haiku/docs/user/interface/Alert.dox

/*
 * Copyright 2011, Haiku inc.
 * Distributed under the terms of the MIT License.
 *
 * Documentation by:
 *		John Scipione <jscipione@gmail.com>
 * Corresponds to:
 *		/trunk/headers/os/interface/Alert.h	 rev 42274
 *		/trunk/src/kits/interface/Alert.cpp	 rev 42274
 */


/*!
	\file Alert.h
	\brief BAlert class definition and support enums.
*/


/*!
	\enum alert_type
	Determines which icon (if any) is displayed in the alert dialog.
	Choose one option. If the constructor doesn't include an
	alert_type argument than \c B_EMPTY_ALERT is used.
*/

/*!
	\var alert_type B_EMPTY_ALERT
	No icon
*/

/*!
	\var alert_type B_INFO_ALERT
	\image html http://api.haiku-os.org/images/alert_info_32.png
	Info icon
*/

/*!
	\var alert_type B_IDEA_ALERT
	\image html http://api.haiku-os.org/images/alert_idea_32.png
	Idea icon
*/

/*!
	\var alert_type B_WARNING_ALERT
	\image html http://api.haiku-os.org/images/alert_warning_32.png
	Warning icon
*/

/*!
	\var alert_type B_STOP_ALERT
	\image html http://api.haiku-os.org/images/alert_stop_32.png
	Stop icon
*/

/*!
	\enum button_spacing
	Determines how the buttons on the alert dialog are spaced relative
	to each other. Choose one option. If the constructor doesn't include a
	button_spacing argument than \c B_EVEN_SPACING is used.
*/

/*!
	\var button_spacing B_EVEN_SPACING
	If the alert dialog has more than one button than the buttons are
	spaced evenly across the bottom of the alert dialog.
*/

/*!
	\var button_spacing B_OFFSET_SPACING
	If the alert dialog has more than one button than the leftmost button
	is offset to the left-hand side of the dialog while the rest of the
	buttons are grouped on the right. This is useful to separate off a
	leftmost "Cancel" or "Delete" button.
*/


/*!
	\class BAlert
	\ingroup interface
	\ingroup libbe
	\brief The BAlert class defines a modal alert dialog which displays a short
		message and provides a set of labeled buttons that allow the user to
		respond.

	The alert can be configured with a set of one to three buttons. These
	buttons are assigned indexes 0, 1, and 2 from right-to-left respectively
	and are automatically positioned by the system. The user can either click
	on one of the buttons or use a shortcut key to select a button.

	The layout of the buttons can be configured by setting the #button_width
	and #button_spacing properties in the BAlert constructor. The icon displayed
	in the alert can also be configured by setting the #alert_type property. The
	right-most button (index 0) is the default button which can be activated
	by pushing the \key{Enter} key.

	Below is an example of an unsaved changes alert dialog:

	\image html BAlert_example.png

	When the user responds by selecting one of the buttons the alert window is
	removed from the screen. The index of the selected button is returned to
	the calling application and the BAlert object is deleted.

	The code used to create and display an alert dialog like the one shown
	above is shown below:

	\code
BAlert* alert = new BAlert("Close and save dialog", "Save changes to...",
	"Cancel", "Don't save", "Save", B_WIDTH_AS_USUAL, B_OFFSET_SPACING,
	B_WARNING_ALERT);
alert->SetShortcut(0, B_ESCAPE);
int32 button_index = alert->Go();
	\endcode

	The messaged displayed in the dialog window along with the button labels
	are set by the strings in the contructor. The Cancel button is offset to
	the left relative to the other buttons by setting the \c B_OFFSET_SPACING
	flag.  The \c B_WARNING_ALERT flag displays the exclamation mark icon in
	the dialog.

	Any alert with a Cancel button should map the \key{Escape} key as shown in
	the example above. You can setup additional shortcut keys for the buttons
	with the SetShortcut() method.

	The Go() method does the work of loading up and removing the alert
	window and returns the index of the button that the user selected.
*/


/*!
	\fn BAlert::BAlert(const char *title, const char *text,
		const char *button1, const char *button2, const char *button3,
		button_width width, alert_type type)
	\brief Creates and initializes a BAlert dialog.

	\param title The title of the window. Since the alert window doesn't have
		   a title tab, the title is not actually displayed anywhere but is
		   useful for debugging purposes.
	\param text The text that is displayed at the top of the window.
	\param button1 Button 1 label
	\param button2 Button 2 label
	\param button3 Button 3 label
	\param width A constant that describes how the button should be sized.
		Options are
		\li \c B_WIDTH_AS_USUAL
		\li \c B_WIDTH_FROM_WIDEST
		\li \c B_WIDTH_FROM_LABEL

		See button_width for details.
	\param type Constant that determines which alert icon is displayed.
		Options are
		\li \c B_EMPTY_ALERT
		\li \c B_INFO_ALERT
		\li \c B_IDEA_ALERT
		\li \c B_WARNING_ALERT
		\li \c B_STOP_ALERT

		See alert_type for details.
*/

/*!
	\fn BAlert::BAlert(const char *title, const char *text, const char *button1,
		const char *button2, const char *button3, button_width width,
		button_spacing spacing, alert_type type)
	\brief Creates and initializes a BAlert dialog.

	You can also set the \a spacing with this constructor.

	\param title The title of the window. Since the alert window doesn't have
		   a title tab, the title is not actually displayed anywhere but is
		   useful for debugging purposes.
	\param text The text that is displayed at the top of the window.
	\param button1 Button 1 label
	\param button2 Button 2 label
	\param button3 Button 3 label
	\param width A constant that describes how the button should be sized.
		Options are
		\li \c B_WIDTH_AS_USUAL
		\li \c B_WIDTH_FROM_WIDEST
		\li \c B_WIDTH_FROM_LABEL

		See button_width for details.
	\param spacing Determines how the buttons are spaced. Options are
		\li \c B_EVEN_SPACING
		\li \c B_OFFSET_SPACING 

		See button_spacing for details.
	\param type Constant that determines which alert icon is displayed.
		Options are
		\li \c B_EMPTY_ALERT
		\li \c B_INFO_ALERT
		\li \c B_IDEA_ALERT
		\li \c B_WARNING_ALERT
		\li \c B_STOP_ALERT

		See alert_type for details.
*/

/*!
	\fn BAlert::BAlert(BMessage* data)
	\brief Unarchives an alert from a BMessage.

	\param data The archive.
*/

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

	Standard Destructor method to delete a BAlert.
*/

/*!
	\fn BArchivable* BAlert::Instantiate(BMessage* data)
	\brief Instantiates a BAlert from a BMessage.
	\param data The message to instantiate the BAlert.
	\returns a BArchivable object of the BAlert.
*/

/*!
	\fn status_t BAlert::Archive(BMessage* data, bool deep) const
	\brief Archives the BAlert into \a archive.

	\param data The target archive which the BAlert \a data will go into.
	\param deep Whether or not to recursively archive the BAlert's children.
	\retval B_OK The archive operation was successful.
	\retval B_BAD_VALUE The archive operation failed.
*/

/*!
	\fn void BAlert::SetShortcut(int32 index, char key)
	\brief Sets the shortcut character which is mapped to a button at the
	specified \a index.

	A button can only have one shortcut except for the rightmost button which,
	in addition to the shortcut you set, is always mapped to \c B_ENTER.

	If you create a "Cancel" button then you should set its shortcut to
	\c B_ESCAPE.

	\param index The \a index of the button to set the shortcut to.
	\param key The shortcut character to set.
*/

/*!
	\fn char BAlert::Shortcut(int32 index) const
	\brief Gets the shortcut character which is mapped to a button at the 
	specified \a index.

	\param index The \a index of the button to get the shortcut of.

	\return The shortcut character mapped to the button at the specified
		\a index.
*/

/*!
	\fn int32 BAlert::Go()
	\brief Displays the alert window.

	This version of Go() that does not include an invoker is
	synchronous. Go() returns once the user has clicked a button and
	the panel has been removed from the screen. The BAlert object is
	deleted before the method returns.

	If the BAlert is sent a \c B_QUIT_REQUESTED message while the alert
	window is still on screen then Go() returns -1.

	\returns The index of the button clicked.
*/

/*!
	\fn status_t BAlert::Go(BInvoker* invoker)
	\brief Displays the alert window from a specified \a invoker.

	This version of Go() with an \a invoker is asynchronous. It returns
	immediately with \c B_OK and the button \a index is set to the field
	of the BMessage that is sent to the target of the \a invoker.

	Go() deletes the BAlert object after the message is sent.

	If you call Go() with a \c NULL invoker argument than the BMessage
	is not sent.

	If the BAlert is sent a \c B_QUIT_REQUESTED method while the alert
	window is still on screen then the message is not sent.

	\returns A status code.
*/

/*!
	\fn void BAlert::MessageReceived(BMessage* msg)
	\brief Initiates an action from a received message.

	\param msg The message

	\see BWindow::MessagedReceived()
*/

/*!
	\fn void BAlert::FrameResized(float newWidth, float newHeight)
	\brief Resizes the alert dialog.

	\param newWidth The new alert dialog width.
	\param newHeight The new alert dialog height.

	\see BWindow::FrameResized()
*/

/*!
	\fn BButton* BAlert::ButtonAt(int32 index) const
	\brief Returns a pointer to the BButton at the specified \a index.

	The \a index of the buttons begins at \c 0 and counts from left to right.
	If a BButton does not exist for the specified \a index then \c NULL is
	returned.

	\param index The \a index of the desired button.

	\return A pointer to the BButton at the specified \a index.
*/

/*!
	\fn BTextView* BAlert::TextView() const
	\brief Returns a TextView containing the text of the Alert.
*/

/*!
	\fn BHandler* BAlert::ResolveSpecifier(BMessage* msg, int32 index,
		BMessage* specifier, int32 form, const char* property)
	\brief Resolves specifiers for properties.
	\see BHandler::ResolveSpecifier()
*/

/*!
	\fn status_t BAlert::GetSupportedSuites(BMessage* data)
	\brief Reports the suites of messages and specifiers that derived classes
		understand.
	
	\param data The message to report the suite of messages and specifiers.

	\see BWindow::GetSupportedSuites()
*/

/*!
	\fn void BAlert::DispatchMessage(BMessage* msg, BHandler* handler)
	\brief Sends out a message.

	\see BWindow::DispatchMessage()
*/

/*!
	\fn void BAlert::Quit()
	\brief Quits the window closing it.

	\see BWindow::Quit()
*/

/*!
	\fn bool BAlert::QuitRequested()
	\brief Hook method that gets called with the window is closed.

	\returns \c true if the window closes.

	\see BWindow::QuitRequested()
*/

/*!
	\fn BPoint BAlert::AlertPosition(float width, float height)
	\brief Resizes the Alert window to the width and height specified and
	return the Point of the top-left corner of the Alert window.

	\param width The desired \a width of the alert window.
	\param height The desired \a height of the alert window.

	\returns The BPoint of the top-left corner of the Alert window.
*/

/*!
	\fn status_t BAlert::Perform(perform_code code, void* _data)
	\brief Performs an action give a perform_code and data

	Currently the only perform code available is \c PERFORM_CODE_SET_LAYOUT.

	\param code The perform code
	\param _data A pointer to some data to perform on

	\return A status code.

	\see BWindow::Perform().
*/