Form.ActiveMdiChild 属性
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
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(); };C#
[System.ComponentModel.Browsable(false)]
public System.Windows.Forms.Form ActiveMdiChild { get; }C#
[System.ComponentModel.Browsable(false)]
public System.Windows.Forms.Form? ActiveMdiChild { get; }[<System.ComponentModel.Browsable(false)>]
member this.ActiveMdiChild : System.Windows.Forms.FormPublic ReadOnly Property ActiveMdiChild As 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
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 = "";
}
}
}
C#
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
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。
| 产品 | 版本 |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |
| Windows Desktop | 3.0, 3.1, 5, 6, 7 |