Control.ControlAccessibleObject(Control) 建構函式

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

初始化 Control.ControlAccessibleObject 類別的新執行個體。

C#

public ControlAccessibleObject (System.Windows.Forms.Control ownerControl);

參數

ownerControl

Control

擁有 Control.ControlAccessibleObject 的 Control。

例外狀況

ArgumentNullException

ownerControl 參數值為 null。

範例

下列程式碼範例會建立衍生自 類別的 CheckBox 核取方塊控制項，並針對要使用的衍生類別建立自訂 Control.ControlAccessibleObject 。 衍生類別 MyCheckBox 預設為 Appearance 的 Button ，因此會顯示為切換按鈕。 衍生 Control.ControlAccessibleObject 類別 MyCheckBoxControlAccessibleObject 會覆寫三個屬性，以考慮外觀的差異。

C#

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

namespace MyCustomControls
{
   public class MyCheckBox : CheckBox
   {
      public MyCheckBox()
      {
         // Make the check box appear like a toggle button.
         this.Appearance = Appearance.Button;
         // Center the text on the button.
         this.TextAlign = ContentAlignment.MiddleCenter;
         // Set the AccessibleDescription text.
         this.AccessibleDescription = "A toggle style button.";
      }
      
      // Create an instance of the AccessibleObject 
      // defined for the 'MyCheckBox' control
      protected override AccessibleObject CreateAccessibilityInstance() 
      {
         return new MyCheckBoxAccessibleObject(this);
      }
   }

   // Accessible object for use with the 'MyCheckBox' control.
   internal class MyCheckBoxAccessibleObject : Control.ControlAccessibleObject 
   {
      public MyCheckBoxAccessibleObject(MyCheckBox owner) : base(owner) 
      {
      }
               
      public override string DefaultAction 
      {
         get
         {
            // Return the DefaultAction based upon 
            // the state of the control.
            if( ((MyCheckBox)Owner).Checked )
            {
               return "Toggle button up";
            }
            else
            {
               return "Toggle button down";
            }
         }
      }

      public override string Name 
      {
         get 
         {
            // Return the Text property of the control 
            // if the AccessibleName is null.
            string name = Owner.AccessibleName;
            if (name != null) 
            {
               return name;
            }
            return ((MyCheckBox)Owner).Text;
         }
         
         set
         {
            base.Name = value;
         }
      }            
               
      public override AccessibleRole Role 
      {
         get 
         {
            // Since the check box appears like a button,
            // make the Role the same as a button.
            return AccessibleRole.PushButton;
         }
      }
   }
}

適用於

另請參閱

• Control.ControlAccessibleObject
• Owner