MMIO Functions - MMIO Messages

The MMIO messages are sent to an I/O procedure as a result of an MMIO function call. For example, when an application calls mmioOpen, the MMIOM_OPEN message is sent to an I/O procedure. An application can also send the MMIO messages to an I/O procedure by issuing mmioSendMessage or by directly calling the I/O procedure.

The mmioSendMessage function should be used only to pass user-defined messages, or messages not automatically generated by an MMIO function, to the I/O procedure of the user's application.

When an application issues mmioSendMessage, it passes an hmmio parameter, which MMIO converts to an MMIOINFO block before sending the parameter to the I/O procedure. When an application calls an I/O procedure directly, a pmmioinfo parameter is passed to the I/O procedure instead of an hmmio. The following is a function prototype for a direct I/O procedure call:

LONG APIENTRY MMIOPROC (PVOID pmmioinfo, USHORT usMsg, LONG lParam1, LONG lParam2);

Message	Description
MMIOM_BEGININSERT	Requests that all subsequent Writes insert data at the current seek position.
MMIOM_BEGINRECORD	Requests all subsequent Writes be considered one logical unit by an UNDO or REDO.
MMIOM_BEGINSTREAM	Sent before the first mmioRead or mmioWrite to start the stream at the optimum rate for the file.
MMIOM_CLEAR	Requests that a specified range be deleted from a file.
MMIOM_CLOSE	Requests that the file be closed.
MMIOM_COPY	Requests that a specified range be copied to the clipboard.
MMIOM_CUT	Requests that a specified range be copied to the clipboard and then deleted.
MMIOM_ENDSTREAM	Sent after the last mmioRead or mmioWrite to end the stream.
MMIOM_DELETE	Requests that information be removed from a file.
MMIOM_ENDINSERT	Requests that all subsequent Writes overwrite data at the current seek position.
MMIOM_ENDRECORD	Indicates that the logical record operation has ended and data structures should be updated, if necessary.
MMIOM_GETCF	Obtains the handle (hmmcf) of the RIFF compound file.
MMIOM_GETCFENTRY	Requests a CTOC entry for an element of a RIFF compound file.
MMIOM_GETFORMATINFO	Requests that the IOProc return an MMFORMATINFO structure.
MMIOM_GETFORMATNAME	Requests the format name for the IOProc.
MMIOM_GETHEADER	Requests that the IOProc return media-specific information.
MMIOM_IDENTIFYFILE	Attempts to determine if any IOProc can process a file.
MMIOM_MULTITRACKREAD	Requests that data be read from a movie file.
MMIOM_MULTITRACKWRITE	Requests that data be written to a movie file.
MMIOM_OPEN	Requests that a file be opened or deleted.
MMIOM_PASTE	Requests that data from the clipboard be inserted into a file.
MMIOM_QUERYHEADERLENGTH	Requests that the IOProc return the size the header.
MMIOM_QUERYIMAGE	Requests that the IOProc return the currently selected image index in the image file.
MMIOM_QUERYIMAGECOUNT	Requests that the IOProc return the number of images stored in the image file.
MMIOM_READ	Requests that bytes be read from an open file.
MMIOM_REDO	Requests that the last logical action which was undone be redone.
MMIOM_SAVE	Requests temporary changes in a file.
MMIOM_SEEK	Requests that the current file position be moved.
MMIOM_SEEKBYTIME	Requests that the file position be moved relative to some unit of time.
MMIOM_SET	Requests that extended file information be set or queried.
MMIOM_SETHEADER	Requests that the IOProc use media-specific information when writing or accepting data.
MMIOM_SETIMAGE	Selects a new image index in the image file.
MMIOM_STATUS	Used to pass appropriate MCI_STATUS requests to an IOProc.
MMIOM_TEMPCHANGE	Requests that all subsequent Writes to the media be treated as temporary changes.
MMIOM_UNDO	Requests that the last logical action, either a delete, insert, undo, or redo, be undone.
MMIOM_WINMSG	Allows an application or an MCD to pass PM messages from a window procedure to an IOProc.
MMIOM_WRITE	Requests that the bytes be written to an open file.

The MMIO messages indicate, to the I/O procedure, the type of MMIO operation to be performed. I/O procedures can be called to process files that might or might not use the RIFF format standard.

Note

The compound-file messages must not be used while creating or appending to the compound file itself.