This notification message is sent by a date and time picker (DTP) control to retrieve the maximum allowable size of the string that will be displayed in callback field. It is sent in the form of a WM_NOTIFY message.
At a Glance
| Header file: | Commctrl.h |
| Windows CE versions: | 2.0 and later |
Syntax
DTN_FORMATQUERY
lpDTFormatQuery = (LPNMDATETIMEFORMATQUERY) lParam;
Parameters
lpDTFormatQuery
Long pointer to an NMDATETIMEFORMATQUERY structure that contains information about the callback field. The structure contains a substring that defines a callback field and receives the maximum allowable size of the of string that will be displayed in the callback field.
Remarks
The owner of the control must calculate the maximum possible width of the text that will be displayed in the callback field, set the szMax member of the NMDATETIMEFORMATQUERY structure, and return zero.
Handling this message prepares the control to adjust for the maximum size of the string that will be displayed in a particular callback field. This enables the control to properly display output at all times, reducing flicker within the control’s display. For additional information about callback fields, see Callback Fields.