BLayout subclass providing convenience methods for derived implementations. More...

Inherited by BCardLayout, and BTwoDimensionalLayout.

Public Member Functions
virtual BAlignment	Alignment ()

virtual status_t	Archive (BMessage *into, bool deep=true) const
	Archives this layout into archive. If deep is true, also archives the items in this layout, calling ItemArchived() for each one.

virtual BRect	Frame ()
	Return the bounding frame of this item.

virtual bool	IsVisible ()
	Return the current local visibility of this item. If an item is not visible, it will not be given space by the BLayout it resides in.

virtual BSize	MaxSize ()

virtual BSize	MinSize ()

virtual status_t	Perform (perform_code d, void *arg)
	Perform some action (Internal method defined for binary compatibility purposes).

virtual BSize	PreferredSize ()

virtual void	SetExplicitAlignment (BAlignment alignment)
	Set this item's explicit alignment, to be used in Alignment().

virtual void	SetExplicitMaxSize (BSize size)
	Set this item's explicit max size, to be used in MaxSize().

virtual void	SetExplicitMinSize (BSize size)
	Set this item's explicit min size, to be used in MinSize().

virtual void	SetExplicitPreferredSize (BSize size)
	Set this item's explicit preferred size, to be used in PreferredSize().

virtual void	SetFrame (BRect frame)
	Set the bounding frame of this item.

virtual void	SetVisible (bool visible)
	Set the local visibility of this item.

Constructors
	BAbstractLayout ()
	Construct a BAbstractLayout.

	BAbstractLayout (BMessage *from)
	Archive constructor.

Hook Methods
virtual BSize	BaseMinSize ()
	Method to be implemented in derived classes return the minimum size constraint for this BAbstractLayout.

virtual BSize	BaseMaxSize ()
	Method to be implemented in derived classes return the maximum size constraint for this BAbstractLayout.

virtual BSize	BasePreferredSize ()
	Method to be implemented in derived classes return the preferred size constraint for this BAbstractLayout.

virtual BAlignment	BaseAlignment ()
	Method to be implemented in derived classes return the preferred alignment for this BAbstractLayout.

Public Member Functions inherited from BLayout
	BLayout ()
	Default constructor.

	BLayout (BMessage *archive)
	Archive constructor.

virtual	~BLayout ()
	Destructor, deletes all BLayoutItem's that this layout manages, and detaches from this BLayout's owner view if there is one.

virtual status_t	Perform (perform_code d, void *arg)
	Perform some action (Internal method defined for binary compatibility purposes).

BView *	Owner () const
	Returns the Owner of this layout, i.e. the view this layout manages.

BView *	TargetView () const
	Returns the target view of this layout.

virtual BView *	View ()
	Returns the same BView* as BLayout::Owner(), this method is inherited from BLayoutItem.

virtual BLayoutItem *	AddView (BView *child)
	Creates a BLayoutItem to represent a BView, and adds that item to this layout.

virtual BLayoutItem *	AddView (int32 index, BView *child)
	Creates a BLayoutItem to represent child, and adds that item at index to this layout. child is added to this BLayout's target view.

virtual bool	AddItem (BLayoutItem *item)
	Adds a BLayoutItem to this layout, and adds the BView it represents to this BLayout's target view.

virtual bool	AddItem (int32 index, BLayoutItem *item)
	Adds item to this layout, and adds the BView item represents to this BLayout's target view.

virtual bool	RemoveView (BView *child)
	Removes and deletes all BLayoutItem representing a BView from this layout.

virtual bool	RemoveItem (BLayoutItem *item)
	Removes a BLayoutItem from this layout, and also removes the view it represents from this BLayout's target view.

virtual BLayoutItem *	RemoveItem (int32 index)
	Remove the BLayoutItem at index.

BLayoutItem *	ItemAt (int32 index) const
	Get the BLayoutItem at index. Returns `NULL` if index is out of bounds.

int32	CountItems () const
	Get the number of BLayoutItem s in this layout.

int32	IndexOfItem (const BLayoutItem *item) const
	Get the index of a BLayoutItem in this layout.

int32	IndexOfView (BView *child) const
	Get the index of child in this layout.

virtual void	Relayout (bool immediate=false)
	Request this BLayout to reposition and resize its items as required.

void	LayoutItems (bool force=false)
	If there is no layout currently ongoing, and force is `false`, creates a new BLayoutContext and calls the DoLayout() method of this BLayout and any BLayout's nested in this BLayout.

BLayoutContext *	LayoutContext () const
	Returns the BLayoutContext this BLayout is currently operating in, or `NULL`.

bool	AncestorsVisible () const
	Get the visibility of the ancestors of this layout.

BRect	LayoutArea ()
	Returns the on-screen area this layout has received to lay out its items in.

virtual void	InvalidateLayout (bool children=false)
	Invalidate this layout and any cached data this layout has relating to positioning and sizing of its items.

void	RequireLayout ()
	Flag this layout as stale, i.e. any cached data may still be valid, but the items need to be repositioned or resized.

bool	IsValid ()
	Returns whether this layout has been invalidated (via BLayout::InvalidateLayout()) and has not yet been validated (by doing a layout, or by its ResetLayoutInvalidation() method.

void	EnableLayoutInvalidation ()
	Re-enable layout invalidation after a call to DisableLayoutInvalidation().

void	DisableLayoutInvalidation ()
	Disable layout invalidation notifications, i.e. calls to this object's InvalidateLayout() method.

Public Member Functions inherited from BLayoutItem
	BLayoutItem (BMessage *from)
	Archive constructor.

virtual status_t	Archive (BMessage *into, bool deep=true) const
	Archive the object into a BMessage.

BLayout *	Layout () const
	Returns the BLayout this BLayoutItem resides in.

virtual status_t	Perform (perform_code d, void *arg)
	Perform some action (Internal method defined for binary compatibility purposes).

bool	RemoveSelf ()
	Remove this layout item from the BLayout it is a part of.

virtual BView *	View ()
	Return the BView this item is representing, or `NULL` if it does not represent any view.

virtual bool	HasHeightForWidth ()
	Returns whether or not this BLayoutItem's height constraints are dependent on its width.

virtual void	GetHeightForWidth (float width, float min, float max, float *preferred)
	Get this BLayoutItem's height constraints for a given width.

void	SetExplicitSize (BSize size)
	Set the explicity size to size.

void	AlignInFrame (BRect frame)
	Position this BLayoutItem within frame, given the value returned by Alignment(), and the size constraints for this item.

void *	LayoutData () const
	Retrieve arbitrary data attached to this BLayoutItem.

void	SetLayoutData (void *data)
	Attach arbitrary data to this BLayoutItem.

Public Member Functions inherited from BArchivable
	BArchivable ()
	Constructor. Does nothing.

	BArchivable (BMessage *from)
	Constructor. Does important behind-the-scenes work in the unarchiving process.

virtual	~BArchivable ()
	Destructor. Does nothing.

virtual status_t	AllArchived (BMessage *archive) const
	Method relating to the use of `BArchiver`.

virtual status_t	AllUnarchived (const BMessage *archive)
	Method relating to the use of `BUnarchiver`.

virtual status_t	Archive (BMessage *into, bool deep=true) const
	Archive the object into a BMessage.

virtual status_t	Perform (perform_code d, void *arg)
	Perform some action (Internal method defined for binary compatibility purposes).

Protected Member Functions
virtual status_t	AllArchived (BMessage *archive) const
	Method relating to the use of `BArchiver`.

virtual status_t	AllUnarchived (const BMessage *from)
	Unarchives the BLayoutItem's for this layout, calling ItemUnarchived() for each one.

virtual void	AncestorVisibilityChanged (bool shown)
	Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

virtual void	AttachedToLayout ()
	Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

virtual void	DetachedFromLayout (BLayout *layout)
	Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

virtual bool	ItemAdded (BLayoutItem *item, int32 atIndex)
	Hook method called when item is added to this layout.

virtual status_t	ItemArchived (BMessage into, BLayoutItem item, int32 index) const
	Hook for derived classes to add data specific to item to the into BMessage. item resides at index.

virtual void	ItemRemoved (BLayoutItem *item, int32 fromIndex)
	Hook method called when item is removed from this layout.

virtual status_t	ItemUnarchived (const BMessage from, BLayoutItem item, int32 index)
	Hook for derived classes to retrieve data specific to item from the from BMessage. item resides at index.

virtual void	LayoutInvalidated (bool children)

virtual void	OwnerChanged (BView *was)
	Hook method called when this layout is attached to a BView.

Protected Member Functions inherited from BLayout
virtual status_t	AllArchived (BMessage *archive) const
	Method relating to the use of `BArchiver`.

virtual void	DoLayout ()=0
	Implemented by derived classes to position and resize the items in this layout.

void	VisibilityChanged (bool show)
	Method to be called by derived classes in their SetVisible() implementation. Calls AncestorVisibilityChanged() on the items in this BLayout.

void	ResetLayoutInvalidation ()
	Reset layout invalidation, causing InvalidateLayout calls to proceed again. This method should be called once any cached data has been validated, or updated to valid values.

virtual status_t	AllArchived (BMessage *into) const
	Method relating to the use of `BArchiver`.

virtual status_t	AllUnarchived (const BMessage *from)
	Method relating to the use of `BUnarchiver`.

Hook methods

Additional Inherited Members
Static Public Member Functions inherited from BArchivable
static BArchivable *	Instantiate (BMessage *archive)
	Static member to restore objects from messages.

Detailed Description

BLayout subclass providing convenience methods for derived implementations.

Since: Haiku R1

This class is designed to reduce the amount of boilerplate code required to write a BLayout subclass. In most cases, you classes should derive from BAbstractLayout rather than BLayout.

When a BAbstractLayout is attached to a BView, many of the methods provided by the BAbstractLayout class are forwarded to the BAbstractLayout's owner BView. When a BAbstractLayout is viewless, these methods are handled locally.

Warning: This class is not yet finalized, if you use it in your software assume that it will break some time in the future.

Constructor & Destructor Documentation

◆ BAbstractLayout() [1/2]

BAbstractLayout::BAbstractLayout ( )

Construct a BAbstractLayout.

Since: Haiku R1

◆ BAbstractLayout() [2/2]

BAbstractLayout::BAbstractLayout ( BMessage * from )

Archive constructor.

Since: Haiku R1

Member Function Documentation

◆ Alignment()

BAlignment BAbstractLayout::Alignment ( )

virtual

Returns the requested alignment for this item.

The value returned from this method is used in BLayoutItem::AlignInFrame(), which BLayouts use to position and resize items. In a vertical BGroupLayout, for example, although each item recieves the same horizontal area, each item can use that area differently, aligning to the left, right or center for example.

Since: Haiku R1

The return value for this method is composed (using BLayoutUtils::ComposeAlignment()) from the values returned by BaseAlignment() and ExplicitAlignment()

Since: Haiku R1

Implements BLayoutItem.

◆ AllArchived()

virtual status_t BAbstractLayout::AllArchived ( BMessage * into ) const

protectedvirtual

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()

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ AllUnarchived()

virtual status_t BAbstractLayout::AllUnarchived ( const BMessage * from )

protectedvirtual

Unarchives the BLayoutItem's for this layout, calling ItemUnarchived() for each one.

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ AncestorVisibilityChanged()

virtual void BAbstractLayout::AncestorVisibilityChanged ( bool shown )

protectedvirtual

Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

Since: Haiku R1

Reimplemented from BLayout.

◆ Archive()

virtual status_t BAbstractLayout::Archive	(	BMessage *	archive,
		bool	deep = `true`
	)		const

virtual

Archives this layout into archive. If deep is true, also archives the items in this layout, calling ItemArchived() for each one.

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ AttachedToLayout()

virtual void BAbstractLayout::AttachedToLayout ( )

protectedvirtual

Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

Since: Haiku R1

Reimplemented from BLayout.

◆ BaseMaxSize()

BSize BAbstractLayout::BaseMaxSize ( )

virtual

Method to be implemented in derived classes return the maximum size constraint for this BAbstractLayout.

Since: Haiku R1

Reimplemented in BCardLayout, and BTwoDimensionalLayout.

◆ BaseMinSize()

BSize BAbstractLayout::BaseMinSize ( )

virtual

Method to be implemented in derived classes return the minimum size constraint for this BAbstractLayout.

Since: Haiku R1

Reimplemented in BCardLayout, and BTwoDimensionalLayout.

◆ BasePreferredSize()

BSize BAbstractLayout::BasePreferredSize ( )

virtual

Method to be implemented in derived classes return the preferred size constraint for this BAbstractLayout.

Since: Haiku R1

Reimplemented in BCardLayout, and BTwoDimensionalLayout.

◆ DetachedFromLayout()

virtual void BAbstractLayout::DetachedFromLayout ( BLayout * layout )

protectedvirtual

Hook method inherited from BLayoutItem, classes derived from BLayout must include the BLayout version of this method in their implementation.

Parameters

layout The BLayout that this BLayout was detached from.

Since: Haiku R1

Reimplemented from BLayout.

◆ Frame()

virtual BRect BAbstractLayout::Frame ( )

virtual

Return the bounding frame of this item.

The returned BRect is in the coordinate system of the target view of the BLayout this item belongs to.

Since: Haiku R1

Implements BLayoutItem.

◆ IsVisible()

virtual bool BAbstractLayout::IsVisible ( )

virtual

Return the current local visibility of this item. If an item is not visible, it will not be given space by the BLayout it resides in.

A simple implementation would return the last thing passed to SetVisible(). A more complex implementation may deal with a BView that could be hidden in any number of ways.

Since: Haiku R1

Implements BLayoutItem.

◆ ItemAdded()

virtual bool BAbstractLayout::ItemAdded	(	BLayoutItem *	item,
		int32	atIndex
	)

protectedvirtual

Hook method called when item is added to this layout.

Parameters

item	The BLayoutItem that is being added.
atIndex	The index of the BLayoutItem.

Returns: true on succcess, false if item will not be added.

Note: This is a good time to allocate data for a BLayoutItem and attach it to item via BLayoutItem::SetLayoutData().

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, and BGroupLayout.

◆ ItemArchived()

virtual status_t BAbstractLayout::ItemArchived	(	BMessage *	into,
		BLayoutItem *	item,
		int32	index
	)		const

protectedvirtual

Hook for derived classes to add data specific to item to the into BMessage. item resides at index.

Note: The same archive is passed to BLayout::ItemArchived() for all items, so any data added for each item will be stored in an array.

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ ItemRemoved()

virtual void BAbstractLayout::ItemRemoved	(	BLayoutItem *	item,
		int32	fromIndex
	)

protectedvirtual

Hook method called when item is removed from this layout.

Parameters

item	The BLayoutItem being removed.
fromIndex	The index where item used to reside.

When this hook is called, item is not yet completely removed. It can no longer be accessed with LayoutItemAt(), nor does it contribute to the value of CountItems(), but the item has not yet had its ItemDetached() hook called.

Note: This is a good time to delete the data you've attached to item via BLayoutItem::SetLayoutData().

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, and BGroupLayout.

◆ ItemUnarchived()

virtual status_t BAbstractLayout::ItemUnarchived	(	const BMessage *	from,
		BLayoutItem *	item,
		int32	index
	)

protectedvirtual

Hook for derived classes to retrieve data specific to item from the from BMessage. item resides at index.

Note: The same archive is passed to BLayout::ItemArchived() for all items, so any data added for each item will be stored in an array. You should pass index to the BMessage methods you will be using in this method.

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ LayoutInvalidated()

virtual void BAbstractLayout::LayoutInvalidated ( bool children )

protectedvirtual

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

Parameters

children Whether or not child layouts have also been invalidated.

Since: Haiku R1

Reimplemented from BLayout.

Reimplemented in BCardLayout, and BTwoDimensionalLayout.

◆ MaxSize()

BSize BAbstractLayout::MaxSize ( )

virtual

Returns the maximum desirable size for this item.

Since: Haiku R1

The return value for this method is composed (using BLayoutUtils::ComposeSize()) from the values returned by BaseMaxSize() and ExplicitMaxSize().

Since: Haiku R1

Implements BLayoutItem.

◆ MinSize()

BSize BAbstractLayout::MinSize ( )

virtual

Returns the minimum desirable size for this item.

Since: Haiku R1; Haiku R1

The return value for this method is composed (using BLayoutUtils::ComposeSize()) from the values returned by BaseMinSize() and ExplicitMinSize().

Implements BLayoutItem.

◆ OwnerChanged()

virtual void BAbstractLayout::OwnerChanged ( BView * was )

protectedvirtual

Hook method called when this layout is attached to a BView.

Parameters

was	The previous owner of this BLayout, for new BLayout s, this will be `NULL`.

Since: Haiku R1

Reimplemented from BLayout.

◆ Perform()

virtual status_t BAbstractLayout::Perform	(	perform_code	d,
		void *	arg
	)

virtual

Perform some action (Internal method defined for binary compatibility purposes).

Reimplemented from BLayout.

Reimplemented in BCardLayout, BGridLayout, BGroupLayout, and BTwoDimensionalLayout.

◆ PreferredSize()

BSize BAbstractLayout::PreferredSize ( )

virtual

Returns the preferred size for this item.

Since: Haiku R1

The return value for this method is composed (using BLayoutUtils::ComposeSize()) from the values returned by BasePreferredSize() and ExplicitPreferredSize().

Since: Haiku R1

Implements BLayoutItem.

◆ SetExplicitAlignment()

virtual void BAbstractLayout::SetExplicitAlignment ( BAlignment alignment )

virtual

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

Since: Haiku R1

Implements BLayoutItem.

◆ SetExplicitMaxSize()

virtual void BAbstractLayout::SetExplicitMaxSize ( BSize size )

virtual

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

Since: Haiku R1

Implements BLayoutItem.

◆ SetExplicitMinSize()

virtual void BAbstractLayout::SetExplicitMinSize ( BSize size )

virtual

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

This forces the minimal size for the item and overrides any constraints that would normally be used to compute it. Most importantly, the minimal size of children is ignored, so setting this can lead to the children not fitting the view.

Since: Haiku R1

Implements BLayoutItem.

◆ SetExplicitPreferredSize()

virtual void BAbstractLayout::SetExplicitPreferredSize ( BSize size )

virtual

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

Since: Haiku R1

Implements BLayoutItem.

◆ SetFrame()

virtual void BAbstractLayout::SetFrame ( BRect frame )

virtual

Set the bounding frame of this item.

frame is in the coordinate system of the target view of the BLayout that this item belongs to.

Since: Haiku R1

Implements BLayoutItem.

Reimplemented in BTwoDimensionalLayout.

◆ SetVisible()

virtual void BAbstractLayout::SetVisible ( bool visible )

virtual

Set the local visibility of this item.

Since: Haiku R1

Implements BLayoutItem.

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ BAbstractLayout() [1/2]

◆ BAbstractLayout() [2/2]

Member Function Documentation

◆ Alignment()

◆ AllArchived()

◆ AllUnarchived()

◆ AncestorVisibilityChanged()

◆ Archive()

◆ AttachedToLayout()

◆ BaseMaxSize()

◆ BaseMinSize()

◆ BasePreferredSize()

◆ DetachedFromLayout()

◆ Frame()

◆ IsVisible()

◆ ItemAdded()

◆ ItemArchived()

◆ ItemRemoved()

◆ ItemUnarchived()

◆ LayoutInvalidated()

◆ MaxSize()

◆ MinSize()

◆ OwnerChanged()

◆ Perform()

◆ PreferredSize()

◆ SetExplicitAlignment()

◆ SetExplicitMaxSize()

◆ SetExplicitMinSize()

◆ SetExplicitPreferredSize()

◆ SetFrame()

◆ SetVisible()