This question already has an answer here:
how to use dependency property to replace the parameter in the constructor of a UserControl?
(1 answer)
Closed 3 years ago.
I'm using WPF 4.5.2, .Net 4.7.2, C# 7
This is the code of my base class fro attached properties
public abstract class BaseAP<Parent, Property> where Parent : BaseAP<Parent , Property>, new()
{
#region Public Events
/// <summary>
/// Fire when the value changes
/// </summary>
public event Action<DependencyObject , DependencyPropertyChangedEventArgs> ValueChanged = ( sender , e ) => { };
#endregion
#region Properties
/// <summary>
/// A singleton instance of the parent class
/// </summary>
public static Parent Instance { get; private set; } = new Parent();
#endregion
#region Attached Properties Definitions
/// <summary>
/// The Attached Property for this class
/// </summary>
public static readonly DependencyProperty ValueProperty = DependencyProperty.RegisterAttached( "Value" , typeof( Property ) , typeof( BaseAP<Parent , Property> ) , new PropertyMetadata( new PropertyChangedCallback( OnValuePropertyChanged ) ) );
/// <summary>
/// The callback event when the <see cref="ValueProperty"/> is changed
/// </summary>
/// <param name="d">The UI-Element that had it's property changed</param>
/// <param name="e">The arguments for the event</param>
private static void OnValuePropertyChanged( DependencyObject d , DependencyPropertyChangedEventArgs e )
{
// --- Call the parent function
Instance.OnValueChanged( d , e );
// --- Call the event listeners
Instance.ValueChanged( d , e );
}
/// <summary>
/// Gets the attached property
/// </summary>
/// <param name="d">The element to get the property from</param>
/// <returns></returns>
public static Property GetValue( DependencyObject d )
{
return ( (Property) d.GetValue( ValueProperty ) );
}
/// <summary>
/// Sets the attached property
/// </summary>
/// <param name="d">The element to set the property to</param>
/// <param name="value">The value to set to the element</param>
public static void SetValue( DependencyObject d , Property value )
{
d.SetValue( ValueProperty , value );
}
#endregion
#region Event Methods
/// <summary>
/// The method is called when any attached property of this type is changed
/// </summary>
/// <param name="d">The ui element that this property was changed for</param>
/// <param name="e">The arguments for this event</param>
public virtual void OnValueChanged( DependencyObject d , DependencyPropertyChangedEventArgs e )
{
SetValue( d , (Property) e.NewValue );
}
#endregion
}
This code was written originally by Luke Malpass (AngelSix)
My used property looks like this
public class APType : BaseAP<APType , Type> { }
In Xaml:
<UserControl local:APType.Value={x:Type local:SomeType} />
SomeType is a regular class, nothing special
In code behind I'm trying this:
Type targetType = GetValue( APType.ValueProperty ) as Type;
Unfortunately, targetType is always null.
What am I doing wrong?
Thanks in avance
You should call GetValue on the UserControl after the Value attached property has been set:
Type type = uc.GetValue(APType.ValueProperty) as Type;
XAML:
<UserControl x:Name="uc" local:APType.Value="{x:Type local:SomeType}">
The property cannot be set before the UserControl has been created.
Related
I have an application that display different datasets (users, nationality, etc) on the screen using radOutlookbar.
I have manage to load the required views in each item to display the data with no problem.
I then built views for each dataset (users, nationality, etc) to display the details about each selected item (i.e:user) within the displayed datasets.
Case:
First, I need to display the respective view for each dataset when I click on it's item.
Second, The displayed view will have an option to edit/add the displayed details.
I want to achieve this scenario using state-base-navigation.
So,
I have a PRISM region inside ItemsControl with ItemsPanelTemplate of grid to host the loaded views, basically I load the views for each dataset.
Question,
How should I show/hide the respective view according to the selected dataset using VSM?
Question 2:
Should I be able to define another nested state inside the loaded view to enable the scenario of edit/add details for each view?
If someone have any idea to do this, will be of great help to have a starting code.
Best regards
May be there's other schemes to access VSM but I prefer to create AttachedProperty for it. Let me explain.
Here is VisualState manager
/// <summary>
/// Class will allow to change VisualSate on ViewModel via attached properties
/// </summary>
public static class VisualStateManagerEx
{
private static PropertyChangedCallback callback = new PropertyChangedCallback(VisualStateChanged);
/// <summary>
/// Gets the state of the visual.
/// </summary>
/// <param name="obj">The obj.</param>
/// <returns></returns>
public static string GetVisualState(DependencyObject obj)
{
return (string)obj.GetValue(VisualStateProperty);
}
/// <summary>
/// Sets the state of the visual.
/// </summary>
/// <param name="obj">The obj.</param>
/// <param name="value">The value.</param>
public static void SetVisualState(DependencyObject obj, string value)
{
obj.SetValue(VisualStateProperty, value);
}
/// <summary>
/// DP for 'VisualState'
/// </summary>
public static readonly DependencyProperty VisualStateProperty =
DependencyProperty.RegisterAttached(
"VisualState",
typeof(string),
typeof(VisualStateManagerEx),
new PropertyMetadata(null, VisualStateManagerEx.callback)
);
/// <summary>
/// Visuals the state changed.
/// </summary>
/// <param name="d">The d.</param>
/// <param name="e">The <see cref="System.Windows.DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
public static void VisualStateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//Control changeStateControl = d as Control;
FrameworkElement changeStateControl = d as FrameworkElement;
if (changeStateControl == null)
throw (new Exception("VisualState works only on Controls type"));
if (Application.Current.Dispatcher.CheckAccess() == false)
{
// Wrong thread
System.Diagnostics.Debug.WriteLine("[VisualStateManagerEx] 'VisualStateChanged' event received on wrong thread -> re-route via Dispatcher");
Application.Current.Dispatcher.BeginInvoke(
//() => { VisualStateChanged(d, e); }
VisualStateManagerEx.callback
, new object[] { d, e }); //recursive
}
else
{
if (string.IsNullOrEmpty(e.NewValue.ToString()) == false)
{
//VisualStateManager.GoToState(changeStateControl, e.NewValue.ToString(), true);
VisualStateManager.GoToElementState(changeStateControl, e.NewValue.ToString(), true);
System.Diagnostics.Debug.WriteLine("[VisualStateManagerEx] Visual state changed to " + e.NewValue.ToString());
}
}
}
}
now - in XAML you attach it to your ViewModel like this:
<UserControl
xmlns:VSManagerEx=clr-namespace:Namespace.namespace;assembly=Assembly01"
VSManagerEx:VisualStateManagerEx.VisualState="{Binding Path=ViewModelVisualState, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
...
...
Now your VSM in XAML is bound to ViewModelVisualState property in ViewModelBase (or whatever will be bound to DataContext of this UserControl. So Actually in your ViewModelBase you using is like this:
/// <summary>
/// Base class for all 'view-models'
/// </summary>
[Export(typeof(ViewModelBase))]
public abstract class ViewModelBase : INavigationAware, INotifyPropertyChanged
{
private SynchronizationContext parentSyncContent;
#region VisualState
private string viewModelVisualState = string.Empty;
/// <summary>
/// Gets or sets the state of the view model visual.
/// </summary>
/// <value>
/// The state of the view model visual.
/// </value>
public virtual string ViewModelVisualState
{
get { return viewModelVisualState; }
set
{
viewModelVisualState = value;
RaisePropertyChanged(this, "ViewModelVisualState");
}
}
#endregion
/// <summary>
/// Raises the property changed.
/// </summary>
/// <param name="Sender">The sender.</param>
/// <param name="PropertyName">Name of the property.</param>
public void RaisePropertyChanged(object Sender, string PropertyName)
{
parentSyncContent.Post((state) =>
{
if (PropertyChanged != null)
PropertyChanged(Sender, new PropertyChangedEventArgs(PropertyName));
}, null);
}
...
...
So - in any ViewModel that inherit from this ViewModelBase could declare it own VMS states and manage them like this:
[Export(typeof(IViewModel1))
public ViewModel1 : ViewModelBase, IViewModel1
{
private const string VM_STATE_WORKING = "WorkingState";
internal void StartWorking()
{
this.ViewModelVisualState = VM_STATE_WORKING;
...
...
Regards question 2: No - you don't need to declare any additional Views inside anything. Read PRISM documentation about Navigation. There's great examples on how to create View/ViewModel that support various presentation logic.
Is this helpful to you ?
I'm trying to convert an event to a command on a devexpress wpf grid context menu item which is derived from FrameworkContentElement instead of FrameworkElement. This causes a runtime error :
{"Cannot attach type \"EventToCommand\" to type \"BarButtonItem\". Instances of type \"EventToCommand\" can only be attached to objects of type \"FrameworkElement\"."}
Is there any workaround?
<dxg:TableView.RowCellMenuCustomizations>
<dxb:BarButtonItem Name="deleteRowItem" Content="Delete" >
<i:Interaction.Triggers>
<i:EventTrigger EventName="ItemClick">
<cmd:EventToCommand Command="{Binding FooChangeCommand}"
PassEventArgsToCommand="True" />
</i:EventTrigger>
</i:Interaction.Triggers>
</dxb:BarButtonItem>
<!--ItemClick="deleteRowItem_ItemClick"/>-->
</dxg:TableView.RowCellMenuCustomizations>
Unfortunately devexpress have run into problems changing the base class to FrameworkElement having intended to make that change...
The FrameworkConentElement is a class that is only available in WPF and not in Silverlight. As MVVM Light is intended to provide a common functionality for all WPF dialects (WPF 3.5, WPF 4, Silverlight 3, Silverlight 4, Sivlverlight 5, WP 7, WP 7.1) it cannot include an implementation that only works in one of the frameworks.
For a discussion about the differences between FrameworkElement and FrameworkContentElement see here.
However, you can just easily implement your own EventToCommand class supporting ContentElement (from which FrameworkContentElement inherits). The class was copied from BL0015 of the MVVM Light source code and modified:
using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Interactivity;
namespace GalaSoft.MvvmLight.Command
{
/// <summary>
/// This <see cref="System.Windows.Interactivity.TriggerAction" /> can be
/// used to bind any event on any FrameworkElement to an <see cref="ICommand" />.
/// Typically, this element is used in XAML to connect the attached element
/// to a command located in a ViewModel. This trigger can only be attached
/// to a FrameworkElement or a class deriving from FrameworkElement.
/// <para>To access the EventArgs of the fired event, use a RelayCommand<EventArgs>
/// and leave the CommandParameter and CommandParameterValue empty!</para>
/// </summary>
////[ClassInfo(typeof(EventToCommand),
//// VersionString = "3.0.0.0",
//// DateString = "201003041420",
//// Description = "A Trigger used to bind any event to an ICommand.",
//// UrlContacts = "http://stackoverflow.com/q/6955785/266919",
//// Email = "")]
public partial class EventToCommandWpf : TriggerAction<DependencyObject>
{
/// <summary>
/// Gets or sets a value indicating whether the EventArgs passed to the
/// event handler will be forwarded to the ICommand's Execute method
/// when the event is fired (if the bound ICommand accepts an argument
/// of type EventArgs).
/// <para>For example, use a RelayCommand<MouseEventArgs> to get
/// the arguments of a MouseMove event.</para>
/// </summary>
public bool PassEventArgsToCommand
{
get;
set;
}
/// <summary>
/// Provides a simple way to invoke this trigger programatically
/// without any EventArgs.
/// </summary>
public void Invoke()
{
Invoke(null);
}
/// <summary>
/// Executes the trigger.
/// <para>To access the EventArgs of the fired event, use a RelayCommand<EventArgs>
/// and leave the CommandParameter and CommandParameterValue empty!</para>
/// </summary>
/// <param name="parameter">The EventArgs of the fired event.</param>
protected override void Invoke(object parameter)
{
if (AssociatedElementIsDisabled())
{
return;
}
var command = GetCommand();
var commandParameter = CommandParameterValue;
if (commandParameter == null
&& PassEventArgsToCommand)
{
commandParameter = parameter;
}
if (command != null
&& command.CanExecute(commandParameter))
{
command.Execute(commandParameter);
}
}
private static void OnCommandChanged(
EventToCommandWpf element,
DependencyPropertyChangedEventArgs e)
{
if (element == null)
{
return;
}
if (e.OldValue != null)
{
((ICommand)e.OldValue).CanExecuteChanged -= element.OnCommandCanExecuteChanged;
}
var command = (ICommand)e.NewValue;
if (command != null)
{
command.CanExecuteChanged += element.OnCommandCanExecuteChanged;
}
element.EnableDisableElement();
}
private bool AssociatedElementIsDisabled()
{
var element = GetAssociatedObject();
return AssociatedObject == null
|| (element != null
&& !element.IsEnabled);
}
private void EnableDisableElement()
{
var element = GetAssociatedObject();
if (element == null)
{
return;
}
var command = this.GetCommand();
if (this.MustToggleIsEnabledValue
&& command != null)
{
SetIsEnabled(element, command.CanExecute(this.CommandParameterValue));
}
}
private void OnCommandCanExecuteChanged(object sender, EventArgs e)
{
EnableDisableElement();
}
/// <summary>
/// Identifies the <see cref="CommandParameter" /> dependency property
/// </summary>
public static readonly DependencyProperty CommandParameterProperty = DependencyProperty.Register(
"CommandParameter",
typeof(object),
typeof(EventToCommandWpf),
new PropertyMetadata(
null,
(s, e) => {
var sender = s as EventToCommandWpf;
if (sender == null)
{
return;
}
if (sender.AssociatedObject == null)
{
return;
}
sender.EnableDisableElement();
}));
/// <summary>
/// Identifies the <see cref="Command" /> dependency property
/// </summary>
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
"Command",
typeof(ICommand),
typeof(EventToCommandWpf),
new PropertyMetadata(
null,
(s, e) => OnCommandChanged(s as EventToCommandWpf, e)));
/// <summary>
/// Identifies the <see cref="MustToggleIsEnabled" /> dependency property
/// </summary>
public static readonly DependencyProperty MustToggleIsEnabledProperty = DependencyProperty.Register(
"MustToggleIsEnabled",
typeof(bool),
typeof(EventToCommandWpf),
new PropertyMetadata(
false,
(s, e) => {
var sender = s as EventToCommandWpf;
if (sender == null)
{
return;
}
if (sender.AssociatedObject == null)
{
return;
}
sender.EnableDisableElement();
}));
private object _commandParameterValue;
private bool? _mustToggleValue;
/// <summary>
/// Gets or sets the ICommand that this trigger is bound to. This
/// is a DependencyProperty.
/// </summary>
public ICommand Command
{
get
{
return (ICommand)GetValue(CommandProperty);
}
set
{
SetValue(CommandProperty, value);
}
}
/// <summary>
/// Gets or sets an object that will be passed to the <see cref="Command" />
/// attached to this trigger. This is a DependencyProperty.
/// </summary>
public object CommandParameter
{
get
{
return this.GetValue(CommandParameterProperty);
}
set
{
SetValue(CommandParameterProperty, value);
}
}
/// <summary>
/// Gets or sets an object that will be passed to the <see cref="Command" />
/// attached to this trigger. This property is here for compatibility
/// with the Silverlight version. This is NOT a DependencyProperty.
/// For databinding, use the <see cref="CommandParameter" /> property.
/// </summary>
public object CommandParameterValue
{
get
{
return this._commandParameterValue ?? this.CommandParameter;
}
set
{
_commandParameterValue = value;
EnableDisableElement();
}
}
/// <summary>
/// Gets or sets a value indicating whether the attached element must be
/// disabled when the <see cref="Command" /> property's CanExecuteChanged
/// event fires. If this property is true, and the command's CanExecute
/// method returns false, the element will be disabled. If this property
/// is false, the element will not be disabled when the command's
/// CanExecute method changes. This is a DependencyProperty.
/// </summary>
public bool MustToggleIsEnabled
{
get
{
return (bool)this.GetValue(MustToggleIsEnabledProperty);
}
set
{
SetValue(MustToggleIsEnabledProperty, value);
}
}
/// <summary>
/// Gets or sets a value indicating whether the attached element must be
/// disabled when the <see cref="Command" /> property's CanExecuteChanged
/// event fires. If this property is true, and the command's CanExecute
/// method returns false, the element will be disabled. This property is here for
/// compatibility with the Silverlight version. This is NOT a DependencyProperty.
/// For databinding, use the <see cref="MustToggleIsEnabled" /> property.
/// </summary>
public bool MustToggleIsEnabledValue
{
get
{
return this._mustToggleValue == null
? this.MustToggleIsEnabled
: this._mustToggleValue.Value;
}
set
{
_mustToggleValue = value;
EnableDisableElement();
}
}
/// <summary>
/// Called when this trigger is attached to a DependencyObject.
/// </summary>
protected override void OnAttached()
{
base.OnAttached();
EnableDisableElement();
}
/// <summary>
/// This method is here for compatibility
/// with the Silverlight version.
/// </summary>
/// <returns>The object to which this trigger
/// is attached casted as a FrameworkElement.</returns>
private IInputElement GetAssociatedObject()
{
return AssociatedObject as IInputElement;
}
private void SetIsEnabled(IInputElement element, bool value)
{
if (element is UIElement)
{
((UIElement)element).IsEnabled = value;
}
else if (element is ContentElement)
{
((ContentElement)element).IsEnabled = value;
}
else
{
throw new InvalidOperationException("Cannot set IsEnabled. Element is neither ContentElemen, nor UIElement.");
}
}
/// <summary>
/// This method is here for compatibility
/// with the Silverlight version.
/// </summary>
/// <returns>The command that must be executed when
/// this trigger is invoked.</returns>
private ICommand GetCommand()
{
return Command;
}
}
}
To inlcude it into your code you have to define a xml namespace pointing to the correct dll and then use it just like the normal EventToCommand class.
NOTE: This class does not work in Silverlight!
For those trying to solve this specific issue using dev express, this will do the trick!
<dxg:TableView.RowCellMenuCustomizations>
<dxb:BarButtonItem Name="deleteRowItem" Content="Delete" Command="{Binding View.DataContext.DeleteSelectionCommand}" />
</dxg:TableView.RowCellMenuCustomizations>
I was following their example which had an event on the button, little realising there was also a command I could use. Then the challenge was working out the binding as the menu item is not on the main visual tree. However the above solves that.
I found this to work with DEV express
<dxb:BarButtonItem Content="123" Name="item1">
<dxmvvm:Interaction.Triggers>
<dxmvvm:EventToCommand EventName="ItemClick" Command="{Binding SomeCommand}" CommandParameter="{Binding ElementName=item1, Path=Content}"/>
</dxmvvm:Interaction.Triggers>
</dxb:BarButtonItem>
I have a problem with WPF Combo box.
I bind a List< Pair < String, String> > (Destinations) on my Combo like that :
My pair class is defined like that :
/// <summary>
/// This class represents a pair.
/// </summary>
public class Pair<T, U>
{
#region Properties
/// <summary>
/// Gets or sets the first value.
/// </summary>
public T First
{
get;
set;
}
/// <summary>
/// Gets or sets the second value.
/// </summary>
public U Second
{
get;
set;
}
#endregion
#region Methods
/// <summary>
/// Default constructor
/// </summary>
public Pair()
{
}
/// <summary>
/// Constructor by initialization.
/// </summary>
/// <param name="pFirst">The first value.</param>
/// <param name="pSecond">The second value.</param>
public Pair(T pFirst, U pSecond)
{
this.First = pFirst;
this.Second = pSecond;
}
#endregion
};
I tried to display only the Second property of my pair as Display of my combo. I tried :
DisplayMemberPath={Binding Destinations.Second} but it doesn't work.
Thanks for your answers.
DisplayMemberPath="Second"
That should work as each item will be a Pair.
I want to be able to route the double-click of a grid to a Command. I'm using Rx to simulate the double click but I can't figure out what control to attach the mouse handler to (the mouse event on the e.Row object in DataGrid.RowLoading event doesn't seem to work).
Anyone got any ideas?
Rx code for handling the Double click is as follows:
Observable.FromEvent<MouseButtonEventArgs>(e.Row, "MouseLeftButtonDown").TimeInterval().Subscribe(evt =>
{
if (evt.Interval.Milliseconds <= 300)
{
// Execute command on double click
}
});
I changed this code from handling MouseLeftButtonDown to MouseLeftButtonUp and it works now. The row must have something else handling the button down events.
Observable.FromEvent<MouseButtonEventArgs>(e.Row, "MouseLeftButtonUp").TimeInterval().Subscribe(evt =>
{
if (evt.Interval != TimeSpan.Zero && evt.Interval.TotalMilliseconds <= 300)
{
// Execute command on double click
}
});
Full source code is included below:
CommandBehaviorBase.cs
using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Interactivity;
/// <summary>
/// Provides the base implementation of all Behaviors that can be attached to a <see cref="FrameworkElement"/> which trigger a command.
/// </summary>
/// <typeparam name="T">The type of control this behavior can be attached to, must derive from <see cref="FrameworkElement"/>.</typeparam>
public abstract class CommandBehaviorBase<T> : Behavior<T> where T : FrameworkElement
{
#region Constants and Fields
/// <summary>The DependencyProperty backing store for CommandParameter. This enables animation, styling, binding, etc...</summary>
public static readonly DependencyProperty CommandParameterProperty =
DependencyProperty.Register(
"CommandParameter",
typeof(object),
typeof(CommandBehaviorBase<T>),
new PropertyMetadata(null, OnCommandParameterPropertyChanged));
/// <summary>The DependencyProperty backing store for Command. This enables animation, styling, binding, etc...</summary>
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
"Command", typeof(ICommand), typeof(CommandBehaviorBase<T>), new PropertyMetadata(null));
#endregion
/// <summary>
/// Gets or sets the command to execute
/// </summary>
public ICommand Command
{
get
{
return (ICommand)this.GetValue(CommandProperty);
}
set
{
this.SetValue(CommandProperty, value);
}
}
/// <summary>
/// Gets or sets the command parameter to execute with.
/// </summary>
public object CommandParameter
{
get
{
return this.GetValue(CommandParameterProperty);
}
set
{
this.SetValue(CommandParameterProperty, value);
}
}
/// <summary>
/// Gets or sets the command binding path (Hack for SL3).
/// </summary>
/// <remarks>This is a hack to overcome the fact that we cannot
/// bind to the Command dependency property due to a limitation in Silverlight 3.0
/// This shouldn't be necessary as in Silverlight 4.0 <see cref="DependencyObject"/> supports data binding hooray!</remarks>
public string CommandPath { get; set; }
/// <summary>
/// Gets or sets a value indicating whether this mapping is currently enabled.
/// </summary>
public bool IsEnabled { get; set; }
/// <summary>
/// Implements the logic that disables the key mapping based on whether the command can be executed.
/// </summary>
/// <summary>
/// Updates the target object's IsEnabled property based on the commands ability to execute.
/// </summary>
public virtual void UpdateEnabledState()
{
if (this.Command == null && !string.IsNullOrEmpty(this.CommandPath))
{
this.Command = this.AssociatedObject.DataContext.GetPropertyPathValue<ICommand>(this.CommandPath, null);
}
if (this.AssociatedObject == null)
{
this.Command = null;
this.CommandParameter = null;
}
else if (this.Command != null)
{
this.IsEnabled = this.Command.CanExecute(this.CommandParameter);
}
}
/// <summary>
/// Executes the command, if it's set, providing the <see cref="CommandParameter"/>
/// </summary>
protected virtual void ExecuteCommand()
{
if (this.Command != null)
{
this.Command.Execute(this.CommandParameter);
}
}
/// <summary>
/// Attaches to the target <see cref="FrameworkElement"/> and sets up the command.
/// </summary>
protected override void OnAttached()
{
base.OnAttached();
this.UpdateEnabledState();
}
/// <summary>
/// Raised when the command parameter changes, re-evaluates whether the Command can execute
/// </summary>
/// <param name="sender">The KeyCommandBehavior that command parameter changed for.</param>
/// <param name="args">The parameter is not used.</param>
private static void OnCommandParameterPropertyChanged(
DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
((CommandBehaviorBase<T>)sender).UpdateEnabledState();
}
}
DoubleClickCommandBehavior.cs
using System;
using System.Linq;
using System.Windows;
using System.Windows.Input;
/// <summary>
/// Provides behavior for any clickable control and will execute a command when the control is double clicked.
/// Does not disable the control if the command cannot be executed.
/// </summary>
public class DoubleClickCommandBehavior : CommandBehaviorBase<FrameworkElement>
{
#region Constants and Fields
/// <summary>
/// Stores the observable that subscribes to click events.
/// </summary>
private IDisposable observable;
#endregion
#region Constructors and Destructors
/// <summary>
/// Initializes a new instance of the DoubleClickCommandBehavior class.
/// </summary>
public DoubleClickCommandBehavior()
{
// Default double-click interval is 220 milliseconds.
this.Interval = 220;
}
#endregion
/// <summary>
/// Gets or sets the double click interval in milliseconds.
/// </summary>
public int Interval
{
get;
set;
}
/// <summary>
/// Subscribes to the MouseLeftButtonUp of the data grid and times the intervals between the events,
/// if the time between clicks is less than the configured interval the command is executed.
/// </summary>
/// <remarks>Originally attached to MouseLeftButtonDown but the events were not firing.</remarks>
protected override void OnAttached()
{
base.OnAttached();
this.observable =
Observable.FromEvent<MouseButtonEventArgs>(this.AssociatedObject, "MouseLeftButtonUp").TimeInterval().
Subscribe(
evt =>
{
if (evt.Interval != TimeSpan.Zero && evt.Interval.TotalMilliseconds <= this.Interval)
{
this.UpdateEnabledState();
this.ExecuteCommand();
}
});
}
/// <summary>
/// Disposes of the observable
/// </summary>
protected override void OnDetaching()
{
if (this.observable != null)
{
this.observable.Dispose();
this.observable = null;
}
base.OnDetaching();
}
}
I'm having similar problems (though not using Rx to handle the double click, instead using a generic DoubleClickTrigger). My specific problem is more related to the fact that I'm not sure how or where to hook up my trigger.
I've tried something like the following:
<data:DataGrid.Resources>
<ControlTemplate x:Key="rowTemplate" TargetType="data:DataGridRow">
<data:DataGridRow>
<fxui:Interaction.Triggers>
<fxui:DoubleClickTrigger>
<Interactivity:InvokeCommandAction Command="{Binding Source={StaticResource selectCommand}}" CommandParameter="{Binding}"/>
</fxui:DoubleClickTrigger>
</fxui:Interaction.Triggers>
</data:DataGridRow>
</ControlTemplate>
</data:DataGrid.Resources>
<data:DataGrid.RowStyle>
<Style TargetType="data:DataGridRow">
<Setter Property="Template" Value="{StaticResource rowTemplate}"/>
</Style>
</data:DataGrid.RowStyle>
With no luck.
Can I databind the state of the visual statemanager to my viewmodel?
No, but you can use an Expression Behavior that watches your ViewModel and changes states accordingly; check out http://blois.us/blog/2009_04_11_houseomirrors_archive.html
Another way of asigning Visual States by name, without any dependency on other classes:
/// <summary>
/// Sets VisualState on a control usign an attached dependency property.
/// This is useful for a MVVM pattern when you don't want to use imperative
/// code on the View.
/// </summary>
/// <example>
/// <TextBlock alloy:VisualStateSetter.VisualStateName="{Binding VisualStateName}"/>
/// </example>
public class VisualStateSetter : DependencyObject
{
/// <summary>
/// Gets the name of the VisualState applied to an object.
/// </summary>
/// <param name="target">The object the VisualState is applied to.</param>
/// <returns>The name of the VisualState.</returns>
public static string GetVisualStateName( DependencyObject target )
{
return (string)target.GetValue( VisualStateNameProperty );
}
/// <summary>
/// Sets the name of the VisualState applied to an object.
/// </summary>
/// <param name="target">The object the VisualState is applied to.</param>
/// <param name="visualStateName">The name of the VisualState.</param>
public static void SetVisualStateName( DependencyObject target, string visualStateName )
{
target.SetValue( VisualStateNameProperty, visualStateName );
}
/// <summary>
/// Attached dependency property that sets the VisualState on any Control.
/// </summary>
public static readonly DependencyProperty VisualStateNameProperty =
DependencyProperty.RegisterAttached(
"VisualStateName",
typeof( string ),
typeof( VisualStateSetter ),
new PropertyMetadata( VisualStateNameChanged ) );
/// <summary>
/// Callback for the event that the value of the VisualStateProperty changes.
/// </summary>
/// <param name="sender">The object the VisualState is applied to.</param>
/// <param name="args">The <see cref="System.Windows.DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
public static void VisualStateNameChanged( object sender, DependencyPropertyChangedEventArgs args )
{
string visualStateName = (string)args.NewValue;
Control control = sender as Control;
if( control == null )
{
throw new InvalidOperationException( "This attached property only supports types derived from Control." );
}
// Apply the visual state.
VisualStateManager.GoToState( control, visualStateName, true );
}
}