Move item implementation to item.c.

git-svn-id: http://svn.drobilla.net/lad/trunk/ganv@5298 a436a847-0d15-0410-975c-d299462d15a1

3 files changed, 825 insertions, 779 deletions

diff --git a/src/canvas-base.c b/src/canvas-base.c
index e30a517..89a3e4e 100644
--- a/src/canvas-base.c
+++ b/src/canvas-base.c
@@ -35,7 +35,6 @@
 /* We must run our idle update handler *before* GDK wants to redraw. */
 #define CANVAS_IDLE_PRIORITY (GDK_PRIORITY_REDRAW - 5)
 
-static void ganv_canvas_base_request_update(GanvCanvasBase* canvas);
 static void add_idle(GanvCanvasBase* canvas);
 
 typedef struct {
@@ -45,689 +44,6 @@ typedef struct {
 	int height;
 } IRect;
 
-/* Some convenience stuff */
-#define GCI_UPDATE_MASK (GANV_CANVAS_BASE_UPDATE_REQUESTED | GANV_CANVAS_BASE_UPDATE_AFFINE \
-                         | GANV_CANVAS_BASE_UPDATE_VISIBILITY)
-
-enum {
-	ITEM_PROP_0,
-	ITEM_PROP_PARENT,
-	ITEM_PROP_X,
-	ITEM_PROP_Y,
-	ITEM_PROP_MANAGED
-};
-
-enum {
-	ITEM_EVENT,
-	ITEM_LAST_SIGNAL
-};
-
-static int emit_event(GanvCanvasBase* canvas, GdkEvent* event);
-
-static guint item_signals[ITEM_LAST_SIGNAL];
-
-G_DEFINE_TYPE(GanvItem, ganv_item, GTK_TYPE_OBJECT)
-
-static GtkObjectClass * item_parent_class;
-
-/* Object initialization function for GanvItem */
-static void
-ganv_item_init(GanvItem* item)
-{
-	item->object.flags |= GANV_ITEM_VISIBLE;
-	item->managed       = FALSE;
-}
-
-/**
- * ganv_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
- * ganv_canvas_base_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
- * ganv_item_construct() to set up the canvas item.
- *
- * Return value: (transfer full): The newly-created item.
- **/
-GanvItem*
-ganv_item_new(GanvItem* parent, GType type, const gchar* first_arg_name, ...)
-{
-	GanvItem* item;
-	va_list   args;
-
-	g_return_val_if_fail(g_type_is_a(type, ganv_item_get_type()), NULL);
-
-	item = GANV_ITEM(g_object_new(type, NULL));
-
-	va_start(args, first_arg_name);
-	ganv_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(GanvItem* item)
-{
-	GanvItemClass* parent_class = GANV_ITEM_GET_CLASS(item->parent);
-	if (!item->managed) {
-		if (parent_class->add) {
-			parent_class->add(item->parent, item);
-		} else {
-			g_warning("item added to non-parent item\n");
-		}
-	}
-	ganv_canvas_base_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
-ganv_item_set_property(GObject* gobject, guint param_id,
-                       const GValue* value, GParamSpec* pspec)
-{
-	g_return_if_fail(GANV_IS_ITEM(gobject));
-
-	GanvItem* item = GANV_ITEM(gobject);
-
-	switch (param_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 = GANV_ITEM(g_value_get_object(value));
-			item->canvas = item->parent->canvas;
-			item_post_create_setup(item);
-		}
-		break;
-	case ITEM_PROP_X:
-		item->x = g_value_get_double(value);
-		ganv_item_request_update(item);
-		break;
-	case ITEM_PROP_Y:
-		item->y = g_value_get_double(value);
-		ganv_item_request_update(item);
-		break;
-	case ITEM_PROP_MANAGED:
-		item->managed = g_value_get_boolean(value);
-		break;
-	default:
-		G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, param_id, pspec);
-		break;
-	}
-}
-
-/* Get_property handler for canvas items */
-static void
-ganv_item_get_property(GObject* gobject, guint param_id,
-                       GValue* value, GParamSpec* pspec)
-{
-	g_return_if_fail(GANV_IS_ITEM(gobject));
-
-	GanvItem* item = GANV_ITEM(gobject);
-
-	switch (param_id) {
-	case ITEM_PROP_PARENT:
-		g_value_set_object(value, item->parent);
-		break;
-	case ITEM_PROP_X:
-		g_value_set_double(value, item->x);
-		break;
-	case ITEM_PROP_Y:
-		g_value_set_double(value, item->y);
-		break;
-	case ITEM_PROP_MANAGED:
-		g_value_set_boolean(value, item->managed);
-		break;
-	default:
-		G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, param_id, pspec);
-		break;
-	}
-}
-
-/**
- * ganv_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
-ganv_item_construct(GanvItem* item, GanvItem* parent,
-                    const gchar* first_arg_name, va_list args)
-{
-	g_return_if_fail(GANV_IS_ITEM(item));
-
-	item->parent = parent;
-	item->canvas = item->parent->canvas;
-	item->layer = 0;
-
-	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(GanvItem* item)
-{
-	if (item->object.flags & GANV_ITEM_VISIBLE) {
-		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
-		                                item->y2 + 1);
-	}
-}
-
-/* Standard object dispose function for canvas items */
-static void
-ganv_item_dispose(GObject* object)
-{
-	GanvItem* item;
-
-	g_return_if_fail(GANV_IS_ITEM(object));
-
-	item = GANV_ITEM(object);
-
-	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_pointer_ungrab(GDK_CURRENT_TIME);
-	}
-
-	if (item->canvas && item == item->canvas->focused_item) {
-		item->canvas->focused_item = NULL;
-	}
-
-	/* Normal destroy stuff */
-
-	if (item->object.flags & GANV_ITEM_MAPPED) {
-		(*GANV_ITEM_GET_CLASS(item)->unmap)(item);
-	}
-
-	if (item->object.flags & GANV_ITEM_REALIZED) {
-		(*GANV_ITEM_GET_CLASS(item)->unrealize)(item);
-	}
-
-	if (!item->managed && item->parent) {
-		if (GANV_ITEM_GET_CLASS(item->parent)->remove) {
-			GANV_ITEM_GET_CLASS(item->parent)->remove(item->parent, item);
-		} else {
-			fprintf(stderr, "warning: Item parent has no remove method\n");
-		}
-	}
-
-	G_OBJECT_CLASS(item_parent_class)->dispose(object);
-	/* items should remove any reference to item->canvas after the
-	   first ::destroy */
-	item->canvas = NULL;
-}
-
-/* Realize handler for canvas items */
-static void
-ganv_item_realize(GanvItem* item)
-{
-	GTK_OBJECT_SET_FLAGS(item, GANV_ITEM_REALIZED);
-
-	ganv_item_request_update(item);
-}
-
-/* Unrealize handler for canvas items */
-static void
-ganv_item_unrealize(GanvItem* item)
-{
-	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_REALIZED);
-}
-
-/* Map handler for canvas items */
-static void
-ganv_item_map(GanvItem* item)
-{
-	GTK_OBJECT_SET_FLAGS(item, GANV_ITEM_MAPPED);
-}
-
-/* Unmap handler for canvas items */
-static void
-ganv_item_unmap(GanvItem* item)
-{
-	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_MAPPED);
-}
-
-/* Update handler for canvas items */
-static void
-ganv_item_update(GanvItem* item, int flags)
-{
-	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_NEED_UPDATE);
-	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_NEED_VIS);
-}
-
-/* Point handler for canvas items */
-static double
-ganv_item_point(GanvItem* item,
-                double x, double y,
-                int cx, int cy,
-                GanvItem** actual_item)
-{
-	*actual_item = NULL;
-	return G_MAXDOUBLE;
-}
-
-void
-ganv_item_invoke_update(GanvItem* item, int flags)
-{
-	int child_flags = flags;
-
-	/* apply object flags to child flags */
-
-	child_flags &= ~GANV_CANVAS_BASE_UPDATE_REQUESTED;
-
-	if (item->object.flags & GANV_ITEM_NEED_UPDATE) {
-		child_flags |= GANV_CANVAS_BASE_UPDATE_REQUESTED;
-	}
-
-	if (item->object.flags & GANV_ITEM_NEED_VIS) {
-		child_flags |= GANV_CANVAS_BASE_UPDATE_VISIBILITY;
-	}
-
-	if (child_flags & GCI_UPDATE_MASK) {
-		if (GANV_ITEM_GET_CLASS(item)->update) {
-			GANV_ITEM_GET_CLASS(item)->update(item, child_flags);
-		}
-	}
-}
-
-/**
- * ganv_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
-ganv_item_set(GanvItem* item, const gchar* first_arg_name, ...)
-{
-	va_list args;
-
-	va_start(args, first_arg_name);
-	ganv_item_set_valist(item, first_arg_name, args);
-	va_end(args);
-}
-
-/**
- * ganv_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
-ganv_item_set_valist(GanvItem* item, const gchar* first_arg_name, va_list args)
-{
-	g_return_if_fail(GANV_IS_ITEM(item));
-
-	g_object_set_valist(G_OBJECT(item), first_arg_name, args);
-
-	item->canvas->need_repick = TRUE;
-}
-
-void
-ganv_item_raise(GanvItem* item)
-{
-	++item->layer;
-}
-
-void
-ganv_item_lower(GanvItem* item)
-{
-	--item->layer;
-}
-
-/**
- * ganv_item_move:
- * @item: A canvas item.
- * @dx: Horizontal offset.
- * @dy: Vertical offset.
- **/
-void
-ganv_item_move(GanvItem* item, double dx, double dy)
-{
-	if (!item || !GANV_IS_ITEM(item)) {
-		return;
-	}
-
-	item->x += dx;
-	item->y += dy;
-
-	ganv_item_request_update(item);
-	item->canvas->need_repick = TRUE;
-}
-
-/**
- * ganv_item_show:
- * @item: A canvas item.
- *
- * Shows a canvas item.  If the item was already shown, then no action is taken.
- **/
-void
-ganv_item_show(GanvItem* item)
-{
-	g_return_if_fail(GANV_IS_ITEM(item));
-
-	if (!(item->object.flags & GANV_ITEM_VISIBLE)) {
-		item->object.flags |= GANV_ITEM_VISIBLE;
-		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
-		                                item->y2 + 1);
-		item->canvas->need_repick = TRUE;
-	}
-}
-
-/**
- * ganv_item_hide:
- * @item: A canvas item.
- *
- * Hides a canvas item.  If the item was already hidden, then no action is
- * taken.
- **/
-void
-ganv_item_hide(GanvItem* item)
-{
-	g_return_if_fail(GANV_IS_ITEM(item));
-
-	if (item->object.flags & GANV_ITEM_VISIBLE) {
-		item->object.flags &= ~GANV_ITEM_VISIBLE;
-		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
-		                                item->y2 + 1);
-		item->canvas->need_repick = TRUE;
-	}
-}
-
-/**
- * ganv_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.
- * @etime: The timestamp required for grabbing the mouse, or GDK_CURRENT_TIME.
- *
- * Specifies that all events that match the specified event mask should be sent
- * to the specified item, and also grabs the mouse by calling
- * gdk_pointer_grab().  The event mask is also used when grabbing the pointer.
- * 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 mouse.
- *
- * Return value: If an item was already grabbed, it returns %GDK_GRAB_ALREADY_GRABBED.  If
- * the specified item was hidden by calling ganv_item_hide(), then it
- * returns %GDK_GRAB_NOT_VIEWABLE.  Else, it returns the result of calling
- * gdk_pointer_grab().
- **/
-int
-ganv_item_grab(GanvItem* item, guint event_mask, GdkCursor* cursor, guint32 etime)
-{
-	int retval;
-
-	g_return_val_if_fail(GANV_IS_ITEM(item), GDK_GRAB_NOT_VIEWABLE);
-	g_return_val_if_fail(GTK_WIDGET_MAPPED(item->canvas), GDK_GRAB_NOT_VIEWABLE);
-
-	if (item->canvas->grabbed_item) {
-		return GDK_GRAB_ALREADY_GRABBED;
-	}
-
-	if (!(item->object.flags & GANV_ITEM_VISIBLE)) {
-		return GDK_GRAB_NOT_VIEWABLE;
-	}
-
-	retval = gdk_pointer_grab(item->canvas->layout.bin_window,
-	                          FALSE,
-	                          event_mask,
-	                          NULL,
-	                          cursor,
-	                          etime);
-
-	if (retval != GDK_GRAB_SUCCESS) {
-		return retval;
-	}
-
-	item->canvas->grabbed_item       = item;
-	item->canvas->grabbed_event_mask = event_mask;
-	item->canvas->current_item       = item; /* So that events go to the grabbed item */
-
-	return retval;
-}
-
-/**
- * ganv_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
-ganv_item_ungrab(GanvItem* item, guint32 etime)
-{
-	g_return_if_fail(GANV_IS_ITEM(item));
-
-	if (item->canvas->grabbed_item != item) {
-		return;
-	}
-
-	item->canvas->grabbed_item = NULL;
-
-	gdk_pointer_ungrab(etime);
-}
-
-void
-ganv_item_i2w_offset(GanvItem* item, double* px, double* py)
-{
-	double x = 0.0;
-	double y = 0.0;
-  	while (item) {
-		x += item->x;
-		y += item->y;
-		item = item->parent;
-	}
-	*px = x;
-	*py = y;
-}
-
-/**
- * ganv_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
-ganv_item_i2w(GanvItem* item, double* x, double* y)
-{
-	/*g_return_if_fail(GANV_IS_ITEM(item));
-	g_return_if_fail(x != NULL);
-	g_return_if_fail(y != NULL);*/
-
-	double off_x;
-	double off_y;
-	ganv_item_i2w_offset(item, &off_x, &off_y);
-
-	*x += off_x;
-	*y += off_y;
-}
-
-void
-ganv_item_i2w_pair(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
-{
-	double off_x;
-	double off_y;
-	ganv_item_i2w_offset(item, &off_x, &off_y);
-
-	*x1 += off_x;
-	*y1 += off_y;
-	*x2 += off_x;
-	*y2 += off_y;
-}
-
-/**
- * ganv_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
-ganv_item_w2i(GanvItem* item, double* x, double* y)
-{
-	double off_x;
-	double off_y;
-	ganv_item_i2w_offset(item, &off_x, &off_y);
-
-	*x -= off_x;
-	*y -= off_y;
-}
-
-/* Returns whether the item is an inferior of or is equal to the parent. */
-static gboolean
-is_descendant(GanvItem* item, GanvItem* parent)
-{
-	for (; item; item = item->parent) {
-		if (item == parent) {
-			return TRUE;
-		}
-	}
-
-	return FALSE;
-}
-
-/**
- * ganv_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
-ganv_item_grab_focus(GanvItem* item)
-{
-	GanvItem* focused_item;
-	GdkEvent  ev;
-
-	g_return_if_fail(GANV_IS_ITEM(item));
-	g_return_if_fail(GTK_WIDGET_CAN_FOCUS(GTK_WIDGET(item->canvas)));
-
-	focused_item = item->canvas->focused_item;
-
-	if (focused_item) {
-		ev.focus_change.type       = GDK_FOCUS_CHANGE;
-		ev.focus_change.window     = GTK_LAYOUT(item->canvas)->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) {
-		ev.focus_change.type       = GDK_FOCUS_CHANGE;
-		ev.focus_change.window     = GTK_LAYOUT(item->canvas)->bin_window;
-		ev.focus_change.send_event = FALSE;
-		ev.focus_change.in         = TRUE;
-
-		emit_event(item->canvas, &ev);
-	}
-}
-
-static void
-ganv_item_default_bounds(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
-{
-	*x1 = *y1 = *x2 = *y2 = 0.0;
-}
-
-/**
- * ganv_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
-ganv_item_get_bounds(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
-{
-	GANV_ITEM_GET_CLASS(item)->bounds(item, x1, y1, x2, y2);
-}
-
-/**
- * ganv_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
-ganv_item_request_update(GanvItem* item)
-{
-	/* Note: At some point, if this short-circuit was enabled, the canvas stopped
-	   updating items entirely when connected modules are removed. */
-	if (item->object.flags & GANV_ITEM_NEED_UPDATE) {
-		return;
-	}
-
-	if (!item->canvas) {
-		/* Item is being / has been destroyed, ignore */
-		return;
-	}
-
-	item->object.flags |= GANV_ITEM_NEED_UPDATE;
-
-	if (item->parent != NULL) {
-		/* Recurse up the tree */
-		ganv_item_request_update(item->parent);
-	} else {
-		/* Have reached the top of the tree, make sure the update call gets scheduled. */
-		ganv_canvas_base_request_update(item->canvas);
-	}
-}
-
 /*** GanvCanvasBase ***/
 
 static void ganv_canvas_base_destroy(GtkObject* object);
@@ -1207,12 +523,25 @@ ganv_canvas_base_size_allocate(GtkWidget* widget, GtkAllocation* allocation)
 	g_signal_emit_by_name(canvas->layout.vadjustment, "changed");
 }
 
+/* Returns whether the item is an inferior of or is equal to the parent. */
+static gboolean
+is_descendant(GanvItem* item, GanvItem* parent)
+{
+	for (; item; item = item->parent) {
+		if (item == parent) {
+			return TRUE;
+		}
+	}
+
+	return FALSE;
+}
+
+
 /* Emits an event for an item in the canvas, be it the current item, grabbed
  * item, or focused item, as appropriate.
  */
-
-static int
-emit_event(GanvCanvasBase* canvas, GdkEvent* event)
+int
+ganv_canvas_base_emit_event(GanvCanvasBase* canvas, GdkEvent* event)
 {
 	GdkEvent* ev;
 	gint      finished;
@@ -1326,8 +655,7 @@ emit_event(GanvCanvasBase* canvas, GdkEvent* event)
 	while (item && !finished) {
 		g_object_ref(G_OBJECT(item));
 
-		g_signal_emit(item, item_signals[ITEM_EVENT], 0,
-		              ev, &finished);
+		ganv_item_emit_event(item, ev, &finished);
 
 		parent = item->parent;
 		g_object_unref(G_OBJECT(item));
@@ -1461,11 +789,11 @@ pick_current_item(GanvCanvasBase* canvas, GdkEvent* event)
 		new_event.crossing.detail    = GDK_NOTIFY_ANCESTOR;
 		new_event.crossing.subwindow = NULL;
 		canvas->in_repick            = TRUE;
-		retval                       = emit_event(canvas, &new_event);
+		retval                       = ganv_canvas_base_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 */
+	/* new_current_item may have been set to NULL during the call to ganv_canvas_base_emit_event() above */
 
 	if ((canvas->new_current_item != canvas->current_item) && button_down) {
 		canvas->left_grabbed_item = TRUE;
@@ -1484,7 +812,7 @@ pick_current_item(GanvCanvasBase* canvas, GdkEvent* 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);
+		retval                       = ganv_canvas_base_emit_event(canvas, &new_event);
 	}
 
 	return retval;
@@ -1543,7 +871,7 @@ ganv_canvas_base_button(GtkWidget* widget, GdkEventButton* event)
 		canvas->state = event->state;
 		pick_current_item(canvas, (GdkEvent*)event);
 		canvas->state ^= mask;
-		retval         = emit_event(canvas, (GdkEvent*)event);
+		retval         = ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 		break;
 
 	case GDK_BUTTON_RELEASE:
@@ -1551,7 +879,7 @@ ganv_canvas_base_button(GtkWidget* widget, GdkEventButton* event)
 		 * after the button has been released
 		 */
 		canvas->state = event->state;
-		retval        = emit_event(canvas, (GdkEvent*)event);
+		retval        = ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 		event->state ^= mask;
 		canvas->state = event->state;
 		pick_current_item(canvas, (GdkEvent*)event);
@@ -1582,7 +910,7 @@ ganv_canvas_base_motion(GtkWidget* widget, GdkEventMotion* event)
 
 	canvas->state = event->state;
 	pick_current_item(canvas, (GdkEvent*)event);
-	return emit_event(canvas, (GdkEvent*)event);
+	return ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 }
 
 static gboolean
@@ -1601,7 +929,7 @@ ganv_canvas_base_scroll(GtkWidget* widget, GdkEventScroll* event)
 
 	canvas->state = event->state;
 	pick_current_item(canvas, (GdkEvent*)event);
-	return emit_event(canvas, (GdkEvent*)event);
+	return ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 }
 
 /* Key event handler for the canvas */
@@ -1615,7 +943,7 @@ ganv_canvas_base_key(GtkWidget* widget, GdkEventKey* event)
 
 	canvas = GANV_CANVAS_BASE(widget);
 
-	if (!emit_event(canvas, (GdkEvent*)event)) {
+	if (!ganv_canvas_base_emit_event(canvas, (GdkEvent*)event)) {
 		GtkWidgetClass* widget_class;
 
 		widget_class = GTK_WIDGET_CLASS(canvas_parent_class);
@@ -1668,7 +996,7 @@ ganv_canvas_base_focus_in(GtkWidget* widget, GdkEventFocus* event)
 	canvas = GANV_CANVAS_BASE(widget);
 
 	if (canvas->focused_item) {
-		return emit_event(canvas, (GdkEvent*)event);
+		return ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 	} else {
 		return FALSE;
 	}
@@ -1685,7 +1013,7 @@ ganv_canvas_base_focus_out(GtkWidget* widget, GdkEventFocus* event)
 	canvas = GANV_CANVAS_BASE(widget);
 
 	if (canvas->focused_item) {
-		return emit_event(canvas, (GdkEvent*)event);
+		return ganv_canvas_base_emit_event(canvas, (GdkEvent*)event);
 	} else {
 		return FALSE;
 	}
@@ -2176,7 +1504,7 @@ ganv_canvas_base_get_item_at(GanvCanvasBase* canvas, double x, double y)
 }
 
 /* Queues an update of the canvas */
-static void
+void
 ganv_canvas_base_request_update(GanvCanvasBase* canvas)
 {
 	GANV_CANVAS_BASE_GET_CLASS(canvas)->request_update(canvas);
@@ -2422,82 +1750,3 @@ ganv_canvas_base_world_to_window(GanvCanvasBase* canvas, double worldx, double w
 		*winy = (canvas->pixels_per_unit) * (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 GanvItemClass */
-static void
-ganv_item_class_init(GanvItemClass* klass)
-{
-	GObjectClass* gobject_class;
-
-	gobject_class = (GObjectClass*)klass;
-
-	item_parent_class = (GtkObjectClass*)g_type_class_peek_parent(klass);
-
-	gobject_class->set_property = ganv_item_set_property;
-	gobject_class->get_property = ganv_item_get_property;
-
-	g_object_class_install_property
-	    (gobject_class, ITEM_PROP_PARENT,
-	    g_param_spec_object("parent", NULL, NULL,
-	                        GANV_TYPE_ITEM,
-	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
-
-	g_object_class_install_property
-	    (gobject_class, ITEM_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
-	    (gobject_class, ITEM_PROP_Y,
-	    g_param_spec_double("y",
-	                        _("Y"),
-	                        _("Y"),
-	                        -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
-	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
-
-	g_object_class_install_property
-	    (gobject_class, ITEM_PROP_MANAGED,
-	    g_param_spec_boolean("managed",
-	                        _("Managed"),
-	                        _("Whether the item is managed by its parent"),
-	                         0,
-	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
-
-	item_signals[ITEM_EVENT]
-	    = g_signal_new("event",
-	                   G_TYPE_FROM_CLASS(klass),
-	                   G_SIGNAL_RUN_LAST,
-	                   G_STRUCT_OFFSET(GanvItemClass, event),
-	                   boolean_handled_accumulator, NULL,
-	                   ganv_marshal_BOOLEAN__BOXED,
-	                   G_TYPE_BOOLEAN, 1,
-	                   GDK_TYPE_EVENT | G_SIGNAL_TYPE_STATIC_SCOPE);
-
-	gobject_class->dispose = ganv_item_dispose;
-
-	klass->realize   = ganv_item_realize;
-	klass->unrealize = ganv_item_unrealize;
-	klass->map       = ganv_item_map;
-	klass->unmap     = ganv_item_unmap;
-	klass->update    = ganv_item_update;
-	klass->point     = ganv_item_point;
-	klass->bounds    = ganv_item_default_bounds;
-}
diff --git a/src/ganv-private.h b/src/ganv-private.h
index 2a4dbe2..d70f00c 100644
--- a/src/ganv-private.h
+++ b/src/ganv-private.h
@@ -206,6 +206,18 @@ ganv_item_i2w_pair(GanvItem* item, double* x1, double* y1, double* x2, double* y
 void
 ganv_item_invoke_update(GanvItem* item, int flags);
 
+void
+ganv_item_emit_event(GanvItem* item, GdkEvent* event, gint* finished);
+
+/* CanvasBase */
+
+void
+ganv_canvas_base_request_update(GanvCanvasBase* canvas);
+
+int
+ganv_canvas_base_emit_event(GanvCanvasBase* canvas, GdkEvent* event);
+
+
 /* Edge */
 
 void
diff --git a/src/item.c b/src/item.c
new file mode 100644
index 0000000..6fcd110
--- /dev/null
+++ b/src/item.c
@@ -0,0 +1,785 @@
+/* This file is part of Ganv.
+ * Copyright 2007-2013 David Robillard <http://drobilla.net>
+ *
+ * Ganv is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or any later version.
+ *
+ * Ganv 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 General Public License for details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with Ganv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Based on GnomeCanvas, by Federico Mena <federico@nuclecu.unam.mx>
+ * and Raph Levien <raph@gimp.org>
+ * Copyright 1997-2000 Free Software Foundation
+ */
+
+#include "ganv/canvas.h"
+#include "ganv/canvas-base.h"
+#include "ganv/node.h"
+
+#include "./boilerplate.h"
+#include "./ganv-marshal.h"
+#include "./ganv-private.h"
+#include "./gettext.h"
+
+#define GCI_UPDATE_MASK (GANV_CANVAS_BASE_UPDATE_REQUESTED \
+                         | GANV_CANVAS_BASE_UPDATE_AFFINE \
+                         | GANV_CANVAS_BASE_UPDATE_VISIBILITY)
+
+enum {
+	ITEM_PROP_0,
+	ITEM_PROP_PARENT,
+	ITEM_PROP_X,
+	ITEM_PROP_Y,
+	ITEM_PROP_MANAGED
+};
+
+enum {
+	ITEM_EVENT,
+	ITEM_LAST_SIGNAL
+};
+
+static guint item_signals[ITEM_LAST_SIGNAL];
+
+G_DEFINE_TYPE(GanvItem, ganv_item, GTK_TYPE_OBJECT)
+
+static GtkObjectClass * item_parent_class;
+
+/* Object initialization function for GanvItem */
+static void
+ganv_item_init(GanvItem* item)
+{
+	item->object.flags |= GANV_ITEM_VISIBLE;
+	item->managed       = FALSE;
+}
+
+/**
+ * ganv_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
+ * ganv_canvas_base_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
+ * ganv_item_construct() to set up the canvas item.
+ *
+ * Return value: (transfer full): The newly-created item.
+ **/
+GanvItem*
+ganv_item_new(GanvItem* parent, GType type, const gchar* first_arg_name, ...)
+{
+	GanvItem* item;
+	va_list   args;
+
+	g_return_val_if_fail(g_type_is_a(type, ganv_item_get_type()), NULL);
+
+	item = GANV_ITEM(g_object_new(type, NULL));
+
+	va_start(args, first_arg_name);
+	ganv_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(GanvItem* item)
+{
+	GanvItemClass* parent_class = GANV_ITEM_GET_CLASS(item->parent);
+	if (!item->managed) {
+		if (parent_class->add) {
+			parent_class->add(item->parent, item);
+		} else {
+			g_warning("item added to non-parent item\n");
+		}
+	}
+	ganv_canvas_base_request_redraw(item->canvas,
+	                                item->x1, item->y1,
+	                                item->x2 + 1, item->y2 + 1);
+	item->canvas->need_repick = TRUE;
+}
+
+static void
+ganv_item_set_property(GObject*      object,
+                       guint         prop_id,
+                       const GValue* value,
+                       GParamSpec*   pspec)
+{
+	g_return_if_fail(object != NULL);
+	g_return_if_fail(GANV_IS_ITEM(object));
+
+	GanvItem* item = GANV_ITEM(object);
+
+	switch (prop_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 = GANV_ITEM(g_value_get_object(value));
+			item->canvas = item->parent->canvas;
+			item_post_create_setup(item);
+		}
+		break;
+	case ITEM_PROP_X:
+		item->x = g_value_get_double(value);
+		ganv_item_request_update(item);
+		break;
+	case ITEM_PROP_Y:
+		item->y = g_value_get_double(value);
+		ganv_item_request_update(item);
+		break;
+	case ITEM_PROP_MANAGED:
+		item->managed = g_value_get_boolean(value);
+		break;
+	default:
+		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+		break;
+	}
+}
+
+static void
+ganv_item_get_property(GObject*    object,
+                       guint       prop_id,
+                       GValue*     value,
+                       GParamSpec* pspec)
+{
+	g_return_if_fail(object != NULL);
+	g_return_if_fail(GANV_IS_ITEM(object));
+
+	GanvItem* item = GANV_ITEM(object);
+
+	switch (prop_id) {
+	case ITEM_PROP_PARENT:
+		g_value_set_object(value, item->parent);
+		break;
+	case ITEM_PROP_X:
+		g_value_set_double(value, item->x);
+		break;
+	case ITEM_PROP_Y:
+		g_value_set_double(value, item->y);
+		break;
+	case ITEM_PROP_MANAGED:
+		g_value_set_boolean(value, item->managed);
+		break;
+	default:
+		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+		break;
+	}
+}
+
+/**
+ * ganv_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
+ganv_item_construct(GanvItem* item, GanvItem* parent,
+                    const gchar* first_arg_name, va_list args)
+{
+	g_return_if_fail(GANV_IS_ITEM(item));
+
+	item->parent = parent;
+	item->canvas = item->parent->canvas;
+	item->layer = 0;
+
+	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(GanvItem* item)
+{
+	if (item->object.flags & GANV_ITEM_VISIBLE) {
+		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
+		                                item->y2 + 1);
+	}
+}
+
+/* Standard object dispose function for canvas items */
+static void
+ganv_item_dispose(GObject* object)
+{
+	GanvItem* item;
+
+	g_return_if_fail(GANV_IS_ITEM(object));
+
+	item = GANV_ITEM(object);
+
+	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_pointer_ungrab(GDK_CURRENT_TIME);
+	}
+
+	if (item->canvas && item == item->canvas->focused_item) {
+		item->canvas->focused_item = NULL;
+	}
+
+	/* Normal destroy stuff */
+
+	if (item->object.flags & GANV_ITEM_MAPPED) {
+		(*GANV_ITEM_GET_CLASS(item)->unmap)(item);
+	}
+
+	if (item->object.flags & GANV_ITEM_REALIZED) {
+		(*GANV_ITEM_GET_CLASS(item)->unrealize)(item);
+	}
+
+	if (!item->managed && item->parent) {
+		if (GANV_ITEM_GET_CLASS(item->parent)->remove) {
+			GANV_ITEM_GET_CLASS(item->parent)->remove(item->parent, item);
+		} else {
+			fprintf(stderr, "warning: Item parent has no remove method\n");
+		}
+	}
+
+	G_OBJECT_CLASS(item_parent_class)->dispose(object);
+	/* items should remove any reference to item->canvas after the
+	   first ::destroy */
+	item->canvas = NULL;
+}
+
+/* Realize handler for canvas items */
+static void
+ganv_item_realize(GanvItem* item)
+{
+	GTK_OBJECT_SET_FLAGS(item, GANV_ITEM_REALIZED);
+
+	ganv_item_request_update(item);
+}
+
+/* Unrealize handler for canvas items */
+static void
+ganv_item_unrealize(GanvItem* item)
+{
+	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_REALIZED);
+}
+
+/* Map handler for canvas items */
+static void
+ganv_item_map(GanvItem* item)
+{
+	GTK_OBJECT_SET_FLAGS(item, GANV_ITEM_MAPPED);
+}
+
+/* Unmap handler for canvas items */
+static void
+ganv_item_unmap(GanvItem* item)
+{
+	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_MAPPED);
+}
+
+/* Update handler for canvas items */
+static void
+ganv_item_update(GanvItem* item, int flags)
+{
+	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_NEED_UPDATE);
+	GTK_OBJECT_UNSET_FLAGS(item, GANV_ITEM_NEED_VIS);
+}
+
+/* Point handler for canvas items */
+static double
+ganv_item_point(GanvItem* item,
+                double x, double y,
+                int cx, int cy,
+                GanvItem** actual_item)
+{
+	*actual_item = NULL;
+	return G_MAXDOUBLE;
+}
+
+void
+ganv_item_invoke_update(GanvItem* item, int flags)
+{
+	int child_flags = flags;
+
+	/* apply object flags to child flags */
+
+	child_flags &= ~GANV_CANVAS_BASE_UPDATE_REQUESTED;
+
+	if (item->object.flags & GANV_ITEM_NEED_UPDATE) {
+		child_flags |= GANV_CANVAS_BASE_UPDATE_REQUESTED;
+	}
+
+	if (item->object.flags & GANV_ITEM_NEED_VIS) {
+		child_flags |= GANV_CANVAS_BASE_UPDATE_VISIBILITY;
+	}
+
+	if (child_flags & GCI_UPDATE_MASK) {
+		if (GANV_ITEM_GET_CLASS(item)->update) {
+			GANV_ITEM_GET_CLASS(item)->update(item, child_flags);
+		}
+	}
+}
+
+/**
+ * ganv_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
+ganv_item_set(GanvItem* item, const gchar* first_arg_name, ...)
+{
+	va_list args;
+
+	va_start(args, first_arg_name);
+	ganv_item_set_valist(item, first_arg_name, args);
+	va_end(args);
+}
+
+/**
+ * ganv_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
+ganv_item_set_valist(GanvItem* item, const gchar* first_arg_name, va_list args)
+{
+	g_return_if_fail(GANV_IS_ITEM(item));
+
+	g_object_set_valist(G_OBJECT(item), first_arg_name, args);
+
+	item->canvas->need_repick = TRUE;
+}
+
+void
+ganv_item_raise(GanvItem* item)
+{
+	++item->layer;
+}
+
+void
+ganv_item_lower(GanvItem* item)
+{
+	--item->layer;
+}
+
+/**
+ * ganv_item_move:
+ * @item: A canvas item.
+ * @dx: Horizontal offset.
+ * @dy: Vertical offset.
+ **/
+void
+ganv_item_move(GanvItem* item, double dx, double dy)
+{
+	if (!item || !GANV_IS_ITEM(item)) {
+		return;
+	}
+
+	item->x += dx;
+	item->y += dy;
+
+	ganv_item_request_update(item);
+	item->canvas->need_repick = TRUE;
+}
+
+/**
+ * ganv_item_show:
+ * @item: A canvas item.
+ *
+ * Shows a canvas item.  If the item was already shown, then no action is taken.
+ **/
+void
+ganv_item_show(GanvItem* item)
+{
+	g_return_if_fail(GANV_IS_ITEM(item));
+
+	if (!(item->object.flags & GANV_ITEM_VISIBLE)) {
+		item->object.flags |= GANV_ITEM_VISIBLE;
+		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
+		                                item->y2 + 1);
+		item->canvas->need_repick = TRUE;
+	}
+}
+
+/**
+ * ganv_item_hide:
+ * @item: A canvas item.
+ *
+ * Hides a canvas item.  If the item was already hidden, then no action is
+ * taken.
+ **/
+void
+ganv_item_hide(GanvItem* item)
+{
+	g_return_if_fail(GANV_IS_ITEM(item));
+
+	if (item->object.flags & GANV_ITEM_VISIBLE) {
+		item->object.flags &= ~GANV_ITEM_VISIBLE;
+		ganv_canvas_base_request_redraw(item->canvas, item->x1, item->y1, item->x2 + 1,
+		                                item->y2 + 1);
+		item->canvas->need_repick = TRUE;
+	}
+}
+
+/**
+ * ganv_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.
+ * @etime: The timestamp required for grabbing the mouse, or GDK_CURRENT_TIME.
+ *
+ * Specifies that all events that match the specified event mask should be sent
+ * to the specified item, and also grabs the mouse by calling
+ * gdk_pointer_grab().  The event mask is also used when grabbing the pointer.
+ * 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 mouse.
+ *
+ * Return value: If an item was already grabbed, it returns %GDK_GRAB_ALREADY_GRABBED.  If
+ * the specified item was hidden by calling ganv_item_hide(), then it
+ * returns %GDK_GRAB_NOT_VIEWABLE.  Else, it returns the result of calling
+ * gdk_pointer_grab().
+ **/
+int
+ganv_item_grab(GanvItem* item, guint event_mask, GdkCursor* cursor, guint32 etime)
+{
+	int retval;
+
+	g_return_val_if_fail(GANV_IS_ITEM(item), GDK_GRAB_NOT_VIEWABLE);
+	g_return_val_if_fail(GTK_WIDGET_MAPPED(item->canvas), GDK_GRAB_NOT_VIEWABLE);
+
+	if (item->canvas->grabbed_item) {
+		return GDK_GRAB_ALREADY_GRABBED;
+	}
+
+	if (!(item->object.flags & GANV_ITEM_VISIBLE)) {
+		return GDK_GRAB_NOT_VIEWABLE;
+	}
+
+	retval = gdk_pointer_grab(item->canvas->layout.bin_window,
+	                          FALSE,
+	                          event_mask,
+	                          NULL,
+	                          cursor,
+	                          etime);
+
+	if (retval != GDK_GRAB_SUCCESS) {
+		return retval;
+	}
+
+	item->canvas->grabbed_item       = item;
+	item->canvas->grabbed_event_mask = event_mask;
+	item->canvas->current_item       = item; /* So that events go to the grabbed item */
+
+	return retval;
+}
+
+/**
+ * ganv_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
+ganv_item_ungrab(GanvItem* item, guint32 etime)
+{
+	g_return_if_fail(GANV_IS_ITEM(item));
+
+	if (item->canvas->grabbed_item != item) {
+		return;
+	}
+
+	item->canvas->grabbed_item = NULL;
+
+	gdk_pointer_ungrab(etime);
+}
+
+void
+ganv_item_i2w_offset(GanvItem* item, double* px, double* py)
+{
+	double x = 0.0;
+	double y = 0.0;
+  	while (item) {
+		x += item->x;
+		y += item->y;
+		item = item->parent;
+	}
+	*px = x;
+	*py = y;
+}
+
+/**
+ * ganv_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
+ganv_item_i2w(GanvItem* item, double* x, double* y)
+{
+	/*g_return_if_fail(GANV_IS_ITEM(item));
+	g_return_if_fail(x != NULL);
+	g_return_if_fail(y != NULL);*/
+
+	double off_x;
+	double off_y;
+	ganv_item_i2w_offset(item, &off_x, &off_y);
+
+	*x += off_x;
+	*y += off_y;
+}
+
+void
+ganv_item_i2w_pair(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
+{
+	double off_x;
+	double off_y;
+	ganv_item_i2w_offset(item, &off_x, &off_y);
+
+	*x1 += off_x;
+	*y1 += off_y;
+	*x2 += off_x;
+	*y2 += off_y;
+}
+
+/**
+ * ganv_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
+ganv_item_w2i(GanvItem* item, double* x, double* y)
+{
+	double off_x;
+	double off_y;
+	ganv_item_i2w_offset(item, &off_x, &off_y);
+
+	*x -= off_x;
+	*y -= off_y;
+}
+
+/**
+ * ganv_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
+ganv_item_grab_focus(GanvItem* item)
+{
+	GanvItem* focused_item;
+	GdkEvent  ev;
+
+	g_return_if_fail(GANV_IS_ITEM(item));
+	g_return_if_fail(GTK_WIDGET_CAN_FOCUS(GTK_WIDGET(item->canvas)));
+
+	focused_item = item->canvas->focused_item;
+
+	if (focused_item) {
+		ev.focus_change.type       = GDK_FOCUS_CHANGE;
+		ev.focus_change.window     = GTK_LAYOUT(item->canvas)->bin_window;
+		ev.focus_change.send_event = FALSE;
+		ev.focus_change.in         = FALSE;
+
+		ganv_canvas_base_emit_event(item->canvas, &ev);
+	}
+
+	item->canvas->focused_item = item;
+	gtk_widget_grab_focus(GTK_WIDGET(item->canvas));
+
+	if (focused_item) {
+		ev.focus_change.type       = GDK_FOCUS_CHANGE;
+		ev.focus_change.window     = GTK_LAYOUT(item->canvas)->bin_window;
+		ev.focus_change.send_event = FALSE;
+		ev.focus_change.in         = TRUE;
+
+		ganv_canvas_base_emit_event(item->canvas, &ev);
+	}
+}
+
+void
+ganv_item_emit_event(GanvItem* item, GdkEvent* event, gint* finished)
+{
+	g_signal_emit(item, item_signals[ITEM_EVENT], 0, event, finished);
+}
+
+static void
+ganv_item_default_bounds(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
+{
+	*x1 = *y1 = *x2 = *y2 = 0.0;
+}
+
+/**
+ * ganv_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
+ganv_item_get_bounds(GanvItem* item, double* x1, double* y1, double* x2, double* y2)
+{
+	GANV_ITEM_GET_CLASS(item)->bounds(item, x1, y1, x2, y2);
+}
+
+/**
+ * ganv_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
+ganv_item_request_update(GanvItem* item)
+{
+	/* Note: At some point, if this short-circuit was enabled, the canvas stopped
+	   updating items entirely when connected modules are removed. */
+	if (item->object.flags & GANV_ITEM_NEED_UPDATE) {
+		return;
+	}
+
+	if (!item->canvas) {
+		/* Item is being / has been destroyed, ignore */
+		return;
+	}
+
+	item->object.flags |= GANV_ITEM_NEED_UPDATE;
+
+	if (item->parent != NULL) {
+		/* Recurse up the tree */
+		ganv_item_request_update(item->parent);
+	} else {
+		/* Have reached the top of the tree, make sure the update call gets scheduled. */
+		ganv_canvas_base_request_update(item->canvas);
+	}
+}
+
+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 GanvItemClass */
+static void
+ganv_item_class_init(GanvItemClass* klass)
+{
+	GObjectClass* gobject_class;
+
+	gobject_class = (GObjectClass*)klass;
+
+	item_parent_class = (GtkObjectClass*)g_type_class_peek_parent(klass);
+
+	gobject_class->set_property = ganv_item_set_property;
+	gobject_class->get_property = ganv_item_get_property;
+
+	g_object_class_install_property
+	    (gobject_class, ITEM_PROP_PARENT,
+	    g_param_spec_object("parent", NULL, NULL,
+	                        GANV_TYPE_ITEM,
+	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
+
+	g_object_class_install_property
+	    (gobject_class, ITEM_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
+	    (gobject_class, ITEM_PROP_Y,
+	    g_param_spec_double("y",
+	                        _("Y"),
+	                        _("Y"),
+	                        -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
+	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
+
+	g_object_class_install_property
+	    (gobject_class, ITEM_PROP_MANAGED,
+	    g_param_spec_boolean("managed",
+	                        _("Managed"),
+	                        _("Whether the item is managed by its parent"),
+	                         0,
+	                        (G_PARAM_READABLE | G_PARAM_WRITABLE)));
+
+	item_signals[ITEM_EVENT]
+	    = g_signal_new("event",
+	                   G_TYPE_FROM_CLASS(klass),
+	                   G_SIGNAL_RUN_LAST,
+	                   G_STRUCT_OFFSET(GanvItemClass, event),
+	                   boolean_handled_accumulator, NULL,
+	                   ganv_marshal_BOOLEAN__BOXED,
+	                   G_TYPE_BOOLEAN, 1,
+	                   GDK_TYPE_EVENT | G_SIGNAL_TYPE_STATIC_SCOPE);
+
+	gobject_class->dispose = ganv_item_dispose;
+
+	klass->realize   = ganv_item_realize;
+	klass->unrealize = ganv_item_unrealize;
+	klass->map       = ganv_item_map;
+	klass->unmap     = ganv_item_unmap;
+	klass->update    = ganv_item_update;
+	klass->point     = ganv_item_point;
+	klass->bounds    = ganv_item_default_bounds;
+}