Task 类
更新:2007 年 11 月
表示命令以及这些命令的输入绑定的集合。
命名空间: Microsoft.Windows.Design.Interaction
程序集: Microsoft.Windows.Design.Interaction(在 Microsoft.Windows.Design.Interaction.dll 中)
语法
声明
Public Class Task
用法
Dim instance As Task
public class Task
public ref class Task
public class Task
备注
Task 表示可与设计器中的用户界面元素关联的输入绑定和命令的集合。当任务处于活动状态时,所有用户输入都定向到该任务,与输入绑定关联的命令可以执行。当任务停用时,用户输入恢复正常。
可以用 RequiresServiceAttribute 和 RequiresContextItemAttribute 属性来装饰任务。如果这样做,则除非所需的服务和上下文项可用,否则将不会使用该任务。
示例
下面的代码示例演示如何使用 Task 类。有关更多信息,请参见如何:创建代理项策略。
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();
}
}
}
继承层次结构
System.Object
Microsoft.Windows.Design.Interaction.Task
线程安全
此类型的任何公共 static(在 Visual Basic 中为 Shared) 成员都是线程安全的。但不保证所有实例成员都是线程安全的。
另请参见
参考
Microsoft.Windows.Design.Interaction 命名空间