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EngMapEvent function (winddi.h)

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The EngMapEvent function maps a user-mode event object to kernel mode.

Syntax

ENGAPI PEVENT EngMapEvent(
  [in] HDEV   hDev,
  [in] HANDLE hUserObject,
       PVOID  Reserved1,
       PVOID  Reserved2,
       PVOID  Reserved3
);

Parameters

[in] hDev

Handle to the physical device associated with the event. This is the GDI handle passed as the hdev parameter to the driver's DrvCompletePDEV function.

[in] hUserObject

Handle to the user-mode event to be mapped.

Reserved1

Is reserved for system use, and must be set to NULL.

Reserved2

Is reserved for system use, and must be set to NULL.

Reserved3

Is reserved for system use, and must be set to NULL.

Return value

EngMapEvent returns a pointer to an event object on success. Otherwise, it returns NULL.

Remarks

After successfully mapping the user event, EngMapEvent automatically sets the event object to the signaled state, attempts to satisfy as many waits as possible, and then resets the event object to the nonsignaled state.

A mapped event provides a mechanism by which an application can wait for a kernel-mode graphics operation to complete. The display driver or video miniport driver signals the application when it is done using the resource for which the event was mapped, thus freeing the application to use the resource.

Display and miniport drivers cannot wait for mapped events, but can set or clear them.

The driver can also perform its own cleanup by calling EngUnmapEvent on the event object returned by EngMapEvent.

Requirements

Requirement Value
Minimum supported client This function is available in Windows XP and later.
Target Platform Universal
Header winddi.h (include Winddi.h)
Library Win32k.lib
DLL Win32k.sys

See also

DrvCompletePDEV

EngUnmapEvent