PRB: WaveOutOpen()/WaveInOpen() Returns MMSYSERR_INVALPARAM (134405)
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) 3.1
- The Microsoft Foundation Classes (MFC), when used with:
This article was previously published under Q134405 SYMPTOMS
The WaveOutOpen() and WaveInOpen() functions return an MMSYSERR_INVALPARAM
error when using a window handle as a callback mechanism.
CAUSE
The documentation for the WaveOutOpen() and WaveInOpen() functions
specifies that the data type of the dwCallback parameter should be a DWORD.
However, when the symbol STRICT is defined (using #define), HWND is no
longer equated to UINT. Instead, it is a NEAR pointer. Therefore, simply
casting a window handle to a DWORD fails when STRICT is defined. The
following code illustrates the statement causing this error:
WaveOutOpen(..., (DWORD) hWnd, ..., CALLBACK_WINDOW)
RESOLUTION
A simple workaround is to cast a window handle to UINT before casting
it to a DWORD. For example:
WaveOutOpen(..., (DWORD) (UINT) hWnd, ...)
MORE INFORMATION
STRICT is a macro which enhances type safety for Windows 3.1 applications.
If it is defined, several data types become distinct. For instance, HDC and
HWND become different types when STRICT is defined.
By default, Microsoft Foundation Classes (MFC) versions 2.0 and above use
STRICT type checking. As a result, the problem described in this article
usually occurs in MFC-based applications. In addition, this error occurs in
any API call where a window handle is cast to a DWORD (32-bits). Please
note that this article only applies to 16-bit applications.
| Modification Type: | Major | Last Reviewed: | 4/9/2004 |
|---|
| Keywords: | kbprb KB134405 |
|---|
|