DrvDocumentEvent function (winddiui.h)
A printer interface DLL's DrvDocumentEvent function can handle certain events associated with printing a document.
Syntax
int DrvDocumentEvent(
HANDLE hPrinter,
HDC hdc,
int iEsc,
ULONG cbIn,
[in] PVOID pvIn,
ULONG cbOut,
[out] PVOID pvOut
);
Parameters
hPrinter
Caller-supplied printer handle.
hdc
Caller-supplied device context handle, generated by a CreateDC This is zero if iEsc is set to DOCUMENTEVENT_CREATEDCPRE. For restrictions on printing from a 32-bit application on a 64-bit version of Windows, see the Remarks section below.
iEsc
Caller-supplied escape code identifying the event to be handled.
For restrictions on printing from a 32-bit application on a 64-bit version of Windows, see the Remarks section below.
This parameter can be one of the following integer constants:
| iEsc constant | Event |
|---|---|
| DOCUMENTEVENT_ABORTDOC | GDI is about to process a call to its AbortDoc function. |
| DOCUMENTEVENT_CREATEDCPOST | GDI has just processed a call to its CreateDC or CreateIC function. This escape code should not be used unless there has been a previous call to DrvDocumentEvent with iEsc set to DOCUMENTEVENT_CREATEDCPRE. |
| DOCUMENTEVENT_CREATEDCPRE | GDI is about to process a call to its CreateDC or CreateIC function. |
| DOCUMENTEVENT_DELETEDC | GDI is about to process a call to its DeleteDC function. |
| DOCUMENTEVENT_ENDDOCPOST | GDI has just processed a call to its EndDoc function. |
| DOCUMENTEVENT_ENDDOCPRE or DOCUMENTEVENT_ENDDOC | GDI is about to process a call to its EndDoc function. |
| DOCUMENTEVENT_ENDPAGE | GDI is about to process a call to its EndPage function. |
| DOCUMENTEVENT_ESCAPE | GDI is about to process a call to its ExtEscape function. |
| DOCUMENTEVENT_QUERYFILTER | The DOCUMENTEVENT_QUERYFILTER event represents an opportunity for the spooler to query the driver for a list of the DOCUMENTEVENT_XXX events to which the driver will respond. This event is issued just prior to a call to DrvDocumentEvent that passes the DOCUMENTEVENT_CREATEDCPRE event. |
| DOCUMENTEVENT_RESETDCPOST | GDI has just processed a call to its ResetDC function. This escape code should not be used unless there has been a previous call to DrvDocumentEvent with iEsc set to DOCUMENTEVENT_RESETDCPRE. |
| DOCUMENTEVENT_RESETDCPRE | GDI is about to process a call to its ResetDC function. |
| DOCUMENTEVENT_STARTDOCPOST | GDI has just processed a call to its StartDoc function. |
| DOCUMENTEVENT_STARTDOCPRE or DOCUMENTEVENT_STARTDOC | GDI is about to process a call to its StartDoc function. |
| DOCUMENTEVENT_STARTPAGE | GDI is about to process a call to its StartPage function. |
cbIn
Caller-supplied size, in bytes, of the buffer pointed to by pvIn.
[in] pvIn
Caller-supplied pointer, the use of which is dependent on the value supplied for iEsc, as follows:
| iEsc constant | pvIn contents |
|---|---|
| DOCUMENTEVENT_ABORTDOC | Not used. |
| DOCUMENTEVENT_CREATEDCPOST | pvIn contains the address of a pointer to the DEVMODEW structure specified in the pvOut parameter in a previous call to this function, for which the iEsc parameter was set to DOCUMENTEVENT_CREATEDCPRE. |
| DOCUMENTEVENT_CREATEDCPRE | pvIn points to a DOCEVENT_CREATEDCPRE structure. |
| DOCUMENTEVENT_DELETEDC | Not used. |
| DOCUMENTEVENT_ENDDOCPOST | Not used. |
| DOCUMENTEVENT_ENDDOCPRE or DOCUMENTEVENT_ENDDOC | Not used. |
| DOCUMENTEVENT_ENDPAGE | Not used. |
| DOCUMENTEVENT_ESCAPE | pvIn points to a DOCEVENT_ESCAPE structure. |
| DOCUMENTEVENT_QUERYFILTER | Same as for DOCUMENTEVENT_CREATEDCPRE. |
| DOCUMENTEVENT_RESETDCPOST | pvIn contains the address of a pointer to the DEVMODEW structure specified in the pvOut parameter in a previous call to this function, for which the iEsc parameter was set to DOCUMENTEVENT_RESETDCPRE. |
| DOCUMENTEVENT_RESETDCPRE | pvIn contains the address of a pointer to the DEVMODEW structure supplied by the caller of the ResetDC function. |
| DOCUMENTEVENT_STARTDOCPOST | pvIn points to a LONG that specifies the print job identifier returned by the StartDoc function. |
| DOCUMENTEVENT_STARTDOCPRE or DOCUMENTEVENT_STARTDOC | pvIn contains the address of a pointer to a DOCINFO structure supplied by the caller of the StartDoc function. |
| DOCUMENTEVENT_STARTPAGE | Not used. |
cbOut
If iEsc is DOCUMENTEVENT_ESCAPE
Function-supplied value that is used as the cbOutput parameter for the ExtEscape function.
If iEsc is DOCUMENTEVENT_QUERYFILTER
Caller-supplied size, in bytes, of the buffer pointer to by pvOut.
For all other iEsc values
Not used.
[out] pvOut
Function-supplied pointer to an output buffer, the use of which is dependent on the value supplied for iEsc, as follows:
| iEsc constant | pvOut contents |
|---|---|
| DOCUMENTEVENT_CREATEDCPRE | Pointer to a driver-supplied DEVMODEW structure, which GDI uses instead of the one supplied by the CreateDC caller. (If NULL, GDI uses the caller-supplied structure.) |
| DOCUMENTEVENT_ESCAPE | Buffer pointer that is used as the lpszOutData parameter for the ExtEscape function. |
| DOCUMENTEVENT_QUERYFILTER | Caller-supplied pointer to buffer containing a DOCEVENT_FILTER structure. |
| DOCUMENTEVENT_RESETDCPRE | Pointer to a driver-supplied DEVMODEW structure, which GDI uses instead of the one supplied by the ResetDC function caller. (If NULL, GDI uses the caller-supplied structure.) |
| All other iEsc values | Not used. |
Return value
The function's return value is dependent on the escape supplied for iEsc. For some escape codes, the return value is not used (see the second list of values). If the function supplies a return value, it must be one of the following:
| Return code | Description |
|---|---|
| DOCUMENTEVENT_FAILURE | The driver supports the escape code identified by iEsc, but a failure occurred. |
| DOCUMENTEVENT_SUCCESS | The driver successfully handled the escape code identified by iEsc. |
| DOCUMENTEVENT_UNSUPPORTED | The driver does not support the escape code identified by iEsc. |
Remarks
A printer interface DLL can optionally provide a DrvDocumentEvent function to perform preprocessing or postprocessing of GDI calls associated with rendering a document. Calls to the DrvDocumentEvent function are made from the user-mode GDI client, when an application makes calls into the GDI client.
For an iEsc value of DOCUMENTEVENT_QUERYFILTER, the spooler can interpret a DOCUMENTEVENT_SUCCESS value returned by DrvDocumentEvent in two ways, depending on whether the driver modified certain members of the DOCEVENT_FILTER structure. (The pvOut parameter points to this structure.) When the spooler allocates memory for a structure of this type, it initializes two members of this structure, cElementsReturned and cElementsNeeded, to known values. After DrvDocumentEvent returns, the spooler determines whether the values of these members have changed, and uses that information to interpret the DrvDocumentEvent return value. The following table summarizes this situation.
| Return value | Status of cElementsReturned, cElementsNeeded | Meaning |
|---|---|---|
| DOCUMENTEVENT_SUCCESS | Driver made no change to either member. | The spooler interprets this return value as equivalent to DOCUMENTEVENT_UNSUPPORTED. The spooler is unable to retrieve the event filter from the driver, so it persists in calling DrvDocumentEvent for all events. |
| DOCUMENTEVENT_SUCCESS | Driver wrote to one or both members. | The spooler accepts this return value without interpretation. If the driver wrote to only one of cElementsNeeded and cElementsReturned, the spooler considers the unchanged member to have a value of zero. The spooler filters out all events listed in the aDocEventCall member of DOCEVENT_FILTER. |
| DOCUMENTEVENT_UNSUPPORTED | Not applicable | The driver does not support DOCUMENTEVENT_QUERYFILTER. The spooler is unable to retrieve the event filter from the driver, so it persists in calling DrvDocumentEvent for all events. |
| DOCUMENTEVENT_FAILURE | Not applicable | The driver supports DOCUMENTEVENT_QUERYFILTER, but encountered an internal error. The spooler is unable to retrieve the event filter from the driver, so it persists in calling DrvDocumentEvent for all events. |
If the escape code name has no suffix or is suffixed with PRE, the GDI client calls DrvDocumentEvent just prior to calling the kernel-mode GDI rendering engine. If the escape code name is suffixed with POST, the GDI client calls DrvDocumentEvent just after the kernel-mode GDI rendering engine returns.
If the escape code supplied in the iEsc parameter is DOCUMENTEVENT_CREATEDCPRE, the following rules apply:
If the job is being sent directly to the printer without spooling, pvIn --> pszDevice points to the printer name. (See the DOCEVENT_CREATEDCPRE structure for more information.)
If the job is being spooled, pvIn --> pszDevice points to the printer port name.
The DrvDocumentEvent function executes in the context of the user-mode caller of the GDI client function. When EMF spooling is disabled, the function can display a user interface. For example, the DrvDocumentEvent function for a FAX driver might display a dialog box to the user before GDI's StartDoc function is processed.
The following restrictions apply when running a 32-bit application on a 64-bit version of Windows:
The only GDI function that DrvDocumentEvent should call is ExtEscape, and only private escapes should be used.
DrvDocumentEvent calls to other GDI functions may produce undefined behavior.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | winddiui.h (include Winddiui.h) |