NativeWindow.CreateHandle(CreateParams) 方法

参考

定义

命名空间:: System.Windows.Forms

程序集:: System.Windows.Forms.dll

重要

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使用指定的创建参数创建一个窗口及其句柄。

public:
 virtual void CreateHandle(System::Windows::Forms::CreateParams ^ cp);

public virtual void CreateHandle (System.Windows.Forms.CreateParams cp);

abstract member CreateHandle : System.Windows.Forms.CreateParams -> unit
override this.CreateHandle : System.Windows.Forms.CreateParams -> unit

Public Overridable Sub CreateHandle (cp As CreateParams)

参数

cp: CreateParams

CreateParams，指定当前窗口的创建参数。

例外

OutOfMemoryException

尝试创建本机窗口时操作系统资源不足。

Win32Exception

本机 Windows API 未能创建指定窗口。

InvalidOperationException

当前本机窗口的句柄已赋值；即 Handle 属性不等于 Zero。

示例

下面的代码示例演示如何创建具有特定操作系统窗口类名称的窗口。该示例创建一个继承自 NativeWindow 的类来实现此目的。

类 MyNativeWindow 创建一个新窗口， ClassName 并将设置为 BUTTON。这会创建 Win32 按钮窗口。设置按钮的位置和大小，并指定其他窗口样式。类演示如何使用 CreateHandle 方法并重写 WndProc 方法来截获收到的窗口消息。尽管该示例查找WM_ACTIVATEAPP消息，但在实际程序中，这可以替换为特定于所创建类型的窗口消息。

注意

某些控件类型将其窗口消息发送到窗口父级，而不是窗口。有关详细信息，请参阅Windows 平台 SDK。

// MyNativeWindow class to create a window given a class name.
ref class MyNativeWindow: public NativeWindow
{
private:

   // Constant values were found in the S"windows.h" header file.
   literal int WS_CHILD = 0x40000000,WS_VISIBLE = 0x10000000,WM_ACTIVATEAPP = 0x001C;
   int windowHandle;

public:
   MyNativeWindow( Form^ parent )
   {
      CreateParams^ cp = gcnew CreateParams;

      // Fill in the CreateParams details.
      cp->Caption = "Click here";
      cp->ClassName = "Button";

      // Set the position on the form
      cp->X = 100;
      cp->Y = 100;
      cp->Height = 100;
      cp->Width = 100;

      // Specify the form as the parent.
      cp->Parent = parent->Handle;

      // Create as a child of the specified parent
      cp->Style = WS_CHILD | WS_VISIBLE;

      // Create the actual window
      this->CreateHandle( cp );
   }

protected:

   // Listen to when the handle changes to keep the variable in sync

   virtual void OnHandleChange() override
   {
      windowHandle = (int)this->Handle;
   }

   virtual void WndProc( Message % m ) override
   {
      // Listen for messages that are sent to the button window. Some messages are sent
      // to the parent window instead of the button's window.
      switch ( m.Msg )
      {
         case WM_ACTIVATEAPP:
            
            // Do something here in response to messages
            break;
      }
      NativeWindow::WndProc( m );
   }
};

// MyNativeWindow class to create a window given a class name.
internal class MyNativeWindow : NativeWindow
{

    // Constant values were found in the "windows.h" header file.
    private const int WS_CHILD = 0x40000000,
                      WS_VISIBLE = 0x10000000,
                      WM_ACTIVATEAPP = 0x001C;

    private int windowHandle;

    public MyNativeWindow(Form parent)
    {

        CreateParams cp = new CreateParams();

        // Fill in the CreateParams details.
        cp.Caption = "Click here";
        cp.ClassName = "Button";

        // Set the position on the form
        cp.X = 100;
        cp.Y = 100;
        cp.Height = 100;
        cp.Width = 100;

        // Specify the form as the parent.
        cp.Parent = parent.Handle;

        // Create as a child of the specified parent
        cp.Style = WS_CHILD | WS_VISIBLE;

        // Create the actual window
        this.CreateHandle(cp);
    }

    // Listen to when the handle changes to keep the variable in sync
    protected override void OnHandleChange()
    {
        windowHandle = (int)this.Handle;
    }

    protected override void WndProc(ref Message m)
    {
        // Listen for messages that are sent to the button window. Some messages are sent
        // to the parent window instead of the button's window.

        switch (m.Msg)
        {
            case WM_ACTIVATEAPP:
                // Do something here in response to messages
                break;
        }
        base.WndProc(ref m);
    }
}

' MyNativeWindow class to create a window given a class name.
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Friend Class MyNativeWindow
    Inherits NativeWindow

    ' Constant values were found in the "windows.h" header file.
    Private Const WS_CHILD As Integer = &H40000000, _
                  WS_VISIBLE As Integer = &H10000000, _
                  WM_ACTIVATEAPP As Integer = &H1C

    Private windowHandle As Integer

    Public Sub New(ByVal parent As Form)

        Dim cp As CreateParams = New CreateParams()

        ' Fill in the CreateParams details.
        cp.Caption = "Click here"
        cp.ClassName = "Button"

        ' Set the position on the form
        cp.X = 100
        cp.Y = 100
        cp.Height = 100
        cp.Width = 100

        ' Specify the form as the parent.
        cp.Parent = parent.Handle

        ' Create as a child of the specified parent
        cp.Style = WS_CHILD Or WS_VISIBLE

        ' Create the actual window
        Me.CreateHandle(cp)
    End Sub

    ' Listen to when the handle changes to keep the variable in sync
    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
    Protected Overrides Sub OnHandleChange()
        windowHandle = Me.Handle.ToInt32()
    End Sub

    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
        Protected Overrides Sub WndProc(ByRef m As Message)
        ' Listen for messages that are sent to the button window. Some messages are sent
        ' to the parent window instead of the button's window.

        Select Case (m.Msg)
            Case WM_ACTIVATEAPP
                ' Do something here in response to messages
        End Select

        MyBase.WndProc(m)
    End Sub

End Class

注解

cp参数指定传递给本机 Win32 CreateWindowEx 方法以创建窗口及其句柄的值。

ClassName如果字段不是 null，则新创建的窗口句柄继承自指定的类。例如，如果 ClassName 设置为 BUTTON，则新创建的窗口基于 Win32 BUTTON 窗口类。对象的 Param 属性 ClassName 必须是 null 或引用声明为结构的类的实例。

此代码是类概述中显示的示例的 NativeWindow 摘录。为了简洁起见，未显示某些代码。有关整个代码列表，请参阅 NativeWindow 。

注意

提供的类名注册到操作系统。

适用于

NativeWindow.CreateHandle(CreateParams) 方法

定义

参数

例外

示例

注解

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