OEMCUIPCALLBACK callback function (printoem.h)

Artikel
08/19/2022

The OEMCUIPCALLBACK function type is used for defining callback functions that are specified by a user interface plug-in's IPrintOemUI::CommonUIProp method. The structure is defined in printoem.h.

Syntax

OEMCUIPCALLBACK Oemcuipcallback;

LONG Oemcuipcallback(
  PCPSUICBPARAM unnamedParam1,
  POEMCUIPPARAM unnamedParam2
)
{...}

Parameters

unnamedParam1

Pointer to a CPSUICBPARAM structure.

unnamedParam2

Pointer to an OEMCUIPPARAM structure.

Return value

See the following Remarks section.

Remarks

A callback function specified by an IPrintOemUI::CommonUIProp method is called when a user modifies a printer property sheet. The callback function's purpose is to process user modifications to customized option items.

When a property sheet item is modified, CPSUI calls the printer driver's printer interface DLL. This DLL contains its own callback function, of type _CPSUICALLBACK, which processes option values contained in its own OPTITEM structures. Then the printer interface DLL's callback function calls the user interface plug-in's callback function. If multiple user interface plug-ins are provided, each plug-in's callback function is called, in turn, in the order in which the plug-ins were installed.

The callback function receives a pointer to a CPSUICBPARAM structure. The structure's Reason member identifies the event that caused the callback function to be called. The function also receives a pointer to the same OEMCUIPPARAM structure that was used when the IPrintOemUI::CommonUIProp method specified the callback function's address.

The CPSUICBPARAM structure's pOptItem and pCurItem members identify the modified option. The callback function can use these pointers, along with the pOEMOptItems and cOEMOptItem members of the OEMCUIPPARAM structure, to determine if the modified option is one that is owned by the user interface plug-in.

When a callback function is called, it must determine if any of its customized OPTITEM structures are affected by the specified Reason value. If they are, the function should process the affected options and return one of the CPSUI_ACTION-prefixed return values described for the _CPSUICALLBACK function type. Otherwise it should return CPSUICB_ACTION_NONE.

The following additional rules apply to callback function return values:

If Reason contains CPSUICB_REASON_APPLYNOW, then the callback must return either CPSUICB_ACTION_ITEMS_APPLIED or CPSUICB_ACTION_NO_APPLY_EXIT. In the latter case, the printer driver interface immediately returns to CPSUI without calling any other user interface plug-in's callback function.
If Reason contains any value except CPSUICB_REASON_APPLYNOW, then the return value must be one of the following:
- CPSUICB_ACTION_REINIT_ITEMS
- CPSUICB_ACTION_OPTIF_CHANGED
- CPSUICB_ACTION_NONE
  
  These return values are listed in order of decreasing priority. If multiple user interface plug-ins exist, the printer interface DLL calls each one's callback function and saves the highest-priority return value, passing it back to CPSUI.

Requirements

Requirement	Value
Target Platform	Desktop
Header	printoem.h (include Printoem.h, Compstui.h)

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