ContainerControl.ActiveControl ContainerControl.ActiveControl ContainerControl.ActiveControl ContainerControl.ActiveControl Property

定义

获取或设置容器控件上的活动控件。Gets or sets the active control on the container control.

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; }
member this.ActiveControl : System.Windows.Forms.Control with get, set
Public Property ActiveControl As Control

属性值

Control 上的当前活动 ContainerControlThe Control that is currently active on the ContainerControl.

实现

异常

分配的 Control 未能激活。The Control assigned could not be activated.

示例

下面的代码示例从ScrollableControl类继承并IContainerControl实现接口。The following code example inherits from the ScrollableControl class and implements the IContainerControl interface. 实现将添加到ActiveControl属性ActivateControl和方法。Implementation is added to the ActiveControl property and the ActivateControl method.

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

ActiveControl属性激活或检索容器控件上的活动控件。The ActiveControl property activates or retrieves the active control on the container control.

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。In order to receive a valid value from this property, the object that calls it must either contain or be contained in the control it is calling. 如果一个窗体尝试调用另一个窗ActiveControl体的属性,它将接收未定义的值。If one form tries to call another form's ActiveControl properties, it will receive an undefined value. 在这种情况下,您需要在窗体间定义自己的通信机制以传递此数据。In this case, you need to define your own communication mechanism between the forms to pass this data.

适用于

另请参阅