gtk2/gtk/gtkcellarea.c

/* gtkcellarea.c
 *
 * Copyright (C) 2010 Openismus GmbH
 *
 * Authors:
 *      Tristan Van Berkom <tristanvb@openismus.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/**
 * SECTION:gtkcellarea
 * @Short_Description: An abstract class for laying out #GtkCellRenderers
 * @Title: GtkCellArea
 *
 * 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 wraps geometrical
 * 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.
 *
 * <refsect2 id="cell-area-geometry-management">
 * <title>Requesting area sizes</title>
 * <para>
 * As outlined in <link linkend="geometry-management">GtkWidget's
 * geometry management section</link>, GTK+ uses a height-for-width
 * geometry managemen 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, 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:
 * <example>
 *   <title>Requesting the width of a hand full of GtkTreeModel rows.</title>
 *   <programlisting>
 * 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);
 *   </programlisting>
 * </example>
 * 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:
 * <example>
 *   <title>A typical #GtkWidgetClass.get_preferred_width() for a layouting widget.</title>
 *   <programlisting>
 * 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);
 * }
 *   </programlisting>
 * </example>
 * 
 * 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:
 * <example>
 *   <title>Requesting the height for width of a hand full of GtkTreeModel rows.</title>
 *   <programlisting>
 * 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);
 *   }
 *   </programlisting>
 * </example>
 *
 * Note that in the above example we would need to cache the heights returned for each
 * treemodel 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 treemodel 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 the scrollbar
 * values while more and mode height is required for the row heights that are calculated
 * in the background.
 * </para>
 * </refsect2>
 * <refsect2 id="cell-area-rendering">
 * <title>Rendering Areas</title>
 * <para>
 * 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 crued example of how to render all the rows at the root level runs as follows:
 * <example>
 *   <title>Requesting the width of a hand full of GtkTreeModel rows.</title>
 *   <programlisting>
 * 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);
 *   }
 *   </programlisting>
 * </example>
 * 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 it's minimum
 * or natural height or if the model content is expected to fit inside the layouting
 * widget with no scrolled window it would make sense to calculate the allocation
 * for each row at #GtkWidget.size_allocate() time using gtk_distribute_natural_allocation().
 * </para>
 * </refsect2>
 * <refsect2 id="cell-area-events-and-focus">
 * <title>Handling Events and Driving Keyboard Focus</title>
 * <para>
 * 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:
 * <example>
 *   <title>Implementing keyboard focus navigation when displaying rows from top to bottom.</title>
 *   <programlisting>
 * 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;
 * }
 *   </programlisting>
 * </example>
 * </para>
 * </refsect2>
 * <refsect2 id="cell-properties">
 * <title>Cell Properties</title>
 * <para>
 * The #GtkCellArea introduces <emphasis>cell properties</emphasis> for #GtkCellRenderers in very
 * much the same way that #GtkContainer introduces <link linkend="child-properties">child properties</link>
 * for #GtkWidgets. This provides some general interfaces for defining the relationship cell areas
 * have with thier cells. For instance in a #GtkCellAreaBox a cell might "expand" and recieve extra
 * space when the area is allocated more than it's 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().
 * </para>
 * </refsect2>
 *
 */

#include "config.h"

#include <stdarg.h>
#include <string.h>
#include <stdlib.h>

#include "gtkintl.h"
#include "gtkcelllayout.h"
#include "gtkcellarea.h"
#include "gtkcellareacontext.h"
#include "gtkmarshalers.h"
#include "gtkprivate.h"

#include <gobject/gvaluecollector.h>


/* GObjectClass */
static void      gtk_cell_area_dispose                             (GObject            *object);
static void      gtk_cell_area_finalize                            (GObject            *object);
static void      gtk_cell_area_set_property                        (GObject            *object,
								    guint               prop_id,
								    const GValue       *value,
								    GParamSpec         *pspec);
static void      gtk_cell_area_get_property                        (GObject            *object,
								    guint               prop_id,
								    GValue             *value,
								    GParamSpec         *pspec);

/* GtkCellAreaClass */
static gint      gtk_cell_area_real_event                          (GtkCellArea          *area,
								    GtkCellAreaContext   *context,
								    GtkWidget            *widget,
								    GdkEvent             *event,
								    const GdkRectangle   *cell_area,
								    GtkCellRendererState  flags);
static void      gtk_cell_area_real_apply_attributes               (GtkCellArea           *area,
								    GtkTreeModel          *tree_model,
								    GtkTreeIter           *iter,
								    gboolean               is_expander,
								    gboolean               is_expanded);
static void      gtk_cell_area_real_get_preferred_height_for_width (GtkCellArea           *area,
								    GtkCellAreaContext    *context,
								    GtkWidget             *widget,
								    gint                   width,
								    gint                  *minimum_height,
								    gint                  *natural_height);
static void      gtk_cell_area_real_get_preferred_width_for_height (GtkCellArea           *area,
								    GtkCellAreaContext    *context,
								    GtkWidget             *widget,
								    gint                   height,
								    gint                  *minimum_width,
								    gint                  *natural_width);
static gboolean  gtk_cell_area_real_is_activatable                 (GtkCellArea           *area);
static gboolean  gtk_cell_area_real_activate                       (GtkCellArea           *area,
								    GtkCellAreaContext    *context,
								    GtkWidget             *widget,
								    const GdkRectangle    *cell_area,
								    GtkCellRendererState   flags);

/* GtkCellLayoutIface */
static void      gtk_cell_area_cell_layout_init              (GtkCellLayoutIface    *iface);
static void      gtk_cell_area_pack_default                  (GtkCellLayout         *cell_layout,
							      GtkCellRenderer       *renderer,
							      gboolean               expand);
static void      gtk_cell_area_clear                         (GtkCellLayout         *cell_layout);
static void      gtk_cell_area_add_attribute                 (GtkCellLayout         *cell_layout,
							      GtkCellRenderer       *renderer,
							      const gchar           *attribute,
							      gint                   column);
static void      gtk_cell_area_set_cell_data_func            (GtkCellLayout         *cell_layout,
							      GtkCellRenderer       *cell,
							      GtkCellLayoutDataFunc  func,
							      gpointer               func_data,
							      GDestroyNotify         destroy);
static void      gtk_cell_area_clear_attributes              (GtkCellLayout         *cell_layout,
							      GtkCellRenderer       *renderer);
static void      gtk_cell_area_reorder                       (GtkCellLayout         *cell_layout,
							      GtkCellRenderer       *cell,
							      gint                   position);
static GList    *gtk_cell_area_get_cells                     (GtkCellLayout         *cell_layout);


/* Used in foreach loop to check if a child renderer is present */
typedef struct {
  GtkCellRenderer *renderer;
  gboolean         has_renderer;
} HasRendererCheck;

/* Attribute/Cell metadata */
typedef struct {
  const gchar *attribute;
  gint         column;
} CellAttribute;

typedef struct {
  GSList          *attributes;

  GtkCellLayoutDataFunc  func;
  gpointer               data;
  GDestroyNotify         destroy;
} CellInfo;

static CellInfo       *cell_info_new       (GtkCellLayoutDataFunc  func,
					    gpointer               data,
					    GDestroyNotify         destroy);
static void            cell_info_free      (CellInfo              *info);
static CellAttribute  *cell_attribute_new  (GtkCellRenderer       *renderer,
					    const gchar           *attribute,
					    gint                   column);
static void            cell_attribute_free (CellAttribute         *attribute);
static gint            cell_attribute_find (CellAttribute         *cell_attribute,
					    const gchar           *attribute);

/* Internal functions/signal emissions */
static void            gtk_cell_area_add_editable     (GtkCellArea        *area,
						       GtkCellRenderer    *renderer,
						       GtkCellEditable    *editable,
						       GdkRectangle       *cell_area);
static void            gtk_cell_area_remove_editable  (GtkCellArea        *area,
						       GtkCellRenderer    *renderer,
						       GtkCellEditable    *editable);
static void            gtk_cell_area_set_edit_widget  (GtkCellArea        *area,
						       GtkCellEditable    *editable);
static void            gtk_cell_area_set_edited_cell  (GtkCellArea        *area,
						       GtkCellRenderer    *renderer);


/* Struct to pass data along while looping over 
 * cell renderers to apply attributes
 */
typedef struct {
  GtkCellArea  *area;
  GtkTreeModel *model;
  GtkTreeIter  *iter;
  gboolean      is_expander;
  gboolean      is_expanded;
} AttributeData;

struct _GtkCellAreaPrivate
{
  /* The GtkCellArea bookkeeps any connected 
   * attributes in this hash table.
   */
  GHashTable      *cell_info;

  /* Current path is saved as a side-effect
   * of gtk_cell_area_apply_attributes() */
  gchar           *current_path;

  /* Current cell being edited and editable widget used */
  GtkCellEditable *edit_widget;
  GtkCellRenderer *edited_cell;

  /* Signal connections to the editable widget */
  gulong           remove_widget_id;

  /* Currently focused cell */
  GtkCellRenderer *focus_cell;

  /* Tracking which cells are focus siblings of focusable cells */
  GHashTable      *focus_siblings;

  /* Detail string to pass to gtk_paint_*() functions */
  gchar           *style_detail;
};

enum {
  PROP_0,
  PROP_FOCUS_CELL,
  PROP_EDITED_CELL,
  PROP_EDIT_WIDGET
};

enum {
  SIGNAL_APPLY_ATTRIBUTES,
  SIGNAL_ADD_EDITABLE,
  SIGNAL_REMOVE_EDITABLE,
  SIGNAL_FOCUS_CHANGED,
  LAST_SIGNAL
};

/* Keep the paramspec pool internal, no need to deliver notifications
 * on cells. at least no percieved need for now */
static GParamSpecPool *cell_property_pool = NULL;
static guint           cell_area_signals[LAST_SIGNAL] = { 0 };

#define PARAM_SPEC_PARAM_ID(pspec)              ((pspec)->param_id)
#define PARAM_SPEC_SET_PARAM_ID(pspec, id)      ((pspec)->param_id = (id))


G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GtkCellArea, gtk_cell_area, G_TYPE_INITIALLY_UNOWNED,
				  G_IMPLEMENT_INTERFACE (GTK_TYPE_CELL_LAYOUT,
							 gtk_cell_area_cell_layout_init));

static void
gtk_cell_area_init (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  area->priv = G_TYPE_INSTANCE_GET_PRIVATE (area,
					    GTK_TYPE_CELL_AREA,
					    GtkCellAreaPrivate);
  priv = area->priv;

  priv->cell_info = g_hash_table_new_full (g_direct_hash, 
					   g_direct_equal,
					   NULL, 
					   (GDestroyNotify)cell_info_free);

  priv->focus_siblings = g_hash_table_new_full (g_direct_hash, 
						g_direct_equal,
						NULL, 
						(GDestroyNotify)g_list_free);

  priv->focus_cell         = NULL;
  priv->edited_cell        = NULL;
  priv->edit_widget        = NULL;

  priv->remove_widget_id   = 0;
}

static void 
gtk_cell_area_class_init (GtkCellAreaClass *class)
{
  GObjectClass *object_class = G_OBJECT_CLASS (class);
  
  /* GObjectClass */
  object_class->dispose      = gtk_cell_area_dispose;
  object_class->finalize     = gtk_cell_area_finalize;
  object_class->get_property = gtk_cell_area_get_property;
  object_class->set_property = gtk_cell_area_set_property;

  /* general */
  class->add              = NULL;
  class->remove           = NULL;
  class->foreach          = NULL;
  class->event            = gtk_cell_area_real_event;
  class->render           = NULL;
  class->apply_attributes = gtk_cell_area_real_apply_attributes;

  /* geometry */
  class->create_context                 = NULL;
  class->get_request_mode               = NULL;
  class->get_preferred_width            = NULL;
  class->get_preferred_height           = NULL;
  class->get_preferred_height_for_width = gtk_cell_area_real_get_preferred_height_for_width;
  class->get_preferred_width_for_height = gtk_cell_area_real_get_preferred_width_for_height;

  /* focus */
  class->is_activatable = gtk_cell_area_real_is_activatable;
  class->activate       = gtk_cell_area_real_activate;
  class->focus          = NULL;

  /* Signals */
  /**
   * GtkCellArea::apply-attributes:
   * @area: the #GtkCellArea to apply the attributes to
   * @model: the #GtkTreeModel to apply the attributes from
   * @iter: the #GtkTreeIter indicating which row to apply the attributes of
   * @is_expander: whether the view shows children for this row
   * @is_expanded: whether the view is currently showing the children of this row
   *
   * This signal is emitted whenever applying attributes to @area from @model
   *
   * Since: 3.0
   */
  cell_area_signals[SIGNAL_APPLY_ATTRIBUTES] =
    g_signal_new (I_("apply-attributes"),
		  G_OBJECT_CLASS_TYPE (object_class),
		  G_SIGNAL_RUN_FIRST,
		  G_STRUCT_OFFSET (GtkCellAreaClass, apply_attributes),
		  NULL, NULL,
		  _gtk_marshal_VOID__OBJECT_BOXED_BOOLEAN_BOOLEAN,
		  G_TYPE_NONE, 4,
		  GTK_TYPE_TREE_MODEL,
		  GTK_TYPE_TREE_ITER,
		  G_TYPE_BOOLEAN,
		  G_TYPE_BOOLEAN);

  /**
   * GtkCellArea::add-editable:
   * @area: the #GtkCellArea where editing started
   * @renderer: the #GtkCellRenderer that started the edited
   * @editable: the #GtkCellEditable widget to add
   * @cell_area: the #GtkWidget relative #GdkRectangle coordinates
   *             where @editable should be added
   * @path: the #GtkTreePath string this edit was initiated for
   *
   * Indicates that editing has started on @renderer and that @editable
   * should be added to the owning cell layouting widget at @cell_area.
   *
   * Since: 3.0
   */
  cell_area_signals[SIGNAL_ADD_EDITABLE] =
    g_signal_new (I_("add-editable"),
		  G_OBJECT_CLASS_TYPE (object_class),
		  G_SIGNAL_RUN_FIRST,
		  0, /* No class closure here */
		  NULL, NULL,
		  _gtk_marshal_VOID__OBJECT_OBJECT_BOXED_STRING,
		  G_TYPE_NONE, 4,
		  GTK_TYPE_CELL_RENDERER,
		  GTK_TYPE_CELL_EDITABLE,
		  GDK_TYPE_RECTANGLE,
		  G_TYPE_STRING);


  /**
   * GtkCellArea::remove-editable:
   * @area: the #GtkCellArea where editing finished
   * @renderer: the #GtkCellRenderer that finished editeding
   * @editable: the #GtkCellEditable widget to remove
   *
   * Indicates that editing finished on @renderer and that @editable
   * should be removed from the owning cell layouting widget.
   *
   * Since: 3.0
   */
  cell_area_signals[SIGNAL_REMOVE_EDITABLE] =
    g_signal_new (I_("remove-editable"),
		  G_OBJECT_CLASS_TYPE (object_class),
		  G_SIGNAL_RUN_FIRST,
		  0, /* No class closure here */
		  NULL, NULL,
		  _gtk_marshal_VOID__OBJECT_OBJECT,
		  G_TYPE_NONE, 2,
		  GTK_TYPE_CELL_RENDERER,
		  GTK_TYPE_CELL_EDITABLE);

  /**
   * GtkCellArea::focus-changed:
   * @area: the #GtkCellArea where focus changed
   * @renderer: the #GtkCellRenderer that has focus
   * @path: the current #GtkTreePath string set for @area
   *
   * Indicates that focus changed on this @area. This signal
   * is emitted either as a result of focus handling or event
   * handling.
   *
   * It's possible that the signal is emitted even if the
   * currently focused renderer did not change, this is
   * because focus may change to the same renderer in the
   * same cell area for a different row of data.
   *
   * Since: 3.0
   */
  cell_area_signals[SIGNAL_FOCUS_CHANGED] =
    g_signal_new (I_("focus-changed"),
		  G_OBJECT_CLASS_TYPE (object_class),
		  G_SIGNAL_RUN_FIRST,
		  0, /* No class closure here */
		  NULL, NULL,
		  _gtk_marshal_VOID__OBJECT_STRING,
		  G_TYPE_NONE, 2,
		  GTK_TYPE_CELL_RENDERER,
		  G_TYPE_STRING);

  /* Properties */
  /**
   * GtkCellArea:focus-cell:
   *
   * The cell in the area that currently has focus
   *
   * Since: 3.0
   */
  g_object_class_install_property (object_class,
                                   PROP_FOCUS_CELL,
                                   g_param_spec_object
				   ("focus-cell",
				    P_("Focus Cell"),
				    P_("The cell which currently has focus"),
				    GTK_TYPE_CELL_RENDERER,
				    GTK_PARAM_READWRITE));

  /**
   * GtkCellArea:edited-cell:
   *
   * The cell in the area that is currently edited
   *
   * This property is read-only and only changes as
   * a result of a call gtk_cell_area_activate_cell().
   *
   * Since: 3.0
   */
  g_object_class_install_property (object_class,
                                   PROP_EDITED_CELL,
                                   g_param_spec_object
				   ("edited-cell",
				    P_("Edited Cell"),
				    P_("The cell which is currently being edited"),
				    GTK_TYPE_CELL_RENDERER,
				    G_PARAM_READABLE));

  /**
   * GtkCellArea:edit-widget:
   *
   * The widget currently editing the edited cell
   *
   * This property is read-only and only changes as
   * a result of a call gtk_cell_area_activate_cell().
   *
   * Since: 3.0
   */
  g_object_class_install_property (object_class,
                                   PROP_EDIT_WIDGET,
                                   g_param_spec_object
				   ("edit-widget",
				    P_("Edit Widget"),
				    P_("The widget currently editing the edited cell"),
				    GTK_TYPE_CELL_RENDERER,
				    G_PARAM_READABLE));

  /* Pool for Cell Properties */
  if (!cell_property_pool)
    cell_property_pool = g_param_spec_pool_new (FALSE);

  g_type_class_add_private (object_class, sizeof (GtkCellAreaPrivate));
}

/*************************************************************
 *                    CellInfo Basics                        *
 *************************************************************/
static CellInfo *
cell_info_new (GtkCellLayoutDataFunc  func,
	       gpointer               data,
	       GDestroyNotify         destroy)
{
  CellInfo *info = g_slice_new0 (CellInfo);

  info->func     = func;
  info->data     = data;
  info->destroy  = destroy;

  return info;
}

static void
cell_info_free (CellInfo *info)
{
  if (info->destroy)
    info->destroy (info->data);

  g_slist_foreach (info->attributes, (GFunc)cell_attribute_free, NULL);
  g_slist_free (info->attributes);

  g_slice_free (CellInfo, info);
}

static CellAttribute  *
cell_attribute_new  (GtkCellRenderer       *renderer,
		     const gchar           *attribute,
		     gint                   column)
{
  GParamSpec *pspec;

  /* Check if the attribute really exists and point to
   * the property string installed on the cell renderer
   * class (dont dup the string) 
   */
  pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (renderer), attribute);

  if (pspec)
    {
      CellAttribute *cell_attribute = g_slice_new (CellAttribute);

      cell_attribute->attribute = pspec->name;
      cell_attribute->column    = column;

      return cell_attribute;
    }

  return NULL;
}

static void
cell_attribute_free (CellAttribute *attribute)
{
  g_slice_free (CellAttribute, attribute);
}

/* GCompareFunc for g_slist_find_custom() */
static gint
cell_attribute_find (CellAttribute *cell_attribute,
		     const gchar   *attribute)
{
  return g_strcmp0 (cell_attribute->attribute, attribute);
}

/*************************************************************
 *                      GObjectClass                         *
 *************************************************************/
static void
gtk_cell_area_finalize (GObject *object)
{
  GtkCellArea        *area   = GTK_CELL_AREA (object);
  GtkCellAreaPrivate *priv   = area->priv;

  /* All cell renderers should already be removed at this point,
   * just kill our (empty) hash tables here. 
   */
  g_hash_table_destroy (priv->cell_info);
  g_hash_table_destroy (priv->focus_siblings);

  g_free (priv->current_path);

  G_OBJECT_CLASS (gtk_cell_area_parent_class)->finalize (object);
}


static void
gtk_cell_area_dispose (GObject *object)
{
  /* This removes every cell renderer that may be added to the GtkCellArea,
   * subclasses should be breaking references to the GtkCellRenderers 
   * at this point.
   */
  gtk_cell_layout_clear (GTK_CELL_LAYOUT (object));

  /* Remove any ref to a focused/edited cell */
  gtk_cell_area_set_focus_cell (GTK_CELL_AREA (object), NULL);
  gtk_cell_area_set_edited_cell (GTK_CELL_AREA (object), NULL);
  gtk_cell_area_set_edit_widget (GTK_CELL_AREA (object), NULL);

  G_OBJECT_CLASS (gtk_cell_area_parent_class)->dispose (object);
}

static void
gtk_cell_area_set_property (GObject       *object,
			    guint          prop_id,
			    const GValue  *value,
			    GParamSpec    *pspec)
{
  GtkCellArea *area = GTK_CELL_AREA (object);

  switch (prop_id)
    {
    case PROP_FOCUS_CELL:
      gtk_cell_area_set_focus_cell (area, (GtkCellRenderer *)g_value_get_object (value));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
gtk_cell_area_get_property (GObject     *object,
			    guint        prop_id,
			    GValue      *value,
			    GParamSpec  *pspec)
{
  GtkCellArea        *area = GTK_CELL_AREA (object);
  GtkCellAreaPrivate *priv = area->priv;

  switch (prop_id)
    {
    case PROP_FOCUS_CELL:
      g_value_set_object (value, priv->focus_cell);
      break;
    case PROP_EDITED_CELL:
      g_value_set_object (value, priv->edited_cell);
      break;
    case PROP_EDIT_WIDGET:
      g_value_set_object (value, priv->edit_widget);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

/*************************************************************
 *                    GtkCellAreaClass                       *
 *************************************************************/
static gint
gtk_cell_area_real_event (GtkCellArea          *area,
			  GtkCellAreaContext   *context,
			  GtkWidget            *widget,
			  GdkEvent             *event,
			  const GdkRectangle   *cell_area,
			  GtkCellRendererState  flags)
{
  GtkCellAreaPrivate *priv = area->priv;

  if (event->type == GDK_KEY_PRESS && (flags & GTK_CELL_RENDERER_FOCUSED) != 0)
    {
      GdkEventKey *key_event = (GdkEventKey *)event;

      /* Cancel any edits in progress */
      if (priv->edited_cell && (key_event->keyval == GDK_KEY_Escape))
	{
	  gtk_cell_area_stop_editing (area, TRUE);
	  return TRUE;
	}
    }

  return FALSE;
}

static void
apply_cell_attributes (GtkCellRenderer *renderer,
		       CellInfo        *info,
		       AttributeData   *data)
{
  CellAttribute *attribute;
  GSList        *list;
  GValue         value = { 0, };
  gboolean       is_expander;
  gboolean       is_expanded;

  g_object_freeze_notify (G_OBJECT (renderer));

  /* Whether a row expands or is presently expanded can only be 
   * provided by the view (as these states can vary across views
   * accessing the same model).
   */
  g_object_get (renderer, "is-expander", &is_expander, NULL);
  if (is_expander != data->is_expander)
    g_object_set (renderer, "is-expander", data->is_expander, NULL);
  
  g_object_get (renderer, "is-expanded", &is_expanded, NULL);
  if (is_expanded != data->is_expanded)
    g_object_set (renderer, "is-expanded", data->is_expanded, NULL);

  /* Apply the attributes directly to the renderer */
  for (list = info->attributes; list; list = list->next)
    {
      attribute = list->data;

      gtk_tree_model_get_value (data->model, data->iter, attribute->column, &value);
      g_object_set_property (G_OBJECT (renderer), attribute->attribute, &value);
      g_value_unset (&value);
    }

  /* Call any GtkCellLayoutDataFunc that may have been set by the user
   */
  if (info->func)
    info->func (GTK_CELL_LAYOUT (data->area), renderer,
		data->model, data->iter, info->data);

  g_object_thaw_notify (G_OBJECT (renderer));
}

static void
gtk_cell_area_real_apply_attributes (GtkCellArea           *area,
				     GtkTreeModel          *tree_model,
				     GtkTreeIter           *iter,
				     gboolean               is_expander,
				     gboolean               is_expanded)
{

  GtkCellAreaPrivate *priv;
  AttributeData       data;
  GtkTreePath        *path;

  priv = area->priv;

  /* Feed in data needed to apply to every renderer */
  data.area        = area;
  data.model       = tree_model;
  data.iter        = iter;
  data.is_expander = is_expander;
  data.is_expanded = is_expanded;

  /* Go over any cells that have attributes or custom GtkCellLayoutDataFuncs and
   * apply the data from the treemodel */
  g_hash_table_foreach (priv->cell_info, (GHFunc)apply_cell_attributes, &data);

  /* Update the currently applied path */
  g_free (priv->current_path);
  path               = gtk_tree_model_get_path (tree_model, iter);
  priv->current_path = gtk_tree_path_to_string (path);
  gtk_tree_path_free (path);
}

static void
gtk_cell_area_real_get_preferred_height_for_width (GtkCellArea        *area,
						   GtkCellAreaContext *context,
						   GtkWidget          *widget,
						   gint                width,
						   gint               *minimum_height,
						   gint               *natural_height)
{
  /* If the area doesnt do height-for-width, fallback on base preferred height */
  GTK_CELL_AREA_GET_CLASS (area)->get_preferred_width (area, context, widget, minimum_height, natural_height);
}

static void
gtk_cell_area_real_get_preferred_width_for_height (GtkCellArea        *area,
						   GtkCellAreaContext *context,
						   GtkWidget          *widget,
						   gint                height,
						   gint               *minimum_width,
						   gint               *natural_width)
{
  /* If the area doesnt do width-for-height, fallback on base preferred width */
  GTK_CELL_AREA_GET_CLASS (area)->get_preferred_width (area, context, widget, minimum_width, natural_width);
}

static gboolean
get_is_activatable (GtkCellRenderer *renderer,
		    gboolean        *activatable)
{

  if (gtk_cell_renderer_is_activatable (renderer))
    *activatable = TRUE;

  return *activatable;
}

static gboolean
gtk_cell_area_real_is_activatable (GtkCellArea *area)
{
  gboolean activatable = FALSE;

  /* Checks if any renderer can focus for the currently applied
   * attributes.
   *
   * Subclasses can override this in the case that they are also
   * rendering widgets as well as renderers.
   */
  gtk_cell_area_foreach (area, (GtkCellCallback)get_is_activatable, &activatable);

  return activatable;
}

static gboolean
gtk_cell_area_real_activate (GtkCellArea         *area,
			     GtkCellAreaContext  *context,
			     GtkWidget           *widget,
			     const GdkRectangle  *cell_area,
			     GtkCellRendererState flags)
{
  GtkCellAreaPrivate *priv = area->priv;
  GdkRectangle        background_area;
  GtkCellRenderer    *activate_cell = NULL;

  if (priv->focus_cell)
    activate_cell = priv->focus_cell;
  else
    {
      GList *cells, *l;

      /* GtkTreeView sometimes wants to activate a cell when no
       * cells are in focus.
       */
      cells = gtk_cell_layout_get_cells (GTK_CELL_LAYOUT (area));
      for (l = cells; l && !activate_cell; l = l->next)
	{
	  GtkCellRenderer *renderer = l->data;

	  if (gtk_cell_renderer_is_activatable (renderer))
	    activate_cell = renderer;
	}
      g_list_free (cells);
    }
  

  if (activate_cell)
    {
      /* Get the allocation of the focused cell.
       */
      gtk_cell_area_get_cell_allocation (area, context, widget, activate_cell,
					 cell_area, &background_area);
      
      /* Activate or Edit the cell
       *
       * Currently just not sending an event, renderers afaics dont use
       * the event argument anyway, worst case is we can synthesize one.
       */
      if (gtk_cell_area_activate_cell (area, widget, activate_cell, NULL,
				       &background_area, flags))
	return TRUE;
    }

  return FALSE;
}

/*************************************************************
 *                   GtkCellLayoutIface                      *
 *************************************************************/
static void
gtk_cell_area_cell_layout_init (GtkCellLayoutIface *iface)
{
  iface->pack_start         = gtk_cell_area_pack_default;
  iface->pack_end           = gtk_cell_area_pack_default;
  iface->clear              = gtk_cell_area_clear;
  iface->add_attribute      = gtk_cell_area_add_attribute;
  iface->set_cell_data_func = gtk_cell_area_set_cell_data_func;
  iface->clear_attributes   = gtk_cell_area_clear_attributes;
  iface->reorder            = gtk_cell_area_reorder;
  iface->get_cells          = gtk_cell_area_get_cells;
}

static void
gtk_cell_area_pack_default (GtkCellLayout         *cell_layout,
			    GtkCellRenderer       *renderer,
			    gboolean               expand)
{
  gtk_cell_area_add (GTK_CELL_AREA (cell_layout), renderer);
}

static void
gtk_cell_area_clear (GtkCellLayout *cell_layout)
{
  GtkCellArea *area = GTK_CELL_AREA (cell_layout);
  GList *l, *cells  =
    gtk_cell_layout_get_cells (cell_layout);

  for (l = cells; l; l = l->next)
    {
      GtkCellRenderer *renderer = l->data;
      gtk_cell_area_remove (area, renderer);
    }

  g_list_free (cells);
}

static void
gtk_cell_area_add_attribute (GtkCellLayout         *cell_layout,
			     GtkCellRenderer       *renderer,
			     const gchar           *attribute,
			     gint                   column)
{
  gtk_cell_area_attribute_connect (GTK_CELL_AREA (cell_layout),
				   renderer, attribute, column);
}

static void
gtk_cell_area_set_cell_data_func (GtkCellLayout         *cell_layout,
				  GtkCellRenderer       *renderer,
				  GtkCellLayoutDataFunc  func,
				  gpointer               func_data,
				  GDestroyNotify         destroy)
{
  GtkCellArea        *area   = GTK_CELL_AREA (cell_layout);
  GtkCellAreaPrivate *priv   = area->priv;
  CellInfo           *info;

  info = g_hash_table_lookup (priv->cell_info, renderer);

  if (info)
    {
      if (info->destroy && info->data)
	info->destroy (info->data);

      if (func)
	{
	  info->func    = func;
	  info->data    = func_data;
	  info->destroy = destroy;
	}
      else
	{
	  info->func    = NULL;
	  info->data    = NULL;
	  info->destroy = NULL;
	}
    }
  else
    {
      info = cell_info_new (func, func_data, destroy);

      g_hash_table_insert (priv->cell_info, renderer, info);
    }
}

static void
gtk_cell_area_clear_attributes (GtkCellLayout         *cell_layout,
				GtkCellRenderer       *renderer)
{
  GtkCellArea        *area = GTK_CELL_AREA (cell_layout);
  GtkCellAreaPrivate *priv = area->priv;
  CellInfo           *info;

  info = g_hash_table_lookup (priv->cell_info, renderer);

  if (info)
    {
      g_slist_foreach (info->attributes, (GFunc)cell_attribute_free, NULL);
      g_slist_free (info->attributes);

      info->attributes = NULL;
    }
}

static void 
gtk_cell_area_reorder (GtkCellLayout   *cell_layout,
		       GtkCellRenderer *cell,
		       gint             position)
{
  g_warning ("GtkCellLayout::reorder not implemented for `%s'", 
	     g_type_name (G_TYPE_FROM_INSTANCE (cell_layout)));
}

static gboolean
accum_cells (GtkCellRenderer *renderer,
	     GList          **accum)
{
  *accum = g_list_prepend (*accum, renderer);

  return FALSE;
}

static GList *
gtk_cell_area_get_cells (GtkCellLayout *cell_layout)
{
  GList *cells = NULL;

  gtk_cell_area_foreach (GTK_CELL_AREA (cell_layout), 
			 (GtkCellCallback)accum_cells,
			 &cells);

  return g_list_reverse (cells);
}


/*************************************************************
 *                            API                            *
 *************************************************************/

/**
 * gtk_cell_area_add:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to add to @area
 *
 * Adds @renderer to @area with the default child cell properties.
 *
 * Since: 3.0
 */
void
gtk_cell_area_add (GtkCellArea        *area,
		   GtkCellRenderer    *renderer)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->add)
    class->add (area, renderer);
  else
    g_warning ("GtkCellAreaClass::add not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_remove:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to remove from @area
 *
 * Removes @renderer from @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_remove (GtkCellArea        *area,
		      GtkCellRenderer    *renderer)
{
  GtkCellAreaClass   *class;
  GtkCellAreaPrivate *priv;
  GList              *renderers, *l;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  class = GTK_CELL_AREA_GET_CLASS (area);
  priv  = area->priv;

  /* Remove any custom attributes and custom cell data func here first */
  g_hash_table_remove (priv->cell_info, renderer);

  /* Remove focus siblings of this renderer */
  g_hash_table_remove (priv->focus_siblings, renderer);

  /* Remove this renderer from any focus renderer's sibling list */ 
  renderers = gtk_cell_layout_get_cells (GTK_CELL_LAYOUT (area));

  for (l = renderers; l; l = l->next)
    {
      GtkCellRenderer *focus_renderer = l->data;

      if (gtk_cell_area_is_focus_sibling (area, focus_renderer, renderer))
	{
	  gtk_cell_area_remove_focus_sibling (area, focus_renderer, renderer);
	  break;
	}
    }

  g_list_free (renderers);

  if (class->remove)
    class->remove (area, renderer);
  else
    g_warning ("GtkCellAreaClass::remove not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

static gboolean
get_has_renderer (GtkCellRenderer  *renderer,
		  HasRendererCheck *check)
{
  if (renderer == check->renderer)
    check->has_renderer = TRUE;

  return check->has_renderer;
}

/**
 * gtk_cell_area_has_renderer:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to check
 *
 * Checks if @area contains @renderer.
 *
 * Return value: %TRUE if @renderer is in the @area.
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_has_renderer (GtkCellArea     *area,
			    GtkCellRenderer *renderer)
{
  HasRendererCheck check = { renderer, FALSE };

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (renderer), FALSE);

  gtk_cell_area_foreach (area, (GtkCellCallback)get_has_renderer, &check);

  return check.has_renderer;
}

/**
 * gtk_cell_area_foreach:
 * @area: a #GtkCellArea
 * @callback: the #GtkCellCallback to call
 * @callback_data: user provided data pointer
 *
 * Calls @callback for every #GtkCellRenderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_foreach (GtkCellArea        *area,
		       GtkCellCallback     callback,
		       gpointer            callback_data)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (callback != NULL);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->foreach)
    class->foreach (area, callback, callback_data);
  else
    g_warning ("GtkCellAreaClass::foreach not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_get_cell_allocation:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext used to hold sizes for @area.
 * @widget: the #GtkWidget that @area is rendering on
 * @renderer: the #GtkCellRenderer to get the allocation for
 * @cell_area: the whole allocated area for @area in @widget
 *             for this row
 * @allocation: (out): where to store the allocation for @renderer
 *
 * Derives the allocation of @renderer inside @area if @area
 * were to be renderered in @cell_area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_get_cell_allocation (GtkCellArea          *area,
				   GtkCellAreaContext   *context,	
				   GtkWidget            *widget,
				   GtkCellRenderer      *renderer,
				   const GdkRectangle   *cell_area,
				   GdkRectangle         *allocation)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_AREA_CONTEXT (context));
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (cell_area != NULL);
  g_return_if_fail (allocation != NULL);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->get_cell_allocation)
    class->get_cell_allocation (area, context, widget, renderer, cell_area, allocation);
  else
    g_warning ("GtkCellAreaClass::get_cell_allocation not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_event:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext for this row of data.
 * @widget: the #GtkWidget that @area is rendering to
 * @event: the #GdkEvent to handle
 * @cell_area: the @widget relative coordinates for @area
 * @flags: the #GtkCellRendererState for @area in this row.
 *
 * Delegates event handling to a #GtkCellArea.
 *
 * Return value: %TRUE if the event was handled by @area.
 *
 * Since: 3.0
 */
gint
gtk_cell_area_event (GtkCellArea          *area,
		     GtkCellAreaContext   *context,
		     GtkWidget            *widget,
		     GdkEvent             *event,
		     const GdkRectangle   *cell_area,
		     GtkCellRendererState  flags)
{
  GtkCellAreaClass *class;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), 0);
  g_return_val_if_fail (GTK_IS_CELL_AREA_CONTEXT (context), 0);
  g_return_val_if_fail (GTK_IS_WIDGET (widget), 0);
  g_return_val_if_fail (event != NULL, 0);
  g_return_val_if_fail (cell_area != NULL, 0);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->event)
    return class->event (area, context, widget, event, cell_area, flags);

  g_warning ("GtkCellAreaClass::event not implemented for `%s'", 
	     g_type_name (G_TYPE_FROM_INSTANCE (area)));
  return 0;
}

/**
 * gtk_cell_area_render:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext for this row of data.
 * @widget: the #GtkWidget that @area is rendering to
 * @cr: the #cairo_t to render with
 * @background_area: the @widget relative coordinates for @area's background
 * @cell_area: the @widget relative coordinates for @area
 * @flags: the #GtkCellRendererState for @area in this row.
 * @paint_focus: whether @area should paint focus on focused cells for focused rows or not.
 *
 * Renders @area's cells according to @area's layout onto @widget at
 * the given coordinates.
 *
 * Since: 3.0
 */
void
gtk_cell_area_render (GtkCellArea          *area,
		      GtkCellAreaContext   *context,
		      GtkWidget            *widget,
		      cairo_t              *cr,
		      const GdkRectangle   *background_area,
		      const GdkRectangle   *cell_area,
		      GtkCellRendererState  flags,
		      gboolean              paint_focus)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_AREA_CONTEXT (context));
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (cr != NULL);
  g_return_if_fail (background_area != NULL);
  g_return_if_fail (cell_area != NULL);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->render)
    class->render (area, context, widget, cr, background_area, cell_area, flags, paint_focus);
  else
    g_warning ("GtkCellAreaClass::render not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_set_style_detail:
 * @area: a #GtkCellArea
 * @detail: the #GtkStyle detail string to set
 *
 * Sets the detail string used in any gtk_paint_*() functions
 * used by @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_set_style_detail (GtkCellArea *area,
				const gchar *detail)
{
  GtkCellAreaPrivate *priv;

  g_return_if_fail (GTK_IS_CELL_AREA (area));

  priv = area->priv;

  if (g_strcmp0 (priv->style_detail, detail) != 0)
    {
      g_free (priv->style_detail);
      priv->style_detail = g_strdup (detail);
    }
}

/**
 * gtk_cell_area_get_style_detail:
 * @area: a #GtkCellArea
 *
 * Gets the detail string used in any gtk_paint_*() functions
 * used by @area.
 *
 * Return value: the detail string, the string belongs to the area and should not be freed.
 *
 * Since: 3.0
 */
G_CONST_RETURN gchar *
gtk_cell_area_get_style_detail (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  priv = area->priv;

  return priv->style_detail;
}

/*************************************************************
 *                      API: Geometry                        *
 *************************************************************/
/**
 * gtk_cell_area_create_context:
 * @area: a #GtkCellArea
 *
 * 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).
 *
 * Return value: (transfer full): a newly created #GtkCellAreaContext which can be used with @area.
 *
 * Since: 3.0
 */
GtkCellAreaContext *
gtk_cell_area_create_context (GtkCellArea *area)
{
  GtkCellAreaClass *class;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->create_context)
    return class->create_context (area);

  g_warning ("GtkCellAreaClass::create_context not implemented for `%s'", 
	     g_type_name (G_TYPE_FROM_INSTANCE (area)));
  
  return NULL;
}


/**
 * gtk_cell_area_get_request_mode:
 * @area: a #GtkCellArea
 *
 * Gets whether the area prefers a height-for-width layout
 * or a width-for-height layout.
 *
 * Return value: The #GtkSizeRequestMode preferred by @area.
 *
 * Since: 3.0
 */
GtkSizeRequestMode 
gtk_cell_area_get_request_mode (GtkCellArea *area)
{
  GtkCellAreaClass *class;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), 
			GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->get_request_mode)
    return class->get_request_mode (area);

  g_warning ("GtkCellAreaClass::get_request_mode not implemented for `%s'", 
	     g_type_name (G_TYPE_FROM_INSTANCE (area)));
  
  return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
}

/**
 * gtk_cell_area_get_preferred_width:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext to perform this request with
 * @widget: the #GtkWidget where @area will be rendering
 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
 *
 * Retrieves a cell area's initial minimum and natural width.
 *
 * @area will store some geometrical information in @context along the way,
 * when requesting sizes over an arbitrary number of rows, its not important
 * to check the @minimum_width and @natural_width of this call but rather to
 * consult gtk_cell_area_context_get_preferred_width() after a series of
 * requests.
 *
 * Since: 3.0
 */
void
gtk_cell_area_get_preferred_width (GtkCellArea        *area,
				   GtkCellAreaContext *context,
				   GtkWidget          *widget,
				   gint               *minimum_width,
				   gint               *natural_width)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_WIDGET (widget));

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->get_preferred_width)
    class->get_preferred_width (area, context, widget, minimum_width, natural_width);
  else
    g_warning ("GtkCellAreaClass::get_preferred_width not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_get_preferred_height_for_width:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext which has already been requested for widths.
 * @widget: the #GtkWidget where @area will be rendering
 * @width: the width for which to check the height of this area
 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
 *
 * Retrieves a cell area's minimum and natural height if it would be given
 * the specified @width.
 *
 * @area stores some geometrical information in @context along the way
 * while calling gtk_cell_area_get_preferred_width(), it's important to
 * perform a series of gtk_cell_area_get_preferred_width() requests with
 * @context first and then call gtk_cell_area_get_preferred_height_for_width()
 * on each cell area individually to get the height for width of each
 * fully requested row.
 *
 * If at some point, the width of a single row changes, it should be
 * requested with gtk_cell_area_get_preferred_width() again and then
 * the full width of the requested rows checked again with
 * gtk_cell_area_context_get_preferred_width().
 *
 * Since: 3.0
 */
void
gtk_cell_area_get_preferred_height_for_width (GtkCellArea        *area,
					      GtkCellAreaContext *context,
					      GtkWidget          *widget,
					      gint                width,
					      gint               *minimum_height,
					      gint               *natural_height)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_WIDGET (widget));

  class = GTK_CELL_AREA_GET_CLASS (area);
  class->get_preferred_height_for_width (area, context, widget, width, minimum_height, natural_height);
}


/**
 * gtk_cell_area_get_preferred_height:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext to perform this request with
 * @widget: the #GtkWidget where @area will be rendering
 * @minimum_height: (out) (allow-none): location to store the minimum height, or %NULL
 * @natural_height: (out) (allow-none): location to store the natural height, or %NULL
 *
 * Retrieves a cell area's initial minimum and natural height.
 *
 * @area will store some geometrical information in @context along the way,
 * when requesting sizes over an arbitrary number of rows, its not important
 * to check the @minimum_height and @natural_height of this call but rather to
 * consult gtk_cell_area_context_get_preferred_height() after a series of
 * requests.
 *
 * Since: 3.0
 */
void
gtk_cell_area_get_preferred_height (GtkCellArea        *area,
				    GtkCellAreaContext *context,
				    GtkWidget          *widget,
				    gint               *minimum_height,
				    gint               *natural_height)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_WIDGET (widget));

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->get_preferred_height)
    class->get_preferred_height (area, context, widget, minimum_height, natural_height);
  else
    g_warning ("GtkCellAreaClass::get_preferred_height not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_get_preferred_width_for_height:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext which has already been requested for widths.
 * @widget: the #GtkWidget where @area will be rendering
 * @height: the height for which to check the width of this area
 * @minimum_width: (out) (allow-none): location to store the minimum width, or %NULL
 * @natural_width: (out) (allow-none): location to store the natural width, or %NULL
 *
 * Retrieves a cell area's minimum and natural width if it would be given
 * the specified @height.
 *
 * @area stores some geometrical information in @context along the way
 * while calling gtk_cell_area_get_preferred_height(), it's important to
 * perform a series of gtk_cell_area_get_preferred_height() requests with
 * @context first and then call gtk_cell_area_get_preferred_width_for_height()
 * on each cell area individually to get the height for width of each
 * fully requested row.
 *
 * If at some point, the height of a single row changes, it should be
 * requested with gtk_cell_area_get_preferred_height() again and then
 * the full height of the requested rows checked again with
 * gtk_cell_area_context_get_preferred_height().
 *
 * Since: 3.0
 */
void
gtk_cell_area_get_preferred_width_for_height (GtkCellArea        *area,
					      GtkCellAreaContext *context,
					      GtkWidget          *widget,
					      gint                height,
					      gint               *minimum_width,
					      gint               *natural_width)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_WIDGET (widget));

  class = GTK_CELL_AREA_GET_CLASS (area);
  class->get_preferred_width_for_height (area, context, widget, height, minimum_width, natural_width);
}

/*************************************************************
 *                      API: Attributes                      *
 *************************************************************/

/**
 * gtk_cell_area_attribute_connect:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to connect an attribute for
 * @attribute: the attribute name
 * @column: the #GtkTreeModel column to fetch attribute values from
 *
 * Connects an @attribute to apply values from @column for the
 * #GtkTreeModel in use.
 *
 * Since: 3.0
 */
void
gtk_cell_area_attribute_connect (GtkCellArea        *area,
				 GtkCellRenderer    *renderer,
				 const gchar        *attribute,
				 gint                column)
{ 
  GtkCellAreaPrivate *priv;
  CellInfo           *info;
  CellAttribute      *cell_attribute;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (attribute != NULL);
  g_return_if_fail (gtk_cell_area_has_renderer (area, renderer));

  priv = area->priv;
  info = g_hash_table_lookup (priv->cell_info, renderer);

  if (!info)
    {
      info = cell_info_new (NULL, NULL, NULL);

      g_hash_table_insert (priv->cell_info, renderer, info);
    }
  else
    {
      GSList *node;

      /* Check we are not adding the same attribute twice */
      if ((node = g_slist_find_custom (info->attributes, attribute,
				       (GCompareFunc)cell_attribute_find)) != NULL)
	{
	  cell_attribute = node->data;

	  g_warning ("Cannot connect attribute `%s' for cell renderer class `%s' "
		     "since `%s' is already attributed to column %d", 
		     attribute,
		     g_type_name (G_TYPE_FROM_INSTANCE (area)),
		     attribute, cell_attribute->column);
	  return;
	}
    }

  cell_attribute = cell_attribute_new (renderer, attribute, column);

  if (!cell_attribute)
    {
      g_warning ("Cannot connect attribute `%s' for cell renderer class `%s' "
		 "since attribute does not exist", 
		 attribute,
		 g_type_name (G_TYPE_FROM_INSTANCE (area)));
      return;
    }

  info->attributes = g_slist_prepend (info->attributes, cell_attribute);
}

/**
 * gtk_cell_area_attribute_disconnect:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to disconnect an attribute for
 * @attribute: the attribute name
 *
 * Disconnects @attribute for the @renderer in @area so that
 * attribute will no longer be updated with values from the
 * model.
 *
 * Since: 3.0
 */
void 
gtk_cell_area_attribute_disconnect (GtkCellArea        *area,
				    GtkCellRenderer    *renderer,
				    const gchar        *attribute)
{
  GtkCellAreaPrivate *priv;
  CellInfo           *info;
  CellAttribute      *cell_attribute;
  GSList             *node;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (attribute != NULL);
  g_return_if_fail (gtk_cell_area_has_renderer (area, renderer));

  priv = area->priv;
  info = g_hash_table_lookup (priv->cell_info, renderer);

  if (info)
    {
      node = g_slist_find_custom (info->attributes, attribute,
				  (GCompareFunc)cell_attribute_find);
      if (node)
	{
	  cell_attribute = node->data;

	  cell_attribute_free (cell_attribute);

	  info->attributes = g_slist_delete_link (info->attributes, node);
	}
    }
}

/**
 * gtk_cell_area_apply_attributes
 * @area: a #GtkCellArea
 * @tree_model: the #GtkTreeModel to pull values from
 * @iter: the #GtkTreeIter in @tree_model to apply values for
 * @is_expander: whether @iter has children
 * @is_expanded: whether @iter is expanded in the view and
 *               children are visible
 *
 * Applies any connected attributes to the renderers in 
 * @area by pulling the values from @tree_model.
 *
 * Since: 3.0
 */
void
gtk_cell_area_apply_attributes (GtkCellArea  *area,
				GtkTreeModel *tree_model,
				GtkTreeIter  *iter,
				gboolean      is_expander,
				gboolean      is_expanded)
{
  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_TREE_MODEL (tree_model));
  g_return_if_fail (iter != NULL);

  g_signal_emit (area, cell_area_signals[SIGNAL_APPLY_ATTRIBUTES], 0, 
		 tree_model, iter, is_expander, is_expanded);
}

/**
 * gtk_cell_area_get_current_path_string:
 * @area: a #GtkCellArea
 *
 * 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.
 *
 * Return value: The current #GtkTreePath string for the current
 * attributes applied to @area. This string belongs to the area and
 * should not be freed.
 *
 * Since: 3.0
 */
G_CONST_RETURN gchar *
gtk_cell_area_get_current_path_string (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  priv = area->priv;

  return priv->current_path;
}


/*************************************************************
 *                    API: Cell Properties                   *
 *************************************************************/
/**
 * gtk_cell_area_class_install_cell_property:
 * @aclass: a #GtkCellAreaClass
 * @property_id: the id for the property
 * @pspec: the #GParamSpec for the property
 *
 * Installs a cell property on a cell area class.
 *
 * Since: 3.0
 */
void
gtk_cell_area_class_install_cell_property (GtkCellAreaClass   *aclass,
					   guint               property_id,
					   GParamSpec         *pspec)
{
  g_return_if_fail (GTK_IS_CELL_AREA_CLASS (aclass));
  g_return_if_fail (G_IS_PARAM_SPEC (pspec));
  if (pspec->flags & G_PARAM_WRITABLE)
    g_return_if_fail (aclass->set_cell_property != NULL);
  if (pspec->flags & G_PARAM_READABLE)
    g_return_if_fail (aclass->get_cell_property != NULL);
  g_return_if_fail (property_id > 0);
  g_return_if_fail (PARAM_SPEC_PARAM_ID (pspec) == 0);  /* paranoid */
  g_return_if_fail ((pspec->flags & (G_PARAM_CONSTRUCT | G_PARAM_CONSTRUCT_ONLY)) == 0);

  if (g_param_spec_pool_lookup (cell_property_pool, pspec->name, G_OBJECT_CLASS_TYPE (aclass), TRUE))
    {
      g_warning (G_STRLOC ": class `%s' already contains a cell property named `%s'",
		 G_OBJECT_CLASS_NAME (aclass), pspec->name);
      return;
    }
  g_param_spec_ref (pspec);
  g_param_spec_sink (pspec);
  PARAM_SPEC_SET_PARAM_ID (pspec, property_id);
  g_param_spec_pool_insert (cell_property_pool, pspec, G_OBJECT_CLASS_TYPE (aclass));
}

/**
 * gtk_cell_area_class_find_cell_property:
 * @aclass: a #GtkCellAreaClass
 * @property_name: the name of the child property to find
 *
 * Finds a cell property of a cell area class by name.
 *
 * Return value: (allow-none): the #GParamSpec of the child property or %NULL if @aclass has no
 *   child property with that name.
 *
 * Since: 3.0
 */
GParamSpec*
gtk_cell_area_class_find_cell_property (GtkCellAreaClass   *aclass,
					const gchar        *property_name)
{
  g_return_val_if_fail (GTK_IS_CELL_AREA_CLASS (aclass), NULL);
  g_return_val_if_fail (property_name != NULL, NULL);

  return g_param_spec_pool_lookup (cell_property_pool,
				   property_name,
				   G_OBJECT_CLASS_TYPE (aclass),
				   TRUE);
}

/**
 * gtk_cell_area_class_list_cell_properties:
 * @aclass: a #GtkCellAreaClass
 * @n_properties: location to return the number of cell properties found
 *
 * Returns all cell properties of a cell area class.
 *
 * Return value: a newly allocated %NULL-terminated array of #GParamSpec*.
 *           The array must be freed with g_free().
 *
 * Since: 3.0
 */
GParamSpec**
gtk_cell_area_class_list_cell_properties (GtkCellAreaClass  *aclass,
					  guint		    *n_properties)
{
  GParamSpec **pspecs;
  guint n;

  g_return_val_if_fail (GTK_IS_CELL_AREA_CLASS (aclass), NULL);

  pspecs = g_param_spec_pool_list (cell_property_pool,
				   G_OBJECT_CLASS_TYPE (aclass),
				   &n);
  if (n_properties)
    *n_properties = n;

  return pspecs;
}

/**
 * gtk_cell_area_add_with_properties:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer to be placed inside @area
 * @first_prop_name: the name of the first cell property to set
 * @Varargs: a %NULL-terminated list of property names and values, starting
 *           with @first_prop_name
 *
 * Adds @renderer to @area, setting cell properties at the same time.
 * See gtk_cell_area_add() and gtk_cell_area_child_set() for more details.
 *
 * Since: 3.0
 */
void
gtk_cell_area_add_with_properties (GtkCellArea        *area,
				   GtkCellRenderer    *renderer,
				   const gchar        *first_prop_name,
				   ...)
{
  GtkCellAreaClass *class;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->add)
    {
      va_list var_args;

      class->add (area, renderer);

      va_start (var_args, first_prop_name);
      gtk_cell_area_cell_set_valist (area, renderer, first_prop_name, var_args);
      va_end (var_args);
    }
  else
    g_warning ("GtkCellAreaClass::add not implemented for `%s'", 
	       g_type_name (G_TYPE_FROM_INSTANCE (area)));
}

/**
 * gtk_cell_area_cell_set:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer which is a cell inside @area
 * @first_prop_name: the name of the first cell property to set
 * @Varargs: a %NULL-terminated list of property names and values, starting
 *           with @first_prop_name
 *
 * Sets one or more cell properties for @cell in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_set (GtkCellArea        *area,
			GtkCellRenderer    *renderer,
			const gchar        *first_prop_name,
			...)
{
  va_list var_args;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  va_start (var_args, first_prop_name);
  gtk_cell_area_cell_set_valist (area, renderer, first_prop_name, var_args);
  va_end (var_args);
}

/**
 * gtk_cell_area_cell_get:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer which is inside @area
 * @first_prop_name: the name of the first cell property to get
 * @Varargs: return location for the first cell property, followed
 *     optionally by more name/return location pairs, followed by %NULL
 *
 * Gets the values of one or more cell properties for @renderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_get (GtkCellArea        *area,
			GtkCellRenderer    *renderer,
			const gchar        *first_prop_name,
			...)
{
  va_list var_args;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  va_start (var_args, first_prop_name);
  gtk_cell_area_cell_get_valist (area, renderer, first_prop_name, var_args);
  va_end (var_args);
}

static inline void
area_get_cell_property (GtkCellArea     *area,
			GtkCellRenderer *renderer,
			GParamSpec      *pspec,
			GValue          *value)
{
  GtkCellAreaClass *class = g_type_class_peek (pspec->owner_type);
  
  class->get_cell_property (area, renderer, PARAM_SPEC_PARAM_ID (pspec), value, pspec);
}

static inline void
area_set_cell_property (GtkCellArea     *area,
			GtkCellRenderer *renderer,
			GParamSpec      *pspec,
			const GValue    *value)
{
  GValue tmp_value = { 0, };
  GtkCellAreaClass *class = g_type_class_peek (pspec->owner_type);

  /* provide a copy to work from, convert (if necessary) and validate */
  g_value_init (&tmp_value, G_PARAM_SPEC_VALUE_TYPE (pspec));
  if (!g_value_transform (value, &tmp_value))
    g_warning ("unable to set cell property `%s' of type `%s' from value of type `%s'",
	       pspec->name,
	       g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)),
	       G_VALUE_TYPE_NAME (value));
  else if (g_param_value_validate (pspec, &tmp_value) && !(pspec->flags & G_PARAM_LAX_VALIDATION))
    {
      gchar *contents = g_strdup_value_contents (value);

      g_warning ("value \"%s\" of type `%s' is invalid for property `%s' of type `%s'",
		 contents,
		 G_VALUE_TYPE_NAME (value),
		 pspec->name,
		 g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
      g_free (contents);
    }
  else
    {
      class->set_cell_property (area, renderer, PARAM_SPEC_PARAM_ID (pspec), &tmp_value, pspec);
    }
  g_value_unset (&tmp_value);
}

/**
 * gtk_cell_area_cell_set_valist:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer which inside @area
 * @first_property_name: the name of the first cell property to set
 * @var_args: a %NULL-terminated list of property names and values, starting
 *           with @first_prop_name
 *
 * Sets one or more cell properties for @renderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_set_valist (GtkCellArea        *area,
			       GtkCellRenderer    *renderer,
			       const gchar        *first_property_name,
			       va_list             var_args)
{
  const gchar *name;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  name = first_property_name;
  while (name)
    {
      GValue value = { 0, };
      gchar *error = NULL;
      GParamSpec *pspec = 
	g_param_spec_pool_lookup (cell_property_pool, name,
				  G_OBJECT_TYPE (area), TRUE);
      if (!pspec)
	{
	  g_warning ("%s: cell area class `%s' has no cell property named `%s'",
		     G_STRLOC, G_OBJECT_TYPE_NAME (area), name);
	  break;
	}
      if (!(pspec->flags & G_PARAM_WRITABLE))
	{
	  g_warning ("%s: cell property `%s' of cell area class `%s' is not writable",
		     G_STRLOC, pspec->name, G_OBJECT_TYPE_NAME (area));
	  break;
	}

      g_value_init (&value, G_PARAM_SPEC_VALUE_TYPE (pspec));
      G_VALUE_COLLECT (&value, var_args, 0, &error);
      if (error)
	{
	  g_warning ("%s: %s", G_STRLOC, error);
	  g_free (error);

	  /* we purposely leak the value here, it might not be
	   * in a sane state if an error condition occoured
	   */
	  break;
	}
      area_set_cell_property (area, renderer, pspec, &value);
      g_value_unset (&value);
      name = va_arg (var_args, gchar*);
    }
}

/**
 * gtk_cell_area_cell_get_valist:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer inside @area
 * @first_property_name: the name of the first property to get
 * @var_args: return location for the first property, followed
 *     optionally by more name/return location pairs, followed by %NULL
 *
 * Gets the values of one or more cell properties for @renderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_get_valist (GtkCellArea        *area,
			       GtkCellRenderer    *renderer,
			       const gchar        *first_property_name,
			       va_list             var_args)
{
  const gchar *name;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));

  name = first_property_name;
  while (name)
    {
      GValue value = { 0, };
      GParamSpec *pspec;
      gchar *error;

      pspec = g_param_spec_pool_lookup (cell_property_pool, name,
					G_OBJECT_TYPE (area), TRUE);
      if (!pspec)
	{
	  g_warning ("%s: cell area class `%s' has no cell property named `%s'",
		     G_STRLOC, G_OBJECT_TYPE_NAME (area), name);
	  break;
	}
      if (!(pspec->flags & G_PARAM_READABLE))
	{
	  g_warning ("%s: cell property `%s' of cell area class `%s' is not readable",
		     G_STRLOC, pspec->name, G_OBJECT_TYPE_NAME (area));
	  break;
	}

      g_value_init (&value, G_PARAM_SPEC_VALUE_TYPE (pspec));
      area_get_cell_property (area, renderer, pspec, &value);
      G_VALUE_LCOPY (&value, var_args, 0, &error);
      if (error)
	{
	  g_warning ("%s: %s", G_STRLOC, error);
	  g_free (error);
	  g_value_unset (&value);
	  break;
	}
      g_value_unset (&value);
      name = va_arg (var_args, gchar*);
    }
}

/**
 * gtk_cell_area_cell_set_property:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer inside @area
 * @property_name: the name of the cell property to set
 * @value: the value to set the cell property to
 *
 * Sets a cell property for @renderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_set_property (GtkCellArea        *area,
				 GtkCellRenderer    *renderer,
				 const gchar        *property_name,
				 const GValue       *value)
{
  GParamSpec *pspec;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (property_name != NULL);
  g_return_if_fail (G_IS_VALUE (value));
  
  pspec = g_param_spec_pool_lookup (cell_property_pool, property_name,
				    G_OBJECT_TYPE (area), TRUE);
  if (!pspec)
    g_warning ("%s: cell area class `%s' has no cell property named `%s'",
	       G_STRLOC, G_OBJECT_TYPE_NAME (area), property_name);
  else if (!(pspec->flags & G_PARAM_WRITABLE))
    g_warning ("%s: cell property `%s' of cell area class `%s' is not writable",
	       G_STRLOC, pspec->name, G_OBJECT_TYPE_NAME (area));
  else
    {
      area_set_cell_property (area, renderer, pspec, value);
    }
}

/**
 * gtk_cell_area_cell_get_property:
 * @area: a #GtkCellArea
 * @renderer: a #GtkCellRenderer inside @area
 * @property_name: the name of the property to get
 * @value: a location to return the value
 *
 * Gets the value of a cell property for @renderer in @area.
 *
 * Since: 3.0
 */
void
gtk_cell_area_cell_get_property (GtkCellArea        *area,
				 GtkCellRenderer    *renderer,
				 const gchar        *property_name,
				 GValue             *value)
{
  GParamSpec *pspec;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (property_name != NULL);
  g_return_if_fail (G_IS_VALUE (value));
  
  pspec = g_param_spec_pool_lookup (cell_property_pool, property_name,
				    G_OBJECT_TYPE (area), TRUE);
  if (!pspec)
    g_warning ("%s: cell area class `%s' has no cell property named `%s'",
	       G_STRLOC, G_OBJECT_TYPE_NAME (area), property_name);
  else if (!(pspec->flags & G_PARAM_READABLE))
    g_warning ("%s: cell property `%s' of cell area class `%s' is not readable",
	       G_STRLOC, pspec->name, G_OBJECT_TYPE_NAME (area));
  else
    {
      GValue *prop_value, tmp_value = { 0, };

      /* auto-conversion of the callers value type
       */
      if (G_VALUE_TYPE (value) == G_PARAM_SPEC_VALUE_TYPE (pspec))
	{
	  g_value_reset (value);
	  prop_value = value;
	}
      else if (!g_value_type_transformable (G_PARAM_SPEC_VALUE_TYPE (pspec), G_VALUE_TYPE (value)))
	{
	  g_warning ("can't retrieve cell property `%s' of type `%s' as value of type `%s'",
		     pspec->name,
		     g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)),
		     G_VALUE_TYPE_NAME (value));
	  return;
	}
      else
	{
	  g_value_init (&tmp_value, G_PARAM_SPEC_VALUE_TYPE (pspec));
	  prop_value = &tmp_value;
	}

      area_get_cell_property (area, renderer, pspec, prop_value);

      if (prop_value != value)
	{
	  g_value_transform (prop_value, value);
	  g_value_unset (&tmp_value);
	}
    }
}

/*************************************************************
 *                         API: Focus                        *
 *************************************************************/

/**
 * gtk_cell_area_is_activatable:
 * @area: a #GtkCellArea
 *
 * Returns whether the area can do anything when activated,
 * after applying new attributes to @area.
 *
 * Return value: whether @area can do anything when activated.
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_is_activatable (GtkCellArea *area)
{
  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);

  return GTK_CELL_AREA_GET_CLASS (area)->is_activatable (area);
}

/**
 * gtk_cell_area_focus:
 * @area: a #GtkCellArea
 * @direction: the #GtkDirectionType
 *
 * 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.
 *
 * Implementing #GtkCellArea classes should implement this
 * method to receive and navigate focus in it's own way particular
 * to how it lays out cells.
 *
 * Return value: %TRUE if focus remains inside @area as a result of this call.
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_focus (GtkCellArea      *area,
		     GtkDirectionType  direction)
{
  GtkCellAreaClass *class;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);

  class = GTK_CELL_AREA_GET_CLASS (area);

  if (class->focus)
    return class->focus (area, direction);

  g_warning ("GtkCellAreaClass::focus not implemented for `%s'", 
	     g_type_name (G_TYPE_FROM_INSTANCE (area)));

  return FALSE;
}

/**
 * gtk_cell_area_activate:
 * @area: a #GtkCellArea
 * @context: the #GtkCellAreaContext in context with the current row data
 * @widget: the #GtkWidget that @area is rendering on
 * @cell_area: the size and location of @area relative to @widget's allocation
 * @flags: the #GtkCellRendererState flags for @area for this row of data.
 *
 * 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.
 *
 * Return value: Whether @area was successfully activated.
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_activate (GtkCellArea         *area,
			GtkCellAreaContext  *context,
			GtkWidget           *widget,
			const GdkRectangle  *cell_area,
			GtkCellRendererState flags)
{
  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);

  return GTK_CELL_AREA_GET_CLASS (area)->activate (area, context, widget, cell_area, flags);
}


/**
 * gtk_cell_area_set_focus_cell:
 * @area: a #GtkCellArea
 * @focus_cell: the #GtkCellRenderer to give focus to
 *
 * This is generally called from #GtkCellArea implementations
 * either gtk_cell_area_grab_focus() or gtk_cell_area_update_focus()
 * is called. It's also up to the #GtkCellArea implementation
 * to update the focused cell when receiving events from
 * gtk_cell_area_event() appropriately.
 *
 * Since: 3.0
 */
void
gtk_cell_area_set_focus_cell (GtkCellArea     *area,
			      GtkCellRenderer *renderer)
{
  GtkCellAreaPrivate *priv;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (renderer == NULL || GTK_IS_CELL_RENDERER (renderer));

  priv = area->priv;

  if (priv->focus_cell != renderer)
    {
      if (priv->focus_cell)
	g_object_unref (priv->focus_cell);

      priv->focus_cell = renderer;

      if (priv->focus_cell)
	g_object_ref (priv->focus_cell);

      g_object_notify (G_OBJECT (area), "focus-cell");
    }

  /* Signal that the current focus renderer for this path changed
   * (it may be that the focus cell did not change, but the row
   * may have changed so we need to signal it) */
  g_signal_emit (area, cell_area_signals[SIGNAL_FOCUS_CHANGED], 0, 
		 priv->focus_cell, priv->current_path);

}

/**
 * gtk_cell_area_get_focus_cell:
 * @area: a #GtkCellArea
 *
 * Retrieves the currently focused cell for @area
 *
 * Return value: the currently focused cell in @area.
 *
 * Since: 3.0
 */
GtkCellRenderer *
gtk_cell_area_get_focus_cell (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  priv = area->priv;

  return priv->focus_cell;
}


/*************************************************************
 *                    API: Focus Siblings                    *
 *************************************************************/

/**
 * gtk_cell_area_add_focus_sibling:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer expected to have focus
 * @sibling: the #GtkCellRenderer to add to @renderer's focus area
 *
 * Adds @sibling to @renderer's focusable area, focus will be drawn
 * around @renderer and all of it's siblings if @renderer can 
 * focus for a given row.
 *
 * Events handled by focus siblings can also activate the given
 * focusable @renderer.
 *
 * Since: 3.0
 */
void
gtk_cell_area_add_focus_sibling (GtkCellArea     *area,
				 GtkCellRenderer *renderer,
				 GtkCellRenderer *sibling)
{
  GtkCellAreaPrivate *priv;
  GList              *siblings;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (GTK_IS_CELL_RENDERER (sibling));
  g_return_if_fail (renderer != sibling);
  g_return_if_fail (gtk_cell_area_has_renderer (area, renderer));
  g_return_if_fail (gtk_cell_area_has_renderer (area, sibling));
  g_return_if_fail (!gtk_cell_area_is_focus_sibling (area, renderer, sibling));

  /* XXX We should also check that sibling is not in any other renderer's sibling
   * list already, a renderer can be sibling of only one focusable renderer
   * at a time.
   */

  priv = area->priv;

  siblings = g_hash_table_lookup (priv->focus_siblings, renderer);

  if (siblings)
    siblings = g_list_append (siblings, sibling);
  else
    {
      siblings = g_list_append (siblings, sibling);
      g_hash_table_insert (priv->focus_siblings, renderer, siblings);
    }
}

/**
 * gtk_cell_area_remove_focus_sibling:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer expected to have focus
 * @sibling: the #GtkCellRenderer to remove from @renderer's focus area
 * 
 * Removes @sibling from @renderer's focus sibling list 
 * (see gtk_cell_area_add_focus_sibling()).
 *
 * Since: 3.0
 */
void
gtk_cell_area_remove_focus_sibling (GtkCellArea     *area,
				    GtkCellRenderer *renderer,
				    GtkCellRenderer *sibling)
{
  GtkCellAreaPrivate *priv;
  GList              *siblings;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (GTK_IS_CELL_RENDERER (sibling));
  g_return_if_fail (gtk_cell_area_is_focus_sibling (area, renderer, sibling));

  priv = area->priv;

  siblings = g_hash_table_lookup (priv->focus_siblings, renderer);

  siblings = g_list_copy (siblings);
  siblings = g_list_remove (siblings, sibling);

  if (!siblings)
    g_hash_table_remove (priv->focus_siblings, renderer);
  else
    g_hash_table_insert (priv->focus_siblings, renderer, siblings);
}

/**
 * gtk_cell_area_is_focus_sibling:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer expected to have focus
 * @sibling: the #GtkCellRenderer to check against @renderer's sibling list
 * 
 * Returns %TRUE if @sibling is one of @renderer's focus siblings
 * (see gtk_cell_area_add_focus_sibling()).
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_is_focus_sibling (GtkCellArea     *area,
				GtkCellRenderer *renderer,
				GtkCellRenderer *sibling)
{
  GtkCellAreaPrivate *priv;
  GList              *siblings, *l;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (renderer), FALSE);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (sibling), FALSE);

  priv = area->priv;

  siblings = g_hash_table_lookup (priv->focus_siblings, renderer);

  for (l = siblings; l; l = l->next)
    {
      GtkCellRenderer *a_sibling = l->data;

      if (a_sibling == sibling)
	return TRUE;
    }

  return FALSE;
}

/**
 * gtk_cell_area_get_focus_siblings:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer expected to have focus
 *
 * Gets the focus sibling cell renderers for @renderer.
 *
 * Return value: (element-type GtkCellRenderer) (transfer none): A #GList of #GtkCellRenderers. 
 *       The returned list is internal and should not be freed.
 *
 * Since: 3.0
 */
const GList *
gtk_cell_area_get_focus_siblings (GtkCellArea     *area,
				  GtkCellRenderer *renderer)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (renderer), NULL);

  priv = area->priv;

  return g_hash_table_lookup (priv->focus_siblings, renderer);  
}

/**
 * gtk_cell_area_get_focus_from_sibling:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer
 *
 * Gets the #GtkCellRenderer which is expected to be focusable
 * for which @renderer is, or may be a sibling.
 *
 * This is handy for #GtkCellArea subclasses when handling events,
 * after determining the renderer at the event location it can
 * then chose to activate the focus cell for which the event
 * cell may have been a sibling.
 *
 * Return value: the #GtkCellRenderer for which @renderer is a sibling, or %NULL.
 *
 * Since: 3.0
 */
GtkCellRenderer *
gtk_cell_area_get_focus_from_sibling (GtkCellArea          *area,
				      GtkCellRenderer      *renderer)
{
  GtkCellRenderer *ret_renderer = NULL;
  GList           *renderers, *l;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (renderer), NULL);

  renderers = gtk_cell_layout_get_cells (GTK_CELL_LAYOUT (area));

  for (l = renderers; l; l = l->next)
    {
      GtkCellRenderer *a_renderer = l->data;
      const GList     *list;

      for (list = gtk_cell_area_get_focus_siblings (area, a_renderer); 
	   list; list = list->next)
	{
	  GtkCellRenderer *sibling_renderer = list->data;

	  if (sibling_renderer == renderer)
	    {
	      ret_renderer = a_renderer;
	      break;
	    }
	}
    }
  g_list_free (renderers);

  return ret_renderer;
}

/*************************************************************
 *              API: Cell Activation/Editing                 *
 *************************************************************/
static void
gtk_cell_area_add_editable (GtkCellArea        *area,
			    GtkCellRenderer    *renderer,
			    GtkCellEditable    *editable,
			    GdkRectangle       *cell_area)
{
  g_signal_emit (area, cell_area_signals[SIGNAL_ADD_EDITABLE], 0, 
		 renderer, editable, cell_area, area->priv->current_path);
}

static void
gtk_cell_area_remove_editable  (GtkCellArea        *area,
				GtkCellRenderer    *renderer,
				GtkCellEditable    *editable)
{
  g_signal_emit (area, cell_area_signals[SIGNAL_REMOVE_EDITABLE], 0, renderer, editable);
}

static void
cell_area_remove_widget_cb (GtkCellEditable *editable,
			    GtkCellArea     *area)
{
  GtkCellAreaPrivate *priv = area->priv;

  g_assert (priv->edit_widget == editable);
  g_assert (priv->edited_cell != NULL);

  gtk_cell_area_remove_editable (area, priv->edited_cell, priv->edit_widget);

  /* Now that we're done with editing the widget and it can be removed,
   * remove our references to the widget and disconnect handlers */
  gtk_cell_area_set_edited_cell (area, NULL);
  gtk_cell_area_set_edit_widget (area, NULL);
}

static void
gtk_cell_area_set_edited_cell (GtkCellArea     *area,
			       GtkCellRenderer *renderer)
{
  GtkCellAreaPrivate *priv;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (renderer == NULL || GTK_IS_CELL_RENDERER (renderer));

  priv = area->priv;

  if (priv->edited_cell != renderer)
    {
      if (priv->edited_cell)
	g_object_unref (priv->edited_cell);

      priv->edited_cell = renderer;

      if (priv->edited_cell)
	g_object_ref (priv->edited_cell);

      g_object_notify (G_OBJECT (area), "edited-cell");
    }
}

static void
gtk_cell_area_set_edit_widget (GtkCellArea     *area,
			       GtkCellEditable *editable)
{
  GtkCellAreaPrivate *priv;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (editable == NULL || GTK_IS_CELL_EDITABLE (editable));

  priv = area->priv;

  if (priv->edit_widget != editable)
    {
      if (priv->edit_widget)
	{
	  g_signal_handler_disconnect (priv->edit_widget, priv->remove_widget_id);

	  g_object_unref (priv->edit_widget);
	}

      priv->edit_widget = editable;

      if (priv->edit_widget)
	{
	  priv->remove_widget_id =
	    g_signal_connect (priv->edit_widget, "remove-widget",
			      G_CALLBACK (cell_area_remove_widget_cb), area);

	  g_object_ref (priv->edit_widget);
	}

      g_object_notify (G_OBJECT (area), "edit-widget");
    }
}

/**
 * gtk_cell_area_get_edited_cell:
 * @area: a #GtkCellArea
 *
 * Gets the #GtkCellRenderer in @area that is currently
 * being edited.
 *
 * Return value: The currently edited #GtkCellRenderer
 *
 * Since: 3.0
 */
GtkCellRenderer   *
gtk_cell_area_get_edited_cell (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  priv = area->priv;

  return priv->edited_cell;
}

/**
 * gtk_cell_area_get_edit_widget:
 * @area: a #GtkCellArea
 *
 * Gets the #GtkCellEditable widget currently used
 * to edit the currently edited cell.
 *
 * Return value: The currently active #GtkCellEditable widget
 *
 * Since: 3.0
 */
GtkCellEditable *
gtk_cell_area_get_edit_widget (GtkCellArea *area)
{
  GtkCellAreaPrivate *priv;

  g_return_val_if_fail (GTK_IS_CELL_AREA (area), NULL);

  priv = area->priv;

  return priv->edit_widget;
}

/**
 * gtk_cell_area_activate_cell:
 * @area: a #GtkCellArea
 * @widget: the #GtkWidget that @area is rendering onto
 * @renderer: the #GtkCellRenderer in @area to activate
 * @event: the #GdkEvent for which cell activation should occur
 * @cell_area: the #GdkRectangle in @widget relative coordinates
 *             of @renderer for the current row.
 * @flags: the #GtkCellRendererState for @renderer
 *
 * This is used by #GtkCellArea subclasses when handling events
 * to activate cells, the base #GtkCellArea class activates cells
 * for keyboard events for free in it's own GtkCellArea->activate()
 * implementation.
 *
 * Return value: whether cell activation was successful
 *
 * Since: 3.0
 */
gboolean
gtk_cell_area_activate_cell (GtkCellArea          *area,
			     GtkWidget            *widget,
			     GtkCellRenderer      *renderer,
			     GdkEvent             *event,
			     const GdkRectangle   *cell_area,
			     GtkCellRendererState  flags)
{
  GtkCellRendererMode mode;
  GdkRectangle        inner_area;
  GtkCellAreaPrivate *priv;
  
  g_return_val_if_fail (GTK_IS_CELL_AREA (area), FALSE);
  g_return_val_if_fail (GTK_IS_WIDGET (widget), FALSE);
  g_return_val_if_fail (GTK_IS_CELL_RENDERER (renderer), FALSE);
  g_return_val_if_fail (cell_area != NULL, FALSE);

  priv = area->priv;

  /* Remove margins from the background area to produce the cell area.
   */
  gtk_cell_area_inner_cell_area (area, widget, cell_area, &inner_area);

  g_object_get (renderer, "mode", &mode, NULL);

  if (mode == GTK_CELL_RENDERER_MODE_ACTIVATABLE)
    {
      if (gtk_cell_renderer_activate (renderer,
				      event, widget,
				      priv->current_path,
				      cell_area,
				      &inner_area,
				      flags))
	return TRUE;
    }
  else if (mode == GTK_CELL_RENDERER_MODE_EDITABLE)
    {
      GtkCellEditable *editable_widget;
      
      editable_widget =
	gtk_cell_renderer_start_editing (renderer,
					 event, widget,
					 priv->current_path,
					 cell_area,
					 &inner_area,
					 flags);
      
      if (editable_widget != NULL)
	{
	  g_return_val_if_fail (GTK_IS_CELL_EDITABLE (editable_widget), FALSE);
	  
	  gtk_cell_area_set_edited_cell (area, renderer);
	  gtk_cell_area_set_edit_widget (area, editable_widget);
	  
	  /* Signal that editing started so that callers can get 
	   * a handle on the editable_widget */
	  gtk_cell_area_add_editable (area, priv->focus_cell, editable_widget, &inner_area);

	  /* If the signal was successfully handled start the editing */
	  if (gtk_widget_get_parent (GTK_WIDGET (editable_widget)))
	    {
	      gtk_cell_editable_start_editing (editable_widget, NULL);
	      gtk_widget_grab_focus (GTK_WIDGET (editable_widget));
	    }
	  else
	    {
	      /* Otherwise clear the editing state and fire a warning */
	      gtk_cell_area_set_edited_cell (area, NULL);
	      gtk_cell_area_set_edit_widget (area, NULL);

	      g_warning ("GtkCellArea::add-editable fired in the dark, no cell editing was started.");
	    }
	  
	  return TRUE;
	}
    }

  return FALSE;
}

/**
 * gtk_cell_area_stop_editing:
 * @area: a #GtkCellArea
 * @canceled: whether editing was canceled.
 *
 * Explicitly stops the editing of the currently
 * edited cell (see gtk_cell_area_get_edited_cell()).
 *
 * If @canceled is %TRUE, the cell renderer will emit
 * the ::editing-canceled signal.
 *
 * Since: 3.0
 */
void
gtk_cell_area_stop_editing (GtkCellArea *area,
			    gboolean     canceled)
{
  GtkCellAreaPrivate *priv;

  g_return_if_fail (GTK_IS_CELL_AREA (area));

  priv = area->priv;

  if (priv->edited_cell)
    {
      GtkCellEditable *edit_widget = g_object_ref (priv->edit_widget);
      GtkCellRenderer *edit_cell   = g_object_ref (priv->edited_cell);

      /* Stop editing of the cell renderer */
      gtk_cell_renderer_stop_editing (priv->edited_cell, canceled);
      
      /* Remove any references to the editable widget */
      gtk_cell_area_set_edited_cell (area, NULL);
      gtk_cell_area_set_edit_widget (area, NULL);

      /* Send the remove-widget signal explicitly (this is done after setting
       * the edit cell/widget NULL to avoid feedback)
       */
      gtk_cell_area_remove_editable (area, edit_cell, edit_widget);
      g_object_unref (edit_cell);
      g_object_unref (edit_widget);
    }
}

/*************************************************************
 *         API: Convenience for area implementations         *
 *************************************************************/

/**
 * gtk_cell_area_inner_cell_area:
 * @area: a #GtkCellArea
 * @widget: the #GtkWidget that @area is rendering onto
 * @cell_area: the @widget relative coordinates where one of @area's cells 
 *             is to be placed
 * @inner_area: (out): the return location for the inner cell area
 *
 * 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().
 *
 * Since: 3.0
 */
void
gtk_cell_area_inner_cell_area (GtkCellArea        *area,
			       GtkWidget          *widget,
			       const GdkRectangle *cell_area,
			       GdkRectangle       *inner_area)
{
  gint focus_line_width;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (cell_area != NULL);
  g_return_if_fail (inner_area != NULL);

  gtk_widget_style_get (widget, "focus-line-width", &focus_line_width, NULL);

  *inner_area = *cell_area;

  inner_area->x      += focus_line_width;
  inner_area->width  -= focus_line_width * 2;
  inner_area->y      += focus_line_width;
  inner_area->height -= focus_line_width * 2;
}

/**
 * gtk_cell_area_request_renderer:
 * @area: a #GtkCellArea
 * @renderer: the #GtkCellRenderer to request size for
 * @orientation: the #GtkOrientation in which to request size
 * @widget: the #GtkWidget that @area is rendering onto
 * @for_size: the allocation contextual size to request for, or -1 if
 * the base request for the orientation is to be returned.
 * @minimum_size: (out) (allow-none): location to store the minimum size, or %NULL
 * @natural_size: (out) (allow-none): location to store the natural size, or %NULL
 *
 * 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.
 *
 * Since: 3.0
 */
void
gtk_cell_area_request_renderer (GtkCellArea        *area,
				GtkCellRenderer    *renderer,
				GtkOrientation      orientation,
				GtkWidget          *widget,
				gint                for_size,
				gint               *minimum_size,
				gint               *natural_size)
{
  GtkCellAreaPrivate *priv;
  gint                focus_line_width;

  g_return_if_fail (GTK_IS_CELL_AREA (area));
  g_return_if_fail (GTK_IS_CELL_RENDERER (renderer));
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (minimum_size != NULL);
  g_return_if_fail (natural_size != NULL);

  priv = area->priv;

  gtk_widget_style_get (widget, "focus-line-width", &focus_line_width, NULL);

  focus_line_width *= 2;

  if (orientation == GTK_ORIENTATION_HORIZONTAL)
    {
      if (for_size < 0)
	  gtk_cell_renderer_get_preferred_width (renderer, widget, minimum_size, natural_size);
      else
	{
	  for_size = MAX (0, for_size - focus_line_width);

	  gtk_cell_renderer_get_preferred_width_for_height (renderer, widget, for_size, 
							    minimum_size, natural_size);
	}
    }
  else /* GTK_ORIENTATION_VERTICAL */
    {
      if (for_size < 0)
	gtk_cell_renderer_get_preferred_height (renderer, widget, minimum_size, natural_size);
      else
	{
	  for_size = MAX (0, for_size - focus_line_width);

	  gtk_cell_renderer_get_preferred_height_for_width (renderer, widget, for_size, 
							    minimum_size, natural_size);
	}
    }

  *minimum_size += focus_line_width;
  *natural_size += focus_line_width;
}