wp7音乐播放器

前台代码：

    <!--layoutroot 是包含所有页面内容的根网格-->
    <grid x:name="layoutroot" background="transparent">
        <grid.rowdefinitions>
            <rowdefinition height="auto"/>
            <rowdefinition height="*"/>
        </grid.rowdefinitions>

        <!--titlepanel 包含应用程序的名称和页标题-->
        <stackpanel x:name="titlepanel" grid.row="0" margin="12,17,0,28">
            <textblock fontsize="25" x:name="applicationtitle" text="我的应用程序" style="{staticresource phonetextnormalstyle}"/>
            <textblock fontsize="60" x:name="pagetitle" text="播放mediaplayer" margin="9,-7,0,0" style="{staticresource phonetexttitle1style}" width="486" />
        </stackpanel>

        <!--contentpanel - 在此处放置其他内容-->
        <grid x:name="contentpanel" grid.row="1" margin="12,0,12,0">
            <image height="216" horizontalalignment="left" margin="35,48,0,0" name="cover" stretch="fill" verticalalignment="top" width="401" />
            <textbox height="72" horizontalalignment="left" margin="1,298,0,0" name="songname" text="" verticalalignment="top" width="460" />
            <button content="播放" height="72" horizontalalignment="left" margin="6,409,0,0" name="btn_play_music" verticalalignment="top" width="444" click="btn_play_music_click_1" />
            <button content="停止" height="72" horizontalalignment="left" margin="12,503,0,0" name="btn_stop" verticalalignment="top" width="438" click="btn_stop_click_1" />

        </grid>
    </grid>

 

后台代码：

 

namespace yinyuebofangqi
{
    public partial class mainpage : phoneapplicationpage
    {
        #region 成员声明
        song _playsong; //声明一个song 类型的变量
        bool _historyitemlaunch;
        const string _playsongkey = "playsong";
        #endregion

        // constructor
        public mainpage()
        {
            initializecomponent();
            _playsong = null;
            _historyitemlaunch = false;

            //声明一个timer 使用线程运行 xna internals 来自于微软xna框架
            dispatchertimer dt = new dispatchertimer();
            dt.interval = timespan.frommilliseconds(33);
            //使用委托调用逐帧调用  frameworkdispatcher.update();
            dt.tick += delegate
            {
                try
                {
                    // 这个函数作用是更新各种xna状态，并触发相应的事件,这个是必须的，否则会报异常
                    frameworkdispatcher.update();

                }
                catch
                {

                    throw;
                }
            };
            dt.start();

            mediaplayer.mediastatechanged += new eventhandler<eventargs>(mediaplayer_mediastatechanged);

        }

        /// <summary>
        /// 当页面进入时调用
        /// </summary>
        /// <param name="e"></param>
        protected override void onnavigatedto(system.windows.navigation.navigationeventargs e)
        {
            medialibrary library = new medialibrary();
            if (navigationcontext.querystring.containskey(_playsongkey))
            {
                string songtoplay = navigationcontext.querystring[_playsongkey];
                foreach (song song in library.songs)
                {
                    if (0 == string.compare(songtoplay, song.name))
                    {
                        _playsong = song;
                    }
                }
                _historyitemlaunch = true;
            }
            else if (mediaplayer.state == mediastate.playing)
            {
                _playsong = mediaplayer.queue.activesong;
            }
            else
            {
                random rd = new random();
                if (library.songs.count > 0)
                {
                    _playsong = library.songs[rd.next(library.songs.count)];
                }
                else
                {
                    songname.text = "no songs in library";
                    btn_play_music.isenabled = false;
                }
            }

            base.onnavigatedto(e);
        }

        void mediaplayer_mediastatechanged(object sender, eventargs e)
        {
            switch (mediaplayer.state)
            {

                case mediastate.playing:
                    btn_play_music.isenabled = false;
                    btn_stop.isenabled = true;
                    break;
                case mediastate.paused:
                case mediastate.stopped:
                    btn_play_music.isenabled = true;
                    btn_stop.isenabled = false;
                    break;
            }
        }

        /// <summary>
        /// 为主窗体添加ui加载完成后的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void phoneapplicationpage_loaded(object sender, routedeventargs e)
        {
            populatesongmetadata();
            setinitialbuttonstate();
            if (_historyitemlaunch)
            {
                playsong();
            }
        }

        /// <summary>
        /// 开始播放音乐
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        //private void btn_play_music_click(object sender, routedeventargs e)
        //{
        //    playsong();
        //}

        ///// <summary>
        ///// 停止播放音乐
        ///// </summary>
        ///// <param name="sender"></param>
        ///// <param name="e"></param>
        //private void btn_stop_click(object sender, routedeventargs e)
        //{
        //    stopsong();
        //}

        /// <summary>
        /// 播放
        /// </summary>
        private void playsong()
        {
            if (_playsong != null)
            {
                mediaplayer.play(_playsong);
            }
        }
        /// <summary>
        /// 停止
        /// </summary>
        private void stopsong()
        {
            if (mediastate.playing == mediaplayer.state)
            {
                mediaplayer.stop();
            }
        }

        /// <summary>
        /// 使用图片读取图片封面
        /// </summary>
        private void populatesongmetadata()
        {
            if (_playsong != null)
            {
                songname.text = _playsong.name;
                stream albumartstream = _playsong.album.getalbumart();
                if (albumartstream == null)
                {
                    streamresourceinfo albumartplaceholder = application.getresourcestream(new uri("applicationicon.png", urikind.relative));
                    albumartstream = albumartplaceholder.stream;
                }
                bitmapimage albumartimage = new bitmapimage();
                albumartimage.setsource(albumartstream);
                cover.source = albumartimage;
            }
        }

        /// <summary>
        /// 初始化按钮
        /// </summary>
        private void setinitialbuttonstate()
        {
            switch (mediaplayer.state)
            {

                case mediastate.playing:
                    btn_play_music.isenabled = false;
                    btn_stop.isenabled = true;
                    break;
                case mediastate.paused:
                case mediastate.stopped:
                    btn_play_music.isenabled = true;
                    btn_stop.isenabled = false;
                    break;
            }
        }

        private void btn_play_music_click_1(object sender, routedeventargs e)
        {
            playsong();
        }

        private void btn_stop_click_1(object sender, routedeventargs e)
        {
            stopsong();
        }

 

    }
}