constructor(player: PlayerCore) {

        // compatibility goal: minimum IE11

        this.player = player;

        // buttons box
        this._buttonsBox = document.getElementById('js-buttons-box');

        // slider (html5 input range)
        this._volumeSlider = document.getElementById('js-player-volume') as HTMLInputElement;

        // loading progress bar (html5 input range)
        this._loadingProgressBar = document.getElementById('js-player-loading-progress') as HTMLInputElement;

        // playing progress bar (html5 input range)
        this._playingProgressBar = document.getElementById('js-player-playing-progress') as HTMLInputElement;

        // start listening to events
        this._createListeners();

        // set the initial volume volume to the volume input range
        this._volumeSlider.value = String(this.player.getVolume());

    }

$(function () {

    let options: ICoreOptions = {
        soundsBaseUrl: 'https://mp3l.jamendo.com/?trackid=',
        playingProgressIntervalTime: 500
    };

    let player = new PlayerCore(options);
    let playerUI = new PlayerUI(player);

    let firstSoundAttributes: ISoundAttributes = {
        sources: '1314412&format=mp31',
        id: 1314412,
        playlistId: 0,
        onLoading: (loadingProgress, maximumValue, currentValue) => {
            console.log('loading: ', loadingProgress, maximumValue, currentValue);
            playerUI.setLoadingProgress(loadingProgress);
        },
        onPlaying: (playingProgress, maximumValue, currentValue) => {
            console.log('playing: ', playingProgress, maximumValue, currentValue);
            playerUI.setPlayingProgress(playingProgress);
        },
        onStarted: (playTimeOffset) => {
            console.log('started', playTimeOffset);
        },
        onPaused: (playTimeOffset) => {
            console.log('paused', playTimeOffset);
        },
        onStopped: (playTimeOffset) => {
            console.log('stopped', playTimeOffset);
        },
        onResumed: (playTimeOffset) => {
            console.log('resumed', playTimeOffset);
        },
        onEnded: (willPlayNext) => {
            console.log('ended', willPlayNext);
            if (!willPlayNext) {
                playerUI.switchPlayerContext('on');
            }
        }
    };

    // add the first song to queue
    let firstSound = player.addSoundToQueue(firstSoundAttributes);

    let secondSoundAttributes: ISoundAttributes = {
        sources: '1214935&format=ogg1',
        id: 1214935,
        playlistId: 0,
        onLoading: (loadingProgress, maximumValue, currentValue) => {
            console.log('loading: ', loadingProgress, maximumValue, currentValue);
            playerUI.setLoadingProgress(loadingProgress);
        },
        onPlaying: (playingProgress, maximumValue, currentValue) => {
            console.log('playing: ', playingProgress, maximumValue, currentValue);
            playerUI.setPlayingProgress(playingProgress);
        },
        onStarted: (playTimeOffset) => {
            console.log('started', playTimeOffset);
        },
        onPaused: (playTimeOffset) => {
            console.log('paused', playTimeOffset);
        },
        onStopped: (playTimeOffset) => {
            console.log('stopped', playTimeOffset);
        },
        onResumed: (playTimeOffset) => {
            console.log('resumed', playTimeOffset);
        },
        onEnded: (willPlayNext) => {
            console.log('ended', willPlayNext);
            if (!willPlayNext) {
                playerUI.switchPlayerContext('on');
            }
        }
    };

    // add another song
    let secondSound = player.addSoundToQueue(secondSoundAttributes);

    

    //let volume = 90;

    //player.setVolume(volume);

    // play first song in the queue
    //player.play();

    // play next song
    //player.play(player.PLAY_SOUND_NEXT);

    // TODO: use the sound to display the loading progress

    // TODO: add two sounds, then play the second one by passing it's id, queue should get rid of first song and immediatly play the second one

    // TODO: add a playlist of multiple songs at once, play some song (not the first one), again queue up until that song should get wiped, then play any previous song by id
    // but as queue won't know that song, we need to trigger some error
    // do this again but this time reset queue and repopulate it, then play the previous song
    // TODO: can we add some playlist support to avoid that the user manually needs to manage the queue? especially to avoid having to reset it when playing earlier song and then rebuild himself?
//.........这里部分代码省略.........

$(function () {

    let options: ICoreOptions = {
        soundsBaseUrl: 'https://mp3l.jamendo.com/?trackid=',
        playingProgressIntervalTime: 500,
        //volume: 80
    };
    
    let player = new PlayerCore(options);

    player.setVolume(80);

    let visualizerAudioGraph: any = {};

    player.getAudioContext().then((audioContext) => {

        let bufferInterval = 1024;
        let numberOfInputChannels = 1;
        let numberOfOutputChannels = 1;

        // create the audio graph
        visualizerAudioGraph.gainNode = audioContext.createGain();
        visualizerAudioGraph.delayNode = audioContext.createDelay(1);
        visualizerAudioGraph.scriptProcessorNode = audioContext.createScriptProcessor(bufferInterval, numberOfInputChannels, numberOfOutputChannels);
        visualizerAudioGraph.analyserNode = audioContext.createAnalyser();

        // analyser options
        visualizerAudioGraph.analyserNode.smoothingTimeConstant = 0.2;
        visualizerAudioGraph.analyserNode.minDecibels = -100;
        visualizerAudioGraph.analyserNode.maxDecibels = -33;
        visualizerAudioGraph.analyserNode.fftSize = 16384;
        //visualizerAudioGraph.analyserNode.fftSize = 2048;

        // connect the nodes
        visualizerAudioGraph.delayNode.connect(audioContext.destination);
        visualizerAudioGraph.scriptProcessorNode.connect(audioContext.destination);
        visualizerAudioGraph.analyserNode.connect(visualizerAudioGraph.scriptProcessorNode);
        visualizerAudioGraph.gainNode.connect(visualizerAudioGraph.delayNode);

        player.setAudioGraph(visualizerAudioGraph);

    });

    let isPlaying = false;

    // canvas painting loop
    function looper() {

        if (!isPlaying) {
            return;
        } 

        window.webkitRequestAnimationFrame(looper);

        // visualizer
        var initialArray = new Uint8Array(visualizerAudioGraph.analyserNode.frequencyBinCount);

        visualizerAudioGraph.analyserNode.getByteFrequencyData(initialArray);

        console.log(initialArray);

        //var binsArray = transformToVisualBins(initialArray);

        //console.log(binsArray);

        var VisualData = GetVisualBins(initialArray)
        var TransformedVisualData = transformToVisualBins(VisualData)

        console.log(TransformedVisualData);

        ctx.clearRect(0, 0, canvas.width, canvas.height); // Clear the canvas
        ctx.fillStyle = 'red'; // Color of the bars

        for (var y = 0; y < SpectrumBarCount; y++) {

            let bar_x = y * barWidth;
            let bar_width = barWidth;
            let bar_height = TransformedVisualData[y];

            //  fillRect( x, y, width, height ) // Explanation of the parameters below
            //ctx.fillRect(0, 0, canvas.width, canvas.height);
            ctx.fillRect(bar_x, (canvas.height / 2) - bar_height, bar_width, bar_height);

            ctx.fillRect(bar_x, canvas.height / 2, bar_width, bar_height);

        }

    }

    // initialize player ui
    let playerUI = new PlayerUI(player);

    // add songs to player queue
    let firstSoundAttributes: ISoundAttributes = {
        sources: '1314412&format=mp31',
        id: 1314412,
        //sources: '1214935&format=ogg1',
        //id: 1214935,
        playlistId: 0,
        onLoading: (loadingProgress, maximumValue, currentValue) => {
//.........这里部分代码省略.........

    player.getAudioContext().then((audioContext) => {

        let bufferInterval = 1024;
        let numberOfInputChannels = 1;
        let numberOfOutputChannels = 1;

        // create the audio graph
        visualizerAudioGraph.gainNode = audioContext.createGain();
        visualizerAudioGraph.delayNode = audioContext.createDelay(1);
        visualizerAudioGraph.scriptProcessorNode = audioContext.createScriptProcessor(bufferInterval, numberOfInputChannels, numberOfOutputChannels);
        visualizerAudioGraph.analyserNode = audioContext.createAnalyser();

        // analyser options
        visualizerAudioGraph.analyserNode.smoothingTimeConstant = 0.2;
        visualizerAudioGraph.analyserNode.minDecibels = -100;
        visualizerAudioGraph.analyserNode.maxDecibels = -33;
        visualizerAudioGraph.analyserNode.fftSize = 16384;
        //visualizerAudioGraph.analyserNode.fftSize = 2048;

        // connect the nodes
        visualizerAudioGraph.delayNode.connect(audioContext.destination);
        visualizerAudioGraph.scriptProcessorNode.connect(audioContext.destination);
        visualizerAudioGraph.analyserNode.connect(visualizerAudioGraph.scriptProcessorNode);
        visualizerAudioGraph.gainNode.connect(visualizerAudioGraph.delayNode);

        player.setAudioGraph(visualizerAudioGraph);

    });

    protected _onChangePlayingProgress(event: Event) {

        let rangeElement = event.target as HTMLInputElement;
        let value = parseInt(rangeElement.value);

        this.player.setPosition(value);

    }

    protected _onChangeVolume(event: Event) {

        // styling the html5 range:
        // http://brennaobrien.com/blog/2014/05/style-input-type-range-in-every-browser.html

        let rangeElement = event.target as HTMLInputElement;
        let value = parseInt(rangeElement.value);

        this.player.setVolume(value);

    }

    protected _onClickButtonsBox(event: Event) {

        event.preventDefault();

        let $button = event.target as HTMLElement;

        if ($button.localName === 'span') {
            $button = $button.parentElement;
        }

        if ($button.id === 'js-play-pause-button') {

            let playerContext = this._buttonsBox.dataset['playerContext'];

            switch (playerContext) {
                // is playing
                case 'on':
                    this.player.pause();
                    break;
                // is paused
                case 'off':
                    this.player.play();
                    break;
            }

            this.switchPlayerContext(playerContext);

        }

        if ($button.id === 'js-previous-button') {

            this.setPlayingProgress(0);

            let playerContext = this._buttonsBox.dataset['playerContext'];

            if (playerContext === 'off') {

                this.switchPlayerContext(playerContext);

            }

            this.player.play('previous');

        }

        if ($button.id === 'js-next-button') {

            this.setPlayingProgress(0);

            let playerContext = this._buttonsBox.dataset['playerContext'];

            if (playerContext === 'off') {

                this.switchPlayerContext(playerContext);

            }

            this.player.play('next');

        }

        if ($button.id === 'js-shuffle-button') {

            // TODO

        }

        if ($button.id === 'js-repeat-button') {

            // TODO

        }

    }