CCHookProc callback function
Receives messages or notifications intended for the default dialog box procedure of the Color dialog box. This is an application-defined or library-defined callback function that is used with the ChooseColor function.
The LPCCHOOKPROC type defines a pointer to this callback function. CCHookProc is a placeholder for the application-defined function name.
UINT_PTR CALLBACK CCHookProc( _In_ HWND hdlg, _In_ UINT uiMsg, _In_ WPARAM wParam, _In_ LPARAM lParam );
- hdlg [in]
A handle to the Color dialog box for which the message is intended.
- uiMsg [in]
The identifier of the message being received.
- wParam [in]
Additional information about the message. The exact meaning depends on the value of the uiMsg parameter.
- lParam [in]
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 CHOOSECOLOR structure containing the values specified when the dialog was created.
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.
When you use the ChooseColor function to create a Color dialog box, you can provide a CCHookProc hook procedure to process messages or notifications intended for the dialog box procedure. To enable the hook procedure, use the CHOOSECOLOR structure that you passed to the dialog creation function. Specify the address of the hook procedure in the lpfnHook member and specify the CC_ENABLEHOOK 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 to 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 to 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 a common dialog box. However, the 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.
Minimum supported client
|Windows 2000 Professional [desktop apps only]|
Minimum supported server
|Windows 2000 Server [desktop apps only]|
- Common Dialog Box Library
Build date: 11/16/2013