Windows Phone 7 程序菜单栏ApplicationBar

ApplicationBar控件时windows phone 7上的一个菜单，它传统的Windows程序的菜单的作用类似。
ApplicationBar（ApplicationBarIconButton和ApplicationBarMenuItem）相关的类定义在Microsoft.Phone.Shell命名空间。与UIElement和FrameworkElement等常规Silverlight编程的类层次是完全分开的，严格说来ApplicationBar不是你的页面的可视化的一部分。
一个ApplicationBar最多可包含四个按钮。如果还有额外的选项可以通过菜单项来添加，这些菜单项默认是不显示的。只有在点击菜单栏右侧的省略号(或省略号下方的区域)时才会显示出来。

该项目包含一个MediaElement MoviePlayer播放影片，而ApplicationBar包含第一，播放，暂停，最后四个选项。

<!--LayoutRoot contains the root grid where all other page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="MOVIE PLAYER" Style="{StaticResource PhoneTextNormalStyle}"/>
        </StackPanel>

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <MediaElement Name="mediaElement" 
                          Source="http://localhost/123.wmv"
                          AutoPlay="False"
                          MediaOpened="OnMediaElementMediaOpened"
                          MediaFailed="OnMediaElementMediaFailed"
                          CurrentStateChanged="OnMediaElementCurrentStateChanged"  />

            <TextBlock Name="statusText"
                       HorizontalAlignment="Left"
                       VerticalAlignment="Bottom" />

            <TextBlock Name="errorText"
                       HorizontalAlignment="Right"
                       VerticalAlignment="Bottom"
                       TextWrapping="Wrap" />
        </Grid>
    </Grid>

    <phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar>
            <shell:ApplicationBarIconButton 
                    x:Name="appbarRewindButton"
                    IconUri="Images/appbar.transport.rew.rest.png" 
                    Text="rewind"
                    IsEnabled="False"
                    Click="OnAppbarRewindClick" />

            <shell:ApplicationBarIconButton 
                    x:Name="appbarPlayButton"
                    IconUri="Images/appbar.transport.play.rest.png" 
                    Text="play"
                    IsEnabled="False"
                    Click="OnAppbarPlayClick" />

            <shell:ApplicationBarIconButton
                    x:Name="appbarPauseButton"
                    IconUri="Images/appbar.transport.pause.rest.png" 
                    Text="pause"
                    IsEnabled="False"
                    Click="OnAppbarPauseClick" />

            <shell:ApplicationBarIconButton
                    x:Name="appbarEndButton"
                    IconUri="Images/appbar.transport.ff.rest.png" 
                    Text="to end"
                    IsEnabled="False"
                    Click="OnAppbarEndClick" />
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>

using System;
using System.Windows;
using System.Windows.Media;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;

namespace MoviePlayer
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();

            // Re-assign names already in the XAML file
            appbarRewindButton = this.ApplicationBar.Buttons[0] as ApplicationBarIconButton;
            appbarPlayButton = this.ApplicationBar.Buttons[1] as ApplicationBarIconButton;
            appbarPauseButton = this.ApplicationBar.Buttons[2] as ApplicationBarIconButton;
            appbarEndButton = this.ApplicationBar.Buttons[3] as ApplicationBarIconButton;
        }

        // ApplicationBar buttons
        void OnAppbarRewindClick(object sender, EventArgs args)
        {
            mediaElement.Position = TimeSpan.Zero;
        }

        void OnAppbarPlayClick(object sender, EventArgs args)
        {
            mediaElement.Play();
        }

        void OnAppbarPauseClick(object sender, EventArgs args)
        {
            mediaElement.Pause();
        }

        void OnAppbarEndClick(object sender, EventArgs args)
        {
            mediaElement.Position = mediaElement.NaturalDuration.TimeSpan;
        }

        // MediaElement events
        void OnMediaElementMediaFailed(object sender, ExceptionRoutedEventArgs args)
        {
            errorText.Text = args.ErrorException.Message;
        }

        void OnMediaElementMediaOpened(object sender, RoutedEventArgs args)
        {
            appbarRewindButton.IsEnabled = true;
            appbarEndButton.IsEnabled = true;
        }

        void OnMediaElementCurrentStateChanged(object sender, RoutedEventArgs args)
        {
            statusText.Text = mediaElement.CurrentState.ToString();

            if (mediaElement.CurrentState == MediaElementState.Stopped ||
                mediaElement.CurrentState == MediaElementState.Paused)
            {
                appbarPlayButton.IsEnabled = true;
                appbarPauseButton.IsEnabled = false;
            }
            else if (mediaElement.CurrentState == MediaElementState.Playing)
            {
                appbarPlayButton.IsEnabled = false;
                appbarPauseButton.IsEnabled = true;
            }
        }
    }
}