Form.ActiveMdiChild 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取当前活动的多文档界面 (MDI) 子窗口。

public:
 property System::Windows::Forms::Form ^ ActiveMdiChild { System::Windows::Forms::Form ^ get(); };

[System.ComponentModel.Browsable(false)]
public System.Windows.Forms.Form ActiveMdiChild { get; }

[System.ComponentModel.Browsable(false)]
public System.Windows.Forms.Form? ActiveMdiChild { get; }

[<System.ComponentModel.Browsable(false)>]
member this.ActiveMdiChild : System.Windows.Forms.Form

Public ReadOnly Property ActiveMdiChild As Form

属性值

Form

返回表示当前活动的 MDI 子窗口的 Form，或者如果当前没有子窗口，则返回 null。

属性

BrowsableAttribute

示例

以下示例获取对活动 MDI 子窗体的引用，并循环访问窗体上的所有 TextBox 控件，并重置其 Text 属性。 此示例要求已创建 MDI 父窗体，并且此方法调用是从 MDI 父窗体进行的。

public:
   void ClearAllChildFormText()
   {
      
      // Obtain a reference to the currently active MDI child form.
      Form^ tempChild = this->ActiveMdiChild;
      
      // Loop through all controls on the child form.
      for ( int i = 0; i < tempChild->Controls->Count; i++ )
      {
         
         // Determine if the current control on the child form is a TextBox.
         if ( dynamic_cast<TextBox^>(tempChild->Controls[ i ]) )
         {
            
            // Clear the contents of the control since it is a TextBox.
            tempChild->Controls[ i ]->Text = "";
         }

      }
   }

public void ClearAllChildFormText()
 {
    // Obtain a reference to the currently active MDI child form.
    Form tempChild = this.ActiveMdiChild;
    
    // Loop through all controls on the child form.
    for (int i = 0; i < tempChild.Controls.Count; i++)
    {
       // Determine if the current control on the child form is a TextBox.
       if (tempChild.Controls[i] is TextBox)
       {
          // Clear the contents of the control since it is a TextBox.
          tempChild.Controls[i].Text = "";
       }
    }
 }

Public Sub ClearAllChildFormText()
    ' Obtain a reference to the currently active MDI child form.
    Dim tempChild As Form = Me.ActiveMdiChild
    
    ' Loop through all controls on the child form.
    Dim i As Integer
    For i = 0 To tempChild.Controls.Count - 1
        ' Determine if the current control on the child form is a TextBox.
        If TypeOf tempChild.Controls(i) Is TextBox Then
            ' Clear the contents of the control since it is a TextBox.
            tempChild.Controls(i).Text = ""
        End If
    Next i
End Sub

注解

可以使用此方法来确定 MDI 应用程序中是否打开了任何 MDI 子窗体。 还可以使用此方法从 MDI 父窗体或应用程序中显示的另一个窗体对 MDI 子窗口执行操作。

如果当前活动窗体不是 MDI 子窗体，则可以使用该 ActiveForm 属性获取对它的引用。

另请参阅

• ActiveForm