CellLayoutT

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: |[ <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][cell-properties] can also be defined in the format by specifying the custom <cell-packing> attribute which can contain multiple <property> elements defined in the normal way.

Here is a UI definition fragment specifying cell properties:

|[ <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

|[<!-- language="C" --> 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).

|[<!-- language="C" --> static void my_combo_box_init (MyComboBox *b) { GtkCellRenderer *cell;

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

Functions

addAttribute
void addAttribute(CellRenderer cell, string attribute, int column)

Adds an attribute mapping to the list in @cell_layout.

clear
void clear()

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

clearAttributes
void clearAttributes(CellRenderer cell)

Clears all existing attributes previously set with gtk_cell_layout_set_attributes().

getArea
CellArea getArea()

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.

getCellLayoutStruct
GtkCellLayout* getCellLayoutStruct(bool transferOwnership)

Get the main Gtk struct

getCells
ListG getCells()

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

packEnd
void packEnd(CellRenderer 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.

packStart
void packStart(CellRenderer 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.

reorder
void reorder(CellRenderer cell, int position)

Re-inserts @cell at @position.

setCellDataFunc
void setCellDataFunc(CellRenderer cell, GtkCellLayoutDataFunc func, void* funcData, GDestroyNotify destroy)

Sets the #GtkCellLayoutDataFunc to use for @cell_layout.

Meta