給 TextBox文本框前添加圖片

擴(kuò)展PhoneTextBox:添加一個(gè)類“ExtentPhoneTextBox”繼承 PhoneTextBox ，在“ExtentPhoneTextBox”類中添加屬性項(xiàng)：
代碼如下:
public class ExtentPhoneTextBox : PhoneTextBox
    {
        /// <summary>
        /// 文本框圖片屬性
        /// </summary>
        public static readonly DependencyProperty TextHeadImageProperty =
            DependencyProperty.Register("TextHeadImage", typeof(ImageSource), typeof(ExtentPhoneTextBox), new PropertyMetadata(null)
            );

        /// <summary>
        /// 文本框頭圖片
        /// </summary>
        public ImageSource TextHeadImage
        {
            get { return base.GetValue(TextHeadImageProperty) as ImageSource; }
            set { base.SetValue(TextHeadImageProperty, value); }
        }

        /// <summary>
        /// 文本圖片寬度
        /// </summary>
        public double TextHeadImageWidth
        {
            get { return (double)GetValue(TextHeadImageWidthProperty); }
            set { SetValue(TextHeadImageWidthProperty, value); }
        }

        // Using a DependencyProperty as the backing store for TextHeadImageWidth.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty TextHeadImageWidthProperty =
            DependencyProperty.Register("TextHeadImageWidth", typeof(double), typeof(ExtentPhoneTextBox), new PropertyMetadata(null));

        /// <summary>
        /// 文本圖片高度
        /// </summary>
        public double TextHeadImageHeight
        {
            get { return (double)GetValue(TextHeadImageHeightProperty); }