clients/dnd.c

   1 /*
   2  * Copyright © 2010 Kristian Høgsberg
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting documentation, and
   8  * that the name of the copyright holders not be used in advertising or
   9  * publicity pertaining to distribution of the software without specific,
  10  * written prior permission.  The copyright holders make no representations
  11  * about the suitability of this software for any purpose.  It is provided "as
  12  * is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20  * OF THIS SOFTWARE.
  21  */
  22
  23 #include <stdint.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <math.h>
  30 #include <sys/time.h>
  31 #include <cairo.h>
  32 #include <glib.h>
  33 #include <gdk-pixbuf/gdk-pixbuf.h>
  34
  35 #include "wayland-client.h"
  36 #include "wayland-glib.h"
  37
  38 #include "window.h"
  39
  40 struct dnd {
  41         struct window *window;
  42         struct display *display;
  43         uint32_t key;
  44         struct item *items[16];
  45 };
  46
  47 struct dnd_drag {
  48         cairo_surface_t *translucent;
  49         cairo_surface_t *opaque;
  50         int hotspot_x, hotspot_y;
  51         struct dnd *dnd;
  52         struct input *input;
  53         uint32_t time;
  54         struct item *item;
  55         int x_offset, y_offset;
  56         const char *mime_type;
  57 };
  58
  59 struct dnd_offer {
  60         int refcount;
  61         struct dnd *dnd;
  62         struct wl_array types;
  63         const char *drag_type;
  64         uint32_t tag;
  65         int x, y;
  66 };
  67
  68 struct item {
  69         cairo_surface_t *surface;
  70         int seed;
  71         int x, y;
  72 };
  73
  74 struct dnd_flower_message {
  75         int seed, x_offset, y_offset;
  76 };
  77
  78
  79 static const int item_width = 64;
  80 static const int item_height = 64;
  81 static const int item_padding = 16;
  82
  83 static struct item *
  84 item_create(struct display *display, int x, int y, int seed)
  85 {
  86         struct item *item;
  87         struct timeval tv;
  88
  89         item = malloc(sizeof *item);
  90         if (item == NULL)
  91                 return NULL;
  92
  93
  94         gettimeofday(&tv, NULL);
  95         item->seed = seed ? seed : tv.tv_usec;
  96         srandom(item->seed);
  97
  98         const int petal_count = 3 + random() % 5;
  99         const double r1 = 20 + random() % 10;
 100         const double r2 = 5 + random() % 12;
 101         const double u = (10 + random() % 90) / 100.0;
 102         const double v = (random() % 90) / 100.0;
 103
 104         cairo_t *cr;
 105         int i;
 106         double t, dt = 2 * M_PI / (petal_count * 2);
 107         double x1, y1, x2, y2, x3, y3;
 108         struct rectangle rect;
 109
 110
 111         rect.width = item_width;
 112         rect.height = item_height;
 113         item->surface = display_create_surface(display, &rect);
 114
 115         item->x = x;
 116         item->y = y;
 117
 118         cr = cairo_create(item->surface);
 119         cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
 120         cairo_set_source_rgba(cr, 0, 0, 0, 0);
 121         cairo_paint(cr);
 122
 123         cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
 124         cairo_translate(cr, item_width / 2, item_height / 2);
 125         t = random();
 126         cairo_move_to(cr, cos(t) * r1, sin(t) * r1);
 127         for (i = 0; i < petal_count; i++, t += dt * 2) {
 128                 x1 = cos(t) * r1;
 129                 y1 = sin(t) * r1;
 130                 x2 = cos(t + dt) * r2;
 131                 y2 = sin(t + dt) * r2;
 132                 x3 = cos(t + 2 * dt) * r1;
 133                 y3 = sin(t + 2 * dt) * r1;
 134
 135                 cairo_curve_to(cr,
 136                                x1 - y1 * u, y1 + x1 * u,
 137                                x2 + y2 * v, y2 - x2 * v,
 138                                x2, y2);
 139
 140                 cairo_curve_to(cr,
 141                                x2 - y2 * v, y2 + x2 * v,
 142                                x3 + y3 * u, y3 - x3 * u,
 143                                x3, y3);
 144         }
 145
 146         cairo_close_path(cr);
 147
 148         cairo_set_source_rgba(cr,
 149                               0.5 + (random() % 50) / 49.0,
 150                               0.5 + (random() % 50) / 49.0,
 151                               0.5 + (random() % 50) / 49.0,
 152                               0.5 + (random() % 100) / 99.0);
 153
 154         cairo_fill_preserve(cr);
 155
 156         cairo_set_line_width(cr, 1);
 157         cairo_set_source_rgba(cr,
 158                               0.5 + (random() % 50) / 49.0,
 159                               0.5 + (random() % 50) / 49.0,
 160                               0.5 + (random() % 50) / 49.0,
 161                               0.5 + (random() % 100) / 99.0);
 162         cairo_stroke(cr);
 163
 164         cairo_destroy(cr);
 165
 166         return item;
 167 }
 168
 169 static void
 170 dnd_draw(struct dnd *dnd)
 171 {
 172         struct rectangle rectangle;
 173         cairo_t *cr;
 174         cairo_surface_t *wsurface, *surface;
 175         int i;
 176
 177         window_draw(dnd->window);
 178
 179         window_get_child_rectangle(dnd->window, &rectangle);
 180
 181         wsurface = window_get_surface(dnd->window);
 182         surface = cairo_surface_create_similar(wsurface,
 183                                                CAIRO_CONTENT_COLOR_ALPHA,
 184                                                rectangle.width,
 185                                                rectangle.height);
 186         cairo_surface_destroy(wsurface);
 187
 188         cr = cairo_create(surface);
 189         cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
 190         cairo_set_source_rgba(cr, 0, 0, 0, 0.8);
 191         cairo_paint(cr);
 192
 193         cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
 194         for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 195                 if (!dnd->items[i])
 196                         continue;
 197                 cairo_set_source_surface(cr, dnd->items[i]->surface,
 198                                          dnd->items[i]->x, dnd->items[i]->y);
 199                 cairo_paint(cr);
 200         }
 201
 202         cairo_destroy(cr);
 203
 204         window_copy_surface(dnd->window, &rectangle, surface);
 205         cairo_surface_destroy(surface);
 206         window_flush(dnd->window);
 207 }
 208
 209 static void
 210 redraw_handler(struct window *window, void *data)
 211 {
 212         struct dnd *dnd = data;
 213
 214         dnd_draw(dnd);
 215 }
 216
 217 static void
 218 keyboard_focus_handler(struct window *window,
 219                        struct input *device, void *data)
 220 {
 221         struct dnd *dnd = data;
 222
 223         window_schedule_redraw(dnd->window);
 224 }
 225
 226 static void
 227 dnd_offer_destroy(struct dnd_offer *dnd_offer)
 228 {
 229         dnd_offer->refcount--;
 230         if (dnd_offer->refcount == 0) {
 231                 wl_array_release(&dnd_offer->types);
 232                 free(dnd_offer);
 233         }
 234 }
 235
 236 static int
 237 dnd_add_item(struct dnd *dnd, struct item *item)
 238 {
 239         int i;
 240
 241         for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 242                 if (dnd->items[i] == 0) {
 243                         dnd->items[i] = item;
 244                         return i;
 245                 }
 246         }
 247         return -1;
 248 }
 249
 250 static struct item *
 251 dnd_get_item(struct dnd *dnd, int32_t x, int32_t y)
 252 {
 253         struct item *item;
 254         struct rectangle rectangle;
 255         int i;
 256
 257         window_get_child_rectangle(dnd->window, &rectangle);
 258
 259         x -= rectangle.x;
 260         y -= rectangle.y;
 261
 262         for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 263                 item = dnd->items[i];
 264                 if (item &&
 265                     item->x <= x && x < item->x + item_width &&
 266                     item->y <= y && y < item->y + item_height)
 267                         return item;
 268         }
 269
 270         return NULL;
 271 }
 272
 273 static void
 274 drag_target(void *data,
 275             struct wl_drag *drag, const char *mime_type)
 276 {
 277         struct dnd_drag *dnd_drag = data;
 278         struct dnd *dnd = dnd_drag->dnd;
 279         struct wl_input_device *device;
 280         cairo_surface_t *surface;
 281         struct wl_buffer *buffer;
 282
 283         fprintf(stderr, "target %s\n", mime_type);
 284         device = input_get_input_device(dnd_drag->input);
 285         dnd_drag->mime_type = mime_type;
 286         if (mime_type)
 287                 surface = dnd_drag->opaque;
 288         else
 289                 surface = dnd_drag->translucent;
 290
 291         buffer = display_get_buffer_for_surface(dnd->display, surface);
 292         wl_input_device_attach(device, dnd_drag->time, buffer,
 293                                dnd_drag->hotspot_x, dnd_drag->hotspot_y);
 294 }
 295
 296 static void
 297 drag_finish(void *data, struct wl_drag *drag, int fd)
 298 {
 299         struct dnd_drag *dnd_drag = data;
 300
 301         if (!dnd_drag->mime_type) {
 302                 dnd_add_item(dnd_drag->dnd, dnd_drag->item);
 303                 window_schedule_redraw(dnd_drag->dnd->window);
 304                 return;
 305         }
 306
 307         struct dnd_flower_message dnd_flower_message;
 308
 309
 310         dnd_flower_message.seed = dnd_drag->item->seed;
 311
 312         dnd_flower_message.x_offset = dnd_drag->x_offset;
 313         dnd_flower_message.y_offset = dnd_drag->y_offset;
 314
 315         fprintf(stderr, "got 'finish', fd %d, sending dnd_flower_message\n", fd);
 316
 317         write(fd, &dnd_flower_message, sizeof dnd_flower_message);
 318         close(fd);
 319
 320         /* The 'finish' event marks the end of the session on the drag
 321          * source side and we need to clean up the drag object created
 322          * and the local state. */
 323         wl_drag_destroy(drag);
 324
 325         /* Destroy the item that has been dragged out */
 326         cairo_surface_destroy(dnd_drag->item->surface);
 327         free(dnd_drag->item);
 328
 329         cairo_surface_destroy(dnd_drag->translucent);
 330         cairo_surface_destroy(dnd_drag->opaque);
 331         free(dnd_drag);
 332 }
 333
 334 static void
 335 drag_reject(void *data, struct wl_drag *drag)
 336 {
 337         struct dnd_drag *dnd_drag = data;
 338
 339         dnd_add_item(dnd_drag->dnd, dnd_drag->item);
 340         window_schedule_redraw(dnd_drag->dnd->window);
 341 }
 342
 343 static const struct wl_drag_listener drag_listener = {
 344         drag_target,
 345         drag_finish,
 346         drag_reject
 347 };
 348
 349 static void
 350 drag_offer_offer(void *data,
 351                  struct wl_drag_offer *offer, const char *type)
 352 {
 353         struct dnd_offer *dnd_offer = data;
 354         char **p;
 355
 356         p = wl_array_add(&dnd_offer->types, sizeof *p);
 357         if (p)
 358                 *p = strdup(type);
 359 }
 360
 361 static void
 362 drag_offer_pointer_focus(void *data,
 363                          struct wl_drag_offer *offer,
 364                          uint32_t time, struct wl_surface *surface,
 365                          int32_t x, int32_t y,
 366                          int32_t surface_x, int32_t surface_y)
 367 {
 368         struct dnd_offer *dnd_offer = data;
 369         struct window *window;
 370         char **p, **end;
 371
 372         /* The last event in a dnd session is pointer_focus with a
 373          * NULL surface, whether or not we get the drop event.  We
 374          * need to clean up the dnd_offer proxy and whatever state we
 375          * allocated. */
 376         if (!surface) {
 377                 fprintf(stderr, "pointer focus NULL, session over\n");
 378                 wl_drag_offer_destroy(offer);
 379                 dnd_offer_destroy(dnd_offer);
 380                 return;
 381         }
 382
 383         fprintf(stderr, "drag pointer focus %p\n", surface);
 384         fprintf(stderr, "offered types:\n");
 385         end = dnd_offer->types.data + dnd_offer->types.size;
 386         for (p = dnd_offer->types.data; p < end; p++)
 387                 fprintf(stderr, "\%s\n", *p);
 388
 389         window = wl_surface_get_user_data(surface);
 390         dnd_offer->dnd = window_get_user_data(window);
 391
 392         if (!dnd_get_item(dnd_offer->dnd, surface_x, surface_y)) {
 393                 wl_drag_offer_accept(offer, time, "application/x-wayland-dnd-flower");
 394                 dnd_offer->drag_type = "application/x-wayland-dnd-flower";
 395                 dnd_offer->x = surface_x;
 396                 dnd_offer->y = surface_y;
 397         } else {
 398                 wl_drag_offer_accept(offer, time, NULL);
 399                 dnd_offer->drag_type = NULL;
 400         }
 401 }
 402
 403 static void
 404 drag_offer_motion(void *data,
 405                   struct wl_drag_offer *offer, uint32_t time,
 406                   int32_t x, int32_t y, int32_t surface_x, int32_t surface_y)
 407 {
 408         struct dnd_offer *dnd_offer = data;
 409
 410         if (!dnd_get_item(dnd_offer->dnd, surface_x, surface_y)) {
 411                 fprintf(stderr, "drag offer motion %d, %d, accepting\n",
 412                         surface_x, surface_y);
 413                 wl_drag_offer_accept(offer, time, "application/x-wayland-dnd-flower");
 414                 dnd_offer->drag_type = "application/x-wayland-dnd-flower";
 415                 dnd_offer->x = surface_x;
 416                 dnd_offer->y = surface_y;
 417         } else {
 418                 fprintf(stderr, "drag offer motion %d, %d, declining\n",
 419                         surface_x, surface_y);
 420                 wl_drag_offer_accept(offer, time, NULL);
 421                 dnd_offer->drag_type = NULL;
 422         }
 423 }
 424
 425 static gboolean
 426 drop_io_func(GIOChannel *source, GIOCondition condition, gpointer data)
 427 {
 428         struct dnd_offer *dnd_offer = data;
 429         struct dnd *dnd = dnd_offer->dnd;
 430         struct dnd_flower_message dnd_flower_message;
 431         int fd;
 432         unsigned int len;
 433         struct item *item;
 434
 435         fd = g_io_channel_unix_get_fd(source);
 436         len = read(fd, &dnd_flower_message, sizeof dnd_flower_message);
 437         fprintf(stderr, "read %d bytes\n", len);
 438
 439         close(fd);
 440         g_source_remove(dnd_offer->tag);
 441
 442         g_io_channel_unref(source);
 443
 444         item = item_create(dnd->display,
 445                            dnd_offer->x - dnd_flower_message.x_offset - 26,
 446                            dnd_offer->y - dnd_flower_message.y_offset - 66,
 447                            dnd_flower_message.seed);
 448
 449         dnd_add_item(dnd, item);
 450         window_schedule_redraw(dnd->window);
 451
 452         dnd_offer_destroy(dnd_offer);
 453
 454         return TRUE;
 455 }
 456
 457 static void
 458 drag_offer_drop(void *data, struct wl_drag_offer *offer)
 459 {
 460         struct dnd_offer *dnd_offer = data;
 461         GIOChannel *channel;
 462         int p[2];
 463
 464         if (!dnd_offer->drag_type) {
 465                 fprintf(stderr, "got 'drop', but no target\n");
 466                 wl_drag_offer_reject(offer);
 467                 return;
 468         }
 469
 470         fprintf(stderr, "got 'drop', sending write end of pipe\n");
 471
 472         dnd_offer->refcount++;
 473         pipe(p);
 474         wl_drag_offer_receive(offer, p[1]);
 475         close(p[1]);
 476
 477         channel = g_io_channel_unix_new(p[0]);
 478         dnd_offer->tag = g_io_add_watch(channel, G_IO_IN,
 479                                         drop_io_func, dnd_offer);
 480 }
 481
 482 static const struct wl_drag_offer_listener drag_offer_listener = {
 483         drag_offer_offer,
 484         drag_offer_pointer_focus,
 485         drag_offer_motion,
 486         drag_offer_drop,
 487 };
 488
 489 static void
 490 drag_offer_handler(struct wl_drag_offer *offer, struct display *display)
 491 {
 492         struct dnd_offer *dnd_offer;
 493
 494         dnd_offer = malloc(sizeof *dnd_offer);
 495         if (dnd_offer == NULL)
 496                 return;
 497
 498         dnd_offer->refcount = 1;
 499
 500         wl_drag_offer_add_listener(offer, &drag_offer_listener, dnd_offer);
 501         wl_array_init(&dnd_offer->types);
 502 }
 503
 504 static cairo_surface_t *
 505 create_drag_cursor(struct dnd_drag *dnd_drag,
 506                    struct item *item, int32_t x, int32_t y, double opacity)
 507 {
 508         struct dnd *dnd = dnd_drag->dnd;
 509         cairo_surface_t *surface, *pointer;
 510         int32_t pointer_width, pointer_height, hotspot_x, hotspot_y;
 511         struct rectangle rectangle;
 512         cairo_pattern_t *pattern;
 513         cairo_t *cr;
 514
 515         pointer = display_get_pointer_surface(dnd->display,
 516                                               POINTER_DRAGGING,
 517                                               &pointer_width,
 518                                               &pointer_height,
 519                                               &hotspot_x,
 520                                               &hotspot_y);
 521
 522         rectangle.width = item_width + 2 * pointer_width;
 523         rectangle.height = item_height + 2 * pointer_height;
 524         surface = display_create_surface(dnd->display, &rectangle);
 525
 526         cr = cairo_create(surface);
 527         cairo_translate(cr, pointer_width, pointer_height);
 528
 529         cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
 530         cairo_set_source_rgba(cr, 0, 0, 0, 0);
 531         cairo_paint(cr);
 532
 533         cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
 534         cairo_set_source_surface(cr, item->surface, 0, 0);
 535         pattern = cairo_pattern_create_rgba(0, 0, 0, opacity);
 536         cairo_mask(cr, pattern);
 537         cairo_pattern_destroy(pattern);
 538
 539         cairo_set_source_surface(cr, pointer,
 540                                  x - item->x - hotspot_x,
 541                                  y - item->y - hotspot_y);
 542         cairo_surface_destroy(pointer);
 543         cairo_paint(cr);
 544         /* FIXME: more cairo-gl brokeness */
 545         display_flush_cairo_device(dnd->display);
 546         cairo_destroy(cr);
 547
 548         dnd_drag->hotspot_x = pointer_width + x - item->x;
 549         dnd_drag->hotspot_y = pointer_height + y - item->y;
 550
 551         return surface;
 552 }
 553
 554 static void
 555 dnd_button_handler(struct window *window,
 556                    struct input *input, uint32_t time,
 557                    int button, int state, void *data)
 558 {
 559         struct dnd *dnd = data;
 560         int32_t x, y;
 561         struct item *item;
 562         struct rectangle rectangle;
 563         struct dnd_drag *dnd_drag;
 564         struct wl_drag *drag;
 565         int i;
 566
 567         window_get_child_rectangle(dnd->window, &rectangle);
 568         input_get_position(input, &x, &y);
 569         item = dnd_get_item(dnd, x, y);
 570         x -= rectangle.x;
 571         y -= rectangle.y;
 572
 573         if (item && state == 1) {
 574                 fprintf(stderr, "start drag, item %p\n", item);
 575
 576                 dnd_drag = malloc(sizeof *dnd_drag);
 577                 dnd_drag->dnd = dnd;
 578                 dnd_drag->input = input;
 579                 dnd_drag->time = time;
 580                 dnd_drag->item = item;
 581                 dnd_drag->x_offset = x - item->x;
 582                 dnd_drag->y_offset = y - item->y;
 583
 584                 for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 585                         if (item == dnd->items[i]){
 586                                 dnd->items[i] = 0;
 587                                 break;
 588                         }
 589                 }
 590
 591                 dnd_drag->opaque =
 592                         create_drag_cursor(dnd_drag, item, x, y, 1);
 593                 dnd_drag->translucent =
 594                         create_drag_cursor(dnd_drag, item, x, y, 0.2);
 595
 596                 drag = window_create_drag(window);
 597                 wl_drag_offer(drag, "application/x-wayland-dnd-flower");
 598                 window_activate_drag(drag, window, input, time);
 599                 wl_drag_add_listener(drag, &drag_listener, dnd_drag);
 600                 window_schedule_redraw(dnd->window);
 601         }
 602 }
 603
 604 static int
 605 dnd_motion_handler(struct window *window,
 606                    struct input *input, uint32_t time,
 607                    int32_t x, int32_t y,
 608                    int32_t sx, int32_t sy, void *data)
 609 {
 610         struct dnd *dnd = data;
 611         struct item *item;
 612
 613         item = dnd_get_item(dnd, sx, sy);
 614
 615         if (item)
 616                 return POINTER_HAND1;
 617         else
 618                 return POINTER_LEFT_PTR;
 619 }
 620
 621 static struct dnd *
 622 dnd_create(struct display *display)
 623 {
 624         struct dnd *dnd;
 625         gchar *title;
 626         int i, x, y;
 627         struct rectangle rectangle;
 628
 629         dnd = malloc(sizeof *dnd);
 630         if (dnd == NULL)
 631                 return dnd;
 632         memset(dnd, 0, sizeof *dnd);
 633
 634         title = g_strdup_printf("Wayland Drag and Drop Demo");
 635
 636         dnd->window = window_create(display, title, 500, 400);
 637         dnd->display = display;
 638         dnd->key = 100;
 639
 640         for (i = 0; i < ARRAY_LENGTH(dnd->items); i++) {
 641                 x = (i % 4) * (item_width + item_padding) + item_padding;
 642                 y = (i / 4) * (item_height + item_padding) + item_padding;
 643                 if ((i ^ (i >> 2)) & 1)
 644                         dnd->items[i] = item_create(display, x, y, 0);
 645                 else
 646                         dnd->items[i] = NULL;
 647         }
 648
 649         window_set_user_data(dnd->window, dnd);
 650         window_set_redraw_handler(dnd->window, redraw_handler);
 651         window_set_keyboard_focus_handler(dnd->window,
 652                                           keyboard_focus_handler);
 653         window_set_button_handler(dnd->window,
 654                                   dnd_button_handler);
 655
 656         window_set_motion_handler(dnd->window,
 657                                   dnd_motion_handler);
 658
 659         rectangle.width = 4 * (item_width + item_padding) + item_padding;
 660         rectangle.height = 4 * (item_height + item_padding) + item_padding;
 661         window_set_child_size(dnd->window, &rectangle);
 662
 663         dnd_draw(dnd);
 664
 665         return dnd;
 666 }
 667
 668 static const GOptionEntry option_entries[] = {
 669         { NULL }
 670 };
 671
 672 int
 673 main(int argc, char *argv[])
 674 {
 675         struct display *d;
 676         struct dnd *dnd;
 677
 678         d = display_create(&argc, &argv, option_entries);
 679         if (d == NULL) {
 680                 fprintf(stderr, "failed to create display: %m\n");
 681                 return -1;
 682         }
 683
 684         display_set_drag_offer_handler(d, drag_offer_handler);
 685
 686         dnd = dnd_create (d);
 687
 688         display_run(d);
 689
 690         return 0;
 691 }