Sets our main struct and passes it to the parent class.
Activates @area, usually by activating the currently focused cell, however some subclasses which embed widgets in the area can also activate a widget if it currently has the focus.
This is used by #GtkCellArea subclasses when handling events to activate cells, the base #GtkCellArea class activates cells for keyboard events for free in its own GtkCellArea->activate() implementation.
Adds @renderer to @area with the default child cell properties.
Adds @sibling to @renderer’s focusable area, focus will be drawn around @renderer and all of its siblings if @renderer can focus for a given row.
Indicates that editing has started on @renderer and that @editable should be added to the owning cell-layouting widget at @cell_area.
This signal is emitted whenever applying attributes to @area from @model
Indicates that focus changed on this @area. This signal is emitted either as a result of focus handling or event handling.
Indicates that editing finished on @renderer and that @editable should be removed from the owning cell-layouting widget.
Applies any connected attributes to the renderers in @area by pulling the values from @tree_model.
Connects an @attribute to apply values from @column for the #GtkTreeModel in use.
Disconnects @attribute for the @renderer in @area so that attribute will no longer be updated with values from the model.
Returns the model column that an attribute has been mapped to, or -1 if the attribute is not mapped.
Gets the value of a cell property for @renderer in @area.
Gets the values of one or more cell properties for @renderer in @area.
Sets a cell property for @renderer in @area.
Sets one or more cell properties for @renderer in @area.
This is sometimes needed for cases where rows need to share alignments in one orientation but may be separately grouped in the opposing orientation.
Creates a #GtkCellAreaContext to be used with @area for all purposes. #GtkCellAreaContext stores geometry information for rows for which it was operated on, it is important to use the same context for the same row of data at all times (i.e. one should render and handle events with the same #GtkCellAreaContext which was used to request the size of those rows of data).
Delegates event handling to a #GtkCellArea.
This should be called by the @area’s owning layout widget when focus is to be passed to @area, or moved within @area for a given @direction and row data.
Calls @callback for every #GtkCellRenderer in @area.
Calls @callback for every #GtkCellRenderer in @area with the allocated rectangle inside @cell_area.
Derives the allocation of @renderer inside @area if @area were to be renderered in @cell_area.
Get the main Gtk struct
Gets the #GtkCellRenderer at @x and @y coordinates inside @area and optionally returns the full cell allocation for it inside @cell_area.
Gets the current #GtkTreePath string for the currently applied #GtkTreeIter, this is implicitly updated when gtk_cell_area_apply_attributes() is called and can be used to interact with renderers from #GtkCellArea subclasses.
Gets the #GtkCellEditable widget currently used to edit the currently edited cell.
Gets the #GtkCellRenderer in @area that is currently being edited.
Retrieves the currently focused cell for @area
Gets the #GtkCellRenderer which is expected to be focusable for which @renderer is, or may be a sibling.
Gets the focus sibling cell renderers for @renderer.
Retrieves a cell area’s initial minimum and natural height.
Retrieves a cell area’s minimum and natural height if it would be given the specified @width.
Retrieves a cell area’s initial minimum and natural width.
Retrieves a cell area’s minimum and natural width if it would be given the specified @height.
Gets whether the area prefers a height-for-width layout or a width-for-height layout.
the main Gtk struct as a void*
Checks if @area contains @renderer.
This is a convenience function for #GtkCellArea implementations to get the inner area where a given #GtkCellRenderer will be rendered. It removes any padding previously added by gtk_cell_area_request_renderer().
Returns whether the area can do anything when activated, after applying new attributes to @area.
Returns whether @sibling is one of @renderer’s focus siblings (see gtk_cell_area_add_focus_sibling()).
Removes @renderer from @area.
Removes @sibling from @renderer’s focus sibling list (see gtk_cell_area_add_focus_sibling()).
Renders @area’s cells according to @area’s layout onto @widget at the given coordinates.
This is a convenience function for #GtkCellArea implementations to request size for cell renderers. It’s important to use this function to request size and then use gtk_cell_area_inner_cell_area() at render and event time since this function will add padding around the cell for focus painting.
Explicitly sets the currently focused cell to @renderer.
Explicitly stops the editing of the currently edited cell.
the main Gtk struct
the main Gtk struct
Get the main Gtk struct
the main Gtk struct as a void*
Gets a D Object from the objects table of associations.
The notify signal is emitted on an object when one of its properties has been changed. Note that getting this signal doesn't guarantee that the value of the property has actually changed, it may also be emitted when the setter for the property is called to reinstate the previous value.
Find the #GParamSpec with the given name for an interface. Generally, the interface vtable passed in as @g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created #GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.
Lists the properties of an interface.Generally, the interface vtable passed in as @g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
Increases the reference count of the object by one and sets a callback to be called when all other references to the object are dropped, or when this is already the last reference to the object and another reference is established.
Adds a weak reference from weak_pointer to @object to indicate that the pointer located at @weak_pointer_location is only valid during the lifetime of @object. When the @object is finalized, @weak_pointer will be set to %NULL.
Creates a binding between @source_property on @source and @target_property on @target. Whenever the @source_property is changed the @target_property is updated using the same value. For instance:
Complete version of g_object_bind_property().
Creates a binding between @source_property on @source and @target_property on @target, allowing you to set the transformation functions to be used by the binding.
This is a variant of g_object_get_data() which returns a 'duplicate' of the value. @dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.
This is a variant of g_object_get_qdata() which returns a 'duplicate' of the value. @dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.
This function is intended for #GObject implementations to re-enforce a floating[floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().
Increases the freeze count on @object. If the freeze count is non-zero, the emission of "notify" signals on @object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one #GObject::notify signal is emitted for each property modified while the object is frozen.
Gets a named field from the objects table of associations (see g_object_set_data()).
Gets a property of an object. @value must have been initialized to the expected type of the property (or a type to which the expected type can be transformed) using g_value_init().
This function gets back user data pointers stored via g_object_set_qdata().
Gets properties of an object.
Gets @n_properties properties for an @object. Obtained properties will be set to @values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
Checks whether @object has a floating[floating-ref] reference.
Emits a "notify" signal for the property @property_name on @object.
Emits a "notify" signal for the property specified by @pspec on @object.
Increases the reference count of @object.
Increase the reference count of @object, and possibly remove the floating[floating-ref] reference, if @object has a floating reference.
Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one.
Removes a weak reference from @object that was previously added using g_object_add_weak_pointer(). The @weak_pointer_location has to match the one used with g_object_add_weak_pointer().
Compares the user data for the key @key on @object with @oldval, and if they are the same, replaces @oldval with @newval.
Compares the user data for the key @quark on @object with @oldval, and if they are the same, replaces @oldval with @newval.
Releases all references to other objects. This can be used to break reference cycles.
Each object carries around a table of associations from strings to pointers. This function lets you set an association.
Like g_object_set_data() except it adds notification for when the association is destroyed, either by setting it to a different value or when the object is destroyed.
Sets a property on an object.
This sets an opaque, named pointer on an object. The name is specified through a #GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the @object with g_object_get_qdata() until the @object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using #NULL as pointer essentially removes the data stored.
This function works like g_object_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with @data as argument when the @object is finalized, or the data is being overwritten by a call to g_object_set_qdata() with the same @quark.
Sets properties on an object.
Sets @n_properties properties for an @object. Properties to be set will be taken from @values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
This function gets back user data pointers stored via g_object_set_qdata() and removes the @data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example: |[<!-- language="C" --> void object_add_to_user_list (GObject *object, const gchar *new_string) { // the quark, naming the object data GQuark quark_string_list = g_quark_from_static_string ("my-string-list"); // retrive the old string list GList *list = g_object_steal_qdata (object, quark_string_list);
Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on @object and when it reaches zero, queued "notify" signals are emitted.
Decreases the reference count of @object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).
This function essentially limits the life time of the @closure to the life time of the object. That is, when the object is finalized, the @closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the @closure, to ensure that an extra reference count is held on @object during invocation of the @closure. Usually, this function will be called on closures that use this @object as closure data.
Adds a weak reference callback to an object. Weak references are used for notification when an object is finalized. They are called "weak references" because they allow you to safely hold a pointer to an object without calling g_object_ref() (g_object_ref() adds a strong reference, that is, forces the object to stay alive).
Removes a weak reference callback to an object.
Clears a reference to a #GObject.
Get the main Gtk struct
the main Gtk struct as a void*
Adds a child to @buildable. @type is an optional string describing how the child should be added.
Constructs a child of @buildable with the name @name.
This is similar to gtk_buildable_parser_finished() but is called once for each custom tag handled by the @buildable.
This is called at the end of each custom element handled by the buildable.
This is called for each unknown element under <child>.
Get the internal child called @childname of the @buildable object.
Gets the name of the @buildable object.
Called when the builder finishes the parsing of a [GtkBuilder UI definition][BUILDER-UI]. Note that this will be called once for each time gtk_builder_add_from_file() or gtk_builder_add_from_string() is called on a builder.
Sets the property name @name to @value on the @buildable object.
Sets the name of the @buildable object.
Get the main Gtk struct
the main Gtk struct as a void*
Adds an attribute mapping to the list in @cell_layout.
Unsets all the mappings on all renderers on @cell_layout and removes all renderers from @cell_layout.
Clears all existing attributes previously set with gtk_cell_layout_set_attributes().
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.
Returns the cell renderers which have been added to @cell_layout.
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.
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.
Re-inserts @cell at @position.
Sets the #GtkCellLayoutDataFunc to use for @cell_layout.
The #GtkCellArea is an abstract class for #GtkCellLayout widgets (also referred to as "layouting widgets") to interface with an arbitrary number of #GtkCellRenderers and interact with the user for a given #GtkTreeModel 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 #GtkCellArea directly unless they are implementing a cell-layouting widget themselves.
Requesting area sizes
As outlined in [GtkWidget’s geometry management section][geometry-management], GTK+ uses a height-for-width geometry management system to compute the sizes of widgets and user interfaces. #GtkCellArea uses the same semantics to calculate the size of an area for an arbitrary number of #GtkTreeModel 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 #GtkTreeViewColumn always lines up the areas from top to bottom while a #GtkIconView 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 #GtkCellArea uses a #GtkCellAreaContext 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 #GtkCellAreaContext is an opaque object specific to the #GtkCellArea 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 #GtkCellAreaContext which was used to request the sizes for a given #GtkTreeModel 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 #GtkTreeModel one would do the following:
|[<!-- language="C" --> 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 #GtkCellAreaContext object and can be consulted at any time.
This can be useful since #GtkCellLayout widgets usually have to support requesting and rendering rows in treemodels with an exceedingly large amount of rows. The #GtkCellLayout 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 #GtkWidgetClass.get_preferred_width() it can simply consult the width accumulated so far in the #GtkCellAreaContext 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:
|[<!-- language="C" --> 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 #GtkCellAreaContext.
Requesting the height for width (or width for height) of an area is a similar task except in this case the #GtkCellAreaContext 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 #GtkCellArea).
In order to request the height for width of all the rows at the root level of a #GtkTreeModel one would do the following:
|[<!-- language="C" --> 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 #GtkWidgetClass.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 #GtkWidgetClass.draw() time.
A crude example of how to render all the rows at the root level runs as follows:
|[<!-- language="C" --> 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 #GtkWidget::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 #GtkCellArea 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 #GtkCellArea::focus-changed signal to fire; as well as #GtkCellArea::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 #GtkCellArea drives keyboard focus from cell to cell in a way similar to #GtkWidget. For layouting widgets that support giving focus to cells it’s important to remember to pass %GTK_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 #GtkWidgetClass.focus() virtual method. The layouting widget is always responsible for knowing where #GtkTreeModel rows are rendered inside the widget, so at #GtkWidgetClass.focus() time the layouting widget should use the #GtkCellArea 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 #GtkWidgetClass.focus() virtual method should be implemented:
|[<!-- language="C" --> 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 #GtkCellArea introduces cell properties for #GtkCellRenderers in very much the same way that #GtkContainer introduces [child properties][child-properties] for #GtkWidgets. This provides some general interfaces for defining the relationship cell areas have with their cells. For instance in a #GtkCellAreaBox 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 #GtkCellAreaContext.
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().