A client-application sends the ICM_SET_STATUS_PROC message if it wants to receive notification messages about the progress of compression or decompression. When received, drivers should periodically send notification messages to the callback function specified with the message during compression or decompression. Support of this callback function is optional but highly recommended if compression or decompression takes longer than approximately one tenth of one second. The callback function prototype statement follows:
LONG MyStatusProc(LPARAM lParam, UINT message)
The lParam parameter specifies the constant specified in the lParam member of the ICSETSTATUSPROC structure.The message parameter specifies one of the following messages the driver sends:
| Message | Description |
|---|---|
| ICSTATUS_START | Indicates the operation is starting. |
| ICSTATUS_STATUS | Indicates the operation is proceeding, and is l percent done. |
| ICSTATUS_END | Indicates the operation is finishing. |
| ICSTATUS_YIELD | Indicates a length operation is proceeding. |