ShowWaveForm'�A C# Implementation of CWaveForm

Environment: VS.NET

Introduction

ShowWaveForm is based from a C++ class, called CWaveFile, written by Alexander Beletsky. This is a port to C#, with some added features. A small .wav file is included in the demo project .zip file for testing.

WaveFile.cs

WaveFile.cs is the main class. It reads and parses the WAV file headers. When passed a PaintEventArgs (typically from an OnPaint() event), it will draw the waveform. The class also allows for zooming in/out on the waveform.

Usage

Using the class is very simple. Here is the sample project file open menu handler:

private void fileOpen_Click(object sender, System.EventArgs e)
{
  OpenFileDialog fileDlg = new OpenFileDialog();

  if ( fileDlg.ShowDialog() == DialogResult.OK )
  {
    wave = new WaveFile( fileDlg.FileName );

    sbpMainPanel.Text = "Reading .WAV file...";

    wave.Read( );

    sbpMainPanel.Text = "Finished Reading .WAV file...";

    m_DrawWave = true;

    Refresh( );

  }
}

And here is the Paint handler of the demo project:

private void Form1_Paint( object sender,
                          System.Windows.Forms.PaintEventArgs e)
{
  Pen pen = new Pen( ForeColor );

  if ( m_DrawWave )
  {
    sbpMainPanel.Text = "Drawing .WAV file...";

    wave.Draw( e, pen );

    sbpMainPanel.Text = "Finished drawing .WAV file...";
  }
}

The last interesting thing in the demo project is the MouseWheel handler, which controls zooming of the waveform:

protected override void OnMouseWheel( MouseEventArgs mea )
{
  if ( mea.Delta * SystemInformation.MouseWheelScrollLines /
                   120 > 0 )
    wave.ZoomIn( );
  else
    wave.ZoomOut( );

  Refresh( );

}

Questions/Discussion

This is my first attempt at programming in C#/.NET. So, please comment on everything in this code! Specifically, I have questions about the following:

  • Drawing the waveform is very slow for large files, perhaps because of using PageScale?
  • How to catch some of the errors that can occur in zooming in/out too far
  • Drawing of stereo waveforms

Downloads

Download demo project - 11 Kb
Download source - 2 Kb


Comments

  • Works on Linux too :)

    Posted by t3rmin4t0r on 06/09/2004 08:52am

    It works - though I think the color handling was ugly (read that as I hate white bgs :) http://demo.dotgnu.org/~t3rmin4t0r/waveform.png No changes except color .. if you look at the terminal , you'll see the compile command too. Anyway nice portable code :)

    Reply
  • Because it's your first attempt, it's very good.

    Posted by Wosiu on 04/13/2004 01:26pm

    Otherwise it would be Average. Thank you very much this is exactly what I was looking for. I'm currently analyzing your code to write something more advanced as my university project ;) thx

    Reply
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