class: CellLayout

[64:7] extends: object

An interface for packing cells GtkCellLayout is an interface to be implemented by all objects which want to provide a GtkTreeViewColumn like API for packing cells, setting attributes and data funcs. One of the notable features provided by implementations of GtkCellLayout are attributes. Attributes let you set the properties in flexible ways. They can just be set to constant values like regular properties. But they can also be mapped to a column of the underlying tree model with gtk_cell_layout_set_attributes(), which means that the value of the attribute can change from cell to cell as they are rendered by the cell renderer. Finally, it is possible to specify a function with gtk_cell_layout_set_cell_data_func() that is called to determine the value of the attribute for each cell that is rendered. ## GtkCellLayouts as GtkBuildable Implementations of GtkCellLayout which also implement the GtkBuildable interface (GtkCellView, GtkIconView, GtkComboBox, GtkEntryCompletion, GtkTreeViewColumn) accept GtkCellRenderer objects as <child> elements in UI definitions. They support a custom <attributes> element for their children, which can contain multiple <attribute> elements. Each <attribute> element has a name attribute which specifies a property of the cell renderer; the content of the element is the attribute value. This is an example of a UI definition fragment specifying attributes: xml <object class="GtkCellView"> <child> <object class="GtkCellRendererText"/> <attributes> <attribute name="text">0</attribute> </attributes> </child> </object> Furthermore for implementations of GtkCellLayout that use a GtkCellArea to lay out cells (all GtkCellLayouts in GTK use a GtkCellArea) cell properties can also be defined in the format by specifying the custom <cell-packing> attribute which can contain multiple <property> elements. Here is a UI definition fragment specifying cell properties: xml <object class="GtkTreeViewColumn"> <child> <object class="GtkCellRendererText"/> <cell-packing> <property name="align">True</property> <property name="expand">False</property> </cell-packing> </child> </object> ## Subclassing GtkCellLayout implementations When subclassing a widget that implements GtkCellLayout like GtkIconView or GtkComboBox, there are some considerations related to the fact that these widgets internally use a GtkCellArea. The cell area is exposed as a construct-only property by these widgets. This means that it is possible to e.g. do c GtkWIdget *combo = g_object_new (GTK_TYPE_COMBO_BOX, "cell-area", my_cell_area, NULL); to use a custom cell area with a combo box. But construct properties are only initialized after instance init() functions have run, which means that using functions which rely on the existence of the cell area in your subclass init() function will cause the default cell area to be instantiated. In this case, a provided construct property value will be ignored (with a warning, to alert you to the problem).

cell = gtk_cell_renderer_pixbuf_new (); // The following call causes the
default cell area for combo boxes, // a GtkCellAreaBox, to be instantiated
gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (b), cell, FALSE); ... }
GtkWidget * my_combo_box_new (GtkCellArea *area) { // This call is going to
cause a warning about area being ignored return g_object_new
(MY_TYPE_COMBO_BOX, "cell-area", area, NULL); } ``` If supporting alternative
cell areas with your derived widget is not important, then this does not have
to concern you. If you want to support alternative cell areas, you can do so
by moving the problematic calls out of `init()` and into a `constructor()`
for your class.

#### Members
- **handleObj**
- **lib**
- **retainedCallbacks**
- **signalHandlerNames**
- **signalSetterHandlers**

#### Methods

- **CellLayout** (`Handle = null`)

	> Creates a new `CellLayout` by wrapping a native handle or another wrapper.

	- **@p** `Handle` is the native handle or another wrapper whose handle to adopt.


- **toNativeHandle** (`Source`)

	> Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from `fn.call(...)`, another generated wrapper exposing `handle()`, or null. Returns null when the argument carries no pointer.

	- **@p** `Source` is the raw handle, raw buffer, wrapper, or null.
	- **@r** `A` raw pointer carrier or null when no pointer is present.


- **getLib** ()

	> Returns the opened native library for this generated wrapper.

	- **@r** `The` opened native library.


- **handle** ()

	> Returns the wrapped NativeHandle.

	- **@r** `The` wrapped NativeHandle.


- **isNull** ()

	> Returns true when the wrapped handle is null.

	- **@r** `A` bool.


- **describe** ()

	> Returns a small string for debugging generated wrappers.

	- **@r** `A` string.


- **add\_attribute** (`object cell, string attribute, int column`)

	> Adds an attribute mapping to the list in @cell_layout. The @column is the column of the model to get a value from, and the @attribute is the property on @cell to be set from that value. So for example if column 2 of the model contains strings, you could have the “text” attribute of a `GtkCellRendererText` get its values from column 2. In this context "attribute" and "property" are used interchangeably.

	- **@p** `cell` is a `GtkCellRenderer`.
	- **@p** `attribute` is a property on the renderer.
	- **@p** `column` is the column position on the model to get the attribute from.
	- **@r** `None.` 


- **clear** ()

	> Unsets all the mappings on all renderers on @cell_layout and removes all renderers from @cell_layout.

	- **@r** `None.` 


- **clear\_attributes** (`object cell`)

	> Clears all existing attributes previously set with gtk_cell_layout_set_attributes().

	- **@p** `cell` is a `GtkCellRenderer` to clear the attribute mapping on.
	- **@r** `None.` 


- **get\_area** ()

	> Returns the underlying `GtkCellArea` which might be @cell_layout if called on a `GtkCellArea` or might be %NULL if no `GtkCellArea` is used by @cell_layout.



- **get\_cells** ()

	> Returns the cell renderers which have been added to @cell_layout.



- **pack\_end** (`object cell, bool expand`)

	> Adds the @cell to the end of @cell_layout. If @expand is %FALSE, then the

	- **@cell** `is` allocated no more space than it needs. Any unused space is divided evenly between cells for which @expand is %TRUE. Note that reusing the same cell renderer is not supported.
	- **@p** `cell` is a `GtkCellRenderer`.
	- **@p** `expand` is %TRUE if @cell is to be given extra space allocated to
	- **@cell_layout.** `` 
	- **@r** `None.` 


- **pack\_start** (`object cell, bool expand`)

	> Packs the @cell into the beginning of @cell_layout. If @expand is %FALSE, then the @cell is allocated no more space than it needs. Any unused space is divided evenly between cells for which @expand is %TRUE. Note that reusing the same cell renderer is not supported.

	- **@p** `cell` is a `GtkCellRenderer`.
	- **@p** `expand` is %TRUE if @cell is to be given extra space allocated to
	- **@cell_layout.** `` 
	- **@r** `None.` 


- **reorder** (`object cell, int position`)

	> Re-inserts @cell at @position. Note that @cell has already to be packed into @cell_layout for this to function properly.

	- **@p** `cell` is a `GtkCellRenderer` to reorder.
	- **@p** `position` is new position to insert @cell at.
	- **@r** `None.` 


- **cells** ()

	> Returns `get_cells` as an Aussom list of wrapper objects. This companion method materializes the full collection up front; use `get_cells()` when lazy or change-notify access is required.

	- **@r** `An` Aussom list of elements.