PageSetupHook
A PageSetupHook
hook procedure is an application-defined or library-defined callback procedure
that is used with the Page Setup common dialog box. The hook procedure receives
messages or notifications intended for the default dialog box procedure.
UINT APIENTRY PageSetupHook(
|
HWND hdlg, |
// handle to the
dialog box window |
|
UINT uiMsg, |
// message
identifier |
|
WPARAM wParam, |
// message
parameter |
|
LPARAM lParam |
// message
parameter |
|
); |
|
Parameters
hdlg
Handle to the
Page Setup dialog box window for which the message is intended.
uiMsg
Identifies
the message being received.
wParam
Specifies
additional information about the message. The exact meaning depends on the
value of the uiMsg parameter.
lParam
Specifies
additional information about the message. The exact meaning depends on the
value of the uiMsg parameter.
If the uiMsg
parameter indicates the WM_INITDIALOG message, lParam is a pointer to a PAGESETUPDLG structure containing the
values specified when the common dialog box was created.
Return Values
If the hook
procedure returns zero, the default dialog box procedure processes the message.
If the hook
procedure returns a nonzero value, the default dialog box procedure ignores the
message.
Remarks
When you use
the PageSetupDlg
function to create a Page Setup common dialog box, you can provide a PageSetupHook
hook procedure to process messages or notifications intended for the dialog box
procedure. To enable the hook procedure, use the PAGESETUPDLG structure that you passed
to the dialog creation function. Specify the pointer to the hook procedure in
the lpfnPageSetupHook member and specify the PSD_ENABLEPAGESETUPHOOK
flag in the Flags member.
The default
dialog box procedure processes the WM_INITDIALOG message before passing it to
the hook procedure. For all other messages, the hook procedure receives the message
first. Then, the return value of the hook procedure determines whether the
default dialog procedure processes the message or ignores it.
If the hook
procedure processes the WM_CTLCOLORDLG message, it must return a valid brush handle for
painting the background of the dialog box. In general, if the hook procedure
processes any WM_CTLCOLOR* message, it must return a valid brush handle for
painting the background of the specified control.
Do not call
the EndDialog
function from the hook procedure. Instead, the hook procedure can call the PostMessage function to post a
WM_COMMAND message with the IDABORT value to the dialog box procedure. Posting
IDABORT closes the dialog box and causes the dialog box function to return
FALSE. If you need to know why the hook procedure closed the dialog box, you
must provide your own communication mechanism between the hook procedure and
your application.
You can
subclass the standard controls of the common dialog box. However, the common
dialog box procedure may also subclass the controls. Because of this, you
should subclass controls when your hook procedure processes the WM_INITDIALOG
message. This ensures that your subclass procedure receives the control-specific
messages before the subclass procedure set by the dialog box procedure.
PageSetupHook is a placeholder for the application-defined or
library-defined function name. The LPPAGESETUPHOOK type is a pointer to
a PageSetupHook hook procedure.
See Also