在很早之前，我曾经写过一个GDI+的时钟，见“C#时钟控件（C# Clock Control）” http://blog.csdn.net/johnsuna/archive/2006/02/13/597746.aspx及“使用C#编写LED样式时钟控件”（http://blog.csdn.net/johnsuna/archive/2006/02/14/598867.aspx），进入WPF时代了，如何用WPF绘制一个时钟呢？

先看效果：

上面显示的是时间值，下面是图形版的时钟。

制作要点：
1. 首先在Expression Blend中画出时钟的样式;
2. 建立时钟的程序辅助类;
3. 将此时钟样式需要动态换掉的部分改成相应的绑定值。

由于具体步骤很多，这里只说说技术难点和要点，着重说明上述第2点部分。
// 时钟控件类：Clock.cs
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.Timers;
using System.Windows.Threading;

namespace BrawDraw.Com.WPF.Clock.ControlLibrary
{
///

Clock Control
///

public class Clock : Control
{
private DispatcherTimer timer;

static Clock()
{
DefaultStyleKeyProperty.OverrideMetadata(typeof(Clock), new FrameworkPropertyMetadata(typeof(Clock)));
}

protected override void OnInitialized(EventArgs e)
{
   base.OnInitialized(e);
   timer = new DispatcherTimer();
   timer.Tick += new EventHandler(Timer_Tick);
   timer.Start();
}

private void Timer_Tick(object sender, EventArgs e)
{
UpdateDateTime();
timer.Interval = TimeSpan.FromMilliseconds(1000 - DateTime.Now.Millisecond);
}

private void UpdateDateTime()
{
this.DateTime = System.DateTime.Now;
}

#region DateTime property
public DateTime DateTime
{
   get
   {
    return (DateTime)GetValue(DateTimeProperty);
   }
   private set
   {
    SetValue(DateTimeProperty, value);
   }
}

public static DependencyProperty DateTimeProperty = DependencyProperty.Register(
    "DateTime",
    typeof(DateTime),
    typeof(Clock),
    new PropertyMetadata(DateTime.Now, new PropertyChangedCallback(OnDateTimeInvalidated)));

public static readonly RoutedEvent DateTimeChangedEvent =
EventManager.RegisterRoutedEvent("DateTimeChanged", RoutingStrategy.Bubble, typeof(RoutedPropertyChangedEventHandler), typeof(Clock));

protected virtual void OnDateTimeChanged(DateTime oldValue, DateTime newValue)
{
   RoutedPropertyChangedEventArgs args = new RoutedPropertyChangedEventArgs(oldValue, newValue);
   args.RoutedEvent = Clock.DateTimeChangedEvent;
   RaiseEvent(args);
}

private static void OnDateTimeInvalidated(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Clock clock = (Clock)d;

DateTime ldValue = (DateTime)e.OldValue;
DateTime newValue = (DateTime)e.NewValue;

clock.OnDateTimeChanged(oldValue, newValue);
}
#endregion
}
}

// 时钟内部时针、分针、秒针角度计算及星期显示的类： ClockConverters.cs
// 由于WPF中旋转角度是以度单位，计算为绕一个圆周时，为360度。所以，计算时以360度来计算。
using System;
using System.Globalization;
using System.Windows.Data;

namespace BrawDraw.Com.WPF.Clock
{
    // 一分钟60秒，一周为360度，所以，一秒钟就占6度，所以是：秒数×6。
    [ValueConversion(typeof(DateTime), typeof(int))]
    public class SecondsConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime date = (DateTime)value;
            return date.Second * 6;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }

// 一小时是60分钟，一周为360度，所以，一分钟就占6度，所以是：分钟数×6。
    [ValueConversion(typeof(DateTime), typeof(int))]
    public class MinutesConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime date = (DateTime)value;
            return date.Minute * 6;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }

// 时钟上显示12小时，一周为360度，这样，每小时占30度，考虑分钟所占角度是分钟数/2，所以结果是：小时数×30 + 分钟数/2。
    [ValueConversion(typeof(DateTime), typeof(int))]
    public class HoursConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime date = (DateTime)value;
            return (date.Hour * 30) + (date.Minute / 2);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }

    [ValueConversion(typeof(DateTime), typeof(string))]
    public class WeekdayConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            DateTime date = (DateTime)value;
            return date.DayOfWeek.ToString().Substring(0,3);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }
}

剩下的就十分简单，程序的显示部分(XAML代码)：
// MainWindow.xaml
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:customControl="clr-namespace:BrawDraw.Com.WPF.Clock.ControlLibrary;assembly=CustomControlLibrary"
xmlns:local="clr-namespace:BrawDraw.Com.WPF.Clock"
    x:Class="BrawDraw.Com.WPF.Clock.Window1"
    Title="WPF Clock" Height="394" Width="332"
    >

Fill="Black" Width="4" Height="30">




                    Fill="DarkOrange" Width="2" Height="40">




                    Fill="Red" Width="1" Height="47">











(已用粗体标注重要的部分)

比较一下使用GDI+和WPF的方便性，从设计的角度来讲，WPF显得更方便，更快捷。从编程的代码量相比，两者差别不是太多，我统计了一下总体代码量，GDI+甚至比WPF更少。运行效率方面，暂未做测试。

ITPub博客

制作简单的WPF时钟

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