View base class. More...

Inheritance diagram for BView:

Public Member Functions
virtual status_t	AllArchived (BMessage *archive) const
	Method relating to the use of `BArchiver`.
virtual void	AllAttached ()
	Similar to AttachedToWindow() but this method is triggered after all child views have already been attached to a window.
virtual void	AllDetached ()
	Similar to AttachedToWindow() but this method is triggered after all child views have already been detached from a window.
virtual status_t	AllUnarchived (const BMessage *archive)
	Method relating to the use of `BUnarchiver`.
virtual status_t	Archive (BMessage *archive, bool deep=true) const
	Archive a handler to a message.
virtual void	AttachedToWindow ()
	Hook method that is called when the object is attached to a window.
virtual void	DetachedFromWindow ()
	Hook method that is called when the object is detached from a window.
virtual void	Draw (BRect updateRect)
	Draws the area of the view that intersects updateRect.
virtual void	DrawAfterChildren (BRect r)
	Perform any drawing that needs to be done after child view have already been drawn.
virtual void	FrameMoved (BPoint newPosition)
	Hook method that gets called when the view is moved.
virtual void	FrameResized (float newWidth, float newHeight)
	Hook method that gets called when the view is resized.
BLayout *	GetLayout () const
	Get the layout of the view.
virtual void	GetPreferredSize (float width, float height)
	Fill out the preferred width and height of the view into the _width and _height parameters.
virtual status_t	GetSupportedSuites (BMessage *data)
	Reports the suites of messages and specifiers that derived classes understand.
virtual void	KeyDown (const char *bytes, int32 numBytes)
	Hook method that is called when a keyboard key is pressed.
virtual void	KeyUp (const char *bytes, int32 numBytes)
	Hook method that is called when a keyboard key is released.
virtual void	MakeFocus (bool focusState=true)
	Gives or removes focus from the control.
virtual BSize	MaxSize ()
	Get the maximum size of the view.
virtual void	MessageReceived (BMessage *message)
	Handle message that has been received by the associated looper.
virtual BSize	MinSize ()
	Get the minimum size of the view.
virtual void	MouseDown (BPoint where)
	Hook method that is called when a mouse button is pressed.
virtual void	MouseMoved (BPoint where, uint32 code, const BMessage *dragMessage)
	Hook method that is called when the mouse is moved.
virtual void	MouseUp (BPoint where)
	Hook method that is called when a mouse button is released.
virtual status_t	Perform (perform_code code, void *data)
	Perform some action. (Internal Method)
virtual BSize	PreferredSize ()
	Get the preferred size of the view.
virtual void	Pulse ()
	Hook method that gets invoked when the view receives a `B_PULSE` message.
virtual void	ResizeToPreferred ()
	Resize the view to its preferred size.
virtual BHandler *	ResolveSpecifier (BMessage msg, int32 index, BMessage specifier, int32 form, const char *property)
	Determine the proper handler for a scripting message.
void	SetExplicitAlignment (BAlignment alignment)
	Set this item's explicit alignment, to be used by Alignment().
void	SetExplicitMaxSize (BSize size)
	Set this item's explicit max size, to be used by MaxSize().
void	SetExplicitMinSize (BSize size)
	Set this item's explicit min size, to be used by MinSize().
void	SetExplicitPreferredSize (BSize size)
	Set this item's explicit preferred size, to be used by PreferredSize().
virtual void	SetLayout (BLayout *layout)
	Set the layout of the view.
virtual void	WindowActivated (bool state)
	Hook method that is called when the attached window becomes activated or deactivated.
Methods triggering or related to laying out this BLayout.
BLayoutContext *	LayoutContext () const
	Returns the BLayoutContext this BLayout is currently operating in, or `NULL`.
Core Handler Functionality
BLooper *	Looper () const
	Return a pointer to the looper that this handler is associated with.
void	SetName (const char *name)
	Set or change the name of this handler.
const char *	Name () const
	Return the name of this handler.
virtual void	SetNextHandler (BHandler *handler)
	Set the next handler in the chain that the message is passed on to if this handler cannot process it.
BHandler *	NextHandler () const
	Return the next hander in the chain to which the message is passed on.
Message Filtering
virtual void	AddFilter (BMessageFilter *filter)
	Add filter as a prerequisite to this handler.
virtual bool	RemoveFilter (BMessageFilter *filter)
	Remove filter from the filter list.
virtual void	SetFilterList (BList *filters)
	Set the internal list of filters to filters.
BList *	FilterList ()
	Return a pointer to the list of filters.
Locking
This class provides some utility functions to look the looper associated with this handler.
bool	LockLooper ()
	Lock the looper associated with this handler.
status_t	LockLooperWithTimeout (bigtime_t timeout)
	Lock the looper associated with this handler, with a time out value.
void	UnlockLooper ()
	Unlock the looper.
Observing
Handlers can function as state machines, which emit messages to observers when the state changes. Use the following methods to subscribe to these notifications. Note that there is a semantic difference between the two StartWatching() methods. The overloaded method that accepts a BHandler, expects as argument an observer that watches this handler. The method that accepts a BMessenger, expects a target that emits the state changes to this handler.
status_t	StartWatching (BMessenger target, uint32 what)
	Subscribe this handler to watch a specific state change of a target.
status_t	StartWatching (BHandler *observer, uint32 what)
	Subscribe an observer for a specific state change of this handler.
status_t	StartWatchingAll (BMessenger target)
	Subscribe this handler to watch a target for all events.
status_t	StartWatchingAll (BHandler *observer)
	Subscribe an observer for a all state changes.
status_t	StopWatching (BMessenger target, uint32 what)
	Unsubscribe this handler from watching a specific state.
status_t	StopWatching (BHandler *observer, uint32 what)
	Unsubscribe an observer from watching a specific state.
status_t	StopWatchingAll (BMessenger target)
	Unsubscribe this handler from watching all states.
status_t	StopWatchingAll (BHandler *observer)
	Unsubscribe an observer from watching all states.
Emitting State Changes
If your handler functions as a state machine, and it has observers (which subscribed using the StartWatching() method), you can emit these state changes.
virtual void	SendNotices (uint32 what, const BMessage *notice=NULL)
	Emit a state change to the observers.
bool	IsWatched () const
	Check if there are any observers watching this handler.
Static Public Member Functions
static BArchivable *	Instantiate (BMessage *archive)
	Static method to instantiate a handler from an archived message.
Protected Member Functions
BLayout Hook methods
virtual void	LayoutInvalidated (bool descendants=false)

Detailed Description

View base class.

Member Function Documentation

void BHandler::AddFilter ( BMessageFilter * filter ) [virtual, inherited]

Add filter as a prerequisite to this handler.

If the handler is associated with a looper, this looper needs to be locked in order for this operation to succeed.

Note that the filter is not copied, rather a pointer to the filter is stored. As such, you need to make sure that the filter object exists as long as it is added to this handler.

See also:: RemoveFilter(), SetFilterList()

virtual status_t BView::AllArchived ( BMessage * into ) const [virtual]

Method relating to the use of BArchiver.

This hook function is called once the first BArchiver that was created in an archiving session is either destroyed, or has its Finish() method called. Implementations of this method can be used, in conjunction with BArchiver::IsArchived(), to reference objects in your archive that you do not own, depending on whether or not those objects were archived by their owners. Implementations of this method should call the implementation of their parent class, the same as for the Archive() method.

Warning:: To guarantee that your AllArchived() method will be called during archival, you must create a BArchiver object in your Archive() implementation.; You should archive any objects you own in your Archive() method implementation, and NOT your AllArchived() method.

See also:: BArchiver BArchiver::Finish()

Reimplemented from BArchivable.

virtual status_t BView::AllUnarchived ( const BMessage * archive ) [virtual]

Method relating to the use of BUnarchiver.

This hook function is called triggered in the BUnarchiver::Finish() method. In this method, you can rebuild references to objects that may be direct children of your object, or may be children of other objects. Implementations of this method should call the implementation of their parent class, the same as for the Archive() method.

Warning:: To guarantee that your AllUnarchived() method will be called during unarchival, you must create a BUnarchiver object in your archive constructor.

See also:: BUnarchiver, BUnarchiver::Finish()

Reimplemented from BArchivable.

virtual status_t BView::Archive	(	BMessage *	data,
		bool	deep = `true`
	)		const `[virtual]`

Archive a handler to a message.

Currently, only the name is archived. The filters, the associated looper and the observers are not stored.

Parameters:

data	The message to archive the object in.
deep	This parameter is ignored, as BHandler does not have children.

Return values:

B_OK	Archiving succeeded.
B_BAD_VALUE	The data parameter is not a valid message.

See also:: BHandler::Instantiate(BMessage *data)

Reimplemented from BHandler.

Reimplemented in BTextView, BListView, BColorControl, BDragger, BControl, BButton, BScrollView, BBox, BChannelControl, and BCheckBox.

void BView::Draw ( BRect updateRect ) [virtual]

Draws the area of the view that intersects updateRect.

Derived classes should override this method to draw their view.

Note:: This is an hook method called by the Interface Kit, you don't have to call it yourself. If you need to forcefully redraw the view consider calling Invalidate() instead.

Parameters:

updateRect The rectangular area to be drawn.

Reimplemented in BTextView, BColorControl, BListView, BBox, BDragger, BScrollView, BButton, BChannelControl, and BCheckBox.

void BView::DrawAfterChildren ( BRect r ) [virtual]

Perform any drawing that needs to be done after child view have already been drawn.

Parameters:

r	The rectangular area to be drawn.

BList * BHandler::FilterList ( ) [inherited]

Return a pointer to the list of filters.

Returns:: A pointer to the list of filters. Do not manipulate the list of filters directly, but use the methods provided by this class, in order to maintain internal consistency.

See also:: AddFilter(), RemoveFilter(), SetFilterList().

void BView::FrameMoved ( BPoint newPosition ) [virtual]

Hook method that gets called when the view is moved.

Parameters:

newPosition The point of the top left corner of the frame that the view has been moved to.

Reimplemented in BColorControl, BBox, BListView, BButton, BScrollView, BDragger, and BCheckBox.

void BView::FrameResized	(	float	newWidth,
		float	newHeight
	)		`[virtual]`

Hook method that gets called when the view is resized.

Parameters:

newWidth	The new width of the view.
newHeight	The new height of the view.

Reimplemented in BTextView, BColorControl, BButton, BListView, BScrollView, BBox, BDragger, BCheckBox, and BChannelControl.

BLayout * BView::GetLayout ( ) const

Get the layout of the view.

Returns:: The layout of the view.

void BView::GetPreferredSize	(	float *	_width,
		float *	_height
	)		`[virtual]`

Fill out the preferred width and height of the view into the _width and _height parameters.

Derived classes should override this method to set the preferred size of object.

Note:: Either the _width or _height parameter may be set to NULL if you only want to get the other one.

Parameters:

[out]	_width	Pointer to a `float` to store the width of the view.
[out]	_height	Pointer to a `float` to store the height of the view.

Reimplemented in BTextView, BListView, BBox, BColorControl, BControl, BDragger, BCheckBox, BButton, BScrollView, and BChannelControl.

static BArchivable* BView::Instantiate ( BMessage * data ) [static]

Static method to instantiate a handler from an archived message.

Returns:: A pointer to the instantiated handler, or NULL if the data is not a valid archived BHandler object.

See also:: BHandler(BMessage* data)

Reimplemented from BHandler.

Reimplemented in BTextView, BListView, BColorControl, BDragger, BControl, BBox, BButton, BScrollView, and BCheckBox.

void BView::KeyDown	(	const char *	bytes,
		int32	numBytes
	)		`[virtual]`

Hook method that is called when a keyboard key is pressed.

Parameters:

bytes	The bytes of the key combination pressed.
numBytes	The number of bytes in bytes.

Reimplemented in BTextView, BListView, BColorControl, BControl, BCheckBox, BButton, and BChannelControl.

void BView::KeyUp	(	const char *	bytes,
		int32	numBytes
	)		`[virtual]`

Hook method that is called when a keyboard key is released.

Parameters:

bytes	The bytes of the key combination pressed.
numBytes	The number of bytes in bytes.

void BLayout::LayoutInvalidated ( bool descendants = false ) [protected, virtual]

Hook method called when this layout becomes invalid. This is a good place to clear any caches your object might hold.

Reimplemented in BTextView, BScrollView, BBox, BButton, and BCheckBox.

bool BHandler::LockLooper ( ) [inherited]

Lock the looper associated with this handler.

Return values:

true	The looper is locked.
false	There was an error acquiring the lock.

See also:: LockLooperWithTimeout(), UnlockLooper()

status_t BHandler::LockLooperWithTimeout ( bigtime_t timeout ) [inherited]

Lock the looper associated with this handler, with a time out value.

Parameters:

timeout The time to wait for acquiring the lock in microseconds. You may also use B_INFINITE_TIMEOUT, in which this method will wait as long as it takes to acquire the lock.

Return values:

B_OK	Locking succeeded.
B_BAD_VALUE	This handler is not associated with a looper (anymore).
B_TIMED_OUT	The time specified in timeout has passed without locking the looper.

See also:: LockLooper(), UnlockLooper()

BLooper * BHandler::Looper ( ) const [inherited]

Return a pointer to the looper that this handler is associated with.

Returns:: If the handler is not yet associated with a looper, it will return NULL.

See also:: BLooper::AddHandler(); LockLooper()

void BView::MakeFocus ( bool focusState = true ) [virtual]

Gives or removes focus from the control.

Parameters:

focusState true to set focus, false to remove it.

Reimplemented in BTextView, BColorControl, BListView, BBox, BDragger, BCheckBox, BButton, BControl, and BScrollView.

BSize BView::MaxSize ( ) [virtual]

Get the maximum size of the view.

Returns:: The maximum size of the view as a BSize.

See also:: BAbstractLayout::MaxSize()

Reimplemented in BTextView, BBox, BListView, BButton, BCheckBox, and BScrollView.

virtual void BView::MessageReceived ( BMessage * message ) [virtual]

Handle message that has been received by the associated looper.

This method is reimplemented by subclasses. If the messages that have been received by a looper pass through the filters, then they end up in the MessageReceived() methods.

The example below shows a very common way to handle message. Usually, this involves parsing the BMessage::what constant and then perform an action based on that.

void
ShowImageApp::MessageReceived(BMessage *message)
{
    switch (message->what) {
        case MSG_FILE_OPEN:
            fOpenPanel->Show();
            break;

        case B_CANCEL:
            // File open panel was closed,
            // start checking count of open windows.
            StartPulse();
            break;
        
        default:
            // We do not handle this message, pass it on to the base class.
            BApplication::MessageReceived(message); 
            break;
    }
}

If your handler cannot process this message, you should pass it on to the base class. Eventually, it will reach the base implementation, which will reply with B_MESSAGE_NOT_UNDERSTOOD.

Attention:: If you want to keep or manipulate the message, have a look at BLooper::DetachCurrentMessage() to receive ownership of the message.

Parameters:

message The message that needs to be handled.

Reimplemented from BHandler.

Reimplemented in BTextView, BListView, BScrollView, BBox, BColorControl, BChannelControl, BDragger, BButton, BCheckBox, and BControl.

BSize BView::MinSize ( ) [virtual]

Get the minimum size of the view.

Returns:: The minimum size of the view as a BSize.

See also:: BAbstractLayout::MinSize()

Reimplemented in BTextView, BBox, BListView, BButton, BCheckBox, and BScrollView.

void BView::MouseDown ( BPoint where ) [virtual]

Hook method that is called when a mouse button is pressed.

Parameters:

where The point on the screen where to mouse pointer is when the mouse button is pressed.

Reimplemented in BTextView, BListView, BScrollView, BBox, BColorControl, BCheckBox, BControl, BDragger, BButton, and BChannelControl.

void BView::MouseUp ( BPoint where ) [virtual]

Hook method that is called when a mouse button is released.

Parameters:

where The point on the screen where to mouse pointer is when the mouse button is released.

Reimplemented in BTextView, BListView, BColorControl, BScrollView, BBox, BCheckBox, BControl, BButton, and BDragger.

const char * BHandler::Name ( ) const [inherited]

Return the name of this handler.

See also:: SetName()

BHandler * BHandler::NextHandler ( ) const [inherited]

Return the next hander in the chain to which the message is passed on.

See also:: SetNextHandler()

status_t BView::Perform	(	perform_code	code,
		void *	_data
	)		`[virtual]`

Perform some action. (Internal Method)

The following perform codes are recognized:

PERFORM_CODE_MIN_SIZE:
PERFORM_CODE_MAX_SIZE:
PERFORM_CODE_PREFERRED_SIZE:
PERFORM_CODE_LAYOUT_ALIGNMENT:
PERFORM_CODE_HAS_HEIGHT_FOR_WIDTH:
PERFORM_CODE_GET_HEIGHT_FOR_WIDTH:
PERFORM_CODE_SET_LAYOUT:
PERFORM_CODE_INVALIDATE_LAYOUT:
PERFORM_CODE_DO_LAYOUT:
PERFORM_CODE_GET_TOOL_TIP_AT:
PERFORM_CODE_ALL_UNARCHIVED:
PERFORM_CODE_ALL_ARCHIVED:

Parameters:

code	The perform code.
_data	A pointer to store some data.

Returns:: A status code.

See also:: BHandler::Perform()

Reimplemented from BHandler.

Reimplemented in BTextView, BListView, BScrollView, BControl, BCheckBox, BBox, BButton, and BDragger.

BSize BView::PreferredSize ( ) [virtual]

Get the preferred size of the view.

Returns:: The preferred size of the view as a BSize.

See also:: BAbstractLayout::PreferredSize()

Reimplemented in BTextView, BBox, BListView, BButton, BCheckBox, and BScrollView.

void BView::Pulse ( ) [virtual]

Hook method that gets invoked when the view receives a B_PULSE message.

An action is performed each time the App Server calls the Pulse() method. The pulse rate is set by SetPulseRate(). You can implement Pulse() to do anything you want. The default version does nothing. The pulse granularity is no better than once per 100,000 microseconds.

See also:: SetPulseRate()

Reimplemented in BTextView.

bool BHandler::RemoveFilter ( BMessageFilter * filter ) [virtual, inherited]

Remove filter from the filter list.

If the handler is associated with a looper, this looper needs to be locked in order for this operation to succeed.

Note that the filter is not deleted, merely removed from the list. You need to take care of the memory yourself.

Return values:

true	The filter was in the filter list and is removed.
false	The filter was not found in the filter list.

See also:: AddFilter(), FilterList()

void BHandler::SendNotices	(	uint32	what,
		const BMessage *	msg = `NULL`
	)		`[virtual, inherited]`

Emit a state change to the observers.

The actual state (specified by what) will not be transmitted. This is merely for internal bookkeeping. It is not entirely unimaginable that you still want to inform the observers of what actually took place. You can use the msg to transmit this, and any other data you want. Note that the message will be copied and slightly altered: the what member of the message will be B_OBSERVER_NOTICE_CHANGE, and the what constant you specified will be stored in the B_OBSERVE_ORIGINAL_WHAT label.

Parameters:

what	The identifier of the state.
msg	Any data associated with the state change. You retain ownership of this data, so make sure you dispose it when you are done.

void BView::SetExplicitAlignment ( BAlignment alignment )

Set this item's explicit alignment, to be used by Alignment().

See also:: BAbstractLayout::SetExplicitAlignment()

void BView::SetExplicitMaxSize ( BSize size )

Set this item's explicit max size, to be used by MaxSize().

See also:: BAbstractLayout::SetExplicitMaxSize()

void BView::SetExplicitMinSize ( BSize size )

Set this item's explicit min size, to be used by MinSize().

See also:: BAbstractLayout::SetExplicitMinSize()

void BView::SetExplicitPreferredSize ( BSize size )

Set this item's explicit preferred size, to be used by PreferredSize().

See also:: BAbstractLayout::SetExplicitPreferredSize()

void BHandler::SetFilterList ( BList * filters ) [virtual, inherited]

Set the internal list of filters to filters.

If the handler is associated with a looper, this looper needs to be locked in order for this operation to succeed.

The internal list will be replaced with the new list of filters. All the existing filters will be deleted.

See also:: AddFilter(), FilterList()

void BView::SetLayout ( BLayout * layout ) [virtual]

Set the layout of the view.

Parameters:

layout The layout to set.

Reimplemented in BColorControl.

void BHandler::SetName ( const char * name ) [inherited]

Set or change the name of this handler.

See also:: Name()

void BHandler::SetNextHandler ( BHandler * handler ) [virtual, inherited]

Set the next handler in the chain that the message is passed on to if this handler cannot process it.

This method has three requirements:

This handler should belong to a looper.
The looper needs to be locked. See LockLooper().
The handler that you pass must be associated with the same looper.

Failure to meet any of these requirements will result in your application crashing.

By default, the handlers are chained in order that they were associated to a looper with BLooper::AddHander().

See also:: NextHandler()

status_t BHandler::StartWatching	(	BMessenger	target,
		uint32	what
	)		`[inherited]`

Subscribe this handler to watch a specific state change of a target.

Use this method to subscribe messengers to watch state changes in this handler, this also means that observers from other teams can be subscribed.

// Handler B watches Handler A
BHandler A, B;
BMessenger messengerA(&A)

B.StartWatching(messengerA, kNetworkConnection);

Parameters:

target	The messenger from which the notifications would be received.
what	The state that needs to be watched.

Returns:: During the call of this method, a notification will be transmitted using the target. If this works, then this method will return B_OK.

See also:: StartWatchingAll(BMessenger), StopWatching(BMessenger, uint32)

status_t BHandler::StartWatching	(	BHandler *	observer,
		uint32	what
	)		`[inherited]`

Subscribe an observer for a specific state change of this handler.

Use this method to subscribe observers to watch this handler. State changes of this handler that match the what argument, will be sent.

// Handler B wants to observe Handler A
BHandler A, B;

A.StartWatching(&B, kNetworkConnection);

Since pointers to handlers can only exist in the local namespace, have a look at StartWatching(BMessenger, uint32) for inter-team watching.

Parameters:

observer	The observer for this handler.
what	The state that needs to be watched.

Returns:: During the call of this method, a notification will be transmitted using the observer. If this works, then this method will return B_OK.

See also:: StartWatchingAll(BHandler*), StopWatching(BHandler*, uint32)

status_t BHandler::StartWatchingAll ( BMessenger target ) [inherited]

Subscribe this handler to watch a target for all events.

This method performs the same task as StartWatching(BMessenger, uint32), but it will subscribe to all the state changes the target knows.

See also:: StartWatching(BMessenger, uint32), StopWatchingAll(BMessenger)

status_t BHandler::StartWatchingAll ( BHandler * observer ) [inherited]

Subscribe an observer for a all state changes.

This method performs the same task as StartWatching(BHandler, uint32), but it will subscribe the observer to all the state changes this handler tracks.

See also:: StartWatching(BHandler*, uint32), StopWatchingAll(BHandler*)

status_t BHandler::StopWatching	(	BMessenger	target,
		uint32	what
	)		`[inherited]`

Unsubscribe this handler from watching a specific state.

This method will unsubscribe this handler from watching a specific event in a target.

See also:: StartWatching(BMessenger, uint32)

status_t BHandler::StopWatching	(	BHandler *	handler,
		uint32	what
	)		`[inherited]`

Unsubscribe an observer from watching a specific state.

This method will unsubscribe the handler from watching a specific event.

See also:: StartWatching(BHandler*, uint32)

status_t BHandler::StopWatchingAll ( BMessenger target ) [inherited]

Unsubscribe this handler from watching all states.

This method will unsubscribe the target from watching all state changes.

See also:: StartWatchingAll(BMessenger)

status_t BHandler::StopWatchingAll ( BHandler * handler ) [inherited]

Unsubscribe an observer from watching all states.

This method will unsubscribe the handler from watching all state changes.

See also:: StartWatchingAll(BHandler*)

void BView::WindowActivated ( bool state ) [virtual]

Hook method that is called when the attached window becomes activated or deactivated.

Parameters:

state true if the window becomes activated, false if the window becomes deactivated.

Reimplemented in BTextView, BColorControl, BListView, BBox, BButton, BScrollView, BCheckBox, and BControl.

Public Member Functions

Static Public Member Functions

Protected Member Functions

Detailed Description

Member Function Documentation