Graphics.UI.Gtk.Abstract.Container

Base class for widgets which contain other widgets

Detail

A Gtk+ user interface is constructed by nesting widgets inside widgets. Container widgets are the inner nodes in the resulting tree of widgets: they contain other widgets. So, for example, you might have a Window containing a Frame containing a Label. If you wanted an image instead of a textual label inside the frame, you might replace the Label widget with a Image widget.

There are two major kinds of container widgets in Gtk+. Both are subclasses of the abstract Container base class.

The first type of container widget has a single child widget and derives from Bin. These containers are decorators, which add some kind of functionality to the child. For example, a Button makes its child into a clickable button; a Frame draws a frame around its child and a Window places its child widget inside a top-level window.

The second type of container can have more than one child; its purpose is to manage layout. This means that these containers assign sizes and positions to their children. For example, a HBox arranges its children in a horizontal row, and a Table arranges the widgets it contains in a two-dimensional grid.

To fulfill its task, a layout container must negotiate the size requirements with its parent and its children. This negotiation is carried out in two phases, size requisition and size allocation.

Size Requisition

The size requisition of a widget is it's desired width and height. This is represented by a Requisition.

How a widget determines its desired size depends on the widget. A Label, for example, requests enough space to display all its text. Container widgets generally base their size request on the requisitions of their children.

The size requisition phase of the widget layout process operates top-down. It starts at a top-level widget, typically a Window. The top-level widget asks its child for its size requisition by calling widgetSizeRequest. To determine its requisition, the child asks its own children for their requisitions and so on. Finally, the top-level widget will get a requisition back from its child.

Size Allocation

When the top-level widget has determined how much space its child would like to have, the second phase of the size negotiation, size allocation, begins. Depending on its configuration (see windowSetResizable), the top-level widget may be able to expand in order to satisfy the size request or it may have to ignore the size request and keep its fixed size. It then tells its child widget how much space it gets by calling widgetSizeAllocate. The child widget divides the space among its children and tells each child how much space it got, and so on. Under normal circumstances, a Window will always give its child the amount of space the child requested.

A child's size allocation is represented by an Allocation. This contains not only a width and height, but also a position (i.e. X and Y coordinates), so that containers can tell their children not only how much space they have gotten, but also where they are positioned inside the space available to the container.

Widgets are required to honor the size allocation they receive; a size request is only a request, and widgets must be able to cope with any size.

Child attributes

Container introduces child attributes - these are object attributes that are not specific to either the container or the contained widget, but rather to their relation. Typical examples of child attributes are the position or pack-type of a widget which is contained in a Box.

The Container class does not itself define any child attributes, they are defined (and documented) by the various Container subclasses.

Child attributes can be set or obtained in a similar way to ordinary attributes. So ordinary attributes are set like so:

set object [ attr := value ]

Whereas child attributes take the child object as a parameter:

set container [ attr child := value ]

And similarily for getting a child attribute's value:

value <- get container (attr child)

Class Hierarchy

| GObject
| +----Object
| +----Widget
| +----Container
| +----Bin
| +----Box
| +----CList
| +----Fixed
| +----Paned
| +----IconView
| +----Layout
| +----List
| +----MenuShell
| +----Notebook
| +----Socket
| +----Table
| +----TextView
| +----Toolbar
| +----TreeView

Types

data Container

Instances

Eq Container

Ord Container

GObjectClass Container

ContainerClass Container

WidgetClass Container

class WidgetClass o => ContainerClass o

Instances

ContainerClass TreeView

ContainerClass Toolbar

ContainerClass TextView

ContainerClass Table

ContainerClass Notebook

ContainerClass MenuBar

ContainerClass RecentChooserMenu

ContainerClass Menu

ContainerClass MenuShell

ContainerClass Layout

ContainerClass IconView

ContainerClass VPaned

ContainerClass HPaned

ContainerClass Paned

ContainerClass Fixed

ContainerClass Grid

ContainerClass Statusbar

ContainerClass FileChooserButton

ContainerClass InfoBar

ContainerClass HBox

ContainerClass FileChooserWidget

ContainerClass FontSelection

ContainerClass ColorSelection

ContainerClass RecentChooserWidget

ContainerClass VBox

ContainerClass VButtonBox

ContainerClass HButtonBox

ContainerClass ButtonBox

ContainerClass Box

ContainerClass SeparatorToolItem

ContainerClass RadioToolButton

ContainerClass ToggleToolButton

ContainerClass MenuToolButton

ContainerClass ToolButton

ContainerClass ToolItem

ContainerClass ComboBox

ContainerClass Expander

ContainerClass Viewport

ContainerClass ScrolledWindow

ContainerClass HandleBox

ContainerClass EventBox

ContainerClass MessageDialog

ContainerClass FontSelectionDialog

ContainerClass FileChooserDialog

ContainerClass ColorSelectionDialog

ContainerClass AboutDialog

ContainerClass Dialog

ContainerClass OffscreenWindow

ContainerClass Assistant

ContainerClass Window

ContainerClass Overlay

ContainerClass SeparatorMenuItem

ContainerClass ImageMenuItem

ContainerClass TearoffMenuItem

ContainerClass RadioMenuItem

ContainerClass CheckMenuItem

ContainerClass MenuItem

ContainerClass FontButton

ContainerClass ColorButton

ContainerClass RadioButton

ContainerClass CheckButton

ContainerClass ToggleButton

ContainerClass LinkButton

ContainerClass VolumeButton

ContainerClass ScaleButton

ContainerClass Button

ContainerClass AspectFrame

ContainerClass Frame

ContainerClass Alignment

ContainerClass Bin

ContainerClass ToolItemGroup

ContainerClass ToolPalette

ContainerClass Container

ContainerClass Plug

ContainerClass Socket

castToContainer :: GObjectClass obj => obj -> Container

gTypeContainer :: GType

toContainer :: ContainerClass o => o -> Container

type ContainerForeachCB = Widget -> IO ()

A function that is invoked for all widgets in a container.

data ResizeMode

Resize mode, for containers

• ResizeParent Pass resize request to the parent
• ResizeQueue Queue resizes on this widget
• ResizeImmediate Perform the resizes now

Constructors

ResizeParent

ResizeQueue

ResizeImmediate

Instances

Enum ResizeMode

Eq ResizeMode

Show ResizeMode

Methods

containerAdd

Arguments

:: (ContainerClass self, WidgetClass widget)

=> self

-> widget

widget - a widget to be placed inside container

-> IO ()

Adds widget to the container. Typically used for simple containers such as Window, Frame, or Button; for more complicated layout containers such as Box or Table, this function will pick default packing parameters that may not be correct. So consider functions such as boxPackStart and tableAttach as an alternative to containerAdd in those cases. A widget may be added to only one container at a time; you can't place the same widget inside two different containers.

containerRemove

Arguments

:: (ContainerClass self, WidgetClass widget)

=> self

-> widget

widget - a current child of container

-> IO ()

Removes widget from container. widget must be inside container.

containerForeach :: ContainerClass self => self -> ContainerForeachCB -> IO ()

Maps callback over each non-internal child of container. See containerForall for details on what constitutes an "internal" child. Most applications should use containerForeach, rather than containerForall.

containerForall

Arguments

:: ContainerClass self

=> self

-> ContainerForeachCB

callback - a callback

-> IO ()

Maps callback over each child of container, including children that are considered "internal" (implementation details of the container). "Internal" children generally weren't added by the user of the container, but were added by the container implementation itself. Most applications should use containerForeach, rather than containerForall.

containerGetChildren :: ContainerClass self => self -> IO [Widget]

Returns the container's non-internal children. See containerForall for details on what constitutes an "internal" child.

containerSetFocusChild

Arguments

:: (ContainerClass self, WidgetClass child)

=> self

-> child

child

-> IO ()

Give the focus to a specific child of the container.

containerSetFocusChain

Arguments

:: ContainerClass self

=> self

-> [Widget]

focusableWidgets - the new focus chain.

-> IO ()

Sets a focus chain, overriding the one computed automatically by Gtk+.

In principle each widget in the chain should be a descendant of the container, but this is not enforced by this method, since it's allowed to set the focus chain before you pack the widgets, or have a widget in the chain that isn't always packed. The necessary checks are done when the focus chain is actually traversed.

containerGetFocusChain :: ContainerClass self => self -> IO (Maybe [Widget])

Retrieves the focus chain of the container, if one has been set explicitly. If no focus chain has been explicitly set, Gtk+ computes the focus chain based on the positions of the children. In that case the function returns Nothing.

containerUnsetFocusChain :: ContainerClass self => self -> IO ()

Removes a focus chain explicitly set with containerSetFocusChain.

containerSetFocusVAdjustment

Arguments

:: ContainerClass self

=> self

-> Adjustment

adjustment - an adjustment which should be adjusted when the focus is moved among the descendents of container

-> IO ()

Hooks up an adjustment to focus handling in a container, so when a child of the container is focused, the adjustment is scrolled to show that widget. This function sets the vertical alignment. See scrolledWindowGetVAdjustment for a typical way of obtaining the adjustment and containerSetFocusHAdjustment for setting the horizontal adjustment.

The adjustments have to be in pixel units and in the same coordinate system as the allocation for immediate children of the container.

containerGetFocusVAdjustment

Arguments

:: ContainerClass self

=> self

-> IO (Maybe Adjustment)

returns the vertical focus adjustment, or Nothing if none has been set.

Retrieves the vertical focus adjustment for the container. See containerSetFocusVAdjustment.

containerSetFocusHAdjustment

Arguments

:: ContainerClass self

=> self

-> Adjustment

adjustment - an adjustment which should be adjusted when the focus is moved among the descendents of container

-> IO ()

Hooks up an adjustment to focus handling in a container, so when a child of the container is focused, the adjustment is scrolled to show that widget. This function sets the horizontal alignment. See scrolledWindowGetHAdjustment for a typical way of obtaining the adjustment and containerSetFocusVAdjustment for setting the vertical adjustment.

The adjustments have to be in pixel units and in the same coordinate system as the allocation for immediate children of the container.

containerGetFocusHAdjustment

Arguments

:: ContainerClass self

=> self

-> IO (Maybe Adjustment)

returns the horizontal focus adjustment, or Nothing if none has been set.

Retrieves the horizontal focus adjustment for the container. See containerSetFocusHAdjustment.

containerResizeChildren :: ContainerClass self => self -> IO ()

Make the container resize its children.

containerSetBorderWidth

Arguments

:: ContainerClass self

=> self

-> Int

borderWidth - amount of blank space to leave outside the container. Valid values are in the range 0-65535 pixels.

-> IO ()

Sets the border width of the container.

The border width of a container is the amount of space to leave around the outside of the container. The only exception to this is Window; because toplevel windows can't leave space outside, they leave the space inside. The border is added on all sides of the container. To add space to only one side, one approach is to create a Alignment widget, call widgetSetUsize to give it a size, and place it on the side of the container as a spacer.

containerGetBorderWidth

Arguments

:: ContainerClass self

=> self

-> IO Int

returns the current border width

Retrieves the border width of the container. See containerSetBorderWidth.

containerGetResizeMode

Arguments

:: ContainerClass self

=> self

-> IO ResizeMode

returns the current resize mode

Returns the resize mode for the container. See containerSetResizeMode.

containerSetResizeMode

Arguments

:: ContainerClass self

=> self

-> ResizeMode

resizeMode - the new resize mode.

-> IO ()

Sets the resize mode for the container.

The resize mode of a container determines whether a resize request will be passed to the container's parent, queued for later execution or executed immediately.

Attributes

containerResizeMode :: ContainerClass self => Attr self ResizeMode

Specify how resize events are handled.

Default value: ResizeParent

containerBorderWidth :: ContainerClass self => Attr self Int

The width of the empty border outside the containers children.

Allowed values: <= (maxBound :: Int)

Default value: 0

containerChild :: (ContainerClass self, WidgetClass widget) => WriteAttr self widget

Can be used to add a new child to the container.

containerFocusHAdjustment :: ContainerClass self => ReadWriteAttr self (Maybe Adjustment) Adjustment

'focusHadjustment' property. See containerGetFocusHAdjustment and containerSetFocusHAdjustment

containerFocusVAdjustment :: ContainerClass self => ReadWriteAttr self (Maybe Adjustment) Adjustment

'focusVadjustment' property. See containerGetFocusVAdjustment and containerSetFocusVAdjustment

Signals

add :: ContainerClass self => Signal self (Widget -> IO ())

A widget was added to the container.

checkResize :: ContainerClass self => Signal self (IO ())

Emitted when widgets need to be queried again for their preferred size.

remove :: ContainerClass self => Signal self (Widget -> IO ())

A widget was removed from the container.

setFocusChild :: ContainerClass self => Signal self (Maybe Widget -> IO ())

A widget in the container received or lost the input focus.

Deprecated