Interface

Gtk.CellLayout

Description [src]

interface Gtk.CellLayout : GObject.Object

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 elements in UI definitions. They support a custom element for their children, which can contain multiple elements. Each 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 attribute which can contain multiple 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

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).

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.

Instance methods

gtk_cell_layout_add_attribute

Adds an attribute mapping to the list in cell_layout.

gtk_cell_layout_clear

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

gtk_cell_layout_clear_attributes

Clears all existing attributes previously set with gtk_cell_layout_set_attributes().

gtk_cell_layout_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.

gtk_cell_layout_get_cells

Returns the cell renderers which have been added to cell_layout.

gtk_cell_layout_pack_end

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.

gtk_cell_layout_pack_start

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.

gtk_cell_layout_reorder

Re-inserts cell at position.

gtk_cell_layout_set_attributes

Sets the attributes in list as the attributes of cell_layout.

gtk_cell_layout_set_cell_data_func

Sets the GtkCellLayoutDataFunc to use for cell_layout.

Interface structure

struct GtkCellLayoutIface {
  void (* pack_start) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    gboolean expand
  );
  void (* pack_end) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    gboolean expand
  );
  void (* clear) (
    GtkCellLayout* cell_layout
  );
  void (* add_attribute) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    const char* attribute,
    int column
  );
  void (* set_cell_data_func) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    GtkCellLayoutDataFunc func,
    gpointer func_data,
    GDestroyNotify destroy
  );
  void (* clear_attributes) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell
  );
  void (* reorder) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    int position
  );
  GList* (* get_cells) (
    GtkCellLayout* cell_layout
  );
  GtkCellArea* (* get_area) (
    GtkCellLayout* cell_layout
  );
  
}
Interface members
pack_start
void (* pack_start) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    gboolean expand
  )
 No description available.
pack_end
void (* pack_end) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    gboolean expand
  )
 No description available.
clear
void (* clear) (
    GtkCellLayout* cell_layout
  )
 No description available.
add_attribute
void (* add_attribute) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    const char* attribute,
    int column
  )
 No description available.
set_cell_data_func
void (* set_cell_data_func) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    GtkCellLayoutDataFunc func,
    gpointer func_data,
    GDestroyNotify destroy
  )
 No description available.
clear_attributes
void (* clear_attributes) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell
  )
 No description available.
reorder
void (* reorder) (
    GtkCellLayout* cell_layout,
    GtkCellRenderer* cell,
    int position
  )
 No description available.
get_cells
GList* (* get_cells) (
    GtkCellLayout* cell_layout
  )
 No description available.
get_area
GtkCellArea* (* get_area) (
    GtkCellLayout* cell_layout
  )
 No description available.

Virtual methods

Gtk.CellLayout.add_attribute

Adds an attribute mapping to the list in cell_layout.

Gtk.CellLayout.clear

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

Gtk.CellLayout.clear_attributes

Clears all existing attributes previously set with gtk_cell_layout_set_attributes().

Gtk.CellLayout.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.

Gtk.CellLayout.get_cells

Returns the cell renderers which have been added to cell_layout.

Gtk.CellLayout.pack_end

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.

Gtk.CellLayout.pack_start

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.

Gtk.CellLayout.reorder

Re-inserts cell at position.

Gtk.CellLayout.set_cell_data_func

Sets the GtkCellLayoutDataFunc to use for cell_layout.