C#中自定義PictureBox控件

Windows Form中的PictureBox有一個缺點，就是當圖形加載時，也就是屬性Image改變時，沒有事件觸發。下面是對這控件的擴展。增加了Image屬性改變前後的事件。

附件是運行效果。

 

public class PictureBoxEx : PictureBox
{
    #region 屬性

    //新的Image屬性
    public new Image Image
    {
        get { return base.Image; }
        set
        {
            ImageChangingEventArgs e = new ImageChangingEventArgs(value);
            OnImageChanging(e);
            if (!e.Cancel)
            {
                base.Image = value;
                OnImageChanged(new ImageChangedEventArgs(base.Image));
            }
        }
    }
    #endregion

    #region 自定義事件
    //自定義 ImageChanging與ImageChanged事件

    [Category("屬性已更改"), Description("當控件上的 Image 屬性值更改後引發的事件。")]
    public event EventHandler<ImageChangedEventArgs> ImageChanged;

    protected virtual void OnImageChanged(ImageChangedEventArgs e)
    {
        if (ImageChanged != null)
            ImageChanged(this, e);
    }

    public delegate void CancelEventHandler(object sender, ImageChangingEventArgs e);
    [Category("屬性已更改"), Description("當控件上的 Image 屬性值更改前引發的事件。")]
    public event CancelEventHandler ImageChanging;

    protected virtual void OnImageChanging(ImageChangingEventArgs e)
    {
        if (ImageChanging != null)
            ImageChanging(this, e);
    }
    #endregion
}

#region 事件類
public class ImageChangedEventArgs : EventArgs
{
    public Image Image
    {
        get { return _Image; }
    }
    private readonly Image _Image;

    public ImageChangedEventArgs(Image image)
    {
        this._Image = image;
    }
}

public class ImageChangingEventArgs : CancelEventArgs
{
    public Image Image
    {
        get { return _Image; }
    }
    private readonly Image _Image;

    public ImageChangingEventArgs(Image image)
    {
        this._Image = image;
    }
}