InputBinding Class

Definition

Namespace:

System.Windows.Input

Assembly:

PresentationCore.dll

Represents a binding between an InputGesture and a command. The command is potentially a RoutedCommand.

public ref class InputBinding : System::Windows::Freezable, System::Windows::Input::ICommandSource

public class InputBinding : System.Windows.Freezable, System.Windows.Input.ICommandSource

type InputBinding = class
    inherit Freezable
    interface ICommandSource

Public Class InputBinding
Inherits Freezable
Implements ICommandSource

Inheritance

Object

DispatcherObject

DependencyObject

Freezable

InputBinding

Derived

System.Windows.Input.KeyBinding

System.Windows.Input.MouseBinding

Implements

ICommandSource

Examples

The following example shows how to use a KeyBinding to bind a KeyGesture to the Open command. When the key gesture is performed, the Open command is invoked.

<Window.InputBindings>
  <KeyBinding Key="B"
              Modifiers="Control" 
              Command="ApplicationCommands.Open" />
</Window.InputBindings>

The following examples show how to bind a custom command to InputBinding objects. These examples create an application that enables the user to change the background color by performing one of the following actions:

• Clicking a button.

• Pressing CTRL+C.

• Right-clicking a StackPanel (outside the ListBox).

The first example creates a class named SimpleDelegateCommand. This class accepts a delegate so that the object creating the command can define the action that occurs when the command executes. SimpleDelegateCommand also defines properties that specify what key and mouse input invokes the command. GestureKey and GestureModifier specify the keyboard input; MouseGesture specifies the mouse input.

 // Create a class that implements ICommand and accepts a delegate.
public class SimpleDelegateCommand : ICommand
{
    // Specify the keys and mouse actions that invoke the command. 
    public Key GestureKey { get; set; }
    public ModifierKeys GestureModifier { get; set; }
    public MouseAction MouseGesture { get; set; }

    Action<object> _executeDelegate;

    public SimpleDelegateCommand(Action<object> executeDelegate)
    {
        _executeDelegate = executeDelegate;
    }

    public void Execute(object parameter)
    {
        _executeDelegate(parameter);
    }

    public bool CanExecute(object parameter) { return true; }
    public event EventHandler CanExecuteChanged;
}

' Create a class that implements ICommand and accepts a delegate. 
Public Class SimpleDelegateCommand
    Implements ICommand

    ' Specify the keys and mouse actions that invoke the command. 
    Private _GestureKey As Key
    Private _GestureModifier As ModifierKeys
    Private _MouseGesture As MouseAction

    Public Property GestureKey() As Key
        Get
            Return _GestureKey
        End Get
        Set(ByVal value As Key)
            _GestureKey = value
        End Set
    End Property

    Public Property GestureModifier() As ModifierKeys
        Get
            Return _GestureModifier
        End Get
        Set(ByVal value As ModifierKeys)
            _GestureModifier = value
        End Set
    End Property

    Public Property MouseGesture() As MouseAction
        Get
            Return _MouseGesture
        End Get
        Set(ByVal value As MouseAction)
            _MouseGesture = value
        End Set
    End Property

    Private _executeDelegate As Action(Of Object)

    Public Sub New(ByVal executeDelegate As Action(Of Object))
        _executeDelegate = executeDelegate
    End Sub

    Public Sub Execute(ByVal parameter As Object) _
        Implements ICommand.Execute

        _executeDelegate(parameter)
    End Sub

    Public Function CanExecute(ByVal parameter As Object) As Boolean _
        Implements ICommand.CanExecute

        Return True
    End Function

    Public Event CanExecuteChanged As EventHandler _
        Implements ICommand.CanExecuteChanged
End Class

The following example creates and initializes the ColorChangeCommand, which is a SimpleDelegateCommand. The example also defines the method that executes when the command is invoked and sets the GestureKey, GestureModifier, and MouseGesture properties. An application would call the InitializeCommand method when the program begins, such as in the constructor of a Window.

public SimpleDelegateCommand ChangeColorCommand
{
    get { return changeColorCommand; }
}

private SimpleDelegateCommand changeColorCommand;

private void InitializeCommand()
{
    originalColor = this.Background;

    changeColorCommand = new SimpleDelegateCommand(x => this.ChangeColor(x));

    DataContext = this;
    changeColorCommand.GestureKey = Key.C;
    changeColorCommand.GestureModifier = ModifierKeys.Control;
    ChangeColorCommand.MouseGesture = MouseAction.RightClick;
}

private Brush originalColor, alternateColor;

// Switch the Background color between
// the original and selected color.
private void ChangeColor(object colorString)
{
    if (colorString == null)
    {
        return;
    }

    Color newColor = 
        (Color)ColorConverter.ConvertFromString((String)colorString);
    
    alternateColor = new SolidColorBrush(newColor);

    if (this.Background == originalColor)
    {
        this.Background = alternateColor;
    }
    else
    {
        this.Background = originalColor;
    }
}

Public ReadOnly Property ChangeColorCommand() As SimpleDelegateCommand
    Get
        Return _changeColorCommand
    End Get
End Property

Private _changeColorCommand As SimpleDelegateCommand
Private originalColor As Brush, alternateColor As Brush

Private Sub InitializeCommand()
    originalColor = Me.Background

    _changeColorCommand = New SimpleDelegateCommand(Function(x) Me.ChangeColor(x))

    DataContext = Me
    _changeColorCommand.GestureKey = Key.C
    _changeColorCommand.GestureModifier = ModifierKeys.Control
    _changeColorCommand.MouseGesture = MouseAction.RightClick
End Sub

' Switch the Background color between 
' the original and selected color. 
Private Function ChangeColor(ByVal colorString As Object) As Integer

    If colorString Is Nothing Then
        Return 0
    End If

    Dim newColor As Color = DirectCast(ColorConverter.ConvertFromString(DirectCast(colorString, [String])), Color)

    alternateColor = New SolidColorBrush(newColor)

    If Brush.Equals(Me.Background, originalColor) Then
        Me.Background = alternateColor
    Else
        Me.Background = originalColor
    End If

    Return 0
End Function

Finally, the following example creates the user interface. The example adds a KeyBinding and a MouseBinding to a StackPanel that contains a Button and a ListBox. When the user selects an item in the ListBox, they can change the color of the background to the selected color. In each case, the CommandParameter property is bound to the selected item in the ListBox, and the Command property is bound to the ColorChangeCommand. The KeyBinding.Key, KeyBinding.Modifiers, and MouseBinding.MouseAction properties are bound to the corresponding properties on the SimpleDelegateCommand class.

<StackPanel Background="Transparent">
  <StackPanel.InputBindings>
    
    <KeyBinding Command="{Binding ChangeColorCommand}"
                CommandParameter="{Binding ElementName=colorPicker, Path=SelectedItem}"
                Key="{Binding ChangeColorCommand.GestureKey}"
                Modifiers="{Binding ChangeColorCommand.GestureModifier}"/>

    <MouseBinding Command="{Binding ChangeColorCommand}"
                  CommandParameter="{Binding ElementName=colorPicker, Path=SelectedItem}"
                  MouseAction="{Binding ChangeColorCommand.MouseGesture}"/>
  
  </StackPanel.InputBindings>
  
  <Button Content="Change Color" 
          Command="{Binding ChangeColorCommand}" 
          CommandParameter="{Binding ElementName=colorPicker, Path=SelectedItem}">
  </Button>

  <ListBox Name="colorPicker"
           Background="Transparent"
           xmlns:sys="clr-namespace:System;assembly=mscorlib">
    <sys:String>Red</sys:String>
    <sys:String>Green</sys:String>
    <sys:String>Blue</sys:String>
    <sys:String>Yellow</sys:String>
    <sys:String>Orange</sys:String>
    <sys:String>Purple</sys:String>
  </ListBox>
</StackPanel>

Remarks

You can specify that user input invokes a command by creating a InputBinding. When the user performs the specified input, the ICommand that is set to the Command property is executed.

You can specify that the InputBinding invokes a command that is defined on an object by creating a binding on the Command, CommandParameter, and CommandTarget properties. This enables you to define a custom command and associate it with user input. For more information, see the second example in the Examples section.

An InputBinding can be defined on a specific object or at the class level by registering a RegisterClassInputBinding with the CommandManager.

The InputBinding class itself does not support XAML usage because it does not expose a public parameterless constructor (there is a parameterless constructor, but it is protected). However, derived classes can expose a public constructor and therefore can set properties on the derived class that are inherited from InputBinding with a XAML usage. Two existing InputBinding-derived classes that can be instantiated in XAML and can set properties in XAML are KeyBinding and MouseBinding. The typical property in WPF programming that is set in XAML and takes one or more InputBinding objects as values is the UIElement.InputBindings property.

XAML Object Element Usage

<inputBindingDerivedClass…/>

XAML Values

inputBindingDerivedClass
A derived class of InputBinding that supports object element syntax, such as KeyBinding or MouseBinding. See Remarks.

Constructors

InputBinding()	Provides base initialization for classes derived from InputBinding.
InputBinding(ICommand, InputGesture)	Initializes a new instance of the InputBinding class with the specified command and input gesture.

Fields

CommandParameterProperty	Identifies the CommandParameter dependency property.
CommandProperty	Identifies the Command dependency property.
CommandTargetProperty	Identifies the CommandTarget dependency property.

Properties

CanFreeze	Gets a value that indicates whether the object can be made unmodifiable. (Inherited from Freezable)
Command	Gets or sets the ICommand associated with this input binding.
CommandParameter	Gets or sets the command-specific data for a particular command.
CommandTarget	Gets or sets the target element of the command.
DependencyObjectType	Gets the DependencyObjectType that wraps the CLR type of this instance. (Inherited from DependencyObject)
Dispatcher	Gets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject)
Gesture	Gets or sets the InputGesture associated with this input binding.
IsFrozen	Gets a value that indicates whether the object is currently modifiable. (Inherited from Freezable)
IsSealed	Gets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject)

Methods

CheckAccess()	Determines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject)
ClearValue(DependencyProperty)	Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject)
ClearValue(DependencyPropertyKey)	Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject)
Clone()	Creates a modifiable clone of the Freezable, making deep copies of the object's values. When copying the object's dependency properties, this method copies expressions (which might no longer resolve) but not animations or their current values. (Inherited from Freezable)
CloneCore(Freezable)	Copies the base (non-animated) values of the properties of the specified object.
CloneCurrentValue()	Creates a modifiable clone (deep copy) of the Freezable using its current values. (Inherited from Freezable)
CloneCurrentValueCore(Freezable)	Copies the current values of the properties of the specified object.
CoerceValue(DependencyProperty)	Coerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject)
CreateInstance()	Initializes a new instance of the Freezable class. (Inherited from Freezable)
CreateInstanceCore()	Creates an instance of an InputBinding.
Equals(Object)	Determines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject)
Freeze()	Makes the current object unmodifiable and sets its IsFrozen property to true. (Inherited from Freezable)
FreezeCore(Boolean)	Makes the Freezable object unmodifiable or tests whether it can be made unmodifiable. (Inherited from Freezable)
GetAsFrozen()	Creates a frozen copy of the Freezable, using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable)
GetAsFrozenCore(Freezable)	Makes the instance a frozen clone of the specified Freezable by using base (non-animated) property values.
GetCurrentValueAsFrozen()	Creates a frozen copy of the Freezable using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable)
GetCurrentValueAsFrozenCore(Freezable)	Makes the current instance a frozen clone of the specified Freezable. If the object has animated dependency properties, their current animated values are copied.
GetHashCode()	Gets a hash code for this DependencyObject. (Inherited from DependencyObject)
GetLocalValueEnumerator()	Creates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject)
GetType()	Gets the Type of the current instance. (Inherited from Object)
GetValue(DependencyProperty)	Returns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject)
InvalidateProperty(DependencyProperty)	Re-evaluates the effective value for the specified dependency property. (Inherited from DependencyObject)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnChanged()	Called when the current Freezable object is modified. (Inherited from Freezable)
OnFreezablePropertyChanged(DependencyObject, DependencyObject)	Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set. (Inherited from Freezable)
OnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty)	This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code. (Inherited from Freezable)
OnPropertyChanged(DependencyPropertyChangedEventArgs)	Overrides the DependencyObject implementation of OnPropertyChanged(DependencyPropertyChangedEventArgs) to also invoke any Changed handlers in response to a changing dependency property of type Freezable. (Inherited from Freezable)
ReadLocalValue(DependencyProperty)	Returns the local value of a dependency property, if it exists. (Inherited from DependencyObject)
ReadPreamble()	Ensures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties. (Inherited from Freezable)
SetCurrentValue(DependencyProperty, Object)	Sets the value of a dependency property without changing its value source. (Inherited from DependencyObject)
SetValue(DependencyProperty, Object)	Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject)
SetValue(DependencyPropertyKey, Object)	Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject)
ShouldSerializeProperty(DependencyProperty)	Returns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject)
ToString()	Returns a string that represents the current object. (Inherited from Object)
VerifyAccess()	Enforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject)
WritePostscript()	Raises the Changed event for the Freezable and invokes its OnChanged() method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties. (Inherited from Freezable)
WritePreamble()	Verifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable)

Events

Changed

Occurs when the Freezable or an object it contains is modified. (Inherited from Freezable)

See also

• InputBindings
• CommandBinding