MM_ACM_FILTERCHOOSE

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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

Parameters

wDropDown

Drop-down list box being initialized and a verify or add operation.

FILTERCHOOSE_CUSTOM_VERIFY The lParam parameter is a pointer to a WAVEFILTER structure to be added to the custom Name drop-down list box.
FILTERCHOOSE_FILTER_ADD The lParam parameter is a pointer to a buffer that will accept a WAVEFILTER structure to be added to the Filter drop-down list box. The application must copy the filter structure to be added into this buffer.
FILTERCHOOSE_FILTER_VERIFY The lParam parameter is a pointer to a WAVEFILTER structure to be added to the Filter drop-down list box.
FILTERCHOOSE_FILTERTAG_ADD The lParam parameter is a pointer to a DWORD that will accept a waveform-audio filter tag to be added to the Filter Tag drop-down list box.
FILTERCHOOSE_FILTERTAG_VERIFY The lParam parameter is a waveform-audio filter tag to be listed in the Filter Tag drop-down list box.

lCustom

Value defined by the list box specified in the wParam parameter.

Return Values

Returns TRUE if an application handles this message or FALSE otherwise.

Remarks

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.

Requirements

**  Windows NT/2000/XP:** Included in Windows NT 3.1 and later.
**  Windows 95/98/Me:** Included in Windows 95 and later.
**  Header:** Declared in Msacm.h.

See Also

Audio Compression Manager, Audio Compression Messages, acmFilterChoose, acmMetrics, SetWindowLong, WAVEFILTER