windows 读取整个mp3文件 显示到带时间轴的波形显示控件代码

以下是一个使用NAudio库来读取MP3文件并在WinForms应用程序中显示波形的示例代码：

using NAudio.Wave;
using System;
using System.Drawing;
using System.Windows.Forms;

namespace WaveformViewer
{
    public partial class Form1 : Form
    {
        private WaveFileReader waveFileReader;
        private WaveOut waveOut;
        private Bitmap bitmap;
        private Graphics graphics;
        private int bytesPerSample = 2;
        private int samplesPerPixel = 128;
        private Pen pen = new Pen(Color.Green, 1);

        public Form1()
        {
            InitializeComponent();
        }

        private void openToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "MP3 Files (*.mp3)|*.mp3";
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                waveFileReader = new WaveFileReader(openFileDialog.FileName);
                waveOut = new WaveOut();
                waveOut.Init(waveFileReader);
                trackBar.Maximum = (int)waveFileReader.TotalTime.TotalSeconds;
                bitmap = new Bitmap(pictureBox.Width, pictureBox.Height);
                graphics = Graphics.FromImage(bitmap);
            }
        }

        private void playToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (waveOut != null)
            {
                waveOut.Play();
                timer.Start();
            }
        }

        private void pauseToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (waveOut != null)
            {
                waveOut.Pause();
                timer.Stop();
            }
        }

        private void stopToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (waveOut != null)
            {
                waveOut.Stop();
                timer.Stop();
                waveFileReader.Position = 0;
            }
        }

        private void timer_Tick(object sender, EventArgs e)
        {
            TimeSpan currentTime = waveOut.GetPositionTimeSpan();
            labelCurrentTime.Text = currentTime.ToString(@"mm\:ss");
            trackBar.Value = (int)currentTime.TotalSeconds;

            int bytesToRead = (int)(waveFileReader.WaveFormat.SampleRate * bytesPerSample * samplesPerPixel);
            byte[] waveData = new byte[bytesToRead];
            int bytesRead = waveFileReader.Read(waveData, 0, bytesToRead);
            if (bytesRead > 0)
            {
                DrawWaveform(waveData, bytesRead);
                pictureBox.Image = bitmap;
            }
        }

        private void DrawWaveform(byte[] waveData, int bytesRead)
        {
            int samples = bytesRead / bytesPerSample;
            int bytesPerPixel = bytesPerSample * samplesPerPixel;
            int pixels = bytesRead / bytesPerPixel;

            for (int i = 0; i < pixels; i++)
            {
                float max = 0;
                float min = 0;
                for (int j = 0; j < samplesPerPixel; j++)
                {
                    float sample = 0;
                    if (bytesPerSample == 2)
                    {
                        sample = BitConverter.ToInt16(waveData, i * bytesPerPixel + j * bytesPerSample) / 32768f;
                    }
                    else if (bytesPerSample == 4)
                    {
                        sample = BitConverter.ToInt32(waveData, i * bytesPerPixel + j * bytesPerSample) / 2147483648f;
                    }
                    if (sample > max)
                    {
                        max = sample;
                    }
                    else if (sample < min)
                    {
                        min = sample;
                    }
                }
                int x = i * samplesPerPixel;
                int y = (int)((1f - max) * pictureBox.Height / 2);
                int height = (int)((max - min) * pictureBox.Height / 2);
                graphics.DrawLine(pen, x, y, x, y + height);
            }
        }

        private void trackBar_ValueChanged(object sender, EventArgs e)
        {
            if (waveOut != null)
            {
                waveOut.Pause();
                waveFileReader.Position = trackBar.Value * waveFileReader.WaveFormat.SampleRate * bytesPerSample;
                waveOut.Play();
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (waveOut != null)
            {
                waveOut.Dispose();
            }
            if (waveFileReader != null)
            {
                waveFileReader.Dispose();
            }
            if (graphics != null)
            {
                graphics.Dispose();
            }
            if (bitmap != null)
            {
                bitmap.Dispose();
            }
        }
    }
}

这个应用程序包含一个菜单，用于打开、播放、暂停和停止MP3文件。它还包含一个带有时间轴的 `TrackBar` 控件，可以用来跳转到文件中的特定位置。当播放时，应用程序会定期从文件中读取一些数据，并将其显示为波形。`samplesPerPixel` 变量控制每个像素所表示的音频样本数，它越大，波形就越平滑。请注意，该示例代码仅适用于16位或32位PCM编码的音频文件，如果您要处理其他编码的文件，需要相应地修改代码。