DrvEnableDriver function (winddi.h)

The DrvEnableDriver function is the initial driver entry point exported by the driver DLL. It fills in a DRVENABLEDATA structure with the driver's graphics DDI version number and the calling addresses of all graphics DDI functions supported by the driver.

Syntax

BOOL DrvEnableDriver(
       ULONG         iEngineVersion,
       ULONG         cj,
  [in] DRVENABLEDATA *pded
);

Parameters

iEngineVersion

Identifies the version of GDI that is currently running.

cj

Is the size in bytes of the structure pointed to by pded. If the structure is larger than expected, extra members should be left unmodified.

[in] pded

Pointer to a DRVENABLEDATA structure. GDI zero-initializes cj bytes before the call. The driver fills in its own data.

Return value

The return value is TRUE if the specified driver is enabled. Otherwise, it is FALSE, and an error code is logged.

Remarks

DrvEnableDriver must be implemented in all graphics drivers. If you use the Windows Driver Kit (WDK) build tools and have set TARGETTYPE to GDI_DRIVER (see Building a Printer Graphics DLL), this function must be named DrvEnableDriver. This is the only display driver function that must be accessed by name. All other display driver functions are accessed through function pointers; therefore, their names are presented in this documentation as pseudonames.

One-time initializations, such as allocating semaphores, can also be performed by this function. The driver should wait until DrvEnablePDEV is called before enabling hardware, such as a display.

When performing version checking using the value provided in iEngineVersion, the driver should use the appropriate DDI_DRIVER_VERSION_Xxx constant (defined in winddi.h) shown in the following table. Drivers should almost never check just for equality since new versions and service pack releases for the operating system will be released in the future. For more information, see DRVENABLEDATA.

Requirements

See also

DRVENABLEDATA

DRVFN

DrvDisableDriver

DrvEnablePDEV