xref: /haiku/docs/user/app/Notification.dox

/*
 * Copyright 2019-2020 Haiku, Inc. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *		Niels Sascha Reedijk, niels.reedijk@gmail.com
 *
 * Corresponds to:
 *		headers/os/app/Notification.h	hrev51445
 *		src/kits/app/Notification.cpp	hrev52287
 */


 /*!
	\file Notification.h
	\ingroup app
	\ingroup libbe
	\brief Provides BNotification class and the notification_type enum.
*/


///// notification_type enum /////


/*!
	\enum notification_type
	\brief Visual style of the notification.

	\since Haiku R1
*/


/*!
	\var notification_type::B_INFORMATION_NOTIFICATION
	\brief Information type

	This will have the notification appear with a grey side bar.

	\image html notification_information_type.png

	\since Haiku R1
*/


/*!
	\var notification_type::B_IMPORTANT_NOTIFICATION
	\brief Important type

	This will have the notification appear with a blue side bar.

	\image html notification_important_type.png

	\since Haiku R1
*/


/*!
	\var notification_type::B_ERROR_NOTIFICATION
	\brief Error type

	This will have the notification appear with a red side bar.

	\image html notification_error_type.png

	\since Haiku R1
*/


/*!
	\var notification_type::B_PROGRESS_NOTIFICATION
	\brief Progress type

	This will have the notification appear with a progress bar.

	\image html notification_progress_type.png

	\since Haiku R1
*/


///// BNotification class /////


/*!
	\class BNotification
	\ingroup app
	\ingroup libbe
	\brief Construct system-default notifications to be displayed to the user.

	Haiku provides a notification system that allows you to display messages to
	the user. There is quite some flexibility in how the message is presented.
	You may use this class to build and send the notification. The properties
	you can set are:
	 - The \link BNotification::BNotification() type of notification\endlink,
	   which can be an information message, a warning, an error, or a progress
	   message.
	 - The \link BNotification::SetGroup() group\endlink, which allows you to
	   organize notification display into different categories.
	 - A \link BNotification::SetTitle() title\endlink, which is a distinct
	   text element at the top of a notification view.
	 - The \link BNotification::SetContent() content\endlink, which is the text
	   message that is shown to the user.
	 - A \link BNotification::SetMessageID() message identifier\endlink that
	   allows you to modify the contents of a message that is being displayed,
	   which is particularly useful for progress notifications.
	 - For progress notifications, the
	   \link BNotification::SetProgress() percentage of completion\endlink can be
	   set.
	 - By default the notification uses the application's icon, but you may
	   set an \link BNotification::SetIcon() alternative icon\endlink.
	 - Finally there are a few ways you can configure the actions that happen
	   when a user clicks the notification. More on that below.

	For example, with the following code, you may display a notification:

	\code{.cpp}
	BNotification notification(B_PROGRESS_NOTIFICATION);
	notification.SetGroup("Group");
	notification.SetTitle("Title");
	notification.SetContent("This is the content");
	notification.SetMessageID("mainwindow_progress");
	notification.SetProgress(0.5);
	notification.Send();
	\endcode

	\image html notification_intro.png

	Note that in the previous code example, we set a
	\link BNotification::SetMessageID message identifier\endlink, which will
	allow to update the notification when we have progressed. The use would be:

	\code{.cpp}
	// After sending the notification, you retain ownership so that you can update it
	notification.SetProgress(0.7);

	// In order to display the update, you send it again
	notification.Send();
	\endcode

	Furthermore, it is possible to support some form of follow-up action, when
	the user clicks the notification. First of all, you need to choose whether
	you want to \link BNotification::SetOnClickApp() open a specific
	application\endlink, or whether you want to
	\link BNotification::SetOnClickFile() open a specific file\endlink and have
	the system determine which application fits that. Additionally, you may
	specify \link BNotification::AddOnClickArg() command line arguments\endlink
	or pass additional \link BNotification::AddOnClickRef() file
	references\endlink for the receiving application to process.

	Finally, a note about the \c notification_server and how it groups and
	handles messages coming from your application. The system is aware of the
	source of the notifications, and identifies your application by it's
	signature. That means that the identification of your application is
	consistent, even if it is restarted, or if you have multiple instances
	running. This impacts the \link BNotification::SetGroup() grouping\endlink
	functionality and the \link BNotification::SetMessageID() message
	updating\endlink functionality. If you have an application that can have
	multiple instances, you will need to make sure that you properly manage
	your group names and identifiers if you want to keep things separate.

	\since Haiku R1
*/


/*!
	\fn BNotification::BNotification(notification_type type)
	\brief Construct an empty message, with the specified \a type.

	The type influences the style of the notification view. See the
	\ref notification_type enumerator for details.

	\since Haiku R1
*/


/*!
	\fn BNotification::BNotification(BMessage* archive)
	\brief Construct a notification from an archive.

	\since Haiku R1
*/


/*!
	\fn virtual BNotification::~BNotification()
	\brief Frees all resources associated with the object.

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::InitCheck() const
	\brief Returns the status of the constructor.

	\since Haiku R1
*/


/*!
	\fn static BArchivable* BNotification::Instantiate(BMessage* archive)
	\brief Returns a new BNotification object from \a archive.

	This class implements the archiving API, and as such, you can
	build a new BNotification object from a previously created
	BMessage archive. However, if the message doesn't contain an archived data
	for a BNotification object, this method returns \c NULL.

	\returns BNotification object from \a archive or \c NULL if it doesn't
	         contain a valid BNotification object.

	\since Haiku R1
*/


/*!
	\fn virtual status_t BNotification::Archive(BMessage* archive,
		bool deep = true) const
	\brief Archives the BNotification in the \c archive.

	\see BArchivable::Archive(), Instantiate() static function.
	\returns \c B_OK: if everything went fine, or other errors that describe why
	         archiving has failed.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::SourceSignature() const
	\brief Returns signature of the application where the notification
	       originated.

	When you build your own notifications, this will contain the signature of
	the current application. If you receive notifications from other
	applications, it will include theirs.

	\returns Signature of the source application.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::SourceName() const
	\brief Returns the name of the application where the notification
	       originated.

	When you build your own notifications, this will contain the name of
	the current application. If you receive notifications from other
	applications, it will include theirs.

	\returns Name of the source application.

	\since Haiku R1
*/


/*!
	\fn notification_type BNotification::Type() const
	\brief Returns the type of the notification.

	\returns A value of the \c notification_type enum that represents
	         notification type.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::Group() const
	\brief Returns the group of the notification.

	\see BNotification::SetGroup() for more information about groups.

	\returns The string of the notification's group.

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetGroup(const BString& group)
	\brief Set a group for the notifcation.

	The default behaviour of the \c notification_server is group the visible
	notifications per running application, and then in order in which they have
	been received. There may be situations where you want to override that
	behavior and group related notifications. When you set a group name, the
	\c notification_server will create a box with the \c group name as label,
	and insert all related notifications in that box.

	\image html notification_group.png

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::Title() const
	\brief Returns the title of the notification.

	\returns The title of the notification as a string.

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetTitle(const BString& title)
	\brief Set a title for the notification.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::Content() const
	\brief Returns the message of the notification.

	\returns The message of the notification as a string.

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetContent(const BString& content)
	\brief Set a message for the notification.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::MessageID() const
	\brief Returns the identifier of the notification.

	\see BNotification::SetMessageID() for the purpose of having an identifier.

	\returns The identifier of the notification as a string.

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetMessageID(const BString& id)
	\brief Sets notification's message identifier.

	If you want to update the contents of an existing notification, you can
	set a identifier for this message. When you send a new or updated message
	with the same identifier, the \c notification_server will update the
	existing message with the new content.

	In order to effectively use this feature, you will have to make sure the
	identifier is unique within the current application.

	\since Haiku R1
*/


/*!
	\fn float BNotification::Progress() const
	\brief Returns the progress for the notification.

	\see BNotification::SetProgress() for more information about this value.

	\returns A value between 0.0 and 1.0 if notification's type is
	         \c B_PROGRESS_NOTIFICATION, or otherwise -1.

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetProgress(float progress)
	\brief Sets progress information.

	When you are building a notification of the type \c B_PROGRESS_NOTIFICATION
	the notification view will show a progress bar and a label that
	expresses the progress in a percentage. Using this method you can set
	what the bar and label express.

	The valid range is between 0.0 and 1.0. If \c progress is lower than 0.0
	(i.e. negative), the value will be set to 0.0. If it is higher than 1.0,
	it will be set to 1.0.

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::OnClickApp() const
	\brief Returns the signature of the application that will be called when
	       the notification is clicked.

	\see More information about this property in BNotification::SetOnClickApp().

	\since Haiku R1
*/


/*!
	\fn void BNotification::SetOnClickApp(const BString& app)
	\brief Set which application should be called when the notification is
	       clicked by the user.

	The value \c app should be a valid application signature, for example
	\c 'application/x-vnd.Haiku-StyledEdit'.

	Using this property has precedence on when BNotification::SetOnClickFile()
	is used. If you want interacting with the notification opening a specific
	file, then you should use this method in combination with
	BNotification::AddOnClickRef().

	\see Additional actions and parameters can be set through
	     BNotification::SetOnClickFile(), BNotification::AddOnClickRef()
		 and BNotification::AddOnClickArg().

	\since Haiku R1
*/


/*!
	\fn const entry_ref* BNotification::OnClickFile() const
	\brief Returns the reference to the file that will be opened when the
	       notification is clicked.

	\see More information about this property in BNotification::SetOnClickFile().

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::SetOnClickFile(const entry_ref* file)
	\brief Set which file should be opened when the notification is
	       clicked by the user.

	The file will be opened by the default application for this file type.

	You cannot use this action in combination with
	BNotification::SetOnClickApp(). If you use this way of setting an action,
	this action will be ignored.

	\see Additional actions and parameters can be set through
	     BNotification::SetOnClickApp(), BNotification::AddOnClickRef()
		 and BNotification::AddOnClickArg().

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::AddOnClickRef(const entry_ref* ref)
	\brief Add a \c ref to the list of arguments passed when a user clicks the
	       notification.

	This method allows you to construct a list of refs, that will be sent to
	the application specified by BNotification::AddOnClickApp(), or the one
	that is associated with BNotification::AddOnClickFile(). The refs will be
	handled by the application's BApplication::RefsReceived() hook method.

	\since Haiku R1
*/


/*!
	\fn int32 BNotification::CountOnClickRefs() const
	\brief Returns the number of refs to be passed when the user clicks on
	       the notification.

	\see BNotification::AddOnClickRef()

	\since Haiku R1
*/


/*!
	\fn const entry_ref* BNotification::OnClickRefAt(int32 index) const
	\brief Returns the ref that is stored at \c index.

	\see BNotification::AddOnClickRef()

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::AddOnClickArg(const BString& arg)
	\brief Add to a list of arguments that are passed to an application when
	       the user clicks on the notification.

	This method allows you to construct a list of arguments, that will be sent
	to the application specified by BNotification::AddOnClickApp(), or the one
	that is associated with BNotification::AddOnClickFile(). The args will be
	handled by the application's BApplication::ArgvReceived() hook method.

	\since Haiku R1
*/


/*!
	\fn int32 BNotification::CountOnClickArgs() const
	\brief Returns the number of args to be passed when the user clicks on
	       the notification.

	\see BNotification::AddOnClickArg()

	\since Haiku R1
*/


/*!
	\fn const char* BNotification::OnClickArgAt(int32 index) const
	\brief Returns the arg that is stored at \c index.

	\see BNotification::AddOnClickArg()
	\since Haiku R1
*/


/*!
	\fn const BBitmap* BNotification::Icon() const
	\brief Returns the icon for the notification.

	\see BNotification::SetIcon() for more information on this property.

	\return Returns a borrowed unchangeable reference to the icon.

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::SetIcon(const BBitmap* icon)
	\brief Set the icon of the notification.

	Set the icon for the notification. By default, the application icon is
	used. This method makes a copy of the \a icon. 

	\param icon The icon that should be displayed with the notification.
	\returns \c B_OK if everything went fine, \c B_NO_MEMORY when the \a icon
	         could not be copied, or another error if something else went
			 wrong.

	\since Haiku R1
*/


/*!
	\fn status_t BNotification::Send(bigtime_t timeout = -1)
	\brief Send the notification to the notification_server.

	The notification is delivered asynchronously to the notification_server,
	which will display it according to its settings and filters.

	After sending, you retain ownership of the notification. The advantage is
	that you can re-use the notification at a later moment, or use the object to
	update the notification. See BNotification::SetMessageID() about updating
	displayed notifications. If you allocate the notification on the heap, be
	sure to free the memory.

	\param timeout The \a timeout in microsecond that the notification should
	       be displayed. If you want to use the default timing, use the default
		   argument or pass \c -1.
	\returns \c B_OK if everything went fine, \c B_BAD_PORT_ID if there was a
	         problem connecting to the \c notification_server, or any other
			 errors if something went wrong transmitting the notification.

	\since Haiku R1
*/