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CPL_NEWINQUIRE message

  • Стаття

Sent to the CPlApplet function of a Control Panel application to request information about a dialog box that the application supports.

Parameters

uAppNum

The dialog box number. This number must be in the range zero through one less than the value returned in response to the CPL_GETCOUNT message (CPL_GETCOUNT – 1).

lpncpli

The address of a NEWCPLINFO structure. The Control Panel application should fill this structure with information about the dialog box.

Return value

If the CPlApplet function processes this message successfully, it should return zero.

Remarks

For better performance, most applications should ignore CPL_NEWINQUIRE and process the CPL_INQUIRE message instead.

The Control Panel sends the CPL_NEWINQUIRE message once for each dialog box supported by your application. The Control Panel also sends a CPL_INQUIRE message for each dialog box. These messages are sent immediately after the CPL_GETCOUNT message. However, the system does not guarantee the order in which the CPL_INQUIRE and CPL_NEWINQUIRE messages are sent.

You can perform initialization for the dialog box when you receive CPL_INQUIRE. If you must allocate memory, do so in response to the CPL_INIT message.

CPL_INQUIRE is the preferred message. This is because CPL_NEWINQUIRE returns information in a form that the system cannot cache. Consequently, applications that process CPL_NEWINQUIRE must be loaded each time the Control Panel needs the information, resulting in a significant reduction in performance.

The only applications that should use CPL_NEWINQUIRE are those that need to change their icon or display strings based on the state of the computer. In this case, your CPL_INQUIRE handler should specify the CPL_DYNAMIC_RES value for the idIcon, idName, or idInfo members of the CPLINFO structure, rather than specifying a valid resource identifier. This causes the Control Panel to send the CPL_NEWINQUIRE message each time it needs the icon and display strings, allowing you to specify information based on the current state of the computer. Of course, this is significantly slower than using cached information.

Requirements

Requirement Value
Minimum supported client
 Windows XP [desktop apps only]
Minimum supported server
 Windows 2000 Server [desktop apps only]
Header
Cpl.h