xref: /haiku/docs/user/interface/PopUpMenu.dox (revision 47852bff02be873c48ec9399e7cc119502bb8c67)

/*
 * Copyright 2013 Haiku, Inc. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *		John Scipione, jscipione@gmail.com
 *
 * Corresponds to:
 *		headers/os/interface/PopUpMenu.h	 hrev46360
 *		src/kits/interface/PopUpMenu.cpp	 hrev46360
 */


/*!
	\file PopUpMenu.h
	\ingroup interface
	\ingroup libbe
	\brief BPopUpMenu class definition and support structures.
*/


/*!
	\class BPopUpMenu
	\ingroup interface
	\ingroup libbe
	\brief Displays a pop-up menu.

	A BPopUpMenu is typically used to display a limited set of
	mutually-exclusive choices rather than as part of a deeply nested
	menu hierarchy. A BPopUpMenu is similar to a BMenu but has a few
	additional methods to make it easier to use the menu as a stand-alone
	menu and to manage the object's lifetime.

	Pop-up menus are used either as a stand-alone menu, usually as
	a context menu activated by \c B_SECONDARY_MOUSE_BUTTON, or
	as a menu attached to a BMenuField or BMenuBar.

	If the pop-up menu is used as a stand-alone menu, the Go() method
	controls how and where the menu pops up and provides several options
	for how the pop-up menu works.

	Once Go() returns the BPopUpMenu object should be destroyed. You can call
	SetAsyncAutoDestruct() passing \c true to destroy the object automatically
	when it returns. This is not advisable if the \a deliversMessage parameter
	of Go() is set \c false because you'll want to examine the return value
	before destroying the BPopUpMenu object.

	If the pop-up menu is used as part of a BMenuField or BMenuBar it behaves
	almost exactly like a BMenu would, but, the menu pops up directly under the
	mouse pointer instead of underneath the BMenuBar or BMenuField.

	\since BeOS R3
*/


/*!
	\fn BPopUpMenu::BPopUpMenu(const char* name, bool radioMode,
		bool labelFromMarked, menu_layout layout)
	\brief Creates a new BPopUpMenu object.

	\attention A BPopUpMenu should never be set to \a B_ITEMS_IN_MATRIX
	           layout. The menu is automatically resized so that its
	           menu items will fit exactly in the menu.

	\param name The menu's name, serves as a label for submenus.
	\param radioMode Whether or not the menu is in radio mode, default is
	       \c true.
	\param labelFromMarked Whether or not the menu is in label-from-marked mode,
	       default is \c true.
	\param layout The menu layout, possibilities include:
	       - \c B_ITEMS_IN_ROW items are displayed in a single row,
	       - \c B_ITEMS_IN_COLUMN items are displayed in a single column,
	            the default layout.

	\see BMenu::SetRadioMode()
	\see BMenu::SetLabelFromMarked()

	\since BeOS R3
*/


/*!
	\fn BPopUpMenu::BPopUpMenu(BMessage* archive)
	\brief Archive constructor.

	\param archive The message data to construct the pop-up menu from.

	\since BeOS R3
*/


/*!
	\fn BPopUpMenu& BPopUpMenu::operator=(const BPopUpMenu& other)
	\brief Assignment overload method.

	\param other The BPopUpMenu object to assign from.

	\return The newly assigned BPopUpMenu object.

	\since BeOS R3
*/


/*!
	\fn BPopUpMenu::~BPopUpMenu()
	\brief Destructor method.

	Also frees the memory used by any attached menu items.

	\since BeOS R3
*/


/*!
	\name Archiving
*/


//! @{


/*!
	\fn status_t BPopUpMenu::Archive(BMessage* data, bool deep) const
	\brief Archives the the BMenuField object into the \a data message.

	\param data A pointer to the BMessage to archive the object into.
	\param deep Whether or not to archive attached menu items as well.

	\return A status code, \c B_OK if everything went well or an error code
	        otherwise.
	\retval B_OK The object was archived successfully.
	\retval B_NO_MEMORY Ran out of memory while archiving the object.

	\since BeOS R3
*/


/*!
	\fn BArchivable* BPopUpMenu::Instantiate(BMessage* data)
	\brief Creates a new BPopUpMenu object from the \a data message.

	\returns A newly created BPopUpMenu object or \c NULL if the message
	         doesn't contain an archived BPopUpMenu.

	\since BeOS R3
*/


//! @}


/*!
	\fn BMenuItem* BPopUpMenu::Go(BPoint where, bool deliversMessage,
		bool openAnyway, bool async)
	\brief Places the menu on screen.

	\param where The location to open the left-top-corner of the pop-up menu
	       in the screen's coordinate system.
	\param deliversMessage if \c true, the menu item posts a message to its
	       target as it normally would when selected by the user.
	       If \a deliversMessage is \c false no message is sent and you are
	       expected to decide what action to take based on the return value.
	\param openAnyway If \c true, the pop-up menu will stay open even once the
	       user has released the mouse button. To dismiss the menu, either a
	       menu item must be selected or it must be dismissed programmatically.
	\param async If \c true the menu will return \c NULL immediately, if
	       \c false the menu will not return until a menu item is selected
	       or it is dismissed by the user. If a menu item was selected a
	       pointer to the menu item is returned, if not, \c NULL is returned.

	\since BeOS R3
*/


/*!
	\fn BMenuItem* BPopUpMenu::Go(BPoint where, bool deliversMessage,
		bool openAnyway, BRect clickToOpen, bool async)
	\brief Places the menu on screen, with \a clickToOpen option.

	The \a clickToOpen rectangle should be specified in the screen's
	coordinate system. \a openAnyway must be set \c true for the \a clickToOpen
	rectangle to work.

	\param where The location to open the left-top-corner of the pop-up menu
	       in the screen's coordinate system.
	\param deliversMessage if \c true, the menu item posts a message to its
	       target as it normally would when selected by the user.
	       If \a deliversMessage is \c false no message is sent and you are
	       expected to decide what action to take based on the return value.
	\param openAnyway If \c true, the pop-up menu will stay open even once the
	       user has released the mouse button. To dismiss the menu, either a
	       menu item must be selected or it must be dismissed programmatically.
	\param clickToOpen If the user releases the mouse button while the cursor
	       is inside the \a clickToOpen rectangle the menu is kept on-screen,
	       if the cursor is located outside of the \a clickToOpen rectangle
	       the menu is removed from the screen and Go() returns.
	\param async If \c true the menu will return \c NULL immediately, if
	       \c false the menu will not return until a menu item is selected
	       or it is dismissed by the user. If a menu item was selected a
	       pointer to the menu item is returned, if not, \c NULL is returned.

	\since BeOS R3
*/


/*!
	\fn void BPopUpMenu::SetAsyncAutoDestruct(bool on)
	\brief Indicates whether or not the BPopUpMenu will delete itself after
	       closing, async-auto-destruct mode is set to \c false by default.

	\param on \c true to turn async-auto-destruct mode on, \c false to turn
	       async-auto-destruct mode off.

	\since BeOS R5
*/


/*!
	\fn bool BPopUpMenu::AsyncAutoDestruct() const
	\brief Returns the current async-auto-destruct setting.

	\return \c true if async-auto-destruct mode is turned on, \c false if
	        async-auto-destruct mode is turned off.

	\see SetAsyncAutoDestruct()

	\since BeOS R5
*/


/*!
	\fn BPoint BPopUpMenu::ScreenLocation()
	\brief Returns where the pop-up menu will appear on screen when it is
	       opened.

	You can override this method in your BPopUpMenu derived class to return
	where the pop-up menu will appear on screen.

	\returns The location that the pop-up-menu will appear on screen in the
	         screen's coordinate system.

	\since BeOS R3
*/