package Implements_Gtk_Buildable is new Glib.Types.Implements (Gtk.Buildable.Gtk_Buildable, Gtk_Cell_Area_Record, Gtk_Cell_Area);
package Implements_Gtk_Cell_Layout is new Glib.Types.Implements (Gtk.Cell_Layout.Gtk_Cell_Layout, Gtk_Cell_Area_Record, Gtk_Cell_Area);
type Gtk_Cell_Area_Record is new GObject_Record with null record;
type Gtk_Cell_Area is access all Gtk_Cell_Area_Record'Class;
type Gtk_Cell_Callback is access function (Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class) return Boolean;
type Gtk_Cell_Alloc_Callback is access function (Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Cell_Area : Gdk.Rectangle.Gdk_Rectangle; Cell_Background : Gdk.Rectangle.Gdk_Rectangle) return Boolean;
type Gtk_Cell_Layout_Data_Func is access procedure (Cell_Layout : Gtk.Cell_Layout.Gtk_Cell_Layout; Cell : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Tree_Model : Gtk.Tree_Model.Gtk_Tree_Model; Iter : Gtk.Tree_Model.Gtk_Tree_Iter);
type Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_Gtk_Cell_Editable_Cairo_Rectangle_Int_UTF8_String_Void is not null access procedure (Self : access Gtk_Cell_Area_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Editable : Gtk.Cell_Editable.Gtk_Cell_Editable; Cell_Area : Cairo.Region.Cairo_Rectangle_Int; Path : UTF8_String);
type Cb_GObject_Gtk_Cell_Renderer_Gtk_Cell_Editable_Cairo_Rectangle_Int_UTF8_String_Void is not null access procedure (Self : access Glib.Object.GObject_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Editable : Gtk.Cell_Editable.Gtk_Cell_Editable; Cell_Area : Cairo.Region.Cairo_Rectangle_Int; Path : UTF8_String);
type Cb_Gtk_Cell_Area_Gtk_Tree_Model_Gtk_Tree_Iter_Boolean_Boolean_Void is not null access procedure (Self : access Gtk_Cell_Area_Record'Class; Model : Gtk.Tree_Model.Gtk_Tree_Model; Iter : Gtk.Tree_Model.Gtk_Tree_Iter; Is_Expander : Boolean; Is_Expanded : Boolean);
type Cb_GObject_Gtk_Tree_Model_Gtk_Tree_Iter_Boolean_Boolean_Void is not null access procedure (Self : access Glib.Object.GObject_Record'Class; Model : Gtk.Tree_Model.Gtk_Tree_Model; Iter : Gtk.Tree_Model.Gtk_Tree_Iter; Is_Expander : Boolean; Is_Expanded : Boolean);
type Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_UTF8_String_Void is not null access procedure (Self : access Gtk_Cell_Area_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Path : UTF8_String);
type Cb_GObject_Gtk_Cell_Renderer_UTF8_String_Void is not null access procedure (Self : access Glib.Object.GObject_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Path : UTF8_String);
type Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_Gtk_Cell_Editable_Void is not null access procedure (Self : access Gtk_Cell_Area_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Editable : Gtk.Cell_Editable.Gtk_Cell_Editable);
type Cb_GObject_Gtk_Cell_Renderer_Gtk_Cell_Editable_Void is not null access procedure (Self : access Glib.Object.GObject_Record'Class; Renderer : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; Editable : Gtk.Cell_Editable.Gtk_Cell_Editable);
Edit_Widget_Property : constant Glib.Properties.Property_Interface;
Edited_Cell_Property : constant Glib.Properties.Property_Object;
Focus_Cell_Property : constant Glib.Properties.Property_Object;
Signal_Add_Editable : constant Glib.Signal_Name := "add-editable";
Signal_Apply_Attributes : constant Glib.Signal_Name := "apply-attributes";
Signal_Focus_Changed : constant Glib.Signal_Name := "focus-changed";
Signal_Remove_Editable : constant Glib.Signal_Name := "remove-editable";
function Get_Type return Glib.GType;
function Activate
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Flags | : Gtk.Cell_Renderer.Gtk_Cell_Renderer_State; | |
Edit_Only | : Boolean) return Boolean; |
function Activate_Cell
( | Self | : not null access Gtk_Cell_Area_Record; |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Event | : Gdk.Event.Gdk_Event; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Flags | : Gtk.Cell_Renderer.Gtk_Cell_Renderer_State) return Boolean; |
procedure Add
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
procedure Add_Focus_Sibling
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Sibling | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
procedure Apply_Attributes
( | Self | : not null access Gtk_Cell_Area_Record; |
Tree_Model | : Gtk.Tree_Model.Gtk_Tree_Model; | |
Iter | : Gtk.Tree_Model.Gtk_Tree_Iter; | |
Is_Expander | : Boolean; | |
Is_Expanded | : Boolean); |
procedure Attribute_Connect
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Attribute | : UTF8_String; | |
Column | : Gint); |
procedure Attribute_Disconnect
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Attribute | : UTF8_String); |
procedure Cell_Get_Property
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Property_Name | : UTF8_String; | |
Value | : in out Glib.Values.GValue); |
procedure Cell_Set_Property
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Property_Name | : UTF8_String; | |
Value | : in out Glib.Values.GValue); |
function Copy_Context
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class) return Gtk.Cell_Area_Context.Gtk_Cell_Area_Context; |
function Create_Context
( | Self | : not null access Gtk_Cell_Area_Record) return Gtk.Cell_Area_Context.Gtk_Cell_Area_Context; |
function Event
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Event | : Gdk.Event.Gdk_Event; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Flags | : Gtk.Cell_Renderer.Gtk_Cell_Renderer_State) return Gint; |
function Focus
( | Self | : not null access Gtk_Cell_Area_Record; |
Direction | : Gtk.Enums.Gtk_Direction_Type) return Boolean; |
procedure Foreach
( | Self | : not null access Gtk_Cell_Area_Record; |
Callback | : Gtk_Cell_Callback); |
procedure Foreach_Alloc
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Background_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Callback | : Gtk_Cell_Alloc_Callback); |
procedure Get_Cell_Allocation
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Cell_Area | : access Gdk.Rectangle.Gdk_Rectangle; | |
Allocation | : access Gdk.Rectangle.Gdk_Rectangle); |
function Get_Current_Path_String
( | Self | : not null access Gtk_Cell_Area_Record) return UTF8_String; |
function Get_Edit_Widget
( | Self | : not null access Gtk_Cell_Area_Record) return Gtk.Cell_Editable.Gtk_Cell_Editable; |
function Get_Edited_Cell
( | Self | : not null access Gtk_Cell_Area_Record) return Gtk.Cell_Renderer.Gtk_Cell_Renderer; |
function Get_Focus_Cell
( | Self | : not null access Gtk_Cell_Area_Record) return Gtk.Cell_Renderer.Gtk_Cell_Renderer; |
procedure Set_Focus_Cell
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
function Get_Focus_From_Sibling
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class) return Gtk.Cell_Renderer.Gtk_Cell_Renderer; |
function Get_Focus_Siblings
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class) return Glib.Object.Object_Simple_List.Glist; |
procedure Get_Preferred_Height
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Minimum_Height | : out Gint; | |
Natural_Height | : out Gint); |
procedure Get_Preferred_Height_For_Width
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Width | : Gint; | |
Minimum_Height | : out Gint; | |
Natural_Height | : out Gint); |
procedure Get_Preferred_Width
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Minimum_Width | : out Gint; | |
Natural_Width | : out Gint); |
procedure Get_Preferred_Width_For_Height
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Height | : Gint; | |
Minimum_Width | : out Gint; | |
Natural_Width | : out Gint); |
function Get_Request_Mode
( | Self | : not null access Gtk_Cell_Area_Record) return Gtk.Enums.Gtk_Size_Request_Mode; |
function Has_Renderer
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class) return Boolean; |
procedure Inner_Cell_Area
( | Self | : not null access Gtk_Cell_Area_Record; |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Inner_Area | : out Gdk.Rectangle.Gdk_Rectangle); |
function Is_Activatable
( | Self | : not null access Gtk_Cell_Area_Record) return Boolean; |
function Is_Focus_Sibling
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Sibling | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class) return Boolean; |
procedure Remove
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
procedure Remove_Focus_Sibling
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Sibling | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
procedure Render
( | Self | : not null access Gtk_Cell_Area_Record; |
Context | : not null access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
Cr | : Cairo.Cairo_Context; | |
Background_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
Flags | : Gtk.Cell_Renderer.Gtk_Cell_Renderer_State; | |
Paint_Focus | : Boolean); |
procedure Request_Renderer
( | Self | : not null access Gtk_Cell_Area_Record; |
Renderer | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Orientation | : Gtk.Enums.Gtk_Orientation; | |
Widget | : not null access Gtk.Widget.Gtk_Widget_Record'Class; | |
For_Size | : Gint; | |
Minimum_Size | : out Gint; | |
Natural_Size | : out Gint); |
procedure Stop_Editing
( | Self | : not null access Gtk_Cell_Area_Record; |
Canceled | : Boolean); |
procedure Set_Cell_Data_Func
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Func | : Gtk_Cell_Layout_Data_Func); |
function Get_Area
( | Context | : access Gtk_Cell_Area_Context_Record) return Gtk.Cell_Area.Gtk_Cell_Area; |
function Get_Area
( | Cell_Layout | : Gtk_Cell_Layout) return Gtk.Cell_Area.Gtk_Cell_Area; |
procedure Get_Cell_At_Position
( | Self | : access Gtk_Cell_Area_Record; |
Context | : access Gtk.Cell_Area_Context.Gtk_Cell_Area_Context_Record'Class; | |
Widget | : access Gtk.Widget.Gtk_Widget_Record'Class; | |
Cell_Area | : Gdk.Rectangle.Gdk_Rectangle; | |
X | : Gint; | |
Y | : Gint; | |
Alloc_Area | : out Gdk.Rectangle.Gdk_Rectangle; | |
Renderer | : out Gtk.Cell_Renderer.Gtk_Cell_Renderer); |
procedure Add_Attribute
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Attribute | : UTF8_String; | |
Column | : Gint); |
procedure Clear
( | Cell_Layout | : not null access Gtk_Cell_Area_Record); |
procedure Clear_Attributes
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class); |
function Get_Cells
( | Cell_Layout | : not null access Gtk_Cell_Area_Record) return Glib.Object.Object_Simple_List.Glist; |
procedure Pack_End
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Expand | : Boolean); |
procedure Pack_Start
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Expand | : Boolean); |
procedure Reorder
( | Cell_Layout | : not null access Gtk_Cell_Area_Record; |
Cell | : not null access Gtk.Cell_Renderer.Gtk_Cell_Renderer_Record'Class; | |
Position | : Gint); |
procedure On_Add_Editable
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_Gtk_Cell_Editable_Cairo_Rectangle_Int_UTF8_String_Void; | |
After | : Boolean := False); |
procedure On_Add_Editable
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_GObject_Gtk_Cell_Renderer_Gtk_Cell_Editable_Cairo_Rectangle_Int_UTF8_String_Void; | |
Slot | : not null access Glib.Object.GObject_Record'Class; | |
After | : Boolean := False); |
procedure On_Apply_Attributes
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_Gtk_Cell_Area_Gtk_Tree_Model_Gtk_Tree_Iter_Boolean_Boolean_Void; | |
After | : Boolean := False); |
procedure On_Apply_Attributes
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_GObject_Gtk_Tree_Model_Gtk_Tree_Iter_Boolean_Boolean_Void; | |
Slot | : not null access Glib.Object.GObject_Record'Class; | |
After | : Boolean := False); |
procedure On_Focus_Changed
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_UTF8_String_Void; | |
After | : Boolean := False); |
procedure On_Focus_Changed
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_GObject_Gtk_Cell_Renderer_UTF8_String_Void; | |
Slot | : not null access Glib.Object.GObject_Record'Class; | |
After | : Boolean := False); |
procedure On_Remove_Editable
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_Gtk_Cell_Area_Gtk_Cell_Renderer_Gtk_Cell_Editable_Void; | |
After | : Boolean := False); |
procedure On_Remove_Editable
( | Self | : not null access Gtk_Cell_Area_Record; |
Call | : Cb_GObject_Gtk_Cell_Renderer_Gtk_Cell_Editable_Void; | |
Slot | : not null access Glib.Object.GObject_Record'Class; | |
After | : Boolean := False); |
function "+"
( | Widget | : access Gtk_Cell_Area_Record'Class) return Gtk.Buildable.Gtk_Buildable renames Implements_Gtk_Buildable.To_Interface; |
function "-"
( | Interf | : Gtk.Buildable.Gtk_Buildable) return Gtk_Cell_Area renames Implements_Gtk_Buildable.To_Object; |
function "+"
( | Widget | : access Gtk_Cell_Area_Record'Class) return Gtk.Cell_Layout.Gtk_Cell_Layout renames Implements_Gtk_Cell_Layout.To_Interface; |
function "-"
( | Interf | : Gtk.Cell_Layout.Gtk_Cell_Layout) return Gtk_Cell_Area renames Implements_Gtk_Cell_Layout.To_Object; |
The Gtk.Cell_Area.Gtk_Cell_Area is an abstract class for Gtk.Cell_Layout.Gtk_Cell_Layout widgets (also referred to as "layouting widgets") to interface with an arbitrary number of Gtk_Cell_Renderers and interact with the user for a given Gtk.Tree_Model.Gtk_Tree_Model row.
The cell area handles events, focus navigation, drawing and size requests and allocations for a given row of data.
Usually users dont have to interact with the Gtk.Cell_Area.Gtk_Cell_Area directly unless they are implementing a cell-layouting widget themselves. == Requesting area sizes == As outlined in <link linkend="geometry-management">GtkWidget's geometry management section</link>, GTK+ uses a height-for-width geometry management system to compute the sizes of widgets and user interfaces.
Gtk.Cell_Area.Gtk_Cell_Area uses the same semantics to calculate the size of an area for an arbitrary number of Gtk.Tree_Model.Gtk_Tree_Model rows.
When requesting the size of a cell area one needs to calculate the size for a handful of rows, and this will be done differently by different layouting widgets. For instance a Gtk.Tree_View_Column.Gtk_Tree_View_Column always lines up the areas from top to bottom while a Gtk.Icon_View.Gtk_Icon_View on the other hand might enforce that all areas received the same width and wrap the areas around, requesting height for more cell areas when allocated less width.
It's also important for areas to maintain some cell alignments with areas rendered for adjacent rows (cells can appear "columnized" inside an area even when the size of cells are different in each row). For this reason the Gtk.Cell_Area.Gtk_Cell_Area uses a Gtk.Cell_Area_Context.Gtk_Cell_Area_Context object to store the alignments and sizes along the way (as well as the overall largest minimum and natural size for all the rows which have been calculated with the said context).
The Gtk.Cell_Area_Context.Gtk_Cell_Area_Context is an opaque object specific to the Gtk.Cell_Area.Gtk_Cell_Area which created it (see Gtk.Cell_Area.Create_Context). The owning cell-layouting widget can create as many contexts as it wishes to calculate sizes of rows which should receive the same size in at least one orientation (horizontally or vertically), However, it's important that the same Gtk.Cell_Area_Context.Gtk_Cell_Area_Context which was used to request the sizes for a given Gtk.Tree_Model.Gtk_Tree_Model row be used when rendering or processing events for that row.
In order to request the width of all the rows at the root level of a Gtk.Tree_Model.Gtk_Tree_Model one would do the following: == Requesting the width of a handful of GtkTreeModel rows == GtkTreeIter iter; gint minimum_width; gint natural_width; valid = gtk_tree_model_get_iter_first (model, &iter); while (valid) { gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE); gtk_cell_area_get_preferred_width (area, context, widget, NULL, NULL); valid = gtk_tree_model_iter_next (model, &iter); } gtk_cell_area_context_get_preferred_width (context, &minimum_width, &natural_width); Note that in this example it's not important to observe the returned minimum and natural width of the area for each row unless the cell-layouting object is actually interested in the widths of individual rows. The overall width is however stored in the accompanying Gtk.Cell_Area_Context.Gtk_Cell_Area_Context object and can be consulted at any time.
This can be useful since Gtk.Cell_Layout.Gtk_Cell_Layout widgets usually have to support requesting and rendering rows in treemodels with an exceedingly large amount of rows. The Gtk.Cell_Layout.Gtk_Cell_Layout widget in that case would calculate the required width of the rows in an idle or timeout source (see g_timeout_add) and when the widget is requested its actual width in Gtk.Widget.GObject_Class.get_preferred_width it can simply consult the width accumulated so far in the Gtk.Cell_Area_Context.Gtk_Cell_Area_Context object.
A simple example where rows are rendered from top to bottom and take up the full width of the layouting widget would look like: == A typical get_preferred_width implementation == static void foo_get_preferred_width (GtkWidget *widget, gint *minimum_size, gint *natural_size) { Foo *foo = FOO (widget); FooPrivate *priv = foo->priv; foo_ensure_at_least_one_handfull_of_rows_have_been_requested (foo); gtk_cell_area_context_get_preferred_width (priv->context, minimum_size, natural_size); } In the above example the Foo widget has to make sure that some row sizes have been calculated (the amount of rows that Foo judged was appropriate to request space for in a single timeout iteration) before simply returning the amount of space required by the area via the Gtk.Cell_Area_Context.Gtk_Cell_Area_Context.
Requesting the height for width (or width for height) of an area is a similar task except in this case the Gtk.Cell_Area_Context.Gtk_Cell_Area_Context does not store the data (actually, it does not know how much space the layouting widget plans to allocate it for every row. It's up to the layouting widget to render each row of data with the appropriate height and width which was requested by the Gtk.Cell_Area.Gtk_Cell_Area).
In order to request the height for width of all the rows at the root level of a Gtk.Tree_Model.Gtk_Tree_Model one would do the following: == Requesting the height for width of a handful of GtkTreeModel rows == GtkTreeIter iter; gint minimum_height; gint natural_height; gint full_minimum_height = 0; gint full_natural_height = 0; valid = gtk_tree_model_get_iter_first (model, &iter); while (valid) { gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE); gtk_cell_area_get_preferred_height_for_width (area, context, widget, width, &minimum_height, &natural_height); if (width_is_for_allocation) cache_row_height (&iter, minimum_height, natural_height); full_minimum_height += minimum_height; full_natural_height += natural_height; valid = gtk_tree_model_iter_next (model, &iter); } Note that in the above example we would need to cache the heights returned for each row so that we would know what sizes to render the areas for each row. However we would only want to really cache the heights if the request is intended for the layouting widgets real allocation.
In some cases the layouting widget is requested the height for an arbitrary for_width, this is a special case for layouting widgets who need to request size for tens of thousands of rows. For this case it's only important that the layouting widget calculate one reasonably sized chunk of rows and return that height synchronously. The reasoning here is that any layouting widget is at least capable of synchronously calculating enough height to fill the screen height (or scrolled window height) in response to a single call to Gtk.Widget.GObject_Class.get_preferred_height_for_width.
Returning a perfect height for width that is larger than the screen area is inconsequential since after the layouting receives an allocation from a scrolled window it simply continues to drive the scrollbar values while more and more height is required for the row heights that are calculated in the background. == Rendering Areas == Once area sizes have been aquired at least for the rows in the visible area of the layouting widget they can be rendered at Gtk.Widget.GObject_Class.draw time.
A crude example of how to render all the rows at the root level runs as follows: == Requesting the width of a handful of GtkTreeModel rows == GtkAllocation allocation; GdkRectangle cell_area = { 0, }; GtkTreeIter iter; gint minimum_width; gint natural_width; gtk_widget_get_allocation (widget, &allocation); cell_area.width = allocation.width; valid = gtk_tree_model_get_iter_first (model, &iter); while (valid) { cell_area.height = get_cached_height_for_row (&iter); gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE); gtk_cell_area_render (area, context, widget, cr, &cell_area, &cell_area, state_flags, FALSE); cell_area.y += cell_area.height; valid = gtk_tree_model_iter_next (model, &iter); } Note that the cached height in this example really depends on how the layouting widget works. The layouting widget might decide to give every row its minimum or natural height or, if the model content is expected to fit inside the layouting widget without scrolling, it would make sense to calculate the allocation for each row at Gtk.Widget.Gtk_Widget::size-allocate time using gtk_distribute_natural_allocation. == Handling Events and Driving Keyboard Focus == Passing events to the area is as simple as handling events on any normal widget and then passing them to the Gtk.Cell_Area.Event API as they come in. Usually Gtk.Cell_Area.Gtk_Cell_Area is only interested in button events, however some customized derived areas can be implemented who are interested in handling other events. Handling an event can trigger the Gtk.Cell_Area.Gtk_Cell_Area::focus-changed signal to fire; as well as Gtk.Cell_Area.Gtk_Cell_Area::add-editable in the case that an editable cell was clicked and needs to start editing. You can call Gtk.Cell_Area.Stop_Editing at any time to cancel any cell editing that is currently in progress.
The Gtk.Cell_Area.Gtk_Cell_Area drives keyboard focus from cell to cell in a way similar to Gtk.Widget.Gtk_Widget. For layouting widgets that support giving focus to cells it's important to remember to pass Gtk.Cell_Renderer.Cell_Renderer_Focused to the area functions for the row that has focus and to tell the area to paint the focus at render time.
Layouting widgets that accept focus on cells should implement the Gtk.Widget.GObject_Class.focus virtual method. The layouting widget is always responsible for knowing where Gtk.Tree_Model.Gtk_Tree_Model rows are rendered inside the widget, so at Gtk.Widget.GObject_Class.focus time the layouting widget should use the Gtk.Cell_Area.Gtk_Cell_Area methods to navigate focus inside the area and then observe the GtkDirectionType to pass the focus to adjacent rows and areas.
A basic example of how the Gtk.Widget.GObject_Class.focus virtual method should be implemented: == Implementing keyboard focus navigation == static gboolean foo_focus (GtkWidget *widget, GtkDirectionType direction) { Foo *foo = FOO (widget); FooPrivate *priv = foo->priv; gint focus_row; gboolean have_focus = FALSE; focus_row = priv->focus_row; if (!gtk_widget_has_focus (widget)) gtk_widget_grab_focus (widget); valid = gtk_tree_model_iter_nth_child (priv->model, &iter, NULL, priv->focus_row); while (valid) { gtk_cell_area_apply_attributes (priv->area, priv->model, &iter, FALSE, FALSE); if (gtk_cell_area_focus (priv->area, direction)) { priv->focus_row = focus_row; have_focus = TRUE; break; } else { if (direction == GTK_DIR_RIGHT || direction == GTK_DIR_LEFT) break; else if (direction == GTK_DIR_UP || direction == GTK_DIR_TAB_BACKWARD) { if (focus_row == 0) break; else { focus_row--; valid = gtk_tree_model_iter_nth_child (priv->model, &iter, NULL, focus_row); } } else { if (focus_row == last_row) break; else { focus_row++; valid = gtk_tree_model_iter_next (priv->model, &iter); } } } } return have_focus; } Note that the layouting widget is responsible for matching the GtkDirectionType values to the way it lays out its cells. == Cell Properties == The Gtk.Cell_Area.Gtk_Cell_Area introduces *cell properties* for Gtk_Cell_Renderers in very much the same way that Gtk.Container.Gtk_Container introduces <link linkend="child-properties">child properties</link> for Gtk_Widgets. This provides some general interfaces for defining the relationship cell areas have with their cells. For instance in a Gtk.Cell_Area_Box.Gtk_Cell_Area_Box a cell might "expand" and receive extra space when the area is allocated more than its full natural request, or a cell might be configured to "align" with adjacent rows which were requested and rendered with the same Gtk.Cell_Area_Context.Gtk_Cell_Area_Context.
Use gtk_cell_area_class_install_cell_property to install cell properties for a cell area class and gtk_cell_area_class_find_cell_property or gtk_cell_area_class_list_cell_properties to get information about existing cell properties.
To set the value of a cell property, use Gtk.Cell_Area.Cell_Set_Property, gtk_cell_area_cell_set or gtk_cell_area_cell_set_valist. To obtain the value of a cell property, use Gtk.Cell_Area.Cell_Get_Property, gtk_cell_area_cell_get or gtk_cell_area_cell_get_valist.