using System;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        //
        // declar NAudio variavle
        //
        private NAudio.Wave.BlockAlignReductionStream stream = null;//cause mp3 file
        private NAudio.Wave.DirectSoundOut output = null;

        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private void read_button_Click(object sender, EventArgs e)
        {
            // read audio file (.mp3)
            OpenFileDialog open = new OpenFileDialog();
            open.Filter = "MP3 file (*.mp3)|*.mp3";
            if (open.ShowDialog() != DialogResult.OK)
            {
                return;
            }
            DisposeWave();
            // use pcm data to restore mp3 file (because NAudio has no mp3 format code)
            NAudio.Wave.WaveStream pcm = NAudio.Wave.WaveFormatConversionStream.CreatePcmStream(new NAudio.Wave.Mp3FileReader(open.FileName));
            stream = new NAudio.Wave.BlockAlignReductionStream(pcm);
            output = new NAudio.Wave.DirectSoundOut();
            // because the stream file is not a IWave file , so need to make a covertion
            output.Init(stream);
            output.Play();
            // when music is playing ,the button can be clicked .
            pause_button.Enabled = true;
        }
        //
        // pause button
        //
        private void pause_button_Click(object sender, EventArgs e)
        {
            if(output != null)
            {
                //when music is plauing , then pause it.
                if(output.PlaybackState == NAudio.Wave.PlaybackState.Playing)
                {
                    output.Pause();
                }
                // when music is paused , then play it .
                else if(output.PlaybackState == NAudio.Wave.PlaybackState.Paused)
                {
                    output.Play();
                }
            }
        }
        private void DisposeWave()
        {
            if (output != null)
            {
                if (output.PlaybackState == NAudio.Wave.PlaybackState.Paused)
                {
                    output.Stop();
                }
                output.Dispose();
                output = null;
            }
            if (stream != null)
            {
                stream.Dispose();
                stream = null;
            }
        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            DisposeWave();
        }

    }
}