C#中自定义PictureBox控件

Windows Form中的PictureBox有一个缺点，就是当图形加载时，也就是属性Image改变时，没有事件触发。下面是对这控件的扩展。增加了Image属性改变前后的事件。

附件是运行效果。

 

public class PictureBoxEx : PictureBox
{
    #region 属性

    //新的Image属性
    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 自定义事件
    //自定义 ImageChanging与ImageChanged事件

    [Category("属性已更改"), Description("当控件上的 Image 属性值更改后引发的事件。")]
    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("属性已更改"), Description("当控件上的 Image 属性值更改前引发的事件。")]
    public event CancelEventHandler ImageChanging;

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

#region 事件类
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;
    }
}