How to Process Date and Time Picker Notifications

This section demonstrates how to process date and time picker notifications.

What you need to know

Technologies

• Windows Controls

Prerequisites

• C/C++
• Windows User Interface Programming

Instructions

A date and time picker (DTP) control sends notification messages to the parent window when events, usually triggered by input from the user, occur in the control. Your application must include code to determine the type of notification message and respond appropriately.

If you plan to use callback fields with the DTP controls in your application, you must be prepared to handle DTN_FORMATQUERY, DTN_FORMAT, and DTN_WMKEYDOWN notification codes. For additional information about callback fields, see Callback fields.

The following C++ code example identifies the notification message sent by a DTP control and calls the appropriate application-defined function. Refer to the following topics for code examples that illustrate how to process the notifications that appear in this example.

BOOL WINAPI DoNotify(HWND hwnd, WPARAM wParam, LPARAM lParam)
{
    LPNMHDR hdr = (LPNMHDR)lParam;

    switch(hdr->code){

        case DTN_DATETIMECHANGE:{
            LPNMDATETIMECHANGE lpChange = (LPNMDATETIMECHANGE)lParam;
            DoDateTimeChange(lpChange);
        }
        break;

        case DTN_FORMATQUERY:{
            LPNMDATETIMEFORMATQUERY lpDTFQuery = (LPNMDATETIMEFORMATQUERY)lParam;

            // Process DTN_FORMATQUERY to ensure that the control
            // displays callback information properly.
            DoFormatQuery(hdr->hwndFrom, lpDTFQuery);
        }
        break;

        case DTN_FORMAT:{
            LPNMDATETIMEFORMAT lpNMFormat = (LPNMDATETIMEFORMAT) lParam;

            // Process DTN_FORMAT to supply information about callback
            // fields (fields) in the DTP control.
            DoFormat(hdr->hwndFrom, lpNMFormat);
        }
        break;

        case DTN_WMKEYDOWN:{
            LPNMDATETIMEWMKEYDOWN lpDTKeystroke = 
                            (LPNMDATETIMEWMKEYDOWN)lParam;

            // Process DTN_WMKEYDOWN to respond to a user's keystroke in
            // a callback field.
            DoWMKeydown(hdr->hwndFrom, lpDTKeystroke);
        }
        break;
    }

    // All of the above notifications require the owner to return zero.
    return FALSE;
}

Related topics

Date and Time Picker Notifications

Date and Time Picker Control Reference

Using Date and Time Picker Controls

Date and Time Picker