nautilus/libnautilus-private/nautilus-icon-dnd.c

/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */

/* nautilus-icon-dnd.c - Drag & drop handling for the icon container widget.

   Copyright (C) 1999, 2000 Free Software Foundation
   Copyright (C) 2000 Eazel, Inc.
   
   The Gnome Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The Gnome Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the Gnome Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.

   Authors: Ettore Perazzoli <ettore@gnu.org>,
            Darin Adler <darin@bentspoon.com>,
	    Andy Hertzfeld <andy@eazel.com>
	    Pavel Cisler <pavel@eazel.com>
*/


#include <config.h>
#include "nautilus-icon-dnd.h"

#include "nautilus-file-dnd.h"
#include "nautilus-icon-private.h"
#include "nautilus-link.h"
#include <eel/eel-background.h>
#include <eel/eel-gdk-pixbuf-extensions.h>
#include <eel/eel-glib-extensions.h>
#include <eel/eel-gnome-extensions.h>
#include <eel/eel-graphic-effects.h>
#include <eel/eel-gtk-extensions.h>
#include <eel/eel-gtk-macros.h>
#include <eel/eel-stock-dialogs.h>
#include <eel/eel-string.h>
#include <eel/eel-vfs-extensions.h>
#include <gdk/gdkkeysyms.h>
#include <gdk/gdkx.h>
#include <gtk/gtkmain.h>
#include <gtk/gtksignal.h>
#include <gtk/gtkstock.h>
#include <libgnome/gnome-i18n.h>
#include <libgnomecanvas/gnome-canvas-rect-ellipse.h>
#include <libgnomeui/gnome-stock-icons.h>
#include <libgnomeui/gnome-uidefs.h>
#include <libgnomevfs/gnome-vfs-uri.h>
#include <libgnomevfs/gnome-vfs-utils.h>
#include <math.h>
#include <stdio.h>
#include <string.h>

static gboolean drag_drop_callback                   (GtkWidget             *widget,
						      GdkDragContext        *context,
						      int                    x,
						      int                    y,
						      guint32                time,
						      gpointer               data);
static void     nautilus_icon_dnd_update_drop_target (NautilusIconContainer *container,
						      GdkDragContext        *context,
						      int                    x,
						      int                    y);
static gboolean drag_motion_callback                 (GtkWidget             *widget,
						      GdkDragContext        *context,
						      int                    x,
						      int                    y,
						      guint32                time);

static void     nautilus_icon_container_receive_dropped_icons    (NautilusIconContainer *container,
								  GdkDragContext *context,
								  int x, int y);
static void     receive_dropped_tile_image                       (NautilusIconContainer *container, 
								  GtkSelectionData *data);
static void     receive_dropped_keyword                          (NautilusIconContainer *container, 
								  char* keyword, 
								  int x, 
								  int y);
static void     receive_dropped_uri_list                         (NautilusIconContainer *container, 
								  char* keyword, 
								  GdkDragAction action,
								  int x, 
								  int y);
static void     nautilus_icon_container_free_drag_data           (NautilusIconContainer *container);
static void     set_drop_target                                  (NautilusIconContainer *container,
								  NautilusIcon *icon);
								  
static GtkTargetEntry drag_types [] = {
	{ EEL_ICON_DND_GNOME_ICON_LIST_TYPE, 0, EEL_ICON_DND_GNOME_ICON_LIST },
	{ EEL_ICON_DND_URI_LIST_TYPE, 0, EEL_ICON_DND_URI_LIST },
	{ EEL_ICON_DND_URL_TYPE, 0, EEL_ICON_DND_URL },
	{ EEL_ICON_DND_TEXT_TYPE, 0, EEL_ICON_DND_TEXT }
};

/* this constant is logically part of the EEL_ICON_DND enumeration; it must be bigger
 * than the last one defined there
 */
#define NAUTILUS_RESET_BACKGROUND_ENUM 10

static GtkTargetEntry drop_types [] = {
	{ EEL_ICON_DND_GNOME_ICON_LIST_TYPE, 0, EEL_ICON_DND_GNOME_ICON_LIST },
	{ EEL_ICON_DND_URI_LIST_TYPE, 0, EEL_ICON_DND_URI_LIST },
	{ EEL_ICON_DND_URL_TYPE, 0, EEL_ICON_DND_URL },
	{ EEL_ICON_DND_COLOR_TYPE, 0, EEL_ICON_DND_COLOR },
	{ EEL_ICON_DND_BGIMAGE_TYPE, 0, EEL_ICON_DND_BGIMAGE },
	{ EEL_ICON_DND_KEYWORD_TYPE, 0, EEL_ICON_DND_KEYWORD },
	{ "x-special/gnome-reset-background",  0, NAUTILUS_RESET_BACKGROUND_ENUM }
};

static GtkTargetList *drop_types_list = NULL;

static GnomeCanvasItem *
create_selection_shadow (NautilusIconContainer *container,
			 GList *list)
{
	GnomeCanvasGroup *group;
	GnomeCanvas *canvas;
	GdkBitmap *stipple;
	int max_x, max_y;
	int min_x, min_y;
	GList *p;

	if (list == NULL) {
		return NULL;
	}

	/* if we're only dragging a single item, don't worry about the shadow */
	if (list->next == NULL) {
		return NULL;
	}
		
	stipple = container->details->dnd_info->drag_info.stipple;
	g_return_val_if_fail (stipple != NULL, NULL);

	canvas = GNOME_CANVAS (container);

	/* Creating a big set of rectangles in the canvas can be expensive, so
           we try to be smart and only create the maximum number of rectangles
           that we will need, in the vertical/horizontal directions.  */

	max_x = GTK_WIDGET (container)->allocation.width;
	min_x = -max_x;

	max_y = GTK_WIDGET (container)->allocation.height;
	min_y = -max_y;

	/* Create a group, so that it's easier to move all the items around at
           once.  */
	group = GNOME_CANVAS_GROUP
		(gnome_canvas_item_new (GNOME_CANVAS_GROUP (canvas->root),
					gnome_canvas_group_get_type (),
					NULL));
	
	for (p = list; p != NULL; p = p->next) {
		EelDragSelectionItem *item;
		int x1, y1, x2, y2;

		item = p->data;

		if (!item->got_icon_position) {
			continue;
		}

		x1 = item->icon_x;
		y1 = item->icon_y;
		x2 = x1 + item->icon_width;
		y2 = y1 + item->icon_height;
			
		if (x2 >= min_x && x1 <= max_x && y2 >= min_y && y1 <= max_y)
			gnome_canvas_item_new
				(group,
				 gnome_canvas_rect_get_type (),
				 "x1", (double) x1,
				 "y1", (double) y1,
				 "x2", (double) x2,
				 "y2", (double) y2,
				 "outline_color", "black",
				 "outline_stipple", stipple,
				 "width_pixels", 1,
				 NULL);
	}

	return GNOME_CANVAS_ITEM (group);
}

/* Set the affine instead of the x and y position.
 * Simple, and setting x and y was broken at one point.
 */
static void
set_shadow_position (GnomeCanvasItem *shadow,
		     double x, double y)
{
	double affine[6];

	affine[0] = 1.0;
	affine[1] = 0.0;
	affine[2] = 0.0;
	affine[3] = 1.0;
	affine[4] = x;
	affine[5] = y;

	gnome_canvas_item_affine_absolute (shadow, affine);
}


/* Source-side handling of the drag. */

/* iteration glue struct */
typedef struct {
	gpointer iterator_context;
	EelDragEachSelectedItemDataGet iteratee;
	gpointer iteratee_data;
} IconGetDataBinderContext;

static gboolean
icon_get_data_binder (NautilusIcon *icon, gpointer data)
{
	IconGetDataBinderContext *context;
	ArtDRect world_rect;
	ArtIRect window_rect;
	char *uri;
	NautilusIconContainer *container;

	context = (IconGetDataBinderContext *)data;

	g_assert (NAUTILUS_IS_ICON_CONTAINER (context->iterator_context));

	container = NAUTILUS_ICON_CONTAINER (context->iterator_context);

	world_rect = nautilus_icon_canvas_item_get_icon_rectangle (icon->item);
	window_rect = eel_gnome_canvas_world_to_window_rectangle
		(GNOME_CANVAS (container), world_rect);

	uri = nautilus_icon_container_get_icon_uri (container, icon);
	if (uri == NULL) {
		g_warning ("no URI for one of the iterated icons");
		return TRUE;
	}

	window_rect = eel_art_irect_offset_by (window_rect, 
		- container->details->dnd_info->drag_info.start_x,
		- container->details->dnd_info->drag_info.start_y);

	window_rect = eel_art_irect_scale_by (window_rect, 
		1 / GNOME_CANVAS (container)->pixels_per_unit);
	
	/* pass the uri, mouse-relative x/y and icon width/height */
	context->iteratee (uri, 
			   (int) window_rect.x0,
			   (int) window_rect.y0,
			   window_rect.x1 - window_rect.x0,
			   window_rect.y1 - window_rect.y0,
			   context->iteratee_data);

	g_free (uri);

	return TRUE;
}

/* Iterate over each selected icon in a NautilusIconContainer,
 * calling each_function on each.
 */
static void
nautilus_icon_container_each_selected_icon (NautilusIconContainer *container,
	gboolean (*each_function) (NautilusIcon *, gpointer), gpointer data)
{
	GList *p;
	NautilusIcon *icon;

	for (p = container->details->icons; p != NULL; p = p->next) {
		icon = p->data;
		if (!icon->is_selected) {
			continue;
		}
		if (!each_function (icon, data)) {
			return;
		}
	}
}

/* Adaptor function used with nautilus_icon_container_each_selected_icon
 * to help iterate over all selected items, passing uris, x, y, w and h
 * values to the iteratee
 */
static void
each_icon_get_data_binder (EelDragEachSelectedItemDataGet iteratee, 
	gpointer iterator_context, gpointer data)
{
	IconGetDataBinderContext context;
	NautilusIconContainer *container;

	g_assert (NAUTILUS_IS_ICON_CONTAINER (iterator_context));
	container = NAUTILUS_ICON_CONTAINER (iterator_context);

	context.iterator_context = iterator_context;
	context.iteratee = iteratee;
	context.iteratee_data = data;
	nautilus_icon_container_each_selected_icon (container, icon_get_data_binder, &context);
}

/* Called when the data for drag&drop is needed */
static void
drag_data_get_callback (GtkWidget *widget,
			GdkDragContext *context,
			GtkSelectionData *selection_data,
			guint info,
			guint32 time,
			gpointer data)
{
	g_assert (widget != NULL);
	g_assert (NAUTILUS_IS_ICON_CONTAINER (widget));
	g_return_if_fail (context != NULL);

	/* Call common function from nautilus-drag that set's up
	 * the selection data in the right format. Pass it means to
	 * iterate all the selected icons.
	 */
	eel_drag_drag_data_get (widget, context, selection_data,
		info, time, widget, each_icon_get_data_binder);
}


/* Target-side handling of the drag.  */

static void
nautilus_icon_container_position_shadow (NautilusIconContainer *container,
					 int x, int y)
{
	GnomeCanvasItem *shadow;
	double world_x, world_y;

	shadow = container->details->dnd_info->shadow;
	if (shadow == NULL) {
		return;
	}
	gnome_canvas_window_to_world (GNOME_CANVAS (container),
				      x, y, &world_x, &world_y);

	set_shadow_position (shadow, world_x, world_y);
	gnome_canvas_item_show (shadow);
}

static void
nautilus_icon_container_dropped_icon_feedback (GtkWidget *widget,
					       GtkSelectionData *data,
					       int x, int y)
{
	NautilusIconContainer *container;
	NautilusIconDndInfo *dnd_info;

	container = NAUTILUS_ICON_CONTAINER (widget);
	dnd_info = container->details->dnd_info;
	
	/* Delete old selection list. */
	eel_drag_destroy_selection_list (dnd_info->drag_info.selection_list);
	dnd_info->drag_info.selection_list = NULL;

	/* Delete old shadow if any. */
	if (dnd_info->shadow != NULL) {
		/* FIXME bugzilla.gnome.org 42484: 
		 * Is a destroy really sufficient here? Who does the unref? */
		gtk_object_destroy (GTK_OBJECT (dnd_info->shadow));
	}

	/* Build the selection list and the shadow. */
	dnd_info->drag_info.selection_list = eel_drag_build_selection_list (data);
	dnd_info->shadow = create_selection_shadow (container, dnd_info->drag_info.selection_list);
	nautilus_icon_container_position_shadow (container, x, y);
}

/** this callback is called in 2 cases.
    It is called upon drag_motion events to get the actual data 
    In that case, it just makes sure it gets the data.
    It is called upon drop_drop events to execute the actual 
    actions on the received action. In that case, it actually first makes sure
    that we have got the data then processes it.
*/

static void
drag_data_received_callback (GtkWidget *widget,
			     GdkDragContext *context,
			     int x,
			     int y,
			     GtkSelectionData *data,
			     guint info,
			     guint32 time,
			     gpointer user_data)
{
    	EelDragInfo *drag_info;
	EelBackground *background;
	
	drag_info = &(NAUTILUS_ICON_CONTAINER (widget)->details->dnd_info->drag_info);

	drag_info->got_drop_data_type = TRUE;
	drag_info->data_type = info;

	switch (info) {
	case EEL_ICON_DND_GNOME_ICON_LIST:
		nautilus_icon_container_dropped_icon_feedback (widget, data, x, y);
		break;
	case EEL_ICON_DND_COLOR:
	case EEL_ICON_DND_BGIMAGE:	
	case EEL_ICON_DND_KEYWORD:
	case EEL_ICON_DND_URI_LIST:
	case NAUTILUS_RESET_BACKGROUND_ENUM:
		/* Save the data so we can do the actual work on drop. */
		g_assert (drag_info->selection_data == NULL);
		drag_info->selection_data = eel_gtk_selection_data_copy_deep (data);
		break;

	/* Netscape keeps sending us the data, even though we accept the first drag */
	case EEL_ICON_DND_URL:
		if (drag_info->selection_data != NULL) {
			eel_gtk_selection_data_free_deep (drag_info->selection_data);
			drag_info->selection_data = eel_gtk_selection_data_copy_deep (data);
		}
		break;

	default:
		g_message ("drag_data_received_callback unknown");
		break;
	}


	/* this is the second use case of this callback.
	 * we have to do the actual work for the drop.
	 */
	if (drag_info->drop_occured) {

		switch (info) {
		case EEL_ICON_DND_GNOME_ICON_LIST:
			nautilus_icon_container_receive_dropped_icons
				(NAUTILUS_ICON_CONTAINER (widget),
				 context, x, y);
			gtk_drag_finish (context, TRUE, FALSE, time);
			break;
		case EEL_ICON_DND_COLOR:
			eel_background_receive_dropped_color
				(eel_get_widget_background (widget),
				 widget, x, y, data);
			gtk_drag_finish (context, TRUE, FALSE, time);
			break;
		case EEL_ICON_DND_BGIMAGE:
			receive_dropped_tile_image
				(NAUTILUS_ICON_CONTAINER (widget),
				 data);
			gtk_drag_finish (context, FALSE, FALSE, time);
			break;
		case EEL_ICON_DND_KEYWORD:
			receive_dropped_keyword
				(NAUTILUS_ICON_CONTAINER (widget),
				 (char*) data->data, x, y);
			gtk_drag_finish (context, FALSE, FALSE, time);
			break;
		case EEL_ICON_DND_URI_LIST:
		case EEL_ICON_DND_URL:
			receive_dropped_uri_list
				(NAUTILUS_ICON_CONTAINER (widget),
				 (char*) data->data, context->action, x, y);
			gtk_drag_finish (context, TRUE, FALSE, time);
			break;

		case NAUTILUS_RESET_BACKGROUND_ENUM:
			background = eel_get_widget_background (widget);
			if (background != NULL) {
				eel_background_reset (background);
			}
			gtk_drag_finish (context, FALSE, FALSE, time);			
			break;	

		default:
			gtk_drag_finish (context, FALSE, FALSE, time);
		}
		
		nautilus_icon_container_free_drag_data (NAUTILUS_ICON_CONTAINER (widget));
		
		set_drop_target (NAUTILUS_ICON_CONTAINER (widget), NULL);

		/* reinitialise it for the next dnd */
		drag_info->drop_occured = FALSE;
	}

}

/* FIXME bugzilla.gnome.org 47445: Needs to become a shared function */
static void
get_data_on_first_target_we_support (GtkWidget *widget, GdkDragContext *context, guint32 time)
{
	GList *target;

	if (drop_types_list == NULL)
		drop_types_list = gtk_target_list_new (drop_types,
						       G_N_ELEMENTS (drop_types));

	for (target = context->targets; target != NULL; target = target->next) {
		guint dummy_info;
		GdkAtom target_atom = GDK_POINTER_TO_ATOM (target->data);

		if (gtk_target_list_find (drop_types_list, 
					  target_atom,
					  &dummy_info)) {
			gtk_drag_get_data (GTK_WIDGET (widget), context,
					   target_atom,
					   time);
			break;
		}
	}
}

static void
nautilus_icon_container_ensure_drag_data (NautilusIconContainer *container,
					  GdkDragContext *context,
					  guint32 time)
{
	NautilusIconDndInfo *dnd_info;

	dnd_info = container->details->dnd_info;

	if (!dnd_info->drag_info.got_drop_data_type) {
		get_data_on_first_target_we_support (GTK_WIDGET (container), context, time);
	}
}

static void
drag_end_callback (GtkWidget *widget,
		   GdkDragContext *context,
		   gpointer data)
{
	NautilusIconContainer *container;
	NautilusIconDndInfo *dnd_info;

	container = NAUTILUS_ICON_CONTAINER (widget);
	dnd_info = container->details->dnd_info;

	eel_drag_destroy_selection_list (dnd_info->drag_info.selection_list);
	dnd_info->drag_info.selection_list = NULL;
}

static NautilusIcon *
nautilus_icon_container_item_at (NautilusIconContainer *container,
				 int x, int y)
{
	GList *p;
	int size;
	ArtDRect point;
	ArtIRect canvas_point;

	/* build the hit-test rectangle. Base the size on the scale factor to ensure that it is
	 * non-empty even at the smallest scale factor
	 */
	
	size = MAX (1, 1 + (1 / GNOME_CANVAS (container)->pixels_per_unit));
	point.x0 = x;
	point.y0 = y;
	point.x1 = x + size;
	point.y1 = y + size;

	for (p = container->details->icons; p != NULL; p = p->next) {
		NautilusIcon *icon;
		icon = p->data;
		
		canvas_point = eel_gnome_canvas_world_to_canvas_rectangle (GNOME_CANVAS_ITEM (icon->item)->canvas,
									   point);
		if (nautilus_icon_canvas_item_hit_test_rectangle (icon->item, canvas_point)) {
			return icon;
		}
	}
	
	return NULL;
}

static char *
get_container_uri (NautilusIconContainer *container)
{
	char *uri;

	/* get the URI associated with the container */
	uri = NULL;
	g_signal_emit_by_name (container, "get_container_uri", &uri);
	return uri;
}

static gboolean
nautilus_icon_container_selection_items_local (NautilusIconContainer *container,
					       GList *items)
{
	char *container_uri_string;
	gboolean result;

	/* must have at least one item */
	g_assert (items);

	result = FALSE;

	/* get the URI associated with the container */
	container_uri_string = get_container_uri (container);
	
	if (eel_uri_is_trash (container_uri_string)) {
		/* Special-case "trash:" because the eel_drag_items_local
		 * would not work for it.
		 */
		result = eel_drag_items_in_trash (items);
	} else {
		result = eel_drag_items_local (container_uri_string, items);
	}
	g_free (container_uri_string);
	
	return result;
}

/* handle dropped tile images */
static void
receive_dropped_tile_image (NautilusIconContainer *container, GtkSelectionData *data)
{
	g_assert (data != NULL);
	eel_background_receive_dropped_background_image
		(eel_get_widget_background (GTK_WIDGET (container)), data->data);
}

/* handle dropped keywords */
static void
receive_dropped_keyword (NautilusIconContainer *container, char* keyword, int x, int y)
{
	char *uri;
	double world_x, world_y;

	NautilusIcon *drop_target_icon;
	NautilusFile *file;
	
	g_assert (keyword != NULL);

	/* find the item we hit with our drop, if any */
  	gnome_canvas_window_to_world (GNOME_CANVAS (container), x, y, &world_x, &world_y);
	drop_target_icon = nautilus_icon_container_item_at (container, world_x, world_y);
	if (drop_target_icon == NULL) {
		return;
	}

	/* FIXME bugzilla.gnome.org 42485: 
	 * This does not belong in the icon code.
	 * It has to be in the file manager.
	 * The icon code has no right to deal with the file directly.
	 * But luckily there's no issue of not getting a file object,
	 * so we don't have to worry about async. issues here.
	 */
	uri = nautilus_icon_container_get_icon_uri (container, drop_target_icon);
	file = nautilus_file_get (uri);
	g_free (uri);
	
	nautilus_drag_file_receive_dropped_keyword (file, keyword);

	nautilus_file_unref (file);
	nautilus_icon_container_update_icon (container, drop_target_icon);
}

/* handle dropped uri list */
static void
receive_dropped_uri_list (NautilusIconContainer *container, char *uri_list, GdkDragAction action, int x, int y)
{	
	if (uri_list == NULL) {
		return;
	}
	
	g_signal_emit_by_name (container, "handle_uri_list",
				 uri_list,
				 action,
				 x, y);
}

static int
auto_scroll_timeout_callback (gpointer data)
{
	NautilusIconContainer *container;
	GtkWidget *widget;
	float x_scroll_delta, y_scroll_delta;
	GdkRectangle exposed_area;

	g_assert (NAUTILUS_IS_ICON_CONTAINER (data));
	widget = GTK_WIDGET (data);
	container = NAUTILUS_ICON_CONTAINER (widget);

	if (container->details->dnd_info->drag_info.waiting_to_autoscroll
	    && container->details->dnd_info->drag_info.start_auto_scroll_in > eel_get_system_time()) {
		/* not yet */
		return TRUE;
	}

	container->details->dnd_info->drag_info.waiting_to_autoscroll = FALSE;

	eel_drag_autoscroll_calculate_delta (widget, &x_scroll_delta, &y_scroll_delta);
	if (x_scroll_delta == 0 && y_scroll_delta == 0) {
		/* no work */
		return TRUE;
	}

	if (!nautilus_icon_container_scroll (container, (int)x_scroll_delta, (int)y_scroll_delta)) {
		/* the scroll value got pinned to a min or max adjustment value,
		 * we ended up not scrolling
		 */
		return TRUE;
	}

	/* update cached drag start offsets */
	container->details->dnd_info->drag_info.start_x -= x_scroll_delta;
	container->details->dnd_info->drag_info.start_y -= y_scroll_delta;

	/* Due to a glitch in GtkLayout, whe need to do an explicit draw of the exposed
	 * area. 
	 * Calculate the size of the area we need to draw
	 */
	exposed_area.x = widget->allocation.x;
	exposed_area.y = widget->allocation.y;
	exposed_area.width = widget->allocation.width;
	exposed_area.height = widget->allocation.height;

	if (x_scroll_delta > 0) {
		exposed_area.x = exposed_area.width - x_scroll_delta;
	} else if (x_scroll_delta < 0) {
		exposed_area.width = -x_scroll_delta;
	}

	if (y_scroll_delta > 0) {
		exposed_area.y = exposed_area.height - y_scroll_delta;
	} else if (y_scroll_delta < 0) {
		exposed_area.height = -y_scroll_delta;
	}

	/* offset it to 0, 0 */
	exposed_area.x -= widget->allocation.x;
	exposed_area.y -= widget->allocation.y;

	gtk_widget_draw (widget, &exposed_area);

	return TRUE;
}

static void
set_up_auto_scroll_if_needed (NautilusIconContainer *container)
{
	eel_drag_autoscroll_start (&container->details->dnd_info->drag_info,
					GTK_WIDGET (container),
					auto_scroll_timeout_callback,
					container);
}

static void
stop_auto_scroll (NautilusIconContainer *container)
{
	eel_drag_autoscroll_stop (&container->details->dnd_info->drag_info);
}

static gboolean
confirm_switch_to_manual_layout (NautilusIconContainer *container)
{
	const char *message;
	GtkDialog *dialog;
	int response;

	/* FIXME bugzilla.gnome.org 40915: Use of the word "directory"
	 * makes this FMIconView specific. Move these messages into
	 * FMIconView so NautilusIconContainer can be used for things
	 * that are not directories?
	 */
	if (nautilus_icon_container_has_stored_icon_positions (container)) {
		if (eel_g_list_exactly_one_item (container->details->dnd_info->drag_info.selection_list)) {
			message = _("This folder uses automatic layout. "
			"Do you want to switch to manual layout and leave this item where you dropped it? "
			"This will clobber the stored manual layout.");
		} else {
			message = _("This folder uses automatic layout. "
			"Do you want to switch to manual layout and leave these items where you dropped them? "
			"This will clobber the stored manual layout.");
		}
	} else {
		if (eel_g_list_exactly_one_item (container->details->dnd_info->drag_info.selection_list)) {
			message = _("This folder uses automatic layout. "
			"Do you want to switch to manual layout and leave this item where you dropped it?");
		} else {
			message = _("This folder uses automatic layout. "
			"Do you want to switch to manual layout and leave these items where you dropped them?");
		}
	}

	dialog = eel_show_yes_no_dialog (message, _("Switch to Manual Layout?"),
					 _("Switch"), GTK_STOCK_CANCEL,
					 GTK_WINDOW (gtk_widget_get_ancestor 
						     (GTK_WIDGET (container), GTK_TYPE_WINDOW)));
	
	response = gtk_dialog_run (dialog);
	gtk_object_destroy (GTK_OBJECT (dialog));

	return response == GTK_RESPONSE_OK;
}

static void
handle_local_move (NautilusIconContainer *container,
		   double world_x, double world_y)
{
	GList *moved_icons, *p;
	EelDragSelectionItem *item;
	NautilusIcon *icon;

	if (container->details->auto_layout) {
		if (!confirm_switch_to_manual_layout (container)) {
			return;
		}
		nautilus_icon_container_freeze_icon_positions (container);
	}

	/* Move and select the icons. */
	moved_icons = NULL;
	for (p = container->details->dnd_info->drag_info.selection_list; p != NULL; p = p->next) {
		item = p->data;
		
		icon = nautilus_icon_container_get_icon_by_uri
			(container, item->uri);

		if (item->got_icon_position) {
			nautilus_icon_container_move_icon
				(container, icon,
				 world_x + item->icon_x, world_y + item->icon_y,
				 icon->scale_x, icon->scale_y,
				 TRUE, TRUE);
		}
		moved_icons = g_list_prepend (moved_icons, icon);
	}		
	nautilus_icon_container_select_list_unselect_others
		(container, moved_icons);
	/* Might have been moved in a way that requires adjusting scroll region. */
	nautilus_icon_container_update_scroll_region (container);
	g_list_free (moved_icons);
}

static void
handle_nonlocal_move (NautilusIconContainer *container,
		      GdkDragContext *context,
		      int x, int y,
		      const char *target_uri,
		      gboolean icon_hit)
{
	GList *source_uris, *p;
	GArray *source_item_locations;
	int index;

	if (container->details->dnd_info->drag_info.selection_list == NULL) {
		return;
	}
	
	source_uris = NULL;
	for (p = container->details->dnd_info->drag_info.selection_list; p != NULL; p = p->next) {
		/* do a shallow copy of all the uri strings of the copied files */
		source_uris = g_list_prepend (source_uris, ((EelDragSelectionItem *)p->data)->uri);
	}
	source_uris = g_list_reverse (source_uris);
	
	source_item_locations = g_array_new (FALSE, TRUE, sizeof (GdkPoint));
	if (!icon_hit) {
		/* Drop onto a container. Pass along the item points to allow placing
		 * the items in their same relative positions in the new container.
		 */
		source_item_locations = g_array_set_size (source_item_locations,
			g_list_length (container->details->dnd_info->drag_info.selection_list));
			
		for (index = 0, p = container->details->dnd_info->drag_info.selection_list;
			p != NULL; index++, p = p->next) {
		     	g_array_index (source_item_locations, GdkPoint, index).x =
		     		((EelDragSelectionItem *)p->data)->icon_x;
		     	g_array_index (source_item_locations, GdkPoint, index).y =
				((EelDragSelectionItem *)p->data)->icon_y;
		}
	}
		
	/* start the copy */
	g_signal_emit_by_name (container, "move_copy_items",
				 source_uris,
				 source_item_locations,
				 target_uri,
				 context->action,
				 x, y);

	g_list_free (source_uris);
	g_array_free (source_item_locations, TRUE);
}

static char *
nautilus_icon_container_find_drop_target (NautilusIconContainer *container,
					  GdkDragContext *context,
					  int x, int y,
					  gboolean *icon_hit)
{
	NautilusIcon *drop_target_icon;
	double world_x, world_y;
	NautilusFile *file;
	char *icon_uri;

	*icon_hit = FALSE;
	if (container->details->dnd_info->drag_info.selection_list == NULL) {
		return NULL;
	}

  	gnome_canvas_window_to_world (GNOME_CANVAS (container),
				      x, y, &world_x, &world_y);
	
	/* FIXME bugzilla.gnome.org 42485: 
	 * These "can_accept_items" tests need to be done by
	 * the icon view, not here. This file is not supposed to know
	 * that the target is a file.
	 */

	/* Find the item we hit with our drop, if any */	
	drop_target_icon = nautilus_icon_container_item_at (container, world_x, world_y);
	if (drop_target_icon != NULL) {
		icon_uri = nautilus_icon_container_get_icon_uri (container, drop_target_icon);
		if (icon_uri != NULL) {
			file = nautilus_file_get (icon_uri);

			if (!nautilus_drag_can_accept_items (file, 
					container->details->dnd_info->drag_info.selection_list)) {
			 	/* the item we dropped our selection on cannot accept the items,
			 	 * do the same thing as if we just dropped the items on the canvas
				 */
				drop_target_icon = NULL;
			}
			
			g_free (icon_uri);
			nautilus_file_unref (file);
		}
	}

	if (drop_target_icon == NULL) {
		*icon_hit = FALSE;
		return get_container_uri (container);
	}
	
	*icon_hit = TRUE;
	return nautilus_icon_container_get_icon_drop_target_uri (container, drop_target_icon);
}

/* FIXME bugzilla.gnome.org 42485: This belongs in FMDirectoryView, not here. */
static gboolean
selection_includes_special_link (GList *selection_list)
{
	GList *node;
	char *uri, *local_path;
	gboolean link_in_selection;

	link_in_selection = FALSE;

	for (node = selection_list; node != NULL; node = node->next) {
		uri = ((EelDragSelectionItem *) node->data)->uri;

		/* FIXME bugzilla.gnome.org 43020: This does sync. I/O and works only locally. */
		local_path = gnome_vfs_get_local_path_from_uri (uri);
		link_in_selection = local_path != NULL
			&& (nautilus_link_local_is_trash_link (local_path) || nautilus_link_local_is_home_link (local_path) ||
			nautilus_link_local_is_volume_link (local_path));
		g_free (local_path);
		
		if (link_in_selection) {
			break;
		}
	}
	
	return link_in_selection;
}

static void
nautilus_icon_container_receive_dropped_icons (NautilusIconContainer *container,
					       GdkDragContext *context,
					       int x, int y)
{
	char *drop_target;
	gboolean local_move_only;
	double world_x, world_y;
	gboolean icon_hit;
	GdkDragAction action;

	drop_target = NULL;

	if (container->details->dnd_info->drag_info.selection_list == NULL) {
		return;
	}

	if (context->action == GDK_ACTION_ASK) {
		/* FIXME bugzilla.gnome.org 42485: This belongs in FMDirectoryView, not here. */
		/* Check for special case items in selection list */
		if (selection_includes_special_link (container->details->dnd_info->drag_info.selection_list)) {
			/* We only want to move the trash */
			action = GDK_ACTION_MOVE;
		} else {
			action = GDK_ACTION_MOVE | GDK_ACTION_COPY | GDK_ACTION_LINK;
		}
		context->action = eel_drag_drop_action_ask (action);
	}

	if (context->action > 0) {
	  	gnome_canvas_window_to_world (GNOME_CANVAS (container),
					      x, y, &world_x, &world_y);

		drop_target = nautilus_icon_container_find_drop_target (container, 
			context, x, y, &icon_hit);

		local_move_only = FALSE;
		if (!icon_hit && context->action == GDK_ACTION_MOVE) {
			/* we can just move the icon positions if the move ended up in
			 * the item's parent container
			 */
			local_move_only = nautilus_icon_container_selection_items_local
				(container, container->details->dnd_info->drag_info.selection_list);
		}

		if (local_move_only) {
			handle_local_move (container, world_x, world_y);
		} else {
			handle_nonlocal_move (container, context, world_x, world_y, drop_target, icon_hit);
		}
	}

	g_free (drop_target);
	eel_drag_destroy_selection_list (container->details->dnd_info->drag_info.selection_list);
	container->details->dnd_info->drag_info.selection_list = NULL;
}

static void
nautilus_icon_container_get_drop_action (NautilusIconContainer *container,
					 GdkDragContext *context,
					 int x, int y,
					 int *default_action,
					 int *non_default_action)
{
	char *drop_target;
	gboolean icon_hit;
	NautilusIcon *icon;
	double world_x, world_y;
	
	icon_hit = FALSE;
	if (!container->details->dnd_info->drag_info.got_drop_data_type) {
		/* drag_data_received_callback didn't get called yet */
		return;
	}

	/* find out if we're over an icon */
  	gnome_canvas_window_to_world (GNOME_CANVAS (container),
				      x, y, &world_x, &world_y);
	
	icon = nautilus_icon_container_item_at (container, world_x, world_y);

	/* case out on the type of object being dragged */
	switch (container->details->dnd_info->drag_info.data_type) {
	case EEL_ICON_DND_GNOME_ICON_LIST:
		if (container->details->dnd_info->drag_info.selection_list == NULL) {
			*default_action = 0;
			*non_default_action = 0;
			return;
		}
		drop_target = nautilus_icon_container_find_drop_target (container,
			context, x, y, &icon_hit);
		if (!drop_target) {
			*default_action = 0;
			*non_default_action = 0;
			return;
		}
		eel_drag_default_drop_action_for_icons (context, drop_target, 
			container->details->dnd_info->drag_info.selection_list, 
			default_action, non_default_action);
		g_free (drop_target);
		break;

	/* handle emblems by setting the action if we're over an object */
	case EEL_ICON_DND_KEYWORD:
		if (icon == NULL) {
			*default_action = 0;
			*non_default_action = 0;
		} else {
			*default_action = context->suggested_action;
			*non_default_action = context->suggested_action;
		}
		
		break;
	
	/* handle colors and backgrounds by setting the action if we're over the background */		
	case EEL_ICON_DND_COLOR:
	case EEL_ICON_DND_BGIMAGE:
	case NAUTILUS_RESET_BACKGROUND_ENUM:
		if (icon == NULL) {
			*default_action = context->suggested_action;
			*non_default_action = context->suggested_action;
		} else {
			*default_action = 0;
			*non_default_action = 0;
		}
	
		break;
	
	case EEL_ICON_DND_URI_LIST:
	case EEL_ICON_DND_URL:
		*default_action = context->suggested_action;
		*non_default_action = context->suggested_action;
		break;
	
	default:
	}

}

static void
set_drop_target (NautilusIconContainer *container,
		 NautilusIcon *icon)
{
	NautilusIcon *old_icon;

	/* Check if current drop target changed, update icon drop
	 * higlight if needed.
	 */
	old_icon = container->details->drop_target;
	if (icon == old_icon) {
		return;
	}

	/* Remember the new drop target for the next round. */
	container->details->drop_target = icon;
	nautilus_icon_container_update_icon (container, old_icon);
	nautilus_icon_container_update_icon (container, icon);
}

static void
nautilus_icon_dnd_update_drop_target (NautilusIconContainer *container,
				      GdkDragContext *context,
				      int x, int y)
{
	NautilusIcon *icon;
	NautilusFile *file;
	double world_x, world_y;
	
	g_assert (NAUTILUS_IS_ICON_CONTAINER (container));
	if ((container->details->dnd_info->drag_info.selection_list == NULL) 
	   && (container->details->dnd_info->drag_info.data_type != EEL_ICON_DND_KEYWORD)) {
		return;
	}

  	gnome_canvas_window_to_world (GNOME_CANVAS (container),
				      x, y, &world_x, &world_y);

	/* Find the item we hit with our drop, if any. */
	icon = nautilus_icon_container_item_at (container, world_x, world_y);

	/* FIXME bugzilla.gnome.org 42485: 
	 * These "can_accept_items" tests need to be done by
	 * the icon view, not here. This file is not supposed to know
	 * that the target is a file.
	 */

	/* Find if target icon accepts our drop. */
	if (icon != NULL && (container->details->dnd_info->drag_info.data_type != EEL_ICON_DND_KEYWORD)) {
		    file = nautilus_file_get (nautilus_icon_container_get_icon_uri (container, icon));

		    if (!nautilus_drag_can_accept_items (file,
							 container->details->dnd_info->drag_info.selection_list)) {
			    icon = NULL;
		    }

		    nautilus_file_unref (file);
	}

	set_drop_target (container, icon);
}

static void
nautilus_icon_container_free_drag_data (NautilusIconContainer *container)
{
	NautilusIconDndInfo *dnd_info;
	
	dnd_info = container->details->dnd_info;
	
	dnd_info->drag_info.got_drop_data_type = FALSE;
	
	if (dnd_info->shadow != NULL) {
		gtk_object_destroy (GTK_OBJECT (dnd_info->shadow));
		dnd_info->shadow = NULL;
	}

	if (dnd_info->drag_info.selection_data != NULL) {
		eel_gtk_selection_data_free_deep (dnd_info->drag_info.selection_data);
		dnd_info->drag_info.selection_data = NULL;
	}
}

static void
drag_leave_callback (GtkWidget *widget,
		     GdkDragContext *context,
		     guint32 time,
		     gpointer data)
{
	NautilusIconDndInfo *dnd_info;

	dnd_info = NAUTILUS_ICON_CONTAINER (widget)->details->dnd_info;
	
	if (dnd_info->shadow != NULL)
		gnome_canvas_item_hide (dnd_info->shadow);
	
	stop_auto_scroll (NAUTILUS_ICON_CONTAINER (widget));
	nautilus_icon_container_free_drag_data(NAUTILUS_ICON_CONTAINER (widget));
}

void
nautilus_icon_dnd_init (NautilusIconContainer *container,
			GdkBitmap *stipple)
{
	g_return_if_fail (container != NULL);
	g_return_if_fail (NAUTILUS_IS_ICON_CONTAINER (container));


	container->details->dnd_info = g_new0 (NautilusIconDndInfo, 1);
	eel_drag_init (&container->details->dnd_info->drag_info,
		drag_types, G_N_ELEMENTS (drag_types), stipple);

	/* Set up the widget as a drag destination.
	 * (But not a source, as drags starting from this widget will be
         * implemented by dealing with events manually.)
	 */
	gtk_drag_dest_set  (GTK_WIDGET (container),
			    0,
			    drop_types, G_N_ELEMENTS (drop_types),
			    GDK_ACTION_COPY | GDK_ACTION_MOVE | GDK_ACTION_LINK
			    | GDK_ACTION_ASK);

	/* Messages for outgoing drag. */
	g_signal_connect (container, "drag_data_get",
			    G_CALLBACK (drag_data_get_callback), NULL);
	g_signal_connect (container, "drag_end",
			    G_CALLBACK (drag_end_callback), NULL);

	/* Messages for incoming drag. */
	g_signal_connect (container, "drag_data_received",
			    G_CALLBACK (drag_data_received_callback), NULL);
	g_signal_connect (container, "drag_motion",
			    G_CALLBACK (drag_motion_callback), NULL);
	g_signal_connect (container, "drag_drop",
			    G_CALLBACK (drag_drop_callback), NULL);
	g_signal_connect (container, "drag_leave",
			    G_CALLBACK (drag_leave_callback), NULL);

}

void
nautilus_icon_dnd_fini (NautilusIconContainer *container)
{
	g_return_if_fail (NAUTILUS_IS_ICON_CONTAINER (container));

	if (container->details->dnd_info != NULL) {
		stop_auto_scroll (container);

		eel_drag_finalize (&container->details->dnd_info->drag_info);
		container->details->dnd_info = NULL;
	}
}

void
nautilus_icon_dnd_begin_drag (NautilusIconContainer *container,
			      GdkDragAction actions,
			      int button,
			      GdkEventMotion *event)
{
	NautilusIconDndInfo *dnd_info;
	GnomeCanvas *canvas;
	GdkDragContext *context;
	GdkPixbuf *pixbuf;
	int x_offset, y_offset;
	ArtDRect world_rect;
	ArtIRect window_rect;
	
	g_return_if_fail (NAUTILUS_IS_ICON_CONTAINER (container));
	g_return_if_fail (event != NULL);

	dnd_info = container->details->dnd_info;
	g_return_if_fail (dnd_info != NULL);
	
	/* Notice that the event is in world coordinates, because of
           the way the canvas handles events.
	*/
	canvas = GNOME_CANVAS (container);
	gnome_canvas_world_to_window (canvas,
				      event->x, event->y,
				      &dnd_info->drag_info.start_x, &dnd_info->drag_info.start_y);
	
	/* start the drag */
	context = gtk_drag_begin (GTK_WIDGET (container),
				  dnd_info->drag_info.target_list,
				  actions,
				  button,
				  (GdkEvent *) event);


        /* create a pixmap and mask to drag with */
        pixbuf = nautilus_icon_canvas_item_get_image (container->details->drag_icon->item);
    
    	/* we want to drag semi-transparent pixbufs, but X is too slow dealing with
	   stippled masks, so we had to remove the code; this comment is left as a memorial
	   to it, with the hope that we get it back someday as X Windows improves */
	
        /* compute the image's offset */
	world_rect = nautilus_icon_canvas_item_get_icon_rectangle (
		container->details->drag_icon->item);
	window_rect = eel_gnome_canvas_world_to_window_rectangle
		(canvas, world_rect);
        x_offset = dnd_info->drag_info.start_x - window_rect.x0;
        y_offset = dnd_info->drag_info.start_y - window_rect.y0;
        
        /* set the icon for dragging */
        gtk_drag_set_icon_pixbuf (context, pixbuf, x_offset, y_offset);
}

static gboolean
drag_motion_callback (GtkWidget *widget,
		      GdkDragContext *context,
		      int x, int y,
		      guint32 time)
{
	int default_action, non_default_action;
	int resulting_action;
	
	nautilus_icon_container_ensure_drag_data (NAUTILUS_ICON_CONTAINER (widget), context, time);
	nautilus_icon_container_position_shadow (NAUTILUS_ICON_CONTAINER (widget), x, y);
	nautilus_icon_dnd_update_drop_target (NAUTILUS_ICON_CONTAINER (widget), context, x, y);
	set_up_auto_scroll_if_needed (NAUTILUS_ICON_CONTAINER (widget));
	/* Find out what the drop actions are based on our drag selection and
	 * the drop target.
	 */
	nautilus_icon_container_get_drop_action (NAUTILUS_ICON_CONTAINER (widget), context, x, y,
						 &default_action, &non_default_action);

	/* set the right drop action, choose based on modifier key state
	 */
	resulting_action = eel_drag_modifier_based_action (default_action, 
								non_default_action);
	gdk_drag_status (context, resulting_action, time);

	return TRUE;
}

static gboolean
drag_drop_callback (GtkWidget *widget,
		    GdkDragContext *context,
		    int x,
		    int y,
		    guint32 time,
		    gpointer data)
{
	NautilusIconDndInfo *dnd_info;

	dnd_info = NAUTILUS_ICON_CONTAINER (widget)->details->dnd_info;

	/* tell the drag_data_received callback that
	   the drop occured and that it can actually
	   process the actions.
	   make sure it is going to be called at least once.
	*/
	dnd_info->drag_info.drop_occured = TRUE;

	get_data_on_first_target_we_support (widget, context, time);

	return FALSE;
}

void
nautilus_icon_dnd_end_drag (NautilusIconContainer *container)
{
	NautilusIconDndInfo *dnd_info;

	g_return_if_fail (NAUTILUS_IS_ICON_CONTAINER (container));
		
	dnd_info = container->details->dnd_info;
	g_return_if_fail (dnd_info != NULL);
	stop_auto_scroll (container);
	/* Do nothing.
	 * Can that possibly be right?
	 */
}