ContainerControl.ActiveControl 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置容器控件上的活动控件。

public:
 property System::Windows::Forms::Control ^ ActiveControl { System::Windows::Forms::Control ^ get(); void set(System::Windows::Forms::Control ^ value); };

[System.ComponentModel.Browsable(false)]
public System.Windows.Forms.Control ActiveControl { get; set; }

[<System.ComponentModel.Browsable(false)>]
member this.ActiveControl : System.Windows.Forms.Control with get, set

Public Property ActiveControl As Control

属性值

Control

ContainerControl 的当前活动 Control。

实现

ActiveControl

属性

BrowsableAttribute

例外

ArgumentException

分配的 Control 未能激活。

示例

下面的代码示例继承自 ScrollableControl 类并实现 IContainerControl 接口。 实现将添加到 ActiveControl 属性和 ActivateControl 方法。

using namespace System;
using namespace System::Windows::Forms;
using namespace System::Drawing;

public ref class MyContainer: public ScrollableControl, public IContainerControl
{
private:
   Control^ activeControl;

public:
   MyContainer()
   {
      // Make the container control Blue so it can be distinguished on the form.
      this->BackColor = Color::Blue;

      // Make the container scrollable.
      this->AutoScroll = true;
   }

   property Control^ ActiveControl 
   {
      // Add implementation to the IContainerControl.ActiveControl property.
      virtual Control^ get()
      {
         return activeControl;
      }

      virtual void set( Control^ value )
      {
         
         // Make sure the control is a member of the ControlCollection.
         if ( this->Controls->Contains( value ) )
         {
            activeControl = value;
         }
      }
   }

   // Add implementations to the IContainerControl.ActivateControl(Control) method.
   virtual bool ActivateControl( Control^ active )
   {
      if ( this->Controls->Contains( active ) )
      {
         // Select the control and scroll the control into view if needed.
         active->Select(  );
         this->ScrollControlIntoView( active );
         this->activeControl = active;
         return true;
      }

      return false;
   }
};

using System;
using System.Windows.Forms;
using System.Drawing;

    public class MyContainer : ScrollableControl, IContainerControl
    {
        private Control activeControl;
        public MyContainer() 
        {
            // Make the container control Blue so it can be distinguished on the form.
            this.BackColor = Color.Blue;
            
            // Make the container scrollable.
            this.AutoScroll = true;
        }

        // Add implementation to the IContainerControl.ActiveControl property.
        public Control ActiveControl
        {
            get
            {
                return activeControl;
            }

            set
            {
                // Make sure the control is a member of the ControlCollection.
                if(this.Controls.Contains(value))
                {
                    activeControl = value;
                }
            }
        }

        // Add implementations to the IContainerControl.ActivateControl(Control) method.
        public bool ActivateControl(Control active)
        {
            if(this.Controls.Contains(active))
            {
                // Select the control and scroll the control into view if needed.
                active.Select();
                this.ScrollControlIntoView(active);
                this.activeControl = active;
                return true;
            }
            return false;
        }
    }

Imports System.Windows.Forms
Imports System.Drawing

   Public Class MyContainerControl
      Inherits ScrollableControl
      Implements IContainerControl 

      Private myActiveControl As Control
      
      Public Sub New()
         ' Make the container control Blue so it can be distinguished on the form.
         Me.BackColor = Color.Blue
         
         ' Make the container scrollable.
         Me.AutoScroll = True
      End Sub 
      
      ' Add implementation to the IContainerControl.ActiveControl property.
      Public Property ActiveControl() As Control Implements IContainerControl.ActiveControl
         Get
            Return Me.myActiveControl
         End Get
         
         Set
            ' Make sure the control is a member of the ControlCollection.
            If Me.Controls.Contains(value) Then
               Me.myActiveControl = value
            End If
         End Set
      End Property
      
      ' Add implementation to the IContainerControl.ActivateControl(Control) method.
      public Function ActivateControl(active As Control) As Boolean Implements IContainerControl.ActivateControl
         If Me.Controls.Contains(active) Then
            ' Select the control and scroll the control into view if needed.
            active.Select()
            Me.ScrollControlIntoView(active)
            Me.myActiveControl = active
            Return True
         End If
         Return False
      End Function 

   End Class

注解

该 ActiveControl 属性激活或检索容器控件上的活动控件。

为了从此属性接收有效值，调用它的对象必须包含或包含在它所调用的控件中。 如果一个窗体尝试调用另一个窗体 ActiveControl 的属性，它将接收未定义的值。 在这种情况下，需要在表单之间定义自己的通信机制才能传递此数据。

另请参阅

• ScrollableControl
• Control