Silverlight 学习——重写DatePicker (二)

一、问题与修改

            在上一篇文章中，出现了一个BUG，设置DatePicer控件输入只读，并非是真真的只读，仍可以进行删除，这与只读的概念相违背了，利用TextBox的IsReadOnly属性可以实现这一要求，不需要自己去定义只读！

二、新的需求

             在很多需求中，只需要选择年，或者是只需要选择月。在界面中，很多程序往往只使用ComboBox来实现这一需求。但是DatePicker完全能够实现，大家都知道DatePicer控件使用了一个隐藏的 Calendar控件！手动更改CalendarMode属性完全可以实现！因此，在DatePicker控件中，添加属性DateMode属性，继承自CalendarMode，通过改变DateMode属性来实现效果！

            同时，要用到扩展方法（在本例中方法名：public static IEnumerable<DependencyObject> Descendents(this DependencyObject root)）｛｝）！它是一个静态类中的一个静态方法，通过此方法在DependencyObject类型中添加Descendents。在本例中的目的是为了找到Calendar控件！具体如何使用，请查找相关的资料了！

二、代码

    public static class ControlsHelper    {        /// <summary>        /// 扩展DependencyObject Descendents方法，递归找到制定的控件        /// </summary>        /// <param name="root"></param>        /// <returns></returns>        public static IEnumerable<DependencyObject> Descendents(this DependencyObject root)        {            int count = VisualTreeHelper.GetChildrenCount(root);            for (int i = 0; i < count; i++)            {                var child = VisualTreeHelper.GetChild(root, i);                yield return child;                foreach (var descendent in Descendents(child))                    yield return descendent;            }        }    }    public class DatePickerEx : DatePicker    {        #region 私有字段        DatePickerTextBox CurrentTextBox;//DatePicker的文本框控件        Popup CurrentPopup;//DatePicker控件的TempPart        Calendar CurrentCalendar;//日历控件        Button CurrentButon;//DatePicker的Button控件        string DateFormat;//定义时间显示格式        string _InputText;        public static readonly DependencyProperty IsReadOnlyProperty = DependencyProperty.Register("IsReadOnly", typeof(bool), typeof(DatePickerEx), new PropertyMetadata(false));        //public static readonly DependencyProperty InputTextProperty = DependencyProperty.Register("InputText", typeof(String), typeof(DatePickerEx), new PropertyMetadata("", InputTextChanged));        public static readonly DependencyProperty DateModeProperty = DependencyProperty.Register("DateMode", typeof(CalendarMode), typeof(DatePickerEx), new PropertyMetadata(CalendarMode.Month, DateModeChanged));        #endregion        #region 属性        /// <summary>        /// 得到手动输入的值        /// </summary>        public string InputText        {            //get { return (string)GetValue(InputTextProperty); }            //set { SetValue(InputTextProperty, value); }            get { return _InputText == null ? "" : _InputText; }            private set { _InputText = value; }        }        /// <summary>        /// 启用和关闭手动输入        /// </summary>        public bool IsReadOnly        {            get { return (bool)GetValue(IsReadOnlyProperty); }            set { SetValue(IsReadOnlyProperty, value); }        }        ///// <summary>        /// 输入时间类型        /// </summary>        public CalendarMode DateMode        {            get { return (CalendarMode)GetValue(DateModeProperty); }            set { SetValue(DateModeProperty, value); }        }        #endregion        #region 重写方法及事件        public override void OnApplyTemplate()        {            base.OnApplyTemplate();            this.CurrentTextBox = GetTemplateChild("TextBox") as DatePickerTextBox;            this.CurrentPopup = GetTemplateChild("Popup") as Popup;            this.CurrentButon = GetTemplateChild("Button") as Button;            #region 注册及绑定事件            if (null != this.CurrentTextBox)            {                //this.CurrentTextBox.BorderThickness = new Thickness(1);                //this.CurrentButon.Margin = new Thickness(-25, 0, 0, 0);                this.SetTextMode(this.CurrentTextBox);                this.CurrentTextBox.IsReadOnly = this.IsReadOnly;                this.CurrentTextBox.TextChanged += ((sender, e) =>                {                    if (this.IsReadOnly)                        this.CurrentTextBox.Text = this.SelectedDate.HasValue ? this.SelectedDate.Value.ToString(this.DateFormat) : "";                    else                    {                        if (this.CurrentTextBox.Text.Trim().Length >= this.DateFormat.Length)                        {                            DateTime timeTemp;                            if (DateTime.TryParse(this.CurrentTextBox.Text.Trim(), out timeTemp))                                this.CurrentTextBox.Text = timeTemp.ToString(this.DateFormat);                        }                        this.InputText = this.CurrentTextBox.Text;                    }                    SetTextMode(this.CurrentTextBox);                });            }            this.CalendarClosed += new RoutedEventHandler(DatePickerEx_CalendarClosed);            if (this.DateMode == CalendarMode.Month)                return;            if (null != this.CurrentPopup)                //利用扩展方法找到Calendar控件                this.CurrentCalendar = this.CurrentPopup.Child.Descendents().OfType<Calendar>().FirstOrDefault();            if (null != this.CurrentButon)                this.CurrentButon.Click += ((sender, e) =>                {                    this.CurrentPopup.IsOpen = true;                });            if (null != this.CurrentCalendar)            {                this.CurrentCalendar.IsTodayHighlighted = true;                this.CurrentCalendar.DisplayModeChanged += new                    EventHandler<CalendarModeChangedEventArgs>(CurrentCalendar_DisplayModeChanged);                this.CurrentCalendar.DisplayMode = this.DateMode;                this.CurrentCalendar.LostMouseCapture += ((sender, e) =>                {                    this.SelectedDate = this.DisplayDate;                });            }            #endregion        }        void CurrentCalendar_DisplayModeChanged(object sender, CalendarModeChangedEventArgs e)        {            this.CurrentCalendar.DisplayModeChanged -= CurrentCalendar_DisplayModeChanged;            this.CurrentCalendar.DisplayModeChanged += CurrentCalendar_DisplayModeChanged;            Calendar cal = (Calendar)sender;            //首次加载以及重新赋值DisplayMode  Calendar视图情况判断            if (e.OldMode.Equals(CalendarMode.Year) && !e.NewMode.Equals(CalendarMode.Month))                cal.DisplayMode = e.NewMode;            else                cal.DisplayMode = this.DateMode;            //仅选择月 Calendar关闭情况判断            if (e.NewMode.Equals(CalendarMode.Month))                this.CurrentPopup.IsOpen = false;            //只选择年。 Calendar 关闭情况判断            if (this.DateMode == CalendarMode.Decade && e.NewMode == CalendarMode.Year && e.OldMode == this.DateMode)                this.CurrentPopup.IsOpen = false;        }        /// <summary>        /// 设置日期显示格式        /// </summary>        /// <param name="tbx"></param>        protected void SetTextMode(DatePickerTextBox tbx)        {            if (null == tbx)                return;            switch (this.DateMode)            {                case CalendarMode.Year:                    DateFormat = "yyyy-MM";                    tbx.Watermark = "<yyyy-MM>";                    break;                case CalendarMode.Decade:                    DateFormat = "yyyy";                    tbx.Watermark = "<yyyy>";                    break;                default:                    DateFormat = "yyyy-MM-dd";                    break;            }            tbx.UpdateLayout();        }        #endregion        //protected override         #region 自定义事件        protected override void OnKeyUp(KeyEventArgs e)        {            base.OnKeyUp(e);            if (!this.IsReadOnly)                this.InputText = this.CurrentTextBox.Text;        }        protected virtual void DatePickerEx_CalendarClosed(object sender, RoutedEventArgs e)        {            if (null != this.SelectedDate)                this.Text = this.SelectedDate.Value.ToString(this.DateFormat);            this.InputText = this.Text;        }        //protected static void InputTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        //{        //    DatePickerEx sender = d as DatePickerEx;        //    if (null != sender.CurrentTextBox)        //        sender.CurrentTextBox.Text = e.NewValue.ToString();        //}        protected static void DateModeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        {            DatePickerEx sender = d as DatePickerEx;            if (null != sender.CurrentCalendar)                sender.CurrentCalendar.DisplayMode = (CalendarMode)e.NewValue;            sender.SetTextMode(sender.CurrentTextBox);        }        #endregion    }