Task Class
Represents a collection of commands and input bindings to those commands.
Namespace: Microsoft.Windows.Design.Interaction
Assembly: Microsoft.Windows.Design.Interaction (in Microsoft.Windows.Design.Interaction.dll)
Syntax
'Declaration
Public Class Task
'Usage
Dim instance As Task
public class Task
public ref class Task
public class Task
Remarks
A Task represents a collection of input bindings and commands that can be associated with a user interface element in the designer. When a task is active, all user input is directed to the task, and commands that are associated with input bindings can be executed. When the task is deactivated, user input returns to normal.
You can adorn a task with RequiresServiceAttribute and RequiresContextItemAttribute attributes. If you do, the task will not be used unless the needed services and context items are available.
Examples
The following code example shows how to use the Task class. For more information, see How to: Create a Surrogate Policy.
Imports System
Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Input
Imports Microsoft.Windows.Design.Interaction
' A DockPanelMarginTask is attached to to the adorner
' offered by the DockPanelAdornerProvider class. When
' you drag the adorner, the target control's Margin
' property changes.
Class DockPanelMarginTask
Inherits Task
Private dragBinding, endDragBinding As InputBinding
Private initialMargin As Thickness
' The DockPanelMarginTask constructor establishes mappings
' between user inputs and commands.
Public Sub New()
Dim beginDrag As New ToolCommand("BeginDrag")
Dim drag As New ToolCommand("Drag")
Dim endDrag As New ToolCommand("EndDrag")
Dim resetMargins As New ToolCommand("ResetMargins")
Me.InputBindings.Add(New InputBinding( _
beginDrag, _
New ToolGesture(ToolAction.DragIntent, MouseButton.Left)))
Me.InputBindings.Add( _
New InputBinding( _
resetMargins, _
New ToolGesture(ToolAction.DoubleClick, MouseButton.Left)))
Me.dragBinding = New InputBinding( _
drag, _
New ToolGesture(ToolAction.Move))
Me.endDragBinding = New InputBinding( _
endDrag, _
New ToolGesture(ToolAction.DragComplete))
Me.ToolCommandBindings.Add(New ToolCommandBinding(beginDrag, AddressOf OnBeginDrag))
Me.ToolCommandBindings.Add(New ToolCommandBinding(drag, AddressOf OnDrag))
Me.ToolCommandBindings.Add(New ToolCommandBinding(endDrag, AddressOf OnEndDrag))
Me.ToolCommandBindings.Add(New ToolCommandBinding(resetMargins, AddressOf OnResetMargins))
End Sub
Private Sub OnBeginDrag(ByVal sender As Object, ByVal args As ExecutedToolEventArgs)
Dim data As GestureData = GestureData.FromEventArgs(args)
Me.BeginFocus(data)
Me.InputBindings.Add(dragBinding)
Me.InputBindings.Add(endDragBinding)
Me.initialMargin = CType(data.ImpliedSource.Properties(FrameworkElement.MarginProperty).ComputedValue, Thickness)
End Sub
Private Sub OnDrag(ByVal sender As Object, ByVal args As ExecutedToolEventArgs)
Dim data As MouseGestureData = MouseGestureData.FromEventArgs(args)
Dim offX As Double = data.PositionDelta.X
Dim offY As Double = data.PositionDelta.Y
Dim newMargin As Thickness = initialMargin
newMargin.Bottom += offY
newMargin.Top += offY
newMargin.Left += offX
newMargin.Right += offX
data.ImpliedSource.Properties(FrameworkElement.MarginProperty).SetValue(newMargin)
End Sub
Private Sub OnEndDrag(ByVal sender As Object, ByVal args As ExecutedToolEventArgs)
Description = "Adjust margin"
Me.Complete()
End Sub
Protected Overrides Sub OnCompleted(ByVal e As EventArgs)
Me.Cleanup()
MyBase.OnCompleted(e)
End Sub
Protected Overrides Sub OnReverted(ByVal e As EventArgs)
Me.Cleanup()
MyBase.OnReverted(e)
End Sub
Private Sub Cleanup()
Me.InputBindings.Remove(dragBinding)
Me.InputBindings.Remove(endDragBinding)
End Sub
Private Sub OnResetMargins(ByVal sender As Object, ByVal args As ExecutedToolEventArgs)
Dim data As GestureData = GestureData.FromEventArgs(args)
data.ImpliedSource.Properties(FrameworkElement.MarginProperty).ClearValue()
End Sub
End Class
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Input;
using Microsoft.Windows.Design.Interaction;
namespace DemoControlLibrary.VisualStudio.Design
{
// A DockPanelMarginTask is attached to to the adorner
// offered by the DockPanelAdornerProvider class. When
// you drag the adorner, the target control's Margin
// property changes.
class DockPanelMarginTask : Task
{
InputBinding dragBinding, endDragBinding;
Thickness initialMargin;
// The DockPanelMarginTask constructor establishes mappings
// between user inputs and commands.
public DockPanelMarginTask()
{
ToolCommand beginDrag = new ToolCommand("BeginDrag");
ToolCommand drag = new ToolCommand("Drag");
ToolCommand endDrag = new ToolCommand("EndDrag");
ToolCommand resetMargins = new ToolCommand("ResetMargins");
this.InputBindings.Add(
new InputBinding(
beginDrag,
new ToolGesture(ToolAction.DragIntent, MouseButton.Left)));
this.InputBindings.Add(
new InputBinding(
resetMargins,
new ToolGesture(ToolAction.DoubleClick, MouseButton.Left)));
this.dragBinding = new InputBinding(
drag,
new ToolGesture(ToolAction.Move));
this.endDragBinding = new InputBinding(
endDrag,
new ToolGesture(ToolAction.DragComplete));
this.ToolCommandBindings.Add(
new ToolCommandBinding(beginDrag, OnBeginDrag));
this.ToolCommandBindings.Add(
new ToolCommandBinding(drag, OnDrag));
this.ToolCommandBindings.Add(
new ToolCommandBinding(endDrag, OnEndDrag));
this.ToolCommandBindings.Add(
new ToolCommandBinding(resetMargins, OnResetMargins));
}
private void OnBeginDrag(object sender, ExecutedToolEventArgs args)
{
GestureData data = GestureData.FromEventArgs(args);
this.BeginFocus(data);
this.InputBindings.Add(dragBinding);
this.InputBindings.Add(endDragBinding);
this.initialMargin = (Thickness)data.ImpliedSource.Properties[
FrameworkElement.MarginProperty].ComputedValue;
}
private void OnDrag(object sender, ExecutedToolEventArgs args)
{
MouseGestureData data = MouseGestureData.FromEventArgs(args);
double offX = data.PositionDelta.X;
double offY = data.PositionDelta.Y;
Thickness newMargin = initialMargin;
newMargin.Bottom += offY;
newMargin.Top += offY;
newMargin.Left += offX;
newMargin.Right += offX;
data.ImpliedSource.Properties[FrameworkElement.MarginProperty].SetValue(newMargin);
}
private void OnEndDrag(object sender, ExecutedToolEventArgs args)
{
Description = "Adjust margin";
this.Complete();
}
protected override void OnCompleted(EventArgs e)
{
this.Cleanup();
base.OnCompleted(e);
}
protected override void OnReverted(EventArgs e)
{
this.Cleanup();
base.OnReverted(e);
}
private void Cleanup()
{
this.InputBindings.Remove(dragBinding);
this.InputBindings.Remove(endDragBinding);
}
private void OnResetMargins(object sender, ExecutedToolEventArgs args)
{
GestureData data = GestureData.FromEventArgs(args);
data.ImpliedSource.Properties[FrameworkElement.MarginProperty].ClearValue();
}
}
}
Inheritance Hierarchy
System.Object
Microsoft.Windows.Design.Interaction.Task
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
See Also
Reference
Microsoft.Windows.Design.Interaction Namespace