This WaveFile manipulation control provides a basic interface for displaying and
editing wave files within a commercial audio-processing application. The app contains code
on displaying the graphical data, using button logic and rudimentary mouse input to
manipulate the waveform data. Thanks go to Ken C. Len’s Histogram
Control for providing much of the underlying control code.
In this sample I simply use random values to generate the waveform amplitude. In a
real-world application you would load/record a wave file and gain access to the individual
sound samples through the waveform audio or other low-level audio API. Mouse input is
still basic at this point but could be easily embellished to allow caret dragging across
portions of the waveform – for cut/copy/paste etc..
The header and implementation code for the CWaveEditCtrl class are in WaveEditCtrl.h
and WaveEditCtrl.cpp
How to use
In your dialog box, dialog derived, or CFromView MDI/SDI derived app – create a static
picture control. Give it a meaningful name and set its’ properties to Rectangle and give
it a Background color (sorry, we’re limited to Ford colors from the 1930’s here). Add the
.h and .cpp files to your project and #include the .h in your app’s header file.
Declare an object of type CWaveEditCtrl like so:
class CWaveEditorView : public CFormView
{
protected:
CWaveEditCtrl m_WaveEditCtrl;
...
};
and in your view’s OnInitialUpdate() function (this
will differ for dialog-based apps) add the following control creation code:
void CWaveEditorView::OnInitialUpdate()
{
CFormView::OnInitialUpdate();
CRect rect;
GetDlgItem(IDC_WAVE_EDIT)->GetWindowRect(rect);
ScreenToClient(rect);
m_WaveEditCtrl.Create(WS_VISIBLE | WS_CHILD, rect, this, 1000);
Don’t forget to add OnSetFocus() and OnKillFocus()
handlers to your view with the appropriate CWaveEditCtrl member function calls –
this will enable system-wide sharing of the caret resource.
Note – When using the CWaveEdit class within a Dialog-based
application I had some problems getting OnSetFocus() to respond. If anyone knows how to
fix this, please let me know.