DialogProc

This function is an application-defined callback function that processes messages sent to a modal or modeless dialog box.

At a Glance

Syntax

BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg,
WPARAM wParam, LPARAM lParam);

Parameters

hwndDlg

Handle to the dialog box.

uMsg

Specifies the message.

wParam

Specifies additional message-specific information.

lParam

Specifies additional message-specific information.

Return Values

Typically, the dialog box procedure should return TRUE if it processed the message, and FALSE if it did not. If the dialog box procedure returns FALSE, the dialog manager performs the default dialog operation in response to the message.

If the dialog box procedure processes a message that requires a specific return value, the dialog box procedure should set the desired return value by calling SetWindowLong(hwndDlg, DWL_MSGRESULT, lResult) immediately before returning TRUE. Note that you must call SetWindowLong immediately before returning TRUE; doing so earlier may result in the DWL_MSGRESULT value being overwritten by a nested dialog box message.

• The following messages are exceptions to the general rules:

  WM_CHARTOITEM	WM_CTLCOLORSCROLLBAR
  WM_COMPAREITEM	WM_CTLCOLORSTATIC
  WM_CTLCOLORBTN	WM_INITDIALOG
  WM_CTLCOLORDLG	WM_QUERYDRAGICON
  WM_CTLCOLOREDIT	WM_VKEYTOITEM
  WM_CTLCOLORLISTBOX

  
  

Consult the documentation for the specific message for details on the semantics of the return value.

Remarks

You should use the dialog box procedure only if you use the dialog box class for the dialog box. This is the default class and is used when no explicit class is specified in the dialog box template. Although the dialog box procedure is similar to a window procedure, it must not call the DefWindowProc function to process unwanted messages. Unwanted messages are processed internally by the dialog box window procedure.

See Also

CreateDialog, CreateDialogIndirect, CreateDialogIndirectParam, CreateDialogParam, DefWindowProc, DialogBox, DialogBoxIndirect, DialogBoxIndirectParam, DialogBoxParam, SetFocus, WM_INITDIALOG