ping pinger = new Ping();
try
{
PingReply reply = pinger.Send(nameOrAddress);
pingable = reply.Status == IPStatus.Success;
}
catch (PingException)
{
// Discard PingExceptions and return false;
}
return pingable;
}
I see the property during debugging in the XAML editor so it seemingly gets recognized and I also see the value would fit. But somehow the setter doesn't get executed.
Someone an idea on this?
Thanks and have a nice day!
You need to raise your PropertyChanged event on pingable to get the view to update.
Basically, in order to get the view to know that it needs to update some control based on a binding, your view model needs to implement INotifyPropertyChanged; any time you want the update the view based on a change in the view model, you need to raise PropertyChanged from the view model and pass it the name of the bound property whose value was updated.
If you RaisePropertyChanged on the getter and setter, it will notify the XAML when the property changes and make the triggers fire.
Try this code:
bool _pingable;
public bool pingable
{
get{return _pingable;}
set{ _pingable = value; RaisePropertyChanged;}
};
While the other two answers before mine point out that INotifyPropertyChanged needs to be implemented -- and that is somewhat important for a normal WPF application -- I don't believe that actually matters here. Your ping request looks synchronous, so the UI isn't actually going to be loaded by the time you update your value, making INotifyPropertyChanged irrelevant.
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
DataContext = this;
Thread.Sleep(2000); // pretending to ping
Flag = true;
}
public bool Flag { get; set; }
}
XAML:
<Grid>
<CheckBox IsChecked="{Binding Flag}" />
</Grid>
This is checked when the window eventually loads. If this were asynchronous, it would be a different story.
I see the property during debugging in the XAML editor
I'm not sure what this means. I suspect the actual problem here is that you don't have a DataContext defined. (Maybe it is, but I can't see it here!)
You've created the property on the window itself, so... what if you switched your trigger to be...
<DataTrigger Binding="{Binding Path=pingable, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}}" Value="false">
Related
I have a ListBox control populated with several ListBox items. Each item contains a "Proceed" button and a "Postpone" button. I would like to hide that ListBox item (presented as a row in my case) once the "Postpone" button is clicked. The code I have currently doesn't seem to have any effect.
XAML:
<ListBox.ItemContainerStyle>
<Style TargetType="{x:Type ListBoxItem}">
<Style.Triggers>
<DataTrigger Binding="{Binding PostponeClicked}" Value="1">
<Setter Property="IsEnabled" Value="False"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ListBox.ItemContainerStyle>
C#:
private void PostponeThirdPartyUpdatesButton_Click(object sender, RoutedEventArgs e)
{
DataTrigger d = new DataTrigger();
d.Binding = new Binding("PostponeClicked");
d.Value = 1;
var context = ((FrameworkElement)sender).DataContext as Tuple<RegScan_ThirdParty.InstalledApplicationFromRegistryScan, RegScan_ThirdParty.ManifestRequiredApplication, RegScan_ThirdParty.RequiredApplicationState>;
Button ThirdPartyPostponeButton = sender as Button;
ThirdPartyPostponeButton.IsEnabled = false;
if (context != null)
{
RegScan_ThirdParty.registryApplicationPostponeWorkflow(context);
}
ThirdPartyPostponeButton.IsEnabled = true;
}
I had to address the same thing once. Each item in your list box should be an object. We'll call it MyObject for now, since I have no idea what your object type is. In the MyObject class, you'll put your Proceed and Postpone commands.
//ViewModelBase implements INotifyPropertyChanged, which allows us to call RaisePropertyChanged, and have the UI update
class MyObject : ViewModelBase
{
private bool isNotPostponed = true;
public bool IsNotPostponed
{
get { return isNotPostponed; }
set
{
isNotPostponed = value;
RaisePropertyChanged("IsNotPostponed");
}
}
private Command postponeCommand;
public Command PostponeCommand
{
get
{
if (postponeCommand == null)
postponeCommand = new Command(PostponeCommand);
return postponeCommand;
}
}
private void Postpone(object x)
{
IsNotPostponed = false;
}
//similar code for Proceed Command
}
Then in the viewmodel of the view that displays the listBox, create a List that you can bind to your listbox (or whatever collection you want to use). I called it MyObjectsList in the XAML below. (I'm not showing the ViewModel code where this object lives, but I assume you have code for binding to the ListBox.) Then in your ItemsControl.ItemTemplate, bind to each MyObject in your List.
<ItemsControl ItemsSource="{Binding MyObjectsList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<DataTemplate.Resources>
<BooleanToVisibilityConverter x:Key="boolToVis"/>
</DataTemplate.Resources>
<StackPanel Visibility="{Binding IsNotPostponed, Converter={StaticResource boolToVis}}">
<Button Command="{Binding PostponeCommand}" Content="Postpone"/>
<Button Command="{Binding ProceedCommand}" Content="Proceed"/>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
When Postpone is clicked, the command will execute Postpone(), which will set IsNotPostponed to false. On setting IsNotPostponed to false, RaisePropertyChanged tells the UI that IsNotPostponed changed (you need to implement the INotifyPropertyChanged interface.) Lastly, when the UI gets the change notification, it converts the bool to a Visibility. True => Visible, False => Collapsed.
[My main idea of this is to set visible/hidden for a usercontrol. I used WPF with Mvvmcross.]
I have a user control call SpinningWheelUserControl. I want to visible/hide it with the datatrigger. Below is my xaml code in App.xaml
In App.xaml I have added the namespace of the usercontrol as below.
xmlns:local="clr-namespace:UserControl"
The following is a style setting for my usercontrol.
<Style x:Key="SpinningWheel" TargetType="{x:Type local:SpinningWheelUserControl}" >
<Style.Triggers>
<DataTrigger Binding="{Binding IsVisible}" Value="true">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
<DataTrigger Binding="{Binding IsVisible}" Value="false">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
There is a class for SpinningWheel
public class SpinningWheelViewModel
: MvxNotifyPropertyChanged
{
public bool IsVisible { get; set; }
}
In a constructor of parent class, i use like this code
SpinningWheel = new SpinningWheelViewModel();
SpinningWheel.IsVisible = false;
The usercontrol is hidden for a first running. But when I change the IsVisble to true, it has no change.
SpinningWheel.IsVisible = true
You need to set Visibility instead of IsVisible like this:
SpinningWheel.Visibility = Visibility.Visible;
Oh now i see, you are setting your custom IsVisibility instead of UIElement property.
Issue with your code is you haven't raised PropertyChanged to let UI know that some property change in underlying source object.
private bool isVisible;
public bool IsVisible
{
get { return isVisible;}
set
{
if(isVisible != value)
{
isVisible = value;
RaisePropertyChanged("IsVisible");
}
}
}
Assuming you have implemented INotifyPropertyChanged on your class.
This n+1 video called N=34 : a data-bound busy dialog shows exactly how to do what you are trying to do.
I have extended the TreeViewItem class to allow me to store extra data within a tree view item. I would like to be able to set the style of the treeview item based on the value of one of the extended properties I have added.
So far I have:
namespace GX3GUIControls
{
public class GX3TreeViewItem : TreeViewItem
{
public bool Archived { get; set; }
public object Value { get; set; }
}
}
<src:GX3ClientPlugin.Resources>
<Style TargetType="{x:Type Controls:GX3TreeViewItem}">
<Style.Triggers>
<DataTrigger Archived="True">
<Setter Property="Background" Value="Gray" />
<Setter Property="FontStyle" Value="Italic" />
</DataTrigger>
</Style.Triggers>
</Style>
</src:GX3ClientPlugin.Resources>
But I get the error - Error 1 The property 'Archived' was not found in type 'DataTrigger
DataTrigger has no Archived property, but you can bind your Achived-property to it via the Binding property like so <DataTrigger Binding="{Binding Path=Archived}" Value="True">
To notify your view if the Achived property changes, you could either:
1.Implement the INotifyPropertyChanged Interface in your GX3TreeViewItem-class: public class GX3TreeViewItem : TreeViewItem, INotifyPropertyChanged, create a method which raises the PropertyChanged Event:
private void PropertyChanged(string prop)
{
if( PropertyChanged != null )
{
PropertyChanged(this, new PropertyChangedEventArgs(prop);
}
}
and place this method in the setter of your property:
private bool _achived;
public bool Achived
{
get
{
return _achived;
}
set
{
_achived = value;
PropertyChanged("Achived");
}
}
2.Or make your property a DependencyProperty.
Honestly it seems like you're doing it wrong. Those properties should be on your data.
You can do something like this,
Style="{Binding Path=Archived, Converter={StaticResource GetStyle}}"
GetStyle is an IValueConverter, no need to extend TreeView imo.
This is not the correct way to implement this. you should take a look at the MVVM Pattern.
Your UI is not the proper place to "store extra data". UI is UI and data is data. This is the worst mistake done by people coming from a winforms or otherwise non-WPF background, using a wrong approach and a wrong mindset in WPF.
This will either not work (because the ItemContainerGenerator of the TreeView knows nothing about your class, or require extra work in overriding the default behavior of such class.
I have a ListView Contained in a UserControl I would like to disabled a button when no items are selected in the UserControl, would it be the right way to do it? So far, it doesn't disable, it just stays enable all the way.
I've included the xaml code.
searchAccountUserControl is the UserControl name property in the xaml.
And AccountListView is the ListView name property in the userControl xaml.
<Button Content="Debit" IsEnabled="true" HorizontalAlignment="Left" Margin="18,175,0,0" Name="DebitButton" Width="128" Grid.Column="1" Height="32" VerticalAlignment="Top" Click="DebitButton_Click">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=searchAccountUserControl.AccountListView, Path=SelectedValue}" Value="{x:Null}" >
<Setter Property="Button.IsEnabled" Value="false"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
Thanks.
Finally i've used :
in my ViewModel :
private bool _isSelected;
public bool IsSelected { get { return _isSelected; }
set { _isSelected = _account.View.CurrentItem != null;
PropertyChanged.SetPropertyAndRaiseEvent(this, ref _isSelected, value,
ReflectionUtility.GetPropertyName(() => IsSelected)); } }
And then Use isEnabled = "{Binding Path=IsSelected}" in the xaml.
There are a few things wrong here.
Precedence, if you set IsEnabled on the control itself the style will never be able to change it.
ElementName, it's an ElementName, not a path, just one string that gives the name of one element. Everything beyond that goes into the Path.
Style syntax, if you set a Style.TargetType you should not set the Setter.Property with a type prefix (although leaving it does not break the setter).
By the way, this alone is enough:
<Button IsEnabled="{Binding SelectedItems.Count, ElementName=lv}" ...
It's obvious that you aren't using Commanding (ICommand Interface). You should either use that (and preferably the Model-View-ViewModel architecture).
But, if you want to stick with code-behind and XAML:
<ListView SelectionChanged="AccountListView_SelectionChanged" ... />
private void AccountListView_SelectionChanged(Object sender, SelectionChangedEventArgs args)
{
DebitButton.IsEnabled = (sender != null);
//etc ...
}
More information on MVVM: http://msdn.microsoft.com/en-us/magazine/dd419663.aspx
You need to set the DataContext of the View (UserControl) to the instance of the ViewModel you want to use. Then, from there, you can bind to properties on the ViewModel, including ICommands. You can either use RelayCommand (see link above) or use Commanding provided by a framework (for example, Prism provides a DelegateCommand). These commands take an Action (Execute) and a Func (CanExecute). Simply provide the logic in your CanExecute. Of course, you'd also have to have your ListView SelectedItem (or SelectedValue) be databound to a property on your ViewModel so you can check to see if it's null within your CanExecute function.
Assuming you use RelayCommand you don't have to explicitly call the RaiseCanExecuteChanged of an ICommand.
public class MyViewModel : ViewModelBase //Implements INotifyPropertyChanged
{
public MyViewModel()
{
DoSomethingCommand = new RelayCommand(DoSomething, CanDoSomething);
}
public ObservableCollection<Object> MyItems { get; set; }
public Object SelectedItem { get; set; }
public RelayCommand DoSomethingCommand { get; set; }
public void DoSomething() { }
public Boolean CanDoSomething() { return (SelectedItem != null); }
}
<ListView ItemsSource="{Binding MyItems}" SelectedItem="{Binding SelectedItem}" ... />
<Button Command="{Binding DoSomethingCommand}" ... />
I am having an issue when using a DataTrigger to manipulate the IsEnabled property of a control. Normally it works fine, however when I initialize the IsEnabled state within the View's Initialized event, the dynamic stylizing no longer works.
Here's my code. I trimmed it down to the simplest example I could.
Why is this occurring, and what can I do to allow me to set IsEnabled both by a style trigger and by initializing it in the code behind?
Thanks in advance!
View:
(Contains a textbox that should be enabled/disabled depending on the value of a checkbox)
<Window x:Class="IsEnabled.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Initialized="Window_Initialized">
<StackPanel Orientation="Vertical">
<TextBox x:Name="txtTarget" Width="200">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=ToggleValue}" Value="True">
<Setter Property="IsEnabled" Value="False" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
<CheckBox x:Name="chkSource" IsChecked="{Binding Path=ToggleValue}" />
</StackPanel>
</Window>
View Codebehind:
(The only addition is the implementation of the Initialized event setting the inital state for IsEnabled)
using System;
using System.Windows;
namespace IsEnabled.Views
{
public partial class MainView : Window
{
public MainView()
{
InitializeComponent();
}
private void Window_Initialized(object sender, EventArgs e)
{
txtTarget.IsEnabled = false;
}
}
}
ViewModel:
(ViewModelBase holds the implementation of the INotifyPropertyChanged interface)
using System;
namespace IsEnabled.ViewModels
{
class MainViewModel : ViewModelBase
{
private bool _ToggleValue;
public bool ToggleValue
{
get { return _ToggleValue; }
set
{
_ToggleValue = value;
OnPropertyChanged(this, "ToggleValue");
}
}
}
}
Have a look at dependency property value precedence, and how changing values from different places, Styles, Triggers, Animations etc. work together.
Add to your Binding Mode=TwoWay and it should work.