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),new PropertyMetadata("",InputTextChanged));
public static readonly DependencyProperty DateModeProperty = DependencyProperty.Register("DateMode",typeof(CalendarMode),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);
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
}
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