WM_PENEVENT Submessages

The following submessages of WM_PENEVENT require different treatment in 32-bit applications:

PE_BEGININPUT

PE_BUFFERWARNING

PE_PENDOWN

PE_PENMOVE

PE_PENUP

PE_TERMINATED

PE_TERMINATING

In 16-bit applications, these submessages store different values in the high-order and low-order words of their lParam:

• wParam = PE_ submessage number

• LOWORD( lParam ) = event reference or termination code

• HIWORD( lParam ) = HPCM handle

This scheme is not possible in Win32-based applications because lParam must contain a single 32-bit handle; therefore, the parameters for the submessages listed above are arranged differently in the 32-bit Pen API:

• LOWORD( wParam ) = PE_ submessage number

• HIWORD( wParam ) = event reference or termination code

• lParam = HPCM handle

To extract data from the parameters, use the following macros defined in the PENWIN.H header file. These macros render the differences in the parameters transparent to an application because they automatically adjust for 16-bit or 32-bit type of programs:

Macro	Description
HpcmFromWpLp	Retrieves HPCM handle returned from StartPenInput. If the application calls DoDefaultPenInput, that function calls StartPenInput internally.
EventRefFromWpLp	Retrieves event reference value for session returned from GetMessageExtraInfo. Both DoDefaultPenInput and StartPenInput take this value as their second argument.
TerminationFromWpLp	Retrieves a PCM_ value indicating the reason for termination from the PE_TERMINATED and PE_TERMINATING submessages.
SubPenMsgFromWpLp	Retrieves PE_ submessage value.

The macros take both wParam and lParam as arguments and automatically return the desired value for both 16-bit and 32-bit applications. For example:

HPCM hpcm; // HPCM handle created by StartPenInput

LONG lInfo; // Return value from GetMessageExtraInfo

int iRet; // Error code

.

.

.

case WM_LBUTTONDOWN:

lInfo = GetMessageExtraInfo( );

if (IsPenEvent( msg, lInfo ))

{

iRet = DoDefaultPenInput( hwnd, LOWORD(lInfo) );

}

.

.

.

case WM_PENEVENT:

switch( SubPenMsgFromWpLp( wParam ) );

{

case PE_PENDOWN:

hpcm = HpcmFromWpLp( wParam, lParam );

//

// Note lInfo and EventRefFromWpLp( wParam, lParam )

// contain the same event reference value.

//

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