/* -*- Mode: C; tab-width: 8; indent-tabs-mode: 8; c-basic-offset: 8 -*- */
/*
 * Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation
 * All rights reserved.
 *
 * This file is part of the Gnome Library.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * published by the Free Software Foundation; either the version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Lesser  General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * License along with the Gnome Library; see the file COPYING.LIB.  If not,
 */
/*
  @NOTATION@
 */
/*
 * GnomeCanvas widget - Tk-like canvas widget for Gnome
 *
 * GnomeCanvas is basically a port of the Tk toolkit's most excellent canvas
 * widget.  Tk is copyrighted by the Regents of the University of California,
 * Sun Microsystems, and other parties.
 *
 *
 * Authors: Federico Mena <federico@nuclecu.unam.mx>
 *          Raph Levien <raph@gimp.org>
 */

/*
 * TO-DO list for the canvas:
 *
 * - Allow to specify whether GnomeCanvasImage sizes are in units or pixels
 *   (scale or don't scale).
 *
 * - Implement a flag for gnome_canvas_item_reparent() that tells the function
 *   to keep the item visually in the same place, that is, to keep it in the
 *   same place with respect to the canvas origin.
 *
 * - GC put functions for items.
 *
 * - Widget item (finish it).
 *
 * - GList *
 *   gnome_canvas_gimme_all_items_contained_in_this_area (GnomeCanvas *canvas,
 *                                                        Rectangle area);
 *
 * - Retrofit all the primitive items with microtile support.
 *
 * - Curve support for line item.
 *
 * - Arc item (Havoc has it; to be integrated in GnomeCanvasEllipse).
 *
 * - Sane font handling API.
 *
 * - Get_arg methods for items:
 *   - How to fetch the outline width and know whether it is in pixels or units?
 */

/*
 * Raph's TODO list for the antialiased canvas integration:
 *
 * - ::point() method for text item not accurate when affine transformed.
 *
 * - Clip rectangle not implemented in aa renderer for text item.
 *
 * - Clip paths only partially implemented.
 *
 * - Add more image loading techniques to work around imlib deficiencies.
 */

#include "evolution-config.h"

#include <math.h>
#include <string.h>
#include <stdio.h>
#include <gdk/gdkprivate.h>
#include <gtk/gtk.h>
#include <cairo-gobject.h>
#include "gailcanvas.h"
#include "gnome-canvas.h"
#include "gnome-canvas-i18n.h"
#include "gnome-canvas-util.h"

/* We must run our idle update handler *before* GDK wants to redraw. */
#define CANVAS_IDLE_PRIORITY (GDK_PRIORITY_REDRAW - 5)

static void gnome_canvas_request_update (GnomeCanvas      *canvas);
static void group_add                   (GnomeCanvasGroup *group,
					 GnomeCanvasItem  *item);
static void group_remove                (GnomeCanvasGroup *group,
					 GnomeCanvasItem  *item);
static void add_idle                    (GnomeCanvas      *canvas);

/*** GnomeCanvasItem ***/

/* Some convenience stuff */
#define GCI_UPDATE_MASK \
	(GNOME_CANVAS_UPDATE_REQUESTED | \
	 GNOME_CANVAS_UPDATE_AFFINE | \
	 GNOME_CANVAS_UPDATE_CLIP | \
	 GNOME_CANVAS_UPDATE_VISIBILITY)
#define GCI_EPSILON 1e-18
#define GCI_PRINT_MATRIX(s,a) \
	g_print ("%s %g %g %g %g %g %g\n", \
	s, (a)[0], (a)[1], (a)[2], (a)[3], (a)[4], (a)[5])

enum {
	ITEM_PROP_0,
	ITEM_PROP_PARENT
};

enum {
	ITEM_EVENT,
	ITEM_LAST_SIGNAL
};

static gint  emit_event                       (GnomeCanvas *canvas, GdkEvent *event);

static guint item_signals[ITEM_LAST_SIGNAL];

G_DEFINE_TYPE (
	GnomeCanvasItem,
	gnome_canvas_item,
	G_TYPE_INITIALLY_UNOWNED)

/* Object initialization function for GnomeCanvasItem */
static void
gnome_canvas_item_init (GnomeCanvasItem *item)
{
	item->flags |= GNOME_CANVAS_ITEM_VISIBLE;

	cairo_matrix_init_identity (&item->matrix);
}

/**
 * gnome_canvas_item_new:
 * @parent: The parent group for the new item.
 * @type: The object type of the item.
 * @first_arg_name: A list of object argument name/value pairs, NULL-terminated,
 * used to configure the item.  For example, "fill_color", "black",
 * "width_units", 5.0, NULL.
 * @Varargs:
 *
 * Creates a new canvas item with @parent as its parent group.  The item is
 * created at the top of its parent's stack, and starts up as visible.  The item
 * is of the specified @type, for example, it can be
 * gnome_canvas_rect_get_type().  The list of object arguments/value pairs is
 * used to configure the item. If you need to pass construct time parameters, you
 * should use g_object_new() to pass the parameters and
 * gnome_canvas_item_construct() to set up the canvas item.
 *
 * Return value: The newly-created item.
 **/
GnomeCanvasItem *
gnome_canvas_item_new (GnomeCanvasGroup *parent,
                       GType type,
                       const gchar *first_arg_name, ...)
{
	GnomeCanvasItem *item;
	va_list args;

	g_return_val_if_fail (GNOME_IS_CANVAS_GROUP (parent), NULL);
	g_return_val_if_fail (g_type_is_a (type, gnome_canvas_item_get_type ()), NULL);

	item = GNOME_CANVAS_ITEM (g_object_new (type, NULL));

	va_start (args, first_arg_name);
	gnome_canvas_item_construct (item, parent, first_arg_name, args);
	va_end (args);

	return item;
}

/* Performs post-creation operations on a canvas item (adding it to its parent
 * group, etc.)
 */
static void
item_post_create_setup (GnomeCanvasItem *item)
{
	group_add (GNOME_CANVAS_GROUP (item->parent), item);

	gnome_canvas_request_redraw (
		item->canvas, item->x1, item->y1, item->x2 + 1, item->y2 + 1);
	item->canvas->need_repick = TRUE;
}

/* Set_property handler for canvas items */
static void
gnome_canvas_item_set_property (GObject *gobject,
                                guint property_id,
                                const GValue *value,
                                GParamSpec *pspec)
{
	GnomeCanvasItem *item;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (gobject));

	item = GNOME_CANVAS_ITEM (gobject);

	switch (property_id) {
	case ITEM_PROP_PARENT:
		if (item->parent != NULL) {
		    g_warning ("Cannot set `parent' argument after item has "
			       "already been constructed.");
		} else if (g_value_get_object (value)) {
			item->parent = GNOME_CANVAS_ITEM (g_value_get_object (value));
			item->canvas = item->parent->canvas;
			item_post_create_setup (item);
		}
		break;
	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
		break;
	}
}

/* Get_property handler for canvas items */
static void
gnome_canvas_item_get_property (GObject *gobject,
                                guint property_id,
                                GValue *value,
                                GParamSpec *pspec)
{
	GnomeCanvasItem *item;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (gobject));

	item = GNOME_CANVAS_ITEM (gobject);

	switch (property_id) {
	case ITEM_PROP_PARENT:
		g_value_set_object (value, item->parent);
		break;

	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
		break;
	}
}

/**
 * gnome_canvas_item_construct:
 * @item: An unconstructed canvas item.
 * @parent: The parent group for the item.
 * @first_arg_name: The name of the first argument for configuring the item.
 * @args: The list of arguments used to configure the item.
 *
 * Constructs a canvas item; meant for use only by item implementations.
 **/
void
gnome_canvas_item_construct (GnomeCanvasItem *item,
                             GnomeCanvasGroup *parent,
                             const gchar *first_arg_name,
                             va_list args)
{
	g_return_if_fail (GNOME_IS_CANVAS_GROUP (parent));
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	item->parent = GNOME_CANVAS_ITEM (parent);
	item->canvas = item->parent->canvas;

	g_object_set_valist (G_OBJECT (item), first_arg_name, args);

	item_post_create_setup (item);
}

/* If the item is visible, requests a redraw of it. */
static void
redraw_if_visible (GnomeCanvasItem *item)
{
	if (item->flags & GNOME_CANVAS_ITEM_VISIBLE)
		gnome_canvas_request_redraw (
			item->canvas, item->x1, item->y1,
			MIN (item->x2 + 1, G_MAXINT), MIN (item->y2 + 1, G_MAXINT));
}

/* Standard object dispose function for canvas items */
static void
gnome_canvas_item_dispose (GObject *object)
{
	GnomeCanvasItemClass *klass;
	GnomeCanvasItem *item;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (object));

	item = GNOME_CANVAS_ITEM (object);
	klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

	if (item->canvas)
		redraw_if_visible (item);

	/* Make the canvas forget about us */

	if (item->canvas && item == item->canvas->current_item) {
		item->canvas->current_item = NULL;
		item->canvas->need_repick = TRUE;
	}

	if (item->canvas && item == item->canvas->new_current_item) {
		item->canvas->new_current_item = NULL;
		item->canvas->need_repick = TRUE;
	}

	if (item->canvas && item == item->canvas->grabbed_item) {
		item->canvas->grabbed_item = NULL;

		gdk_device_ungrab (
			item->canvas->grabbed_device, GDK_CURRENT_TIME);
		g_object_unref (item->canvas->grabbed_device);
		item->canvas->grabbed_device = NULL;
	}

	if (item->canvas && item == item->canvas->focused_item)
		item->canvas->focused_item = NULL;

	/* Normal dispose stuff */

	if (item->flags & GNOME_CANVAS_ITEM_MAPPED) {
		if (klass)
			klass->unmap (item);
	}

	if (item->flags & GNOME_CANVAS_ITEM_REALIZED) {
		if (klass)
			klass->unrealize (item);
	}

	if (item->parent)
		group_remove (GNOME_CANVAS_GROUP (item->parent), item);

	if (klass && klass->dispose)
		klass->dispose (item);

	G_OBJECT_CLASS (gnome_canvas_item_parent_class)->dispose (object);
	/* items should remove any reference to item->canvas after the
	 * first ::dispose */
	item->canvas = NULL;
}

/* Update handler for canvas items */
static void
gnome_canvas_item_update (GnomeCanvasItem *item,
                          const cairo_matrix_t *matrix,
                          gint flags)
{
	item->flags &= ~GNOME_CANVAS_ITEM_NEED_UPDATE;
	item->flags &= ~GNOME_CANVAS_ITEM_NEED_AFFINE;
	item->flags &= ~GNOME_CANVAS_ITEM_NEED_CLIP;
	item->flags &= ~GNOME_CANVAS_ITEM_NEED_VIS;
}

/* Realize handler for canvas items */
static void
gnome_canvas_item_realize (GnomeCanvasItem *item)
{
	item->flags |= GNOME_CANVAS_ITEM_REALIZED;

	gnome_canvas_item_request_update (item);
}

/* Unrealize handler for canvas items */
static void
gnome_canvas_item_unrealize (GnomeCanvasItem *item)
{
	item->flags &= ~GNOME_CANVAS_ITEM_REALIZED;
}

/* Map handler for canvas items */
static void
gnome_canvas_item_map (GnomeCanvasItem *item)
{
	item->flags |= GNOME_CANVAS_ITEM_MAPPED;
}

/* Unmap handler for canvas items */
static void
gnome_canvas_item_unmap (GnomeCanvasItem *item)
{
	item->flags &= ~GNOME_CANVAS_ITEM_MAPPED;
}

/* Dispose handler for canvas items */
static void
gnome_canvas_item_dispose_item (GnomeCanvasItem *item)
{
	/* Placeholder so subclasses can safely chain up. */
}

static void
gnome_canvas_item_draw (GnomeCanvasItem *item,
                        cairo_t *cr,
                        gint x,
                        gint y,
                        gint width,
                        gint height)
{
	/* Placeholder so subclasses can safely chain up. */
}

static GnomeCanvasItem *
gnome_canvas_item_point (GnomeCanvasItem *item,
                         gdouble x,
                         gdouble y,
                         gint cx,
                         gint cy)
{
	/* Placeholder so subclasses can safely chain up. */

	return NULL;
}

static void
gnome_canvas_item_bounds (GnomeCanvasItem *item,
                          gdouble *x1,
                          gdouble *y1,
                          gdouble *x2,
                          gdouble *y2)
{
	/* Placeholder so subclasses can safely chain up. */
}

static gboolean
gnome_canvas_item_event (GnomeCanvasItem *item,
                         GdkEvent *event)
{
	/* Placeholder so subclasses can safely chain up. */

	return FALSE;  /* event was not handled */
}

/*
 * This routine invokes the update method of the item
 * Please notice, that we take parent to canvas pixel matrix as argument
 * unlike virtual method ::update, whose argument is item 2 canvas pixel
 * matrix
 *
 * I will try to force somewhat meaningful naming for affines (Lauris)
 * General naming rule is FROM2TO, where FROM and TO are abbreviations
 * So p2cpx is Parent2CanvasPixel and i2cpx is Item2CanvasPixel
 * I hope that this helps to keep track of what really happens
 *
 */

static void
gnome_canvas_item_invoke_update (GnomeCanvasItem *item,
                                 const cairo_matrix_t *p2c,
                                 gint flags)
{
	gint child_flags;
	cairo_matrix_t i2c;

	child_flags = flags;
	if (!(item->flags & GNOME_CANVAS_ITEM_VISIBLE))
		child_flags &= ~GNOME_CANVAS_UPDATE_IS_VISIBLE;

	/* Calculate actual item transformation matrix */

	cairo_matrix_multiply (&i2c, &item->matrix, p2c);

	/* apply object flags to child flags */

	child_flags &= ~GNOME_CANVAS_UPDATE_REQUESTED;

	if (item->flags & GNOME_CANVAS_ITEM_NEED_UPDATE)
		child_flags |= GNOME_CANVAS_UPDATE_REQUESTED;

	if (item->flags & GNOME_CANVAS_ITEM_NEED_AFFINE)
		child_flags |= GNOME_CANVAS_UPDATE_AFFINE;

	if (item->flags & GNOME_CANVAS_ITEM_NEED_CLIP)
		child_flags |= GNOME_CANVAS_UPDATE_CLIP;

	if (item->flags & GNOME_CANVAS_ITEM_NEED_VIS)
		child_flags |= GNOME_CANVAS_UPDATE_VISIBILITY;

	if (child_flags & GCI_UPDATE_MASK) {
		GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

		if (klass && klass->update)
			klass->update (item, &i2c, child_flags);
	}
}

/*
 * This routine invokes the point method of the item.
 * The arguments x, y should be in the parent item local coordinates.
 *
 * This is potentially evil, as we are relying on matrix inversion (Lauris)
 */

static GnomeCanvasItem *
gnome_canvas_item_invoke_point (GnomeCanvasItem *item,
                                gdouble x,
                                gdouble y,
                                gint cx,
                                gint cy)
{
	GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);
	cairo_matrix_t inverse;

	/* Calculate x & y in item local coordinates */
	inverse = item->matrix;
	if (cairo_matrix_invert (&inverse) != CAIRO_STATUS_SUCCESS)
		return NULL;

	cairo_matrix_transform_point (&inverse, &x, &y);

	if (klass && klass->point)
		return klass->point (item, x, y, cx, cy);

	return NULL;
}

/**
 * gnome_canvas_item_set:
 * @item: A canvas item.
 * @first_arg_name: The list of object argument name/value pairs used to
 *                  configure the item.
 * @Varargs:
 *
 * Configures a canvas item.  The arguments in the item are set to the
 * specified values, and the item is repainted as appropriate.
 **/
void
gnome_canvas_item_set (GnomeCanvasItem *item,
                       const gchar *first_arg_name,
                       ...)
{
	va_list args;

	va_start (args, first_arg_name);
	gnome_canvas_item_set_valist (item, first_arg_name, args);
	va_end (args);
}

/**
 * gnome_canvas_item_set_valist:
 * @item: A canvas item.
 * @first_arg_name: The name of the first argument used to configure the item.
 * @args: The list of object argument name/value pairs used to configure the item.
 *
 * Configures a canvas item.  The arguments in the item are set to the specified
 * values, and the item is repainted as appropriate.
 **/
void
gnome_canvas_item_set_valist (GnomeCanvasItem *item,
                              const gchar *first_arg_name,
                              va_list args)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	g_object_set_valist (G_OBJECT (item), first_arg_name, args);

	item->canvas->need_repick = TRUE;
}

/**
 * gnome_canvas_item_transform:
 * @item: A canvas item.
 * @matrix: An affine transformation matrix.
 *
 * Combines the specified affine transformation matrix with the item's current
 * transformation.
 **/
void
gnome_canvas_item_transform (GnomeCanvasItem *item,
                             const cairo_matrix_t *matrix)
{
	cairo_matrix_t i2p;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (matrix != NULL);

	/* Calculate actual item transformation matrix */
	cairo_matrix_multiply (&i2p, matrix, &item->matrix);

	gnome_canvas_item_set_matrix (item, &i2p);
}

/**
 * gnome_canvas_item_set_matrix:
 * @item: A canvas item.
 * @matrix: An affine transformation matrix or %NULL for the identity matrix.
 *
 * Makes the item's affine transformation matrix be equal to the specified
 * matrix. NULL is treated as identity.
 **/
void
gnome_canvas_item_set_matrix (GnomeCanvasItem *item,
                              const cairo_matrix_t *matrix)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (matrix) {
		item->matrix = *matrix;
	} else {
		cairo_matrix_init_identity (&item->matrix);
	}

	if (!(item->flags & GNOME_CANVAS_ITEM_NEED_AFFINE)) {
		/* Request update */
		item->flags |= GNOME_CANVAS_ITEM_NEED_AFFINE;
		gnome_canvas_item_request_update (item);
	}

	item->canvas->need_repick = TRUE;
}

/**
 * gnome_canvas_item_move:
 * @item: A canvas item.
 * @dx: Horizontal offset.
 * @dy: Vertical offset.
 *
 * Moves a canvas item by creating an affine transformation matrix for
 * translation by using the specified values. This happens in item
 * local coordinate system, so if you have nontrivial transform, it
 * most probably does not do, what you want.
 **/
void
gnome_canvas_item_move (GnomeCanvasItem *item,
                        gdouble dx,
                        gdouble dy)
{
	cairo_matrix_t translate;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	cairo_matrix_init_translate (&translate, dx, dy);

	gnome_canvas_item_transform (item, &translate);
}

/* Convenience function to reorder items in a group's child list.  This puts the
 * specified link after the "before" link. Returns TRUE if the list was changed.
 */
static gboolean
put_item_after (GList *link,
                GList *before)
{
	GnomeCanvasGroup *parent;
	GList *old_before, *old_after;
	GList *after;

	parent = GNOME_CANVAS_GROUP (GNOME_CANVAS_ITEM (link->data)->parent);

	if (before)
		after = before->next;
	else
		after = parent->item_list;

	if (before == link || after == link)
		return FALSE;

	/* Unlink */

	old_before = link->prev;
	old_after = link->next;

	if (old_before)
		old_before->next = old_after;
	else
		parent->item_list = old_after;

	if (old_after)
		old_after->prev = old_before;
	else
		parent->item_list_end = old_before;

	/* Relink */

	link->prev = before;
	if (before)
		before->next = link;
	else
		parent->item_list = link;

	link->next = after;
	if (after)
		after->prev = link;
	else
		parent->item_list_end = link;

	return TRUE;
}

/**
 * gnome_canvas_item_raise:
 * @item: A canvas item.
 * @positions: Number of steps to raise the item.
 *
 * Raises the item in its parent's stack by the specified number of positions.
 * If the number of positions is greater than the distance to the top of the
 * stack, then the item is put at the top.
 **/
void
gnome_canvas_item_raise (GnomeCanvasItem *item,
                         gint positions)
{
	GList *link, *before;
	GnomeCanvasGroup *parent;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (positions >= 0);

	if (!item->parent || positions == 0)
		return;

	parent = GNOME_CANVAS_GROUP (item->parent);
	link = g_list_find (parent->item_list, item);
	g_return_if_fail (link != NULL);

	for (before = link; positions && before; positions--)
		before = before->next;

	if (!before)
		before = parent->item_list_end;

	if (put_item_after (link, before)) {
		redraw_if_visible (item);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_lower:
 * @item: A canvas item.
 * @positions: Number of steps to lower the item.
 *
 * Lowers the item in its parent's stack by the specified number of positions.
 * If the number of positions is greater than the distance to the bottom of the
 * stack, then the item is put at the bottom.
 **/
void
gnome_canvas_item_lower (GnomeCanvasItem *item,
                         gint positions)
{
	GList *link, *before;
	GnomeCanvasGroup *parent;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (positions >= 1);

	if (!item->parent || positions == 0)
		return;

	parent = GNOME_CANVAS_GROUP (item->parent);
	link = g_list_find (parent->item_list, item);
	g_return_if_fail (link != NULL);

	if (link->prev)
		for (before = link->prev; positions && before; positions--)
			before = before->prev;
	else
		before = NULL;

	if (put_item_after (link, before)) {
		redraw_if_visible (item);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_raise_to_top:
 * @item: A canvas item.
 *
 * Raises an item to the top of its parent's stack.
 **/
void
gnome_canvas_item_raise_to_top (GnomeCanvasItem *item)
{
	GList *link;
	GnomeCanvasGroup *parent;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (!item->parent)
		return;

	parent = GNOME_CANVAS_GROUP (item->parent);
	link = g_list_find (parent->item_list, item);
	g_return_if_fail (link != NULL);

	if (put_item_after (link, parent->item_list_end)) {
		redraw_if_visible (item);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_lower_to_bottom:
 * @item: A canvas item.
 *
 * Lowers an item to the bottom of its parent's stack.
 **/
void
gnome_canvas_item_lower_to_bottom (GnomeCanvasItem *item)
{
	GList *link;
	GnomeCanvasGroup *parent;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (!item->parent)
		return;

	parent = GNOME_CANVAS_GROUP (item->parent);
	link = g_list_find (parent->item_list, item);
	g_return_if_fail (link != NULL);

	if (put_item_after (link, NULL)) {
		redraw_if_visible (item);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_show:
 * @item: A canvas item.
 *
 * Shows a canvas item.  If the item was already shown, then no action is taken.
 **/
void
gnome_canvas_item_show (GnomeCanvasItem *item)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (!(item->flags & GNOME_CANVAS_ITEM_VISIBLE)) {
		item->flags |= GNOME_CANVAS_ITEM_VISIBLE;
		gnome_canvas_request_redraw (
			item->canvas, item->x1, item->y1,
			item->x2 + 1, item->y2 + 1);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_hide:
 * @item: A canvas item.
 *
 * Hides a canvas item.  If the item was already hidden, then no action is
 * taken.
 **/
void
gnome_canvas_item_hide (GnomeCanvasItem *item)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (item->flags & GNOME_CANVAS_ITEM_VISIBLE) {
		item->flags &= ~GNOME_CANVAS_ITEM_VISIBLE;
		gnome_canvas_request_redraw (
			item->canvas, item->x1, item->y1,
			item->x2 + 1, item->y2 + 1);
		item->canvas->need_repick = TRUE;
	}
}

/**
 * gnome_canvas_item_grab:
 * @item: A canvas item.
 * @event_mask: Mask of events that will be sent to this item.
 * @cursor: If non-NULL, the cursor that will be used while the grab is active.
 * @device: The pointer device to grab.
 * @etime: The timestamp required for grabbing @device, or GDK_CURRENT_TIME.
 *
 * Specifies that all events that match the specified event mask should be sent
 * to the specified item, and also grabs @device by calling gdk_device_grab().
 * The event mask is also used when grabbing the @device.  If @cursor is not
 * NULL, then that cursor is used while the grab is active.  The @etime
 * parameter is the timestamp required for grabbing the @device.
 *
 * Return value: If an item was already grabbed, it returns
 * %GDK_GRAB_ALREADY_GRABBED.  If the specified item was hidden by calling
 * gnome_canvas_item_hide(), then it returns %GDK_GRAB_NOT_VIEWABLE.  Else,
 * it returns the result of calling gdk_device_grab().
 **/
gint
gnome_canvas_item_grab (GnomeCanvasItem *item,
                        guint event_mask,
                        GdkCursor *cursor,
                        GdkDevice *device,
                        guint32 etime)
{
	GtkLayout *layout;
	GdkWindow *bin_window;
	gint retval;

	g_return_val_if_fail (
		GNOME_IS_CANVAS_ITEM (item), GDK_GRAB_NOT_VIEWABLE);
	g_return_val_if_fail (
		gtk_widget_get_mapped (GTK_WIDGET (item->canvas)),
		GDK_GRAB_NOT_VIEWABLE);
	g_return_val_if_fail (
		GDK_IS_DEVICE (device), GDK_GRAB_NOT_VIEWABLE);

	if (item->canvas->grabbed_item)
		return GDK_GRAB_ALREADY_GRABBED;

	if (!(item->flags & GNOME_CANVAS_ITEM_VISIBLE))
		return GDK_GRAB_NOT_VIEWABLE;

	layout = GTK_LAYOUT (item->canvas);
	bin_window = gtk_layout_get_bin_window (layout);

	retval = gdk_device_grab (
		device, bin_window, GDK_OWNERSHIP_NONE,
		FALSE, event_mask, cursor, etime);

	if (retval != GDK_GRAB_SUCCESS)
		return retval;

	item->canvas->grabbed_item = item;
	item->canvas->grabbed_device = g_object_ref (device);
	item->canvas->grabbed_event_mask = event_mask;
	item->canvas->current_item = item; /* So that events go to the grabbed item */

	return retval;
}

/**
 * gnome_canvas_item_ungrab:
 * @item: A canvas item that holds a grab.
 * @etime: The timestamp for ungrabbing the mouse.
 *
 * Ungrabs the item, which must have been grabbed in the canvas, and ungrabs the
 * mouse.
 **/
void
gnome_canvas_item_ungrab (GnomeCanvasItem *item,
                          guint32 etime)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	if (item->canvas->grabbed_item != item)
		return;

	item->canvas->grabbed_item = NULL;

	g_return_if_fail (item->canvas->grabbed_device != NULL);
	gdk_device_ungrab (item->canvas->grabbed_device, etime);

	g_object_unref (item->canvas->grabbed_device);
	item->canvas->grabbed_device = NULL;
}

void
gnome_canvas_item_i2w_matrix (GnomeCanvasItem *item,
                              cairo_matrix_t *matrix)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (matrix != NULL);

	cairo_matrix_init_identity (matrix);

	while (item) {
		cairo_matrix_multiply (matrix, matrix, &item->matrix);

		item = item->parent;
	}
}

void
gnome_canvas_item_w2i_matrix (GnomeCanvasItem *item,
                              cairo_matrix_t *matrix)
{
	cairo_status_t status;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (matrix != NULL);

	gnome_canvas_item_i2w_matrix (item, matrix);
	status = cairo_matrix_invert (matrix);
	g_return_if_fail (status == CAIRO_STATUS_SUCCESS);
}

/**
 * gnome_canvas_item_w2i:
 * @item: A canvas item.
 * @x: X coordinate to convert (input/output value).
 * @y: Y coordinate to convert (input/output value).
 *
 * Converts a coordinate pair from world coordinates to item-relative
 * coordinates.
 **/
void
gnome_canvas_item_w2i (GnomeCanvasItem *item,
                       gdouble *x,
                       gdouble *y)
{
	cairo_matrix_t matrix;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (x != NULL);
	g_return_if_fail (y != NULL);

	gnome_canvas_item_w2i_matrix (item, &matrix);
	cairo_matrix_transform_point (&matrix, x, y);
}

/**
 * gnome_canvas_item_i2w:
 * @item: A canvas item.
 * @x: X coordinate to convert (input/output value).
 * @y: Y coordinate to convert (input/output value).
 *
 * Converts a coordinate pair from item-relative coordinates to world
 * coordinates.
 **/
void
gnome_canvas_item_i2w (GnomeCanvasItem *item,
                       gdouble *x,
                       gdouble *y)
{
	cairo_matrix_t matrix;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (x != NULL);
	g_return_if_fail (y != NULL);

	gnome_canvas_item_i2w_matrix (item, &matrix);
	cairo_matrix_transform_point (&matrix, x, y);
}

/**
 * gnome_canvas_item_i2c_matrix:
 * @item: A canvas item.
 * @matrix: Matrix to take the resulting transformation matrix (return value).
 *
 * Gets the affine transform that converts from item-relative coordinates to
 * canvas pixel coordinates.
 **/
void
gnome_canvas_item_i2c_matrix (GnomeCanvasItem *item,
                              cairo_matrix_t *matrix)
{
	cairo_matrix_t i2w, w2c;

	gnome_canvas_item_i2w_matrix (item, &i2w);
	gnome_canvas_w2c_matrix (item->canvas, &w2c);
	cairo_matrix_multiply (matrix, &i2w, &w2c);
}

/* Returns whether the item is an inferior of or is equal to the parent. */
static gint
is_descendant (GnomeCanvasItem *item,
               GnomeCanvasItem *parent)
{
	for (; item; item = item->parent)
		if (item == parent)
			return TRUE;

	return FALSE;
}

/**
 * gnome_canvas_item_reparent:
 * @item: A canvas item.
 * @new_group: A canvas group.
 *
 * Changes the parent of the specified item to be the new group.  The item keeps
 * its group-relative coordinates as for its old parent, so the item may change
 * its absolute position within the canvas.
 **/
void
gnome_canvas_item_reparent (GnomeCanvasItem *item,
                            GnomeCanvasGroup *new_group)
{
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (GNOME_IS_CANVAS_GROUP (new_group));

	/* Both items need to be in the same canvas */
	g_return_if_fail (item->canvas == GNOME_CANVAS_ITEM (new_group)->canvas);

	/* The group cannot be an inferior of the item or be the item itself --
	 * this also takes care of the case where the item is the root item of
	 * the canvas.  */
	g_return_if_fail (!is_descendant (GNOME_CANVAS_ITEM (new_group), item));

	/* Everything is ok, now actually reparent the item */

	g_object_ref (item); /* protect it from the unref in group_remove */

	redraw_if_visible (item);

	group_remove (GNOME_CANVAS_GROUP (item->parent), item);
	item->parent = GNOME_CANVAS_ITEM (new_group);
	group_add (new_group, item);

	/* Redraw and repick */

	redraw_if_visible (item);
	item->canvas->need_repick = TRUE;

	g_object_unref (item);
}

/**
 * gnome_canvas_item_grab_focus:
 * @item: A canvas item.
 *
 * Makes the specified item take the keyboard focus, so all keyboard events will
 * be sent to it.  If the canvas widget itself did not have the focus, it grabs
 * it as well.
 **/
void
gnome_canvas_item_grab_focus (GnomeCanvasItem *item)
{
	GnomeCanvasItem *focused_item;
	GdkEvent ev;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
	g_return_if_fail (gtk_widget_get_can_focus (GTK_WIDGET (item->canvas)));

	focused_item = item->canvas->focused_item;

	if (focused_item) {
		GtkLayout *layout;
		GdkWindow *bin_window;

		layout = GTK_LAYOUT (item->canvas);
		bin_window = gtk_layout_get_bin_window (layout);

		ev.focus_change.type = GDK_FOCUS_CHANGE;
		ev.focus_change.window = bin_window;
		ev.focus_change.send_event = FALSE;
		ev.focus_change.in = FALSE;

		emit_event (item->canvas, &ev);
	}

	item->canvas->focused_item = item;
	gtk_widget_grab_focus (GTK_WIDGET (item->canvas));

	if (focused_item) {
		GtkLayout *layout;
		GdkWindow *bin_window;

		layout = GTK_LAYOUT (item->canvas);
		bin_window = gtk_layout_get_bin_window (layout);

		ev.focus_change.type = GDK_FOCUS_CHANGE;
		ev.focus_change.window = bin_window;
		ev.focus_change.send_event = FALSE;
		ev.focus_change.in = TRUE;

		emit_event (item->canvas, &ev);
	}
}

/**
 * gnome_canvas_item_get_bounds:
 * @item: A canvas item.
 * @x1: Leftmost edge of the bounding box (return value).
 * @y1: Upper edge of the bounding box (return value).
 * @x2: Rightmost edge of the bounding box (return value).
 * @y2: Lower edge of the bounding box (return value).
 *
 * Queries the bounding box of a canvas item.  The bounds are returned in the
 * coordinate system of the item's parent.
 **/
void
gnome_canvas_item_get_bounds (GnomeCanvasItem *item,
                              gdouble *x1,
                              gdouble *y1,
                              gdouble *x2,
                              gdouble *y2)
{
	GnomeCanvasItemClass *klass;
	gdouble tx1, ty1, tx2, ty2;

	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	klass = GNOME_CANVAS_ITEM_GET_CLASS (item);
	g_return_if_fail (klass != NULL);

	tx1 = ty1 = tx2 = ty2 = 0.0;

	/* Get the item's bounds in its coordinate system */

	if (klass->bounds)
		klass->bounds (item, &tx1, &ty1, &tx2, &ty2);

	/* Make the bounds relative to the item's parent coordinate system */
	gnome_canvas_matrix_transform_rect (&item->matrix, &tx1, &ty1, &tx2, &ty2);

	/* Return the values */

	if (x1)
		*x1 = tx1;

	if (y1)
		*y1 = ty1;

	if (x2)
		*x2 = tx2;

	if (y2)
		*y2 = ty2;
}

/**
 * gnome_canvas_item_request_update
 * @item: A canvas item.
 *
 * To be used only by item implementations.  Requests that the canvas queue an
 * update for the specified item.
 **/
void
gnome_canvas_item_request_update (GnomeCanvasItem *item)
{
	if (item->flags & GNOME_CANVAS_ITEM_NEED_UPDATE)
		return;

	item->flags |= GNOME_CANVAS_ITEM_NEED_UPDATE;

	if (item->parent != NULL) {
		/* Recurse up the tree */
		gnome_canvas_item_request_update (item->parent);
	} else {
		/* Have reached the top of the tree, make
		 * sure the update call gets scheduled. */
		gnome_canvas_request_update (item->canvas);
	}
}

/*** GnomeCanvasGroup ***/

enum {
	GROUP_PROP_0,
	GROUP_PROP_X,
	GROUP_PROP_Y
};

static void gnome_canvas_group_set_property (GObject               *object,
					    guint                  property_id,
					    const GValue          *value,
					    GParamSpec            *pspec);
static void gnome_canvas_group_get_property (GObject               *object,
					    guint                  property_id,
					    GValue                *value,
					    GParamSpec            *pspec);

static void gnome_canvas_group_dispose     (GnomeCanvasItem *object);

static void   gnome_canvas_group_update      (GnomeCanvasItem *item,
                                              const cairo_matrix_t *matrix,
					      gint flags);
static void   gnome_canvas_group_realize     (GnomeCanvasItem *item);
static void   gnome_canvas_group_unrealize   (GnomeCanvasItem *item);
static void   gnome_canvas_group_map         (GnomeCanvasItem *item);
static void   gnome_canvas_group_unmap       (GnomeCanvasItem *item);
static void   gnome_canvas_group_draw        (GnomeCanvasItem *item,
					      cairo_t *cr,
					      gint x, gint y,
					      gint width, gint height);
static GnomeCanvasItem *gnome_canvas_group_point (GnomeCanvasItem *item,
					      gdouble x, gdouble y,
					      gint cx, gint cy);
static void   gnome_canvas_group_bounds      (GnomeCanvasItem *item,
					      gdouble *x1, gdouble *y1,
					      gdouble *x2, gdouble *y2);

G_DEFINE_TYPE (
	GnomeCanvasGroup,
	gnome_canvas_group,
	GNOME_TYPE_CANVAS_ITEM)

/* Class initialization function for GnomeCanvasGroupClass */
static void
gnome_canvas_group_class_init (GnomeCanvasGroupClass *class)
{
	GObjectClass *object_class;
	GnomeCanvasItemClass *item_class;

	object_class = (GObjectClass *) class;
	item_class = (GnomeCanvasItemClass *) class;

	object_class->set_property = gnome_canvas_group_set_property;
	object_class->get_property = gnome_canvas_group_get_property;

	g_object_class_install_property (
		object_class,
		GROUP_PROP_X,
		g_param_spec_double (
			"x",
			"X",
			"X",
			-G_MAXDOUBLE,
			G_MAXDOUBLE,
			0.0,
			G_PARAM_READABLE |
			G_PARAM_WRITABLE));

	g_object_class_install_property (
		object_class,
		GROUP_PROP_Y,
		g_param_spec_double (
			"y",
			"Y",
			"Y",
			-G_MAXDOUBLE,
			G_MAXDOUBLE,
			0.0,
			G_PARAM_READABLE |
			G_PARAM_WRITABLE));

	item_class->dispose = gnome_canvas_group_dispose;
	item_class->update = gnome_canvas_group_update;
	item_class->realize = gnome_canvas_group_realize;
	item_class->unrealize = gnome_canvas_group_unrealize;
	item_class->map = gnome_canvas_group_map;
	item_class->unmap = gnome_canvas_group_unmap;
	item_class->draw = gnome_canvas_group_draw;
	item_class->point = gnome_canvas_group_point;
	item_class->bounds = gnome_canvas_group_bounds;
}

/* Object initialization function for GnomeCanvasGroup */
static void
gnome_canvas_group_init (GnomeCanvasGroup *group)
{
}

/* Set_property handler for canvas groups */
static void
gnome_canvas_group_set_property (GObject *gobject,
                                 guint property_id,
                                 const GValue *value,
                                 GParamSpec *pspec)
{
	GnomeCanvasItem *item;

	g_return_if_fail (GNOME_IS_CANVAS_GROUP (gobject));

	item = GNOME_CANVAS_ITEM (gobject);

	switch (property_id) {
	case GROUP_PROP_X:
		item->matrix.x0 = g_value_get_double (value);
		break;

	case GROUP_PROP_Y:
		item->matrix.y0 = g_value_get_double (value);
		break;

	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
		break;
	}
}

/* Get_property handler for canvas groups */
static void
gnome_canvas_group_get_property (GObject *gobject,
                                 guint property_id,
                                 GValue *value,
                                 GParamSpec *pspec)
{
	GnomeCanvasItem *item;

	g_return_if_fail (GNOME_IS_CANVAS_GROUP (gobject));

	item = GNOME_CANVAS_ITEM (gobject);

	switch (property_id) {
	case GROUP_PROP_X:
		g_value_set_double (value, item->matrix.x0);
		break;

	case GROUP_PROP_Y:
		g_value_set_double (value, item->matrix.y0);
		break;

	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
		break;
	}
}

/* Dispose handler for canvas groups */
static void
gnome_canvas_group_dispose (GnomeCanvasItem *object)
{
	GnomeCanvasGroup *group;

	g_return_if_fail (GNOME_IS_CANVAS_GROUP (object));

	group = GNOME_CANVAS_GROUP (object);

	while (group->item_list) {
		/* child is unref'ed by the child's group_remove (). */
		g_object_run_dispose (G_OBJECT (group->item_list->data));
	}

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->
		dispose (object);
}

/* Update handler for canvas groups */
static void
gnome_canvas_group_update (GnomeCanvasItem *item,
                           const cairo_matrix_t *i2c,
                           gint flags)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *i;
	gdouble x1, y1, x2, y2;

	group = GNOME_CANVAS_GROUP (item);

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->
		update (item, i2c, flags);

	x1 = G_MAXDOUBLE;
	y1 = G_MAXDOUBLE;
	x2 = -G_MAXDOUBLE;
	y2 = -G_MAXDOUBLE;

	for (list = group->item_list; list; list = list->next) {
		i = list->data;

		gnome_canvas_item_invoke_update (i, i2c, flags);

		x1 = MIN (x1, i->x1);
		x2 = MAX (x2, i->x2);
		y1 = MIN (y1, i->y1);
		y2 = MAX (y2, i->y2);
	}
	if (x1 >= x2 || y1 >= y2) {
		item->x1 = item->x2 = item->y1 = item->y2 = 0;
	} else {
		item->x1 = x1;
		item->y1 = y1;
		item->x2 = x2;
		item->y2 = y2;
	}
}

/* Realize handler for canvas groups */
static void
gnome_canvas_group_realize (GnomeCanvasItem *item)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *i;

	group = GNOME_CANVAS_GROUP (item);

	for (list = group->item_list; list; list = list->next) {
		i = list->data;

		if (!(i->flags & GNOME_CANVAS_ITEM_REALIZED)) {
			GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (i);

			if (klass)
				klass->realize (i);
		}
	}

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->realize (item);
}

/* Unrealize handler for canvas groups */
static void
gnome_canvas_group_unrealize (GnomeCanvasItem *item)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *i;

	group = GNOME_CANVAS_GROUP (item);

	for (list = group->item_list; list; list = list->next) {
		i = list->data;

		if (i->flags & GNOME_CANVAS_ITEM_REALIZED) {
			GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (i);

			if (klass)
				klass->unrealize (i);
		}
	}

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->
		unrealize (item);
}

/* Map handler for canvas groups */
static void
gnome_canvas_group_map (GnomeCanvasItem *item)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *i;

	group = GNOME_CANVAS_GROUP (item);

	for (list = group->item_list; list; list = list->next) {
		i = list->data;

		if (!(i->flags & GNOME_CANVAS_ITEM_MAPPED)) {
			GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (i);

			if (klass)
				klass->map (i);
		}
	}

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->map (item);
}

/* Unmap handler for canvas groups */
static void
gnome_canvas_group_unmap (GnomeCanvasItem *item)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *i;

	group = GNOME_CANVAS_GROUP (item);

	for (list = group->item_list; list; list = list->next) {
		i = list->data;

		if (i->flags & GNOME_CANVAS_ITEM_MAPPED) {
			GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (i);

			if (klass)
				klass->unmap (i);
		}
	}

	GNOME_CANVAS_ITEM_CLASS (gnome_canvas_group_parent_class)->unmap (item);
}

/* Draw handler for canvas groups */
static void
gnome_canvas_group_draw (GnomeCanvasItem *item,
                         cairo_t *cr,
                         gint x,
                         gint y,
                         gint width,
                         gint height)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *child = NULL;

	group = GNOME_CANVAS_GROUP (item);

	for (list = group->item_list; list; list = list->next) {
		child = list->data;

		if ((child->flags & GNOME_CANVAS_ITEM_VISIBLE)
		    && ((child->x1 < (x + width))
		    && (child->y1 < (y + height))
		    && (child->x2 > x)
		    && (child->y2 > y))) {
			GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (child);

			if (klass && klass->draw) {
				cairo_save (cr);

				klass->draw (child, cr, x, y, width, height);

				cairo_restore (cr);
			}
		}
	}
}

/* Point handler for canvas groups */
static GnomeCanvasItem *
gnome_canvas_group_point (GnomeCanvasItem *item,
                          gdouble x,
                          gdouble y,
                          gint cx,
                          gint cy)
{
	GnomeCanvasGroup *group;
	GList *list;
	GnomeCanvasItem *child, *point_item;

	group = GNOME_CANVAS_GROUP (item);

	for (list = g_list_last (group->item_list); list; list = list->prev) {
		child = list->data;

		if ((child->x1 > cx) || (child->y1 > cy))
			continue;

		if ((child->x2 < cx) || (child->y2 < cy))
			continue;

		if (!(child->flags & GNOME_CANVAS_ITEM_VISIBLE))
			continue;

		point_item = gnome_canvas_item_invoke_point (child, x, y, cx, cy);
		if (point_item)
			return point_item;
	}

	return NULL;
}

/* Bounds handler for canvas groups */
static void
gnome_canvas_group_bounds (GnomeCanvasItem *item,
                           gdouble *x1,
                           gdouble *y1,
                           gdouble *x2,
                           gdouble *y2)
{
	GnomeCanvasGroup *group;
	GnomeCanvasItem *child;
	GList *list;
	gdouble tx1, ty1, tx2, ty2;
	gdouble minx, miny, maxx, maxy;
	gint set;

	group = GNOME_CANVAS_GROUP (item);

	/* Get the bounds of the first visible item */

	child = NULL; /* Unnecessary but eliminates a warning. */

	set = FALSE;

	for (list = group->item_list; list; list = list->next) {
		child = list->data;

		if (child->flags & GNOME_CANVAS_ITEM_VISIBLE) {
			set = TRUE;
			gnome_canvas_item_get_bounds (child, &minx, &miny, &maxx, &maxy);
			break;
		}
	}

	/* If there were no visible items, return an empty bounding box */

	if (!set) {
		*x1 = *y1 = *x2 = *y2 = 0.0;
		return;
	}

	/* Now we can grow the bounds using the rest of the items */

	list = list->next;

	for (; list; list = list->next) {
		child = list->data;

		if (!(child->flags & GNOME_CANVAS_ITEM_VISIBLE))
			continue;

		gnome_canvas_item_get_bounds (child, &tx1, &ty1, &tx2, &ty2);

		if (tx1 < minx)
			minx = tx1;

		if (ty1 < miny)
			miny = ty1;

		if (tx2 > maxx)
			maxx = tx2;

		if (ty2 > maxy)
			maxy = ty2;
	}

	*x1 = minx;
	*y1 = miny;
	*x2 = maxx;
	*y2 = maxy;
}

/* Adds an item to a group */
static void
group_add (GnomeCanvasGroup *group,
           GnomeCanvasItem *item)
{
	g_object_ref_sink (item);

	if (!group->item_list) {
		group->item_list = g_list_append (group->item_list, item);
		group->item_list_end = group->item_list;
	} else
		group->item_list_end = g_list_append (group->item_list_end, item)->next;

	if (group->item.flags & GNOME_CANVAS_ITEM_REALIZED) {
		GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

		if (klass)
			klass->realize (item);
	}

	if (group->item.flags & GNOME_CANVAS_ITEM_MAPPED) {
		GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

		if (klass)
			klass->map (item);
	}

	g_object_notify (G_OBJECT (item), "parent");
}

/* Removes an item from a group */
static void
group_remove (GnomeCanvasGroup *group,
              GnomeCanvasItem *item)
{
	GList *children;

	g_return_if_fail (GNOME_IS_CANVAS_GROUP (group));
	g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

	for (children = group->item_list; children; children = children->next)
		if (children->data == item) {
			if (item->flags & GNOME_CANVAS_ITEM_MAPPED) {
				GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

				if (klass)
					klass->unmap (item);
			}

			if (item->flags & GNOME_CANVAS_ITEM_REALIZED) {
				GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (item);

				if (klass)
					klass->unrealize (item);
			}

			/* Unparent the child */

			item->parent = NULL;
			g_object_unref (item);

			/* Remove it from the list */

			if (children == group->item_list_end)
				group->item_list_end = children->prev;

			group->item_list = g_list_remove_link (group->item_list, children);
			g_list_free (children);
			break;
		}
}

/*** GnomeCanvas ***/

enum {
	DRAW_BACKGROUND,
	LAST_SIGNAL
};

static void gnome_canvas_dispose             (GObject          *object);
static void gnome_canvas_map                 (GtkWidget        *widget);
static void gnome_canvas_unmap               (GtkWidget        *widget);
static void gnome_canvas_realize             (GtkWidget        *widget);
static void gnome_canvas_unrealize           (GtkWidget        *widget);
static void gnome_canvas_size_allocate       (GtkWidget        *widget,
					      GtkAllocation    *allocation);
static gint gnome_canvas_draw                (GtkWidget        *widget,
					      cairo_t          *cr);
static void gnome_canvas_drag_end            (GtkWidget        *widget,
					      GdkDragContext   *context);
static gint gnome_canvas_button              (GtkWidget        *widget,
					      GdkEventButton   *event);
static gint gnome_canvas_motion              (GtkWidget        *widget,
					      GdkEventMotion   *event);
static gboolean gnome_canvas_key             (GtkWidget        *widget,
					      GdkEventKey      *event);
static gint gnome_canvas_crossing            (GtkWidget        *widget,
					      GdkEventCrossing *event);
static gint gnome_canvas_focus_in            (GtkWidget        *widget,
					      GdkEventFocus    *event);
static gint gnome_canvas_focus_out           (GtkWidget        *widget,
					      GdkEventFocus    *event);
static void gnome_canvas_request_update_real (GnomeCanvas      *canvas);
static void gnome_canvas_draw_background     (GnomeCanvas      *canvas,
					      cairo_t          *cr,
					      gint              x,
					      gint              y,
					      gint              width,
					      gint              height);

static guint canvas_signals[LAST_SIGNAL];

enum {
        PROP_0,
	PROP_FOCUSED_ITEM,
};

G_DEFINE_TYPE (
	GnomeCanvas,
	gnome_canvas,
	GTK_TYPE_LAYOUT)

static void
gnome_canvas_paint_rect (GnomeCanvas *canvas,
                         cairo_t *cr,
                         gint x0,
                         gint y0,
                         gint x1,
                         gint y1)
{
	GtkWidget *widget;
	GtkAllocation allocation;
	GtkScrollable *scrollable;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;
	gint draw_x1, draw_y1;
	gint draw_x2, draw_y2;
	gint draw_width, draw_height;
	gdouble hadjustment_value;
	gdouble vadjustment_value;

	g_return_if_fail (!canvas->need_update);

	widget = GTK_WIDGET (canvas);
	gtk_widget_get_allocation (widget, &allocation);

	scrollable = GTK_SCROLLABLE (canvas);
	hadjustment = gtk_scrollable_get_hadjustment (scrollable);
	vadjustment = gtk_scrollable_get_vadjustment (scrollable);

	hadjustment_value = gtk_adjustment_get_value (hadjustment);
	vadjustment_value = gtk_adjustment_get_value (vadjustment);

	draw_x1 = MAX (x0, hadjustment_value - canvas->zoom_xofs);
	draw_y1 = MAX (y0, vadjustment_value - canvas->zoom_yofs);
	draw_x2 = MIN (draw_x1 + allocation.width, x1);
	draw_y2 = MIN (draw_y1 + allocation.height, y1);

	draw_width = draw_x2 - draw_x1;
	draw_height = draw_y2 - draw_y1;

	if (draw_width < 1 || draw_height < 1)
		return;

	canvas->draw_xofs = draw_x1;
	canvas->draw_yofs = draw_y1;

	cairo_save (cr);

	g_signal_emit (
		canvas, canvas_signals[DRAW_BACKGROUND], 0, cr,
		draw_x1, draw_y1, draw_width, draw_height);

	cairo_restore (cr);

	if (canvas->root->flags & GNOME_CANVAS_ITEM_VISIBLE) {
		GnomeCanvasItemClass *klass = GNOME_CANVAS_ITEM_GET_CLASS (canvas->root);

		if (klass && klass->draw) {
			cairo_save (cr);

			klass->draw (
				canvas->root, cr,
				draw_x1, draw_y1,
				draw_width, draw_height);

			cairo_restore (cr);
		}
	}
}

static void
gnome_canvas_get_property (GObject *object,
                           guint property_id,
                           GValue *value,
                           GParamSpec *pspec)
{
	switch (property_id) {
	case PROP_FOCUSED_ITEM:
		g_value_set_object (value, GNOME_CANVAS (object)->focused_item);
		break;
	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
		break;
	}
}

static void
gnome_canvas_set_property (GObject *object,
                           guint property_id,
                           const GValue *value,
                           GParamSpec *pspec)
{
	switch (property_id) {
	case PROP_FOCUSED_ITEM:
		GNOME_CANVAS (object)->focused_item = g_value_get_object (value);
		break;
	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
		break;
	}
}

/* Class initialization function for GnomeCanvasClass */
static void
gnome_canvas_class_init (GnomeCanvasClass *class)
{
	GObjectClass   *object_class;
	GtkWidgetClass *widget_class;

	object_class = (GObjectClass *) class;
	widget_class = (GtkWidgetClass *) class;

	object_class->set_property = gnome_canvas_set_property;
	object_class->get_property = gnome_canvas_get_property;
	object_class->dispose = gnome_canvas_dispose;

	widget_class->map = gnome_canvas_map;
	widget_class->unmap = gnome_canvas_unmap;
	widget_class->realize = gnome_canvas_realize;
	widget_class->unrealize = gnome_canvas_unrealize;
	widget_class->size_allocate = gnome_canvas_size_allocate;
	widget_class->draw = gnome_canvas_draw;
	widget_class->drag_end = gnome_canvas_drag_end;
	widget_class->button_press_event = gnome_canvas_button;
	widget_class->button_release_event = gnome_canvas_button;
	widget_class->motion_notify_event = gnome_canvas_motion;
	widget_class->key_press_event = gnome_canvas_key;
	widget_class->key_release_event = gnome_canvas_key;
	widget_class->enter_notify_event = gnome_canvas_crossing;
	widget_class->leave_notify_event = gnome_canvas_crossing;
	widget_class->focus_in_event = gnome_canvas_focus_in;
	widget_class->focus_out_event = gnome_canvas_focus_out;

	class->draw_background = gnome_canvas_draw_background;
	class->request_update = gnome_canvas_request_update_real;

	g_object_class_install_property (
		object_class,
		PROP_FOCUSED_ITEM,
		g_param_spec_object (
			"focused_item",
			NULL,
			NULL,
			GNOME_TYPE_CANVAS_ITEM,
			G_PARAM_READABLE |
			G_PARAM_WRITABLE));

	canvas_signals[DRAW_BACKGROUND] = g_signal_new (
		"draw_background",
		G_TYPE_FROM_CLASS (object_class),
		G_SIGNAL_RUN_LAST,
		G_STRUCT_OFFSET (GnomeCanvasClass, draw_background),
		NULL, NULL, NULL,
		G_TYPE_NONE, 5,
		CAIRO_GOBJECT_TYPE_CONTEXT,
		G_TYPE_INT,
		G_TYPE_INT,
		G_TYPE_INT,
		G_TYPE_INT);

	gtk_widget_class_set_accessible_type (widget_class, GAIL_TYPE_CANVAS);
	gail_canvas_a11y_init ();
}

/* Callback used when the root item of a canvas is destroyed.  The user should
 * never ever do this, so we panic if this happens.
 */
G_GNUC_NORETURN static void
panic_root_finalized (gpointer data,
                      GObject *gone_object)
{
	g_error ("Eeeek, root item %p of canvas %p was destroyed!", gone_object, data);
}

/* Object initialization function for GnomeCanvas */
static void
gnome_canvas_init (GnomeCanvas *canvas)
{
	GtkLayout *layout;
	guint layout_width, layout_height;

	layout = GTK_LAYOUT (canvas);
	gtk_layout_get_size (layout, &layout_width, &layout_height);

	gtk_widget_set_can_focus (GTK_WIDGET (canvas), TRUE);

	canvas->need_update = FALSE;
	canvas->idle_id = 0;

	canvas->scroll_x1 = 0.0;
	canvas->scroll_y1 = 0.0;
	canvas->scroll_x2 = layout_width;
	canvas->scroll_y2 = layout_height;

	canvas->pick_event.type = GDK_LEAVE_NOTIFY;
	canvas->pick_event.crossing.x = 0;
	canvas->pick_event.crossing.y = 0;

	gtk_scrollable_set_hadjustment (GTK_SCROLLABLE (canvas), NULL);
	gtk_scrollable_set_vadjustment (GTK_SCROLLABLE (canvas), NULL);

	/* Create the root item as a special case */

	canvas->root = GNOME_CANVAS_ITEM (
		g_object_new (gnome_canvas_group_get_type (), NULL));
	canvas->root->canvas = canvas;

	g_object_ref_sink (canvas->root);

	g_object_weak_ref (G_OBJECT (canvas->root), panic_root_finalized, canvas);

	canvas->need_repick = TRUE;
}

/* Convenience function to remove the idle handler of a canvas */
static void
remove_idle (GnomeCanvas *canvas)
{
	if (canvas->idle_id == 0)
		return;

	g_source_remove (canvas->idle_id);
	canvas->idle_id = 0;
}

/* Removes the transient state of the canvas (idle handler, grabs). */
static void
shutdown_transients (GnomeCanvas *canvas)
{
	if (canvas->grabbed_device != NULL) {
		gdk_device_ungrab (canvas->grabbed_device, GDK_CURRENT_TIME);
		g_object_unref (canvas->grabbed_device);
		canvas->grabbed_device = NULL;
	}

	canvas->grabbed_item = NULL;

	remove_idle (canvas);
}

/* Dispose handler for GnomeCanvas */
static void
gnome_canvas_dispose (GObject *object)
{
	GnomeCanvas *canvas;

	g_return_if_fail (GNOME_IS_CANVAS (object));

	/* remember, dispose can be run multiple times! */

	canvas = GNOME_CANVAS (object);

	if (canvas->root) {
		g_object_weak_unref (G_OBJECT (canvas->root), panic_root_finalized, canvas);
		g_object_unref (canvas->root);
		canvas->root = NULL;
	}

	shutdown_transients (canvas);

	/* Chain up to parent's dispose() method. */
	G_OBJECT_CLASS (gnome_canvas_parent_class)->dispose (object);
}

/**
 * gnome_canvas_new:
 *
 * Creates a new empty canvas in non-antialiased mode.
 *
 * Return value: A newly-created canvas.
 **/
GtkWidget *
gnome_canvas_new (void)
{
	return GTK_WIDGET (g_object_new (gnome_canvas_get_type (), NULL));
}

/* Map handler for the canvas */
static void
gnome_canvas_map (GtkWidget *widget)
{
	GnomeCanvas *canvas;
	GnomeCanvasItemClass *klass;

	g_return_if_fail (GNOME_IS_CANVAS (widget));

	/* Normal widget mapping stuff */

	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->map (widget);

	canvas = GNOME_CANVAS (widget);

	if (canvas->need_update)
		add_idle (canvas);

	/* Map items */

	klass = GNOME_CANVAS_ITEM_GET_CLASS (canvas->root);
	g_return_if_fail (klass != NULL);

	if (klass->map)
		klass->map (canvas->root);
}

/* Unmap handler for the canvas */
static void
gnome_canvas_unmap (GtkWidget *widget)
{
	GnomeCanvas *canvas;
	GnomeCanvasItemClass *klass;

	g_return_if_fail (GNOME_IS_CANVAS (widget));

	canvas = GNOME_CANVAS (widget);

	shutdown_transients (canvas);

	/* Unmap items */

	klass = GNOME_CANVAS_ITEM_GET_CLASS (canvas->root);
	g_return_if_fail (klass != NULL);

	if (klass->unmap)
		klass->unmap (canvas->root);

	/* Normal widget unmapping stuff */

	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->unmap (widget);
}

/* Realize handler for the canvas */
static void
gnome_canvas_realize (GtkWidget *widget)
{
	GnomeCanvas *canvas;
	GnomeCanvasItemClass *klass;
	GtkLayout *layout;
	GdkWindow *bin_window;

	g_return_if_fail (GNOME_IS_CANVAS (widget));

	/* Normal widget realization stuff */

	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->realize (widget);

	canvas = GNOME_CANVAS (widget);

	layout = GTK_LAYOUT (canvas);
	bin_window = gtk_layout_get_bin_window (layout);

	gdk_window_set_events (
		bin_window,
		(gdk_window_get_events (bin_window)
		| GDK_EXPOSURE_MASK
		| GDK_SCROLL_MASK
		| GDK_BUTTON_PRESS_MASK
		| GDK_BUTTON_RELEASE_MASK
		| GDK_POINTER_MOTION_MASK
		| GDK_KEY_PRESS_MASK
		| GDK_KEY_RELEASE_MASK
		| GDK_ENTER_NOTIFY_MASK
		| GDK_LEAVE_NOTIFY_MASK
		| GDK_FOCUS_CHANGE_MASK));

	klass = GNOME_CANVAS_ITEM_GET_CLASS (canvas->root);
	g_return_if_fail (klass != NULL);

	/* Create our own temporary pixmap gc and realize all the items */

	klass->realize (canvas->root);
}

/* Unrealize handler for the canvas */
static void
gnome_canvas_unrealize (GtkWidget *widget)
{
	GnomeCanvas *canvas;
	GnomeCanvasItemClass *klass;

	g_return_if_fail (GNOME_IS_CANVAS (widget));

	canvas = GNOME_CANVAS (widget);

	shutdown_transients (canvas);

	/* Unrealize items and parent widget */

	klass = GNOME_CANVAS_ITEM_GET_CLASS (canvas->root);
	g_return_if_fail (klass != NULL);

	klass->unrealize (canvas->root);

	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->unrealize (widget);
}

/* Handles scrolling of the canvas.  Adjusts the scrolling and zooming offset to
 * keep as much as possible of the canvas scrolling region in view.
 */
static void
scroll_to (GnomeCanvas *canvas,
           gint cx,
           gint cy)
{
	GtkWidget *widget;
	GtkAllocation allocation;
	GtkScrollable *scrollable;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;
	guint layout_width, layout_height;
	gint scroll_width, scroll_height;
	gint right_limit, bottom_limit;
	gint old_zoom_xofs, old_zoom_yofs;
	gint canvas_width, canvas_height;

	widget = GTK_WIDGET (canvas);
	gtk_widget_get_allocation (widget, &allocation);

	scrollable = GTK_SCROLLABLE (canvas);
	hadjustment = gtk_scrollable_get_hadjustment (scrollable);
	vadjustment = gtk_scrollable_get_vadjustment (scrollable);

	gtk_layout_get_size (GTK_LAYOUT (canvas), &layout_width, &layout_height);

	canvas_width = allocation.width;
	canvas_height = allocation.height;

	scroll_width =
		floor ((canvas->scroll_x2 - canvas->scroll_x1) + 0.5);
	scroll_height =
		floor ((canvas->scroll_y2 - canvas->scroll_y1) + 0.5);

	right_limit = scroll_width - canvas_width;
	bottom_limit = scroll_height - canvas_height;

	old_zoom_xofs = canvas->zoom_xofs;
	old_zoom_yofs = canvas->zoom_yofs;

	if (right_limit < 0) {
		cx = 0;
		canvas->zoom_xofs = (canvas_width - scroll_width) / 2;
		scroll_width = canvas_width;
	} else if (cx < 0) {
		cx = 0;
		canvas->zoom_xofs = 0;
	} else if (cx > right_limit) {
		cx = right_limit;
		canvas->zoom_xofs = 0;
	} else
		canvas->zoom_xofs = 0;

	if (bottom_limit < 0) {
		cy = 0;
		canvas->zoom_yofs = (canvas_height - scroll_height) / 2;
		scroll_height = canvas_height;
	} else if (cy < 0) {
		cy = 0;
		canvas->zoom_yofs = 0;
	} else if (cy > bottom_limit) {
		cy = bottom_limit;
		canvas->zoom_yofs = 0;
	} else
		canvas->zoom_yofs = 0;

	if ((canvas->zoom_xofs != old_zoom_xofs) ||
	    (canvas->zoom_yofs != old_zoom_yofs)) {
		/* This can only occur, if either canvas size or widget
		 * size changes.  So I think we can request full redraw
		 * here.  The reason is, that coverage UTA will be
		 * invalidated by offset change. */
		/* FIXME Strictly this is not correct - we have to remove
		 *       our own idle (Lauris) */
		/* More stuff - we have to mark root as needing fresh affine
		 * (Lauris) */
		if (!(canvas->root->flags & GNOME_CANVAS_ITEM_NEED_AFFINE)) {
			canvas->root->flags |= GNOME_CANVAS_ITEM_NEED_AFFINE;
			gnome_canvas_request_update (canvas);
		}
		gtk_widget_queue_draw (GTK_WIDGET (canvas));
	}

	if (hadjustment)
		gtk_adjustment_set_value (hadjustment, cx);

	if (vadjustment)
		gtk_adjustment_set_value (vadjustment, cy);

	if ((scroll_width != (gint) layout_width)
	    || (scroll_height != (gint) layout_height))
		gtk_layout_set_size (GTK_LAYOUT (canvas), scroll_width, scroll_height);
}

/* Size allocation handler for the canvas */
static void
gnome_canvas_size_allocate (GtkWidget *widget,
                            GtkAllocation *allocation)
{
	GtkScrollable *scrollable;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;

	g_return_if_fail (GNOME_IS_CANVAS (widget));
	g_return_if_fail (allocation != NULL);

	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->
		size_allocate (widget, allocation);

	scrollable = GTK_SCROLLABLE (widget);
	hadjustment = gtk_scrollable_get_hadjustment (scrollable);
	vadjustment = gtk_scrollable_get_vadjustment (scrollable);

	/* Recenter the view, if appropriate */

	g_object_freeze_notify (G_OBJECT (hadjustment));
	g_object_freeze_notify (G_OBJECT (vadjustment));

	gtk_adjustment_set_page_size (hadjustment, allocation->width);
	gtk_adjustment_set_page_increment (hadjustment, allocation->width / 2);

	gtk_adjustment_set_page_size (vadjustment, allocation->height);
	gtk_adjustment_set_page_increment (vadjustment, allocation->height / 2);

	scroll_to (
		GNOME_CANVAS (widget),
		gtk_adjustment_get_value (hadjustment),
		gtk_adjustment_get_value (vadjustment));

	g_object_thaw_notify (G_OBJECT (hadjustment));
	g_object_thaw_notify (G_OBJECT (vadjustment));
}

static gboolean
gnome_canvas_draw (GtkWidget *widget,
                   cairo_t *cr)
{
	GnomeCanvas *canvas = GNOME_CANVAS (widget);
	cairo_rectangle_int_t rect;
	GtkLayout *layout;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;
	gdouble hadjustment_value;
	gdouble vadjustment_value;

	layout = GTK_LAYOUT (canvas);
	hadjustment = gtk_scrollable_get_hadjustment (GTK_SCROLLABLE (layout));
	vadjustment = gtk_scrollable_get_vadjustment (GTK_SCROLLABLE (layout));

	hadjustment_value = gtk_adjustment_get_value (hadjustment);
	vadjustment_value = gtk_adjustment_get_value (vadjustment);

	gdk_cairo_get_clip_rectangle (cr, &rect);

	if (canvas->need_update) {
		cairo_matrix_t w2c;

		/* We start updating root with w2c matrix */
		gnome_canvas_w2c_matrix (canvas, &w2c);

		gnome_canvas_item_invoke_update (canvas->root, &w2c, 0);

		canvas->need_update = FALSE;
	}

	cairo_save (cr);
	cairo_translate (
		cr,
		-canvas->zoom_xofs + rect.x,
		-canvas->zoom_yofs + rect.y);

	rect.x += hadjustment_value;
	rect.y += vadjustment_value;

	/* No pending updates, draw exposed area immediately */
	gnome_canvas_paint_rect (
		canvas, cr,
		rect.x, rect.y,
		rect.x + rect.width,
		rect.y + rect.height);
	cairo_restore (cr);

	/* And call expose on parent container class */
	GTK_WIDGET_CLASS (gnome_canvas_parent_class)->draw (widget, cr);

	return FALSE;
}

static void
gnome_canvas_drag_end (GtkWidget *widget,
		       GdkDragContext *context)
{
	GnomeCanvas *canvas = GNOME_CANVAS (widget);

	if (canvas->grabbed_item) {
		gnome_canvas_item_ungrab (canvas->grabbed_item, GDK_CURRENT_TIME);
	}

	if (GTK_WIDGET_CLASS (gnome_canvas_parent_class)->drag_end)
		GTK_WIDGET_CLASS (gnome_canvas_parent_class)->drag_end (widget, context);
}

/* Emits an event for an item in the canvas, be it the current item, grabbed
 * item, or focused item, as appropriate.
 */

static gint
emit_event (GnomeCanvas *canvas,
            GdkEvent *event)
{
	GdkEvent *ev;
	gint finished;
	GnomeCanvasItem *item;
	GnomeCanvasItem *parent;
	guint mask;

	/* Perform checks for grabbed items */

	if (canvas->grabbed_item &&
	    !is_descendant (canvas->current_item, canvas->grabbed_item)) {
		/* I think this warning is annoying and I don't know what it's for
		 * so I'll disable it for now.
		 */
/*                g_warning ("emit_event() returning FALSE!\n");*/
		return FALSE;
	}

	if (canvas->grabbed_item) {
		switch (event->type) {
		case GDK_ENTER_NOTIFY:
			mask = GDK_ENTER_NOTIFY_MASK;
			break;

		case GDK_LEAVE_NOTIFY:
			mask = GDK_LEAVE_NOTIFY_MASK;
			break;

		case GDK_MOTION_NOTIFY:
			mask = GDK_POINTER_MOTION_MASK;
			break;

		case GDK_BUTTON_PRESS:
		case GDK_2BUTTON_PRESS:
		case GDK_3BUTTON_PRESS:
			mask = GDK_BUTTON_PRESS_MASK;
			break;

		case GDK_BUTTON_RELEASE:
			mask = GDK_BUTTON_RELEASE_MASK;
			break;

		case GDK_KEY_PRESS:
			mask = GDK_KEY_PRESS_MASK;
			break;

		case GDK_KEY_RELEASE:
			mask = GDK_KEY_RELEASE_MASK;
			break;

		case GDK_SCROLL:
			mask = GDK_SCROLL_MASK;
			break;

		default:
			mask = 0;
			break;
		}

		if (!(mask & canvas->grabbed_event_mask))
			return FALSE;
	}

	/* Convert to world coordinates -- we have two cases because of diferent
	 * offsets of the fields in the event structures.
	 */

	ev = gdk_event_copy (event);

	switch (ev->type)
	{
	case GDK_ENTER_NOTIFY:
	case GDK_LEAVE_NOTIFY:
		gnome_canvas_window_to_world (
			canvas,
			ev->crossing.x, ev->crossing.y,
			&ev->crossing.x, &ev->crossing.y);
		break;

	case GDK_MOTION_NOTIFY:
	case GDK_BUTTON_PRESS:
	case GDK_2BUTTON_PRESS:
	case GDK_3BUTTON_PRESS:
	case GDK_BUTTON_RELEASE:
		gnome_canvas_window_to_world (
			canvas,
			ev->motion.x, ev->motion.y,
			&ev->motion.x, &ev->motion.y);
		break;

	default:
		break;
	}

	/* Choose where we send the event */

	item = canvas->current_item;

	if (canvas->focused_item
	    && ((event->type == GDK_KEY_PRESS) ||
		(event->type == GDK_KEY_RELEASE) ||
		(event->type == GDK_FOCUS_CHANGE)))
		item = canvas->focused_item;

	/* The event is propagated up the hierarchy (for if someone connected to
	 * a group instead of a leaf event), and emission is stopped if a
	 * handler returns TRUE, just like for GtkWidget events.
	 */

	finished = FALSE;

	while (item && !finished) {
		g_object_ref (item);

		g_signal_emit (
			item, item_signals[ITEM_EVENT], 0,
			ev, &finished);

		parent = item->parent;
		g_object_unref (item);

		item = parent;
	}

	gdk_event_free (ev);

	return finished;
}

/* Re-picks the current item in the canvas, based on the event's coordinates.
 * Also emits enter/leave events for items as appropriate.
 */
static gint
pick_current_item (GnomeCanvas *canvas,
                   GdkEvent *event)
{
	gint button_down;
	gdouble x, y;
	gint cx, cy;
	gint retval;

	retval = FALSE;

	/* If a button is down, we'll perform enter and leave events on the
	 * current item, but not enter on any other item.  This is more or less
	 * like X pointer grabbing for canvas items.
	 */
	button_down = canvas->state & (GDK_BUTTON1_MASK
				       | GDK_BUTTON2_MASK
				       | GDK_BUTTON3_MASK
				       | GDK_BUTTON4_MASK
				       | GDK_BUTTON5_MASK);
	if (!button_down)
		canvas->left_grabbed_item = FALSE;

	/* Save the event in the canvas.  This is used to synthesize enter and
	 * leave events in case the current item changes.  It is also used to
	 * re-pick the current item if the current one gets deleted.  Also,
	 * synthesize an enter event.
	 */
	if (event != &canvas->pick_event) {
		if ((event->type == GDK_MOTION_NOTIFY) ||
		    (event->type == GDK_BUTTON_RELEASE)) {
			/* these fields have the same offsets in both types of events */

			canvas->pick_event.crossing.type = GDK_ENTER_NOTIFY;
			canvas->pick_event.crossing.window = event->motion.window;
			canvas->pick_event.crossing.send_event = event->motion.send_event;
			canvas->pick_event.crossing.subwindow = NULL;
			canvas->pick_event.crossing.x = event->motion.x;
			canvas->pick_event.crossing.y = event->motion.y;
			canvas->pick_event.crossing.mode = GDK_CROSSING_NORMAL;
			canvas->pick_event.crossing.detail = GDK_NOTIFY_NONLINEAR;
			canvas->pick_event.crossing.focus = FALSE;
			canvas->pick_event.crossing.state = event->motion.state;

			/* these fields don't have the same offsets in both types of events */

			if (event->type == GDK_MOTION_NOTIFY) {
				canvas->pick_event.crossing.x_root = event->motion.x_root;
				canvas->pick_event.crossing.y_root = event->motion.y_root;
			} else {
				canvas->pick_event.crossing.x_root = event->button.x_root;
				canvas->pick_event.crossing.y_root = event->button.y_root;
			}
		} else
			canvas->pick_event = *event;
	}

	/* Don't do anything else if this is a recursive call */

	if (canvas->in_repick)
		return retval;

	/* LeaveNotify means that there is no current item, so we don't look for one */

	if (canvas->pick_event.type != GDK_LEAVE_NOTIFY) {
		/* these fields don't have the same offsets in both types of events */

		if (canvas->pick_event.type == GDK_ENTER_NOTIFY) {
			x = canvas->pick_event.crossing.x - canvas->zoom_xofs;
			y = canvas->pick_event.crossing.y - canvas->zoom_yofs;
		} else {
			x = canvas->pick_event.motion.x - canvas->zoom_xofs;
			y = canvas->pick_event.motion.y - canvas->zoom_yofs;
		}

		/* canvas pixel coords */

		cx = (gint) (x + 0.5);
		cy = (gint) (y + 0.5);

		/* world coords */

		x = canvas->scroll_x1 + x;
		y = canvas->scroll_y1 + y;

		/* find the closest item */

		if (canvas->root->flags & GNOME_CANVAS_ITEM_VISIBLE)
			canvas->new_current_item =
				gnome_canvas_item_invoke_point (
				canvas->root, x, y, cx, cy);
		else
			canvas->new_current_item = NULL;
	} else
		canvas->new_current_item = NULL;

	if ((canvas->new_current_item == canvas->current_item)
	    && !canvas->left_grabbed_item)
		return retval; /* current item did not change */

	/* Synthesize events for old and new current items */

	if ((canvas->new_current_item != canvas->current_item)
	    && (canvas->current_item != NULL)
	    && !canvas->left_grabbed_item) {
		GdkEvent new_event;

		new_event = canvas->pick_event;
		new_event.type = GDK_LEAVE_NOTIFY;

		new_event.crossing.detail = GDK_NOTIFY_ANCESTOR;
		new_event.crossing.subwindow = NULL;
		canvas->in_repick = TRUE;
		retval = emit_event (canvas, &new_event);
		canvas->in_repick = FALSE;
	}

	/* new_current_item may have been set to NULL during the
	 * call to emit_event() above */

	if ((canvas->new_current_item != canvas->current_item) && button_down) {
		canvas->left_grabbed_item = TRUE;
		return retval;
	}

	/* Handle the rest of cases */

	canvas->left_grabbed_item = FALSE;
	canvas->current_item = canvas->new_current_item;

	if (canvas->current_item != NULL) {
		GdkEvent new_event;

		new_event = canvas->pick_event;
		new_event.type = GDK_ENTER_NOTIFY;
		new_event.crossing.detail = GDK_NOTIFY_ANCESTOR;
		new_event.crossing.subwindow = NULL;
		retval = emit_event (canvas, &new_event);
	}

	return retval;
}

/* Button event handler for the canvas */
static gint
gnome_canvas_button (GtkWidget *widget,
                     GdkEventButton *event)
{
	GnomeCanvas *canvas;
	GtkLayout *layout;
	GdkWindow *bin_window;
	gint mask;
	gint retval;

	g_return_val_if_fail (GNOME_IS_CANVAS (widget), FALSE);
	g_return_val_if_fail (event != NULL, FALSE);

	retval = FALSE;

	canvas = GNOME_CANVAS (widget);

	layout = GTK_LAYOUT (canvas);
	bin_window = gtk_layout_get_bin_window (layout);

	/*
	 * dispatch normally regardless of the event's window if an item has
	 * has a pointer grab in effect
	 */
	if (!canvas->grabbed_item && event->window != bin_window)
		return retval;

	switch (event->button) {
		case 1:
			mask = GDK_BUTTON1_MASK;
			break;
		case 2:
			mask = GDK_BUTTON2_MASK;
			break;
		case 3:
			mask = GDK_BUTTON3_MASK;
			break;
		case 4:
			mask = GDK_BUTTON4_MASK;
			break;
		case 5:
			mask = GDK_BUTTON5_MASK;
			break;
		default:
			mask = 0;
	}

	switch (event->type) {
		case GDK_BUTTON_PRESS:
		case GDK_2BUTTON_PRESS:
		case GDK_3BUTTON_PRESS:
			/* Pick the current item as if the button were
			 * not pressed, and then process the event. */
			canvas->state = event->state;
			pick_current_item (canvas, (GdkEvent *) event);
			canvas->state ^= mask;
			retval = emit_event (canvas, (GdkEvent *) event);
			break;

		case GDK_BUTTON_RELEASE:
			/* Process the event as if the button were pressed,
			 * then repick after the button has been released. */
			canvas->state = event->state;
			retval = emit_event (canvas, (GdkEvent *) event);
			event->state ^= mask;
			canvas->state = event->state;
			pick_current_item (canvas, (GdkEvent *) event);
			event->state ^= mask;
			break;

		default:
			g_warn_if_reached ();
	}

	return retval;
}

/* Motion event handler for the canvas */
static gint
gnome_canvas_motion (GtkWidget *widget,
                     GdkEventMotion *event)
{
	GnomeCanvas *canvas;
	GtkLayout *layout;
	GdkWindow *bin_window;

	g_return_val_if_fail (GNOME_IS_CANVAS (widget), FALSE);
	g_return_val_if_fail (event != NULL, FALSE);

	canvas = GNOME_CANVAS (widget);

	layout = GTK_LAYOUT (widget);
	bin_window = gtk_layout_get_bin_window (layout);

	if (event->window != bin_window)
		return FALSE;

	canvas->state = event->state;
	pick_current_item (canvas, (GdkEvent *) event);
	return emit_event (canvas, (GdkEvent *) event);
}

/* Key event handler for the canvas */
static gboolean
gnome_canvas_key (GtkWidget *widget,
                  GdkEventKey *event)
{
	GnomeCanvas *canvas;

	g_return_val_if_fail (GNOME_IS_CANVAS (widget), FALSE);
	g_return_val_if_fail (event != NULL, FALSE);

	canvas = GNOME_CANVAS (widget);

	if (!emit_event (canvas, (GdkEvent *) event)) {
		GtkWidgetClass *widget_class;

		widget_class = GTK_WIDGET_CLASS (gnome_canvas_parent_class);

		if (event->type == GDK_KEY_PRESS) {
			if (widget_class->key_press_event)
				return (* widget_class->key_press_event) (widget, event);
		} else if (event->type == GDK_KEY_RELEASE) {
			if (widget_class->key_release_event)
				return (* widget_class->key_release_event) (widget, event);
		} else
			g_warn_if_reached ();

		return FALSE;
	} else
		return TRUE;
}

/* Crossing event handler for the canvas */
static gint
gnome_canvas_crossing (GtkWidget *widget,
                       GdkEventCrossing *event)
{
	GnomeCanvas *canvas;
	GtkLayout *layout;
	GdkWindow *bin_window;

	g_return_val_if_fail (GNOME_IS_CANVAS (widget), FALSE);
	g_return_val_if_fail (event != NULL, FALSE);

	canvas = GNOME_CANVAS (widget);

	layout = GTK_LAYOUT (canvas);
	bin_window = gtk_layout_get_bin_window (layout);

	if (event->window != bin_window)
		return FALSE;

	/* XXX Detect and disregard synthesized crossing events generated
	 *     by synth_crossing() in gtkwidget.c.  The pointer coordinates
	 *     are invalid and pick_current_item() relies on them. */
	if (event->x == 0 && event->y == 0 &&
	    event->x_root == 0 && event->y_root == 0)
		return FALSE;

	canvas->state = event->state;
	return pick_current_item (canvas, (GdkEvent *) event);
}

/* Focus in handler for the canvas */
static gint
gnome_canvas_focus_in (GtkWidget *widget,
                       GdkEventFocus *event)
{
	GnomeCanvas *canvas;

	/* XXX Can't access flags directly anymore, but is it really needed?
	 *     If so, could we call gtk_widget_send_focus_change() instead? */
#if 0
	GTK_WIDGET_SET_FLAGS (widget, GTK_HAS_FOCUS);
#endif

	canvas = GNOME_CANVAS (widget);

	if (canvas->focused_item)
		return emit_event (canvas, (GdkEvent *) event);
	else
		return FALSE;
}

/* Focus out handler for the canvas */
static gint
gnome_canvas_focus_out (GtkWidget *widget,
                        GdkEventFocus *event)
{
	GnomeCanvas *canvas;

	/* XXX Can't access flags directly anymore, but is it really needed?
	 *     If so, could we call gtk_widget_send_focus_change() instead? */
#if 0
	GTK_WIDGET_UNSET_FLAGS (widget, GTK_HAS_FOCUS);
#endif

	canvas = GNOME_CANVAS (widget);

	if (canvas->focused_item)
		return emit_event (canvas, (GdkEvent *) event);
	else
		return FALSE;
}

static void
gnome_canvas_draw_background (GnomeCanvas *canvas,
                              cairo_t *cr,
                              gint x,
                              gint y,
                              gint width,
                              gint height)
{
	GtkStyleContext *style_context;
	GdkRGBA rgba;

	style_context = gtk_widget_get_style_context (GTK_WIDGET (canvas));
	if (!gtk_style_context_lookup_color (style_context, "theme_bg_color", &rgba))
		gdk_rgba_parse (&rgba, "#aaaaaa");

	cairo_save (cr);
	gdk_cairo_set_source_rgba (cr, &rgba);
	cairo_paint (cr);
	cairo_restore (cr);
}

static void
do_update (GnomeCanvas *canvas)
{
	/* Cause the update if necessary */

update_again:
	if (canvas->need_update) {
		cairo_matrix_t w2c;

		/* We start updating root with w2c matrix */
		gnome_canvas_w2c_matrix (canvas, &w2c);

		gnome_canvas_item_invoke_update (canvas->root, &w2c, 0);

		canvas->need_update = FALSE;
	}

	/* Pick new current item */

	while (canvas->need_repick) {
		canvas->need_repick = FALSE;
		pick_current_item (canvas, &canvas->pick_event);
	}

	/* it is possible that during picking we emitted an event in which
	 * the user then called some function which then requested update
	 * of something.  Without this we'd be left in a state where
	 * need_update would have been left TRUE and the canvas would have
	 * been left unpainted. */
	if (canvas->need_update) {
		goto update_again;
	}
}

/* Idle handler for the canvas.  It deals with pending updates and redraws. */
static gboolean
idle_handler (gpointer data)
{
	GnomeCanvas *canvas;

	canvas = GNOME_CANVAS (data);

	do_update (canvas);

	/* Reset idle id */
	canvas->idle_id = 0;

	return FALSE;
}

/* Convenience function to add an idle handler to a canvas */
static void
add_idle (GnomeCanvas *canvas)
{
	g_return_if_fail (canvas->need_update);

	if (!canvas->idle_id)
		canvas->idle_id = g_idle_add_full (
			CANVAS_IDLE_PRIORITY,
			idle_handler,
			canvas,
			NULL);

/*	canvas->idle_id = gtk_idle_add (idle_handler, canvas); */
}

/**
 * gnome_canvas_root:
 * @canvas: A canvas.
 *
 * Queries the root group of a canvas.
 *
 * Return value: The root group of the specified canvas.
 **/
GnomeCanvasGroup *
gnome_canvas_root (GnomeCanvas *canvas)
{
	g_return_val_if_fail (GNOME_IS_CANVAS (canvas), NULL);

	return GNOME_CANVAS_GROUP (canvas->root);
}

/**
 * gnome_canvas_set_scroll_region:
 * @canvas: A canvas.
 * @x1: Leftmost limit of the scrolling region.
 * @y1: Upper limit of the scrolling region.
 * @x2: Rightmost limit of the scrolling region.
 * @y2: Lower limit of the scrolling region.
 *
 * Sets the scrolling region of a canvas to the specified rectangle.  The canvas
 * will then be able to scroll only within this region.  The view of the canvas
 * is adjusted as appropriate to display as much of the new region as possible.
 **/
void
gnome_canvas_set_scroll_region (GnomeCanvas *canvas,
                                gdouble x1,
                                gdouble y1,
                                gdouble x2,
                                gdouble y2)
{
	GtkScrollable *scrollable;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;
	gdouble hadjustment_value;
	gdouble vadjustment_value;
	gdouble wxofs, wyofs;
	gint xofs, yofs;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	scrollable = GTK_SCROLLABLE (canvas);
	hadjustment = gtk_scrollable_get_hadjustment (scrollable);
	vadjustment = gtk_scrollable_get_vadjustment (scrollable);

	hadjustment_value = gtk_adjustment_get_value (hadjustment);
	vadjustment_value = gtk_adjustment_get_value (vadjustment);

	/*
	 * Set the new scrolling region.  If possible, do not move the
	 * visible contents of the canvas.
	 */

	gnome_canvas_c2w (
		canvas,
		hadjustment_value + canvas->zoom_xofs,
		vadjustment_value + canvas->zoom_yofs,
		&wxofs, &wyofs);

	canvas->scroll_x1 = x1;
	canvas->scroll_y1 = y1;
	canvas->scroll_x2 = x2;
	canvas->scroll_y2 = y2;

	gnome_canvas_w2c (canvas, wxofs, wyofs, &xofs, &yofs);

	scroll_to (canvas, xofs, yofs);

	canvas->need_repick = TRUE;
#if 0
	/* todo: should be requesting update */
	(* GNOME_CANVAS_ITEM_CLASS (canvas->root->object.class)->update) (
		canvas->root, NULL, NULL, 0);
#endif
}

/**
 * gnome_canvas_get_scroll_region:
 * @canvas: A canvas.
 * @x1: Leftmost limit of the scrolling region (return value).
 * @y1: Upper limit of the scrolling region (return value).
 * @x2: Rightmost limit of the scrolling region (return value).
 * @y2: Lower limit of the scrolling region (return value).
 *
 * Queries the scrolling region of a canvas.
 **/
void
gnome_canvas_get_scroll_region (GnomeCanvas *canvas,
                                gdouble *x1,
                                gdouble *y1,
                                gdouble *x2,
                                gdouble *y2)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	if (x1)
		*x1 = canvas->scroll_x1;

	if (y1)
		*y1 = canvas->scroll_y1;

	if (x2)
		*x2 = canvas->scroll_x2;

	if (y2)
		*y2 = canvas->scroll_y2;
}

/**
 * gnome_canvas_scroll_to:
 * @canvas: A canvas.
 * @cx: Horizontal scrolling offset in canvas pixel units.
 * @cy: Vertical scrolling offset in canvas pixel units.
 *
 * Makes a canvas scroll to the specified offsets, given in canvas pixel units.
 * The canvas will adjust the view so that it is not outside the scrolling
 * region.  This function is typically not used, as it is better to hook
 * scrollbars to the canvas layout's scrolling adjusments.
 **/
void
gnome_canvas_scroll_to (GnomeCanvas *canvas,
                        gint cx,
                        gint cy)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	scroll_to (canvas, cx, cy);
}

/**
 * gnome_canvas_get_scroll_offsets:
 * @canvas: A canvas.
 * @cx: Horizontal scrolling offset (return value).
 * @cy: Vertical scrolling offset (return value).
 *
 * Queries the scrolling offsets of a canvas.  The values are returned in canvas
 * pixel units.
 **/
void
gnome_canvas_get_scroll_offsets (GnomeCanvas *canvas,
                                 gint *cx,
                                 gint *cy)
{
	GtkAdjustment *adjustment;
	GtkScrollable *scrollable;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	scrollable = GTK_SCROLLABLE (canvas);

	if (cx) {
		adjustment = gtk_scrollable_get_hadjustment (scrollable);
		*cx = (gint) gtk_adjustment_get_value (adjustment);
	}

	if (cy) {
		adjustment = gtk_scrollable_get_vadjustment (scrollable);
		*cy = (gint) gtk_adjustment_get_value (adjustment);
	}
}

/**
 * gnome_canvas_get_item_at:
 * @canvas: A canvas.
 * @x: X position in world coordinates.
 * @y: Y position in world coordinates.
 *
 * Looks for the item that is under the specified position, which must be
 * specified in world coordinates.
 *
 * Return value: The sought item, or NULL if no item is at the specified
 * coordinates.
 **/
GnomeCanvasItem *
gnome_canvas_get_item_at (GnomeCanvas *canvas,
                          gdouble x,
                          gdouble y)
{
	gint cx, cy;

	g_return_val_if_fail (GNOME_IS_CANVAS (canvas), NULL);

	gnome_canvas_w2c (canvas, x, y, &cx, &cy);

	return gnome_canvas_item_invoke_point (canvas->root, x, y, cx, cy);
}

/* Queues an update of the canvas */
static void
gnome_canvas_request_update (GnomeCanvas *canvas)
{
	GNOME_CANVAS_GET_CLASS (canvas)->request_update (canvas);
}

static void
gnome_canvas_request_update_real (GnomeCanvas *canvas)
{
	if (canvas->need_update)
		return;

	canvas->need_update = TRUE;
	if (gtk_widget_get_mapped ((GtkWidget *) canvas))
		add_idle (canvas);
}

static inline void
get_visible_rect (GnomeCanvas *canvas,
                  GdkRectangle *visible)
{
	GtkAllocation allocation;
	GtkScrollable *scrollable;
	GtkAdjustment *hadjustment;
	GtkAdjustment *vadjustment;
	gdouble hadjustment_value;
	gdouble vadjustment_value;

	gtk_widget_get_allocation (GTK_WIDGET (canvas), &allocation);

	scrollable = GTK_SCROLLABLE (canvas);
	hadjustment = gtk_scrollable_get_hadjustment (scrollable);
	vadjustment = gtk_scrollable_get_vadjustment (scrollable);

	hadjustment_value = gtk_adjustment_get_value (hadjustment);
	vadjustment_value = gtk_adjustment_get_value (vadjustment);

	visible->x = hadjustment_value - canvas->zoom_xofs;
	visible->y = vadjustment_value - canvas->zoom_yofs;
	visible->width = allocation.width;
	visible->height = allocation.height;
}

/**
 * gnome_canvas_request_redraw:
 * @canvas: A canvas.
 * @x1: Leftmost coordinate of the rectangle to be redrawn.
 * @y1: Upper coordinate of the rectangle to be redrawn.
 * @x2: Rightmost coordinate of the rectangle to be redrawn, plus 1.
 * @y2: Lower coordinate of the rectangle to be redrawn, plus 1.
 *
 * Convenience function that informs a canvas that the specified rectangle needs
 * to be repainted.  The rectangle includes @x1 and @y1, but not @x2 and @y2.  To
 * be used only by item implementations.
 **/
void
gnome_canvas_request_redraw (GnomeCanvas *canvas,
                             gint x1,
                             gint y1,
                             gint x2,
                             gint y2)
{
	GdkRectangle area, clip;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	if (!gtk_widget_is_drawable (GTK_WIDGET (canvas)) || (x1 >= x2) || (y1 >= y2))
		return;

	area.x = x1;
	area.y = y1;
	area.width = x2 - x1 + 1;
	area.height = y2 - y1 + 1;

	get_visible_rect (canvas, &clip);
	if (!gdk_rectangle_intersect (&area, &clip, &area))
		return;

	gdk_window_invalidate_rect (
		gtk_layout_get_bin_window (GTK_LAYOUT (canvas)),
		&area, FALSE);
}

/**
 * gnome_canvas_w2c_matrix:
 * @canvas: A canvas.
 * @matrix: (out): matrix to initialize
 *
 * Gets the transformtion matrix that converts from world coordinates to canvas
 * pixel coordinates.
 **/
void
gnome_canvas_w2c_matrix (GnomeCanvas *canvas,
                         cairo_matrix_t *matrix)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));
	g_return_if_fail (matrix != NULL);

	cairo_matrix_init_translate (
		matrix, -canvas->scroll_x1, -canvas->scroll_y1);
}

/**
 * gnome_canvas_c2w_matrix:
 * @canvas: A canvas.
 * @matrix: (out): matrix to initialize
 *
 * Gets the transformtion matrix that converts from canvas pixel coordinates to
 * world coordinates.
 **/
void
gnome_canvas_c2w_matrix (GnomeCanvas *canvas,
                         cairo_matrix_t *matrix)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));
	g_return_if_fail (matrix != NULL);

	cairo_matrix_init_translate (
		matrix, canvas->scroll_x1, canvas->scroll_y1);
}

/**
 * gnome_canvas_w2c:
 * @canvas: A canvas.
 * @wx: World X coordinate.
 * @wy: World Y coordinate.
 * @cx: X pixel coordinate (return value).
 * @cy: Y pixel coordinate (return value).
 *
 * Converts world coordinates into canvas pixel coordinates.
 **/
void
gnome_canvas_w2c (GnomeCanvas *canvas,
                  gdouble wx,
                  gdouble wy,
                  gint *cx,
                  gint *cy)
{
	cairo_matrix_t w2c;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	gnome_canvas_w2c_matrix (canvas, &w2c);
	cairo_matrix_transform_point (&w2c, &wx, &wy);

	if (cx)
		*cx = floor (wx + 0.5);
	if (cy)
		*cy = floor (wy + 0.5);
}

/**
 * gnome_canvas_w2c_d:
 * @canvas: A canvas.
 * @wx: World X coordinate.
 * @wy: World Y coordinate.
 * @cx: X pixel coordinate (return value).
 * @cy: Y pixel coordinate (return value).
 *
 * Converts world coordinates into canvas pixel coordinates.  This
 * version returns coordinates in floating point coordinates, for
 * greater precision.
 **/
void
gnome_canvas_w2c_d (GnomeCanvas *canvas,
                    gdouble wx,
                    gdouble wy,
                    gdouble *cx,
                    gdouble *cy)
{
	cairo_matrix_t w2c;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	gnome_canvas_w2c_matrix (canvas, &w2c);
	cairo_matrix_transform_point (&w2c, &wx, &wy);

	if (cx)
		*cx = wx;
	if (cy)
		*cy = wy;
}

/**
 * gnome_canvas_c2w:
 * @canvas: A canvas.
 * @cx: Canvas pixel X coordinate.
 * @cy: Canvas pixel Y coordinate.
 * @wx: X world coordinate (return value).
 * @wy: Y world coordinate (return value).
 *
 * Converts canvas pixel coordinates to world coordinates.
 **/
void
gnome_canvas_c2w (GnomeCanvas *canvas,
                  gint cx,
                  gint cy,
                  gdouble *wx,
                  gdouble *wy)
{
	cairo_matrix_t c2w;
	gdouble x, y;

	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	x = cx;
	y = cy;
	gnome_canvas_c2w_matrix (canvas, &c2w);
	cairo_matrix_transform_point (&c2w, &x, &y);

	if (wx)
		*wx = x;
	if (wy)
		*wy = y;
}

/**
 * gnome_canvas_window_to_world:
 * @canvas: A canvas.
 * @winx: Window-relative X coordinate.
 * @winy: Window-relative Y coordinate.
 * @worldx: X world coordinate (return value).
 * @worldy: Y world coordinate (return value).
 *
 * Converts window-relative coordinates into world coordinates.  You can use
 * this when you need to convert mouse coordinates into world coordinates, for
 * example.
 **/
void
gnome_canvas_window_to_world (GnomeCanvas *canvas,
                              gdouble winx,
                              gdouble winy,
                              gdouble *worldx,
                              gdouble *worldy)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	if (worldx)
		*worldx = canvas->scroll_x1 + (winx - canvas->zoom_xofs);

	if (worldy)
		*worldy = canvas->scroll_y1 + (winy - canvas->zoom_yofs);
}

/**
 * gnome_canvas_world_to_window:
 * @canvas: A canvas.
 * @worldx: World X coordinate.
 * @worldy: World Y coordinate.
 * @winx: X window-relative coordinate.
 * @winy: Y window-relative coordinate.
 *
 * Converts world coordinates into window-relative coordinates.
 **/
void
gnome_canvas_world_to_window (GnomeCanvas *canvas,
                              gdouble worldx,
                              gdouble worldy,
                              gdouble *winx,
                              gdouble *winy)
{
	g_return_if_fail (GNOME_IS_CANVAS (canvas));

	if (winx)
		*winx = (worldx - canvas->scroll_x1) + canvas->zoom_xofs;

	if (winy)
		*winy = (worldy - canvas->scroll_y1) + canvas->zoom_yofs;
}

static gboolean
boolean_handled_accumulator (GSignalInvocationHint *ihint,
                             GValue *return_accu,
                             const GValue *handler_return,
                             gpointer dummy)
{
	gboolean continue_emission;
	gboolean signal_handled;

	signal_handled = g_value_get_boolean (handler_return);
	g_value_set_boolean (return_accu, signal_handled);
	continue_emission = !signal_handled;

	return continue_emission;
}

/* Class initialization function for GnomeCanvasItemClass */
static void
gnome_canvas_item_class_init (GnomeCanvasItemClass *class)
{
	GObjectClass *gobject_class;

	gobject_class = (GObjectClass *) class;

	gobject_class->set_property = gnome_canvas_item_set_property;
	gobject_class->get_property = gnome_canvas_item_get_property;

	g_object_class_install_property (
		gobject_class,
		ITEM_PROP_PARENT,
		g_param_spec_object (
			"parent",
			NULL,
			NULL,
			GNOME_TYPE_CANVAS_ITEM,
			G_PARAM_READABLE |
			G_PARAM_WRITABLE));

	item_signals[ITEM_EVENT] = g_signal_new (
		"event",
		G_TYPE_FROM_CLASS (class),
		G_SIGNAL_RUN_LAST,
		G_STRUCT_OFFSET (GnomeCanvasItemClass, event),
		boolean_handled_accumulator, NULL, NULL,
		G_TYPE_BOOLEAN, 1,
		GDK_TYPE_EVENT | G_SIGNAL_TYPE_STATIC_SCOPE);

	gobject_class->dispose = gnome_canvas_item_dispose;

	class->update = gnome_canvas_item_update;
	class->realize = gnome_canvas_item_realize;
	class->unrealize = gnome_canvas_item_unrealize;
	class->map = gnome_canvas_item_map;
	class->unmap = gnome_canvas_item_unmap;
	class->dispose = gnome_canvas_item_dispose_item;
	class->draw = gnome_canvas_item_draw;
	class->point = gnome_canvas_item_point;
	class->bounds = gnome_canvas_item_bounds;
	class->event = gnome_canvas_item_event;
}
