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演练：使用 ElementHost 控件映射属性

  • 项目

本演练演示如何使用 PropertyMap 属性将 Windows 窗体属性映射到托管 WPF 元素上的相应属性。

本演练涉及以下任务：

  • 创建项目。

  • 定义新的属性映射。

  • 删除默认属性映射。

  • 扩展默认属性映射。

完成后，你将能够将 Windows 窗体属性映射到托管元素上相应的 WPF 属性。

先决条件

你需要满足以下条件才能完成本演练：

  • Visual Studio 2017

创建项目

创建项目

  1. 创建名为 PropertyMappingWithElementHost 的 Windows 窗体应用项目。

  2. 在解决方案资源管理器中，添加对下列 WPF 程序集的引用。

    • PresentationCore

    • PresentationFramework

    • WindowsBase

    • WindowsFormsIntegration

  3. 将以下代码复制到 Form1 代码文件的顶部。

    using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Forms.Integration;

    Imports System.Windows
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Forms.Integration

  4. 在 Windows 窗体设计器中打开 Form1。 双击窗体，为 Load 事件添加事件处理程序。

  5. 返回到 Windows 窗体设计器，并为窗体的 Resize 事件添加事件处理程序。 有关详细信息，请参阅如何：使用设计器创建事件处理程序。

  6. 在 Form1 类中声明 ElementHost 字段。

    ElementHost elemHost = null;

    Private elemHost As ElementHost = Nothing

定义新的属性映射

ElementHost 控件提供了若干默认的属性映射。 在 ElementHost 控件的 PropertyMap 上调用 Add 方法来添加新的属性映射。

定义新的属性映射

  1. 将以下代码复制到 Form1 类的定义中。

    // The AddMarginMapping method adds a new property mapping
// for the Margin property.
private void AddMarginMapping()
{
    elemHost.PropertyMap.Add(
        "Margin",
        new PropertyTranslator(OnMarginChange));
}

// The OnMarginChange method implements the mapping
// from the Windows Forms Margin property to the
// Windows Presentation Foundation Margin property.
//
// The provided Padding value is used to construct
// a Thickness value for the hosted element's Margin
// property.
private void OnMarginChange(object h, String propertyName, object value)
{
    ElementHost host = h as ElementHost;
    Padding p = (Padding)value;
    System.Windows.Controls.Button wpfButton =
        host.Child as System.Windows.Controls.Button;

    Thickness t = new Thickness(p.Left, p.Top, p.Right, p.Bottom );

    wpfButton.Margin = t;
}

    ' The AddMarginMapping method adds a new property mapping
' for the Margin property.
Private Sub AddMarginMapping()

    elemHost.PropertyMap.Add( _
        "Margin", _
        New PropertyTranslator(AddressOf OnMarginChange))

End Sub


' The OnMarginChange method implements the mapping 
' from the Windows Forms Margin property to the
' Windows Presentation Foundation Margin property.
'
' The provided Padding value is used to construct 
' a Thickness value for the hosted element's Margin
' property.
Private Sub OnMarginChange( _
ByVal h As Object, _
ByVal propertyName As String, _
ByVal value As Object)

    Dim host As ElementHost = h
    Dim p As Padding = CType(value, Padding)
    Dim wpfButton As System.Windows.Controls.Button = host.Child


    Dim t As New Thickness(p.Left, p.Top, p.Right, p.Bottom)

    wpfButton.Margin = t

End Sub

    AddMarginMapping 方法将为 Margin 属性添加新映射。

    OnMarginChange 方法将 Margin 属性转换为 WPF Margin 属性。

  2. 将以下代码复制到 Form1 类的定义中。

    // The AddRegionMapping method assigns a custom
// mapping for the Region property.
private void AddRegionMapping()
{
    elemHost.PropertyMap.Add(
        "Region",
        new PropertyTranslator(OnRegionChange));
}

// The OnRegionChange method assigns an EllipseGeometry to
// the hosted element's Clip property.
private void OnRegionChange(
    object h,
    String propertyName,
    object value)
{
    ElementHost host = h as ElementHost;
    System.Windows.Controls.Button wpfButton =
        host.Child as System.Windows.Controls.Button;

    wpfButton.Clip = new EllipseGeometry(new Rect(
        0,
        0,
        wpfButton.ActualWidth,
        wpfButton.ActualHeight));
}

// The Form1_Resize method handles the form's Resize event.
// It calls the OnRegionChange method explicitly to
// assign a new clipping geometry to the hosted element.
private void Form1_Resize(object sender, EventArgs e)
{
    this.OnRegionChange(elemHost, "Region", null);
}

    ' The AddRegionMapping method assigns a custom 
' mapping for the Region property.
Private Sub AddRegionMapping()

    elemHost.PropertyMap.Add( _
        "Region", _
        New PropertyTranslator(AddressOf OnRegionChange))

End Sub


' The OnRegionChange method assigns an EllipseGeometry to
' the hosted element's Clip property.
Private Sub OnRegionChange( _
ByVal h As Object, _
ByVal propertyName As String, _
ByVal value As Object)

    Dim host As ElementHost = h

    Dim wpfButton As System.Windows.Controls.Button = host.Child

    wpfButton.Clip = New EllipseGeometry(New Rect( _
        0, _
        0, _
        wpfButton.ActualWidth, _
        wpfButton.ActualHeight))

End Sub


' The Form1_Resize method handles the form's Resize event.
' It calls the OnRegionChange method explicitly to 
' assign a new clipping geometry to the hosted element.
Private Sub Form1_Resize( _
ByVal sender As Object, _
ByVal e As EventArgs) Handles MyBase.Resize

    If elemHost IsNot Nothing Then
        Me.OnRegionChange(elemHost, "Region", Nothing)
    End If

End Sub

    AddRegionMapping 方法将为 Region 属性添加新映射。

    OnRegionChange 方法将 Region 属性转换为 WPF Clip 属性。

    Form1_Resize 方法处理窗体的 Resize 事件并调整剪切区域的大小以适应托管元素。

删除默认属性映射

在 ElementHost 控件的 PropertyMap 上调用 Remove 方法来删除默认属性映射。

删除默认属性映射

  • 将以下代码复制到 Form1 类的定义中。

    // The RemoveCursorMapping method deletes the default
// mapping for the Cursor property.
private void RemoveCursorMapping()
{
    elemHost.PropertyMap.Remove("Cursor");
}

    ' The RemoveCursorMapping method deletes the default
' mapping for the Cursor property.
Private Sub RemoveCursorMapping()
    elemHost.PropertyMap.Remove("Cursor")
End Sub

    RemoveCursorMapping 方法删除 Cursor 属性的默认映射。

扩展默认属性映射

可以使用默认属性映射，并使用自己的映射对其进行扩展。

扩展默认属性映射

  • 将以下代码复制到 Form1 类的定义中。

    // The ExtendBackColorMapping method adds a property
// translator if a mapping already exists.
private void ExtendBackColorMapping()
{
    if (elemHost.PropertyMap["BackColor"] != null)
    {
        elemHost.PropertyMap["BackColor"] +=
            new PropertyTranslator(OnBackColorChange);
    }
}

// The OnBackColorChange method assigns a specific image
// to the hosted element's Background property.
private void OnBackColorChange(object h, String propertyName, object value)
{
    ElementHost host = h as ElementHost;
    System.Windows.Controls.Button wpfButton =
        host.Child as System.Windows.Controls.Button;

    ImageBrush b = new ImageBrush(new BitmapImage(
        new Uri(@"file:///C:\WINDOWS\Santa Fe Stucco.bmp")));
    wpfButton.Background = b;
}

    ' The ExtendBackColorMapping method adds a property
' translator if a mapping already exists.
Private Sub ExtendBackColorMapping()

    If elemHost.PropertyMap("BackColor") IsNot Nothing Then

        elemHost.PropertyMap("BackColor") = PropertyTranslator.Combine( _
            elemHost.PropertyMap("BackColor"), _
            PropertyTranslator.CreateDelegate( _
            GetType(PropertyTranslator), _
            Me, _
            "OnBackColorChange"))
    End If

End Sub


' The OnBackColorChange method assigns a specific image 
' to the hosted element's Background property.
Private Sub OnBackColorChange( _
ByVal h As Object, _
ByVal propertyName As String, _
ByVal value As Object)

    Dim host As ElementHost = h
    Dim wpfButton As System.Windows.Controls.Button = host.Child
    Dim b As New ImageBrush(New BitmapImage( _
        New Uri("file:///C:\WINDOWS\Santa Fe Stucco.bmp")))
    wpfButton.Background = b

End Sub

    ExtendBackColorMapping 方法将自定义属性转换器添加到现有的 BackColor 属性映射。

    OnBackColorChange 方法将特定图像分配给托管控件的 Background 属性。 在应用默认属性映射后会调用 OnBackColorChange 方法。

初始化属性映射

  1. 将以下代码复制到 Form1 类的定义中。

    private void Form1_Load(object sender, EventArgs e)
{
    // Create the ElementHost control.
    elemHost = new ElementHost();
    elemHost.Dock = DockStyle.Fill;
    this.Controls.Add(elemHost);

    // Create a Windows Presentation Foundation Button element
    // and assign it as the ElementHost control's child.
    System.Windows.Controls.Button wpfButton = new System.Windows.Controls.Button();
    wpfButton.Content = "Windows Presentation Foundation Button";
    elemHost.Child = wpfButton;

    // Map the Margin property.
    this.AddMarginMapping();

    // Remove the mapping for the Cursor property.
    this.RemoveCursorMapping();

    // Add a mapping for the Region property.
    this.AddRegionMapping();

    // Add another mapping for the BackColor property.
    this.ExtendBackColorMapping();

    // Cause the OnMarginChange delegate to be called.
    elemHost.Margin = new Padding(23, 23, 23, 23);

    // Cause the OnRegionChange delegate to be called.
    elemHost.Region = new Region();

    // Cause the OnBackColorChange delegate to be called.
    elemHost.BackColor = System.Drawing.Color.AliceBlue;
}

    Private Sub Form1_Load( _
ByVal sender As Object, _
ByVal e As EventArgs) Handles MyBase.Load

    ' Create the ElementHost control.
    elemHost = New ElementHost()
    elemHost.Dock = DockStyle.Fill
    Me.Controls.Add(elemHost)

    ' Create a Windows Presentation Foundation Button element 
    ' and assign it as the ElementHost control's child. 
    Dim wpfButton As New System.Windows.Controls.Button()
    wpfButton.Content = "Windows Presentation Foundation Button"
    elemHost.Child = wpfButton

    ' Map the Margin property.
    Me.AddMarginMapping()

    ' Remove the mapping for the Cursor property.
    Me.RemoveCursorMapping()

    ' Add a mapping for the Region property.
    Me.AddRegionMapping()

    ' Add another mapping for the BackColor property.
    Me.ExtendBackColorMapping()

    ' Cause the OnMarginChange delegate to be called.
    elemHost.Margin = New Padding(23, 23, 23, 23)

    ' Cause the OnRegionChange delegate to be called.
    elemHost.Region = New [Region]()

    ' Cause the OnBackColorChange delegate to be called.
    elemHost.BackColor = System.Drawing.Color.AliceBlue

End Sub

    Form1_Load 方法处理 Load 事件并执行以下初始化。

    • 创建 WPF Button 元素。

    • 调用先前在演练中定义的方法来设置属性映射。

    • 将初始值分配给映射的属性。

  2. 按 F5 生成并运行应用程序。

另请参阅