The MM_ACM_FILTERCHOOSE message notifies an acmFilterChoose dialog box hook function before adding an element to one of the three drop-down list boxes. This message allows an application to further customize the selections available through the user interface.
MM_ACM_FILTERCHOOSE
wParam = (WPARAM) wDropDown
lParam = (LONG) lCustom
Returns TRUE if an application handles this message or FALSE otherwise.
If the application processes the FILTERCHOOSE_FILTER_ADD operation, the size of the memory buffer supplied in lParam will be determined from the acmMetrics function.
If the application processes a verify operation, the application must precede the return value with SetWindowLong(hwnd, DWL_MSGRESULT, (LONG) FALSE) to prevent the dialog box from listing this selection or with SetWindowLong(hwnd, DWL_MSGRESULT, (LONG)TRUE) to allow the dialog box to list this selection. If processing an add operation, the application must precede the return with SetWindowLong(hwnd, DWL_MSGRESULT, (LONG)FALSE) to indicate that no more additions are required or with SetWindowLong(hwnd, DWL_MSGRESULT, (LONG)TRUE) if more additions are required.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in msacm.h.
Audio Compression Manager Overview, Audio Compression Messages, acmFilterChoose, acmMetrics, SetWindowLong, WAVEFILTER