1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */

/* Edge resistance for move/resize operations */

/*
 * Copyright (C) 2005, 2006 Elijah Newren
 *
 * This program 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 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#include <config.h>
#include "edge-resistance.h"
#include "boxes.h"
#include "display-private.h"
#include "workspace.h"

/* A simple macro for whether a given window's edges are potentially
 * relevant for resistance/snapping during a move/resize operation
 */
#define WINDOW_EDGES_RELEVANT(window, display) \
  meta_window_should_be_showing (window) &&    \
  window->screen == display->grab_screen &&    \
  window         != display->grab_window &&    \
  window->type   != META_WINDOW_DESKTOP &&     \
  window->type   != META_WINDOW_MENU    &&     \
  window->type   != META_WINDOW_SPLASHSCREEN

struct ResistanceDataForAnEdge
{
  gboolean     timeout_setup;
  guint        timeout_id;
  int          timeout_edge_pos;
  gboolean     timeout_over;
  GSourceFunc  timeout_func;
  MetaWindow  *window;
  int          keyboard_buildup;
};
typedef struct ResistanceDataForAnEdge ResistanceDataForAnEdge;

struct MetaEdgeResistanceData
{
  GArray *left_edges;
  GArray *right_edges;
  GArray *top_edges;
  GArray *bottom_edges;

  ResistanceDataForAnEdge left_data;
  ResistanceDataForAnEdge right_data;
  ResistanceDataForAnEdge top_data;
  ResistanceDataForAnEdge bottom_data;
};

static void compute_resistance_and_snapping_edges (MetaDisplay *display);

/* !WARNING!: this function can return invalid indices (namely, either -1 or
 * edges->len); this is by design, but you need to remember this.
 */
static int
find_index_of_edge_near_position (const GArray *edges,
                                  int           position,
                                  gboolean      want_interval_min,
                                  gboolean      horizontal)
{
  /* This is basically like a binary search, except that we're trying to
   * find a range instead of an exact value.  So, if we have in our array
   *   Value: 3  27 316 316 316 505 522 800 1213
   *   Index: 0   1   2   3   4   5   6   7    8
   * and we call this function with position=500 & want_interval_min=TRUE
   * then we should get 5 (because 505 is the first value bigger than 500).
   * If we call this function with position=805 and want_interval_min=FALSE
   * then we should get 7 (because 800 is the last value smaller than 800).
   * A couple more, to make things clear:
   *    position  want_interval_min  correct_answer
   *         316               TRUE               2
   *         316              FALSE               4
   *           2              FALSE              -1
   *        2000               TRUE               9
   */
  int low, high, mid;
  int compare;
  MetaEdge *edge;

  /* Initialize mid, edge, & compare in the off change that the array only
   * has one element.
   */
  mid  = 0;
  edge = g_array_index (edges, MetaEdge*, mid);
  compare = horizontal ? edge->rect.x : edge->rect.y;

  /* Begin the search... */
  low  = 0;
  high = edges->len - 1;
  while (low < high)
    {
      mid = low + (high - low)/2;
      edge = g_array_index (edges, MetaEdge*, mid);
      compare = horizontal ? edge->rect.x : edge->rect.y;

      if (compare == position)
        break;

      if (compare > position)
        high = mid - 1;
      else
        low = mid + 1;
    }

  /* mid should now be _really_ close to the index we want, so we start
   * linearly searching.  However, note that we don't know if mid is less
   * than or greater than what we need and it's possible that there are
   * several equal values equal to what we were searching for and we ended
   * up in the middle of them instead of at the end.  So we may need to
   * move mid multiple locations over.
   */
  if (want_interval_min)
    {
      while (compare >= position && mid > 0)
        {
          mid--;
          edge = g_array_index (edges, MetaEdge*, mid);
          compare = horizontal ? edge->rect.x : edge->rect.y;
        }
      while (compare < position && mid < (int)edges->len - 1)
        {
          mid++;
          edge = g_array_index (edges, MetaEdge*, mid);
          compare = horizontal ? edge->rect.x : edge->rect.y;
        }

      /* Special case for no values in array big enough */
      if (compare < position)
        return edges->len;

      /* Return the found value */
      return mid;
    }
  else
    {
      while (compare <= position && mid < (int)edges->len - 1)
        {
          mid++;
          edge = g_array_index (edges, MetaEdge*, mid);
          compare = horizontal ? edge->rect.x : edge->rect.y;
        }
      while (compare > position && mid > 0)
        {
          mid--;
          edge = g_array_index (edges, MetaEdge*, mid);
          compare = horizontal ? edge->rect.x : edge->rect.y;
        }

      /* Special case for no values in array small enough */
      if (compare > position)
        return -1;

      /* Return the found value */
      return mid;
    }
}

static gboolean
points_on_same_side (int ref, int pt1, int pt2)
{
  return (pt1 - ref) * (pt2 - ref) > 0;
}

static int
find_nearest_position (const GArray        *edges,
                       int                  position,
                       int                  old_position,
                       const MetaRectangle *new_rect,
                       gboolean             horizontal,
                       gboolean             only_forward)
{
  /* This is basically just a binary search except that we're looking
   * for the value closest to position, rather than finding that
   * actual value.  Also, we ignore any edges that aren't relevant
   * given the horizontal/vertical position of new_rect.
   */
  int low, high, mid;
  int compare;
  MetaEdge *edge;
  int best, best_dist, i;
  gboolean edges_align;

  /* Initialize mid, edge, & compare in the off change that the array only
   * has one element.
   */
  mid  = 0;
  edge = g_array_index (edges, MetaEdge*, mid);
  compare = horizontal ? edge->rect.x : edge->rect.y;<--- compare is assigned

  /* Begin the search... */
  low  = 0;
  high = edges->len - 1;
  while (low < high)
    {
      mid = low + (high - low)/2;
      edge = g_array_index (edges, MetaEdge*, mid);
      compare = horizontal ? edge->rect.x : edge->rect.y;

      if (compare == position)
        break;

      if (compare > position)
        high = mid - 1;
      else
        low = mid + 1;
    }

  /* mid should now be _really_ close to the index we want, so we
   * start searching nearby for something that overlaps and is closer
   * than the original position.
   */
  best = old_position;
  best_dist = INT_MAX;

  /* Start the search at mid */
  edge = g_array_index (edges, MetaEdge*, mid);
  compare = horizontal ? edge->rect.x : edge->rect.y;<--- compare is overwritten
  edges_align = meta_rectangle_edge_aligns (new_rect, edge);
  if (edges_align &&
      (!only_forward || !points_on_same_side (position, compare, old_position)))
    {
      int dist = ABS (compare - position);
      if (dist < best_dist)
        {
          best = compare;
          best_dist = dist;
        }
    }

  /* Now start searching higher than mid */
  for (i = mid + 1; i < (int)edges->len; i++)
    {
      edge = g_array_index (edges, MetaEdge*, i);
      compare = horizontal ? edge->rect.x : edge->rect.y;

      edges_align = horizontal ?
        meta_rectangle_vert_overlap (&edge->rect, new_rect) :
        meta_rectangle_horiz_overlap (&edge->rect, new_rect);

      if (edges_align &&
          (!only_forward ||
           !points_on_same_side (position, compare, old_position)))
        {
          int dist = ABS (compare - position);
          if (dist < best_dist)
            {
              best = compare;
              best_dist = dist;
            }
          break;
        }
    }

  /* Now start searching lower than mid */
  for (i = mid-1; i >= 0; i--)
    {
      edge = g_array_index (edges, MetaEdge*, i);
      compare = horizontal ? edge->rect.x : edge->rect.y;

      edges_align = horizontal ?
        meta_rectangle_vert_overlap (&edge->rect, new_rect) :
        meta_rectangle_horiz_overlap (&edge->rect, new_rect);

      if (edges_align &&
          (!only_forward ||
           !points_on_same_side (position, compare, old_position)))
        {
          int dist = ABS (compare - position);
          if (dist < best_dist)
            {
              best = compare;
            }
          break;
        }
    }

  /* Return the best one found */
  return best;
}

static gboolean
movement_towards_edge (MetaSide side, int increment)
{
  switch (side)
    {
    case META_SIDE_LEFT:
    case META_SIDE_TOP:
      return increment < 0;
    case META_SIDE_RIGHT:
    case META_SIDE_BOTTOM:
      return increment > 0;
    default:
      g_assert_not_reached ();
    }
}

static gboolean
edge_resistance_timeout (gpointer data)
{
  ResistanceDataForAnEdge *resistance_data = data;

  resistance_data->timeout_over = TRUE;
  resistance_data->timeout_id = 0;
  (*resistance_data->timeout_func)(resistance_data->window);

  return FALSE;
}

static int
apply_edge_resistance (MetaWindow                *window,
                       int                        old_pos,
                       int                        new_pos,
                       const MetaRectangle       *old_rect,
                       const MetaRectangle       *new_rect,
                       GArray                    *edges,
                       ResistanceDataForAnEdge   *resistance_data,
                       GSourceFunc                timeout_func,
                       gboolean                   xdir,
                       gboolean                   keyboard_op)
{
  int i, begin, end;
  int last_edge;
  gboolean increasing = new_pos > old_pos;
  int      increment = increasing ? 1 : -1;

  const int PIXEL_DISTANCE_THRESHOLD_TOWARDS_WINDOW    = 16;
  const int PIXEL_DISTANCE_THRESHOLD_AWAYFROM_WINDOW   =  0;
  const int PIXEL_DISTANCE_THRESHOLD_TOWARDS_XINERAMA  = 32;
  const int PIXEL_DISTANCE_THRESHOLD_AWAYFROM_XINERAMA =  0;
  const int PIXEL_DISTANCE_THRESHOLD_TOWARDS_SCREEN    = 32;
  const int PIXEL_DISTANCE_THRESHOLD_AWAYFROM_SCREEN   =  0;
  const int TIMEOUT_RESISTANCE_LENGTH_MS_WINDOW   =   0;
  const int TIMEOUT_RESISTANCE_LENGTH_MS_XINERAMA =   0;
  const int TIMEOUT_RESISTANCE_LENGTH_MS_SCREEN   =   0;

  /* Quit if no movement was specified */
  if (old_pos == new_pos)
    return new_pos;

  /* Remove the old timeout if it's no longer relevant */
  if (resistance_data->timeout_setup &&
      ((resistance_data->timeout_edge_pos > old_pos &&
        resistance_data->timeout_edge_pos > new_pos)  ||
       (resistance_data->timeout_edge_pos < old_pos &&
        resistance_data->timeout_edge_pos < new_pos)))
    {
      resistance_data->timeout_setup = FALSE;
      if (resistance_data->timeout_id != 0)
        {
          g_source_remove (resistance_data->timeout_id);
          resistance_data->timeout_id = 0;
        }
    }

  /* Get the range of indices in the edge array that we move past/to. */
  begin = find_index_of_edge_near_position (edges, old_pos,  increasing, xdir);
  end   = find_index_of_edge_near_position (edges, new_pos, !increasing, xdir);

  /* begin and end can be outside the array index, if the window is partially
   * off the screen
   */
  last_edge = edges->len - 1;
  begin = CLAMP (begin, 0, last_edge);
  end   = CLAMP (end,   0, last_edge);

  /* Loop over all these edges we're moving past/to. */
  i = begin;
  while ((increasing  && i <= end) ||
         (!increasing && i >= end))
    {
      gboolean  edges_align;
      MetaEdge *edge = g_array_index (edges, MetaEdge*, i);
      int       compare = xdir ? edge->rect.x : edge->rect.y;

      /* Find out if this edge is relevant */
      edges_align = meta_rectangle_edge_aligns (new_rect, edge)  ||
                    meta_rectangle_edge_aligns (old_rect, edge);

      /* Nothing to do unless the edges align */
      if (!edges_align)
        {
          /* Go to the next edge in the range */
          i += increment;
          continue;
        }

      /* Rest is easier to read if we split on keyboard vs. mouse op */
      if (keyboard_op)
        {
          if ((old_pos < compare && compare < new_pos) ||
              (old_pos > compare && compare > new_pos))
            return compare;
        }
      else /* mouse op */
        {
          int threshold;

          /* TIMEOUT RESISTANCE: If the edge is relevant and we're moving
           * towards it, then we may want to have some kind of time delay
           * before the user can move past this edge.
           */
          if (movement_towards_edge (edge->side_type, increment))
            {
              /* First, determine the length of time for the resistance */
              int timeout_length_ms = 0;
              switch (edge->edge_type)
                {
                case META_EDGE_WINDOW:
                  timeout_length_ms = TIMEOUT_RESISTANCE_LENGTH_MS_WINDOW;
                  break;
                case META_EDGE_XINERAMA:
                  timeout_length_ms = TIMEOUT_RESISTANCE_LENGTH_MS_XINERAMA;
                  break;
                case META_EDGE_SCREEN:
                  timeout_length_ms = TIMEOUT_RESISTANCE_LENGTH_MS_SCREEN;
                  break;
                }

              if (!resistance_data->timeout_setup &&
                  timeout_length_ms != 0)
                {
                  resistance_data->timeout_id =
                    g_timeout_add (timeout_length_ms,
                                   edge_resistance_timeout,
                                   resistance_data);
                  resistance_data->timeout_setup = TRUE;
                  resistance_data->timeout_edge_pos = compare;
                  resistance_data->timeout_over = FALSE;
                  resistance_data->timeout_func = timeout_func;
                  resistance_data->window = window;
                }
              if (!resistance_data->timeout_over &&
                  timeout_length_ms != 0)
                return compare;
            }

          /* PIXEL DISTANCE MOUSE RESISTANCE: If the edge matters and the
           * user hasn't moved at least threshold pixels past this edge,
           * stop movement at this edge.  (Note that this is different from
           * keyboard resistance precisely because keyboard move ops are
           * relative to previous positions, whereas mouse move ops are
           * relative to differences in mouse position and mouse position
           * is an absolute quantity rather than a relative quantity)
           */

          /* First, determine the threshold */
          switch (edge->edge_type)
            {
            case META_EDGE_WINDOW:
              if (movement_towards_edge (edge->side_type, increment))
                threshold = PIXEL_DISTANCE_THRESHOLD_TOWARDS_WINDOW;
              else
                threshold = PIXEL_DISTANCE_THRESHOLD_AWAYFROM_WINDOW;
              break;
            case META_EDGE_XINERAMA:
              if (movement_towards_edge (edge->side_type, increment))
                threshold = PIXEL_DISTANCE_THRESHOLD_TOWARDS_XINERAMA;
              else
                threshold = PIXEL_DISTANCE_THRESHOLD_AWAYFROM_XINERAMA;
              break;
            case META_EDGE_SCREEN:
              if (movement_towards_edge (edge->side_type, increment))
                threshold = PIXEL_DISTANCE_THRESHOLD_TOWARDS_SCREEN;
              else
                threshold = PIXEL_DISTANCE_THRESHOLD_AWAYFROM_SCREEN;
              break;
            default:
              threshold = 0;
            }

          if (ABS (compare - new_pos) < threshold)
            return compare;
        }

      /* Go to the next edge in the range */
      i += increment;
    }

  return new_pos;
}

static int
apply_edge_snapping (int                  old_pos,
                     int                  new_pos,
                     const MetaRectangle *new_rect,
                     GArray              *edges,<--- Parameter 'edges' can be declared as pointer to const
                     gboolean             xdir,
                     gboolean             keyboard_op)
{
  int snap_to;

  if (old_pos == new_pos)
    return new_pos;

  snap_to = find_nearest_position (edges,
                                   new_pos,
                                   old_pos,
                                   new_rect,
                                   xdir,
                                   keyboard_op);

  /* If mouse snap-moving, the user could easily accidentally move just a
   * couple pixels in a direction they didn't mean to move; so ignore snap
   * movement in those cases unless it's only a small number of pixels
   * anyway.
   */
  if (!keyboard_op &&
      ABS (snap_to - old_pos) >= 8 &&
      ABS (new_pos - old_pos) < 8)
    return old_pos;
  else
    /* Otherwise, return the snapping position found */
    return snap_to;
}

/* This function takes the position (including any frame) of the window and
 * a proposed new position (ignoring edge resistance/snapping), and then
 * applies edge resistance to EACH edge (separately) updating new_outer.
 * It returns true if new_outer is modified, false otherwise.
 *
 * display->grab_edge_resistance_data MUST already be setup or calling this
 * function will cause a crash.
 */
static gboolean
apply_edge_resistance_to_each_side (MetaDisplay         *display,
                                    MetaWindow          *window,
                                    const MetaRectangle *old_outer,
                                    MetaRectangle       *new_outer,
                                    GSourceFunc          timeout_func,
                                    gboolean             auto_snap,
                                    gboolean             keyboard_op,
                                    gboolean             is_resize)
{
  MetaEdgeResistanceData *edge_data;
  MetaRectangle           modified_rect;
  gboolean                modified;
  int new_left, new_right, new_top, new_bottom;

  if (display->grab_edge_resistance_data == NULL)
    compute_resistance_and_snapping_edges (display);

  edge_data = display->grab_edge_resistance_data;

  if (auto_snap)
    {
      /* Do the auto snapping instead of normal edge resistance; in all
       * cases, we allow snapping to opposite kinds of edges (e.g. left
       * sides of windows to both left and right edges.
       */

      new_left   = apply_edge_snapping (BOX_LEFT (*old_outer),
                                        BOX_LEFT (*new_outer),
                                        new_outer,
                                        edge_data->left_edges,
                                        TRUE,
                                        keyboard_op);

      new_right  = apply_edge_snapping (BOX_RIGHT (*old_outer),
                                        BOX_RIGHT (*new_outer),
                                        new_outer,
                                        edge_data->right_edges,
                                        TRUE,
                                        keyboard_op);

      new_top    = apply_edge_snapping (BOX_TOP (*old_outer),
                                        BOX_TOP (*new_outer),
                                        new_outer,
                                        edge_data->top_edges,
                                        FALSE,
                                        keyboard_op);

      new_bottom = apply_edge_snapping (BOX_BOTTOM (*old_outer),
                                        BOX_BOTTOM (*new_outer),
                                        new_outer,
                                        edge_data->bottom_edges,
                                        FALSE,
                                        keyboard_op);
    }
  else
    {
      /* Disable edge resistance for resizes when windows have size
       * increment hints; see #346782.  For all other cases, apply
       * them.
       */
      if (!is_resize || window->size_hints.width_inc == 1)
        {
          /* Now, apply the normal horizontal edge resistance */
          new_left   = apply_edge_resistance (window,
                                              BOX_LEFT (*old_outer),
                                              BOX_LEFT (*new_outer),
                                              old_outer,
                                              new_outer,
                                              edge_data->left_edges,
                                              &edge_data->left_data,
                                              timeout_func,
                                              TRUE,
                                              keyboard_op);
          new_right  = apply_edge_resistance (window,
                                              BOX_RIGHT (*old_outer),
                                              BOX_RIGHT (*new_outer),
                                              old_outer,
                                              new_outer,
                                              edge_data->right_edges,
                                              &edge_data->right_data,
                                              timeout_func,
                                              TRUE,
                                              keyboard_op);
        }
      else
        {
          new_left  = new_outer->x;
          new_right = new_outer->x + new_outer->width;
        }
      /* Same for vertical resizes... */
      if (!is_resize || window->size_hints.height_inc == 1)
        {
          new_top    = apply_edge_resistance (window,
                                              BOX_TOP (*old_outer),
                                              BOX_TOP (*new_outer),
                                              old_outer,
                                              new_outer,
                                              edge_data->top_edges,
                                              &edge_data->top_data,
                                              timeout_func,
                                              FALSE,
                                              keyboard_op);
          new_bottom = apply_edge_resistance (window,
                                              BOX_BOTTOM (*old_outer),
                                              BOX_BOTTOM (*new_outer),
                                              old_outer,
                                              new_outer,
                                              edge_data->bottom_edges,
                                              &edge_data->bottom_data,
                                              timeout_func,
                                              FALSE,
                                              keyboard_op);
        }
      else
        {
          new_top    = new_outer->y;
          new_bottom = new_outer->y + new_outer->height;
        }
    }

  /* Determine whether anything changed, and save the changes */
  modified_rect = meta_rect (new_left,
                             new_top,
                             new_right - new_left,
                             new_bottom - new_top);
  modified = !meta_rectangle_equal (new_outer, &modified_rect);
  *new_outer = modified_rect;
  return modified;
}

void
meta_display_cleanup_edges (MetaDisplay *display)
{
  guint i,j;
  MetaEdgeResistanceData *edge_data = display->grab_edge_resistance_data;
  GHashTable *edges_to_be_freed;

  if (edge_data == NULL) /* Not currently cached */
    return;

  /* We first need to clean out any window edges */
  edges_to_be_freed = g_hash_table_new_full (g_direct_hash, g_direct_equal,
                                             g_free, NULL);
  for (i = 0; i < 4; i++)
    {
      GArray *tmp = NULL;
      MetaSide side;
      switch (i)
        {
        case 0:
          tmp = edge_data->left_edges;
          side = META_SIDE_LEFT;
          break;
        case 1:
          tmp = edge_data->right_edges;
          side = META_SIDE_RIGHT;
          break;
        case 2:
          tmp = edge_data->top_edges;
          side = META_SIDE_TOP;
          break;
        case 3:
          tmp = edge_data->bottom_edges;
          side = META_SIDE_BOTTOM;
          break;
        default:
          g_assert_not_reached ();
        }

      for (j = 0; j < tmp->len; j++)
        {
          MetaEdge *edge = g_array_index (tmp, MetaEdge*, j);
          if (edge->edge_type == META_EDGE_WINDOW &&
              edge->side_type == side)
            {
              /* The same edge will appear in two arrays, and we can't free
               * it yet we still need to compare edge->side_type for the other
               * array that it is in.  So store it in a hash table for later
               * freeing.  Could also do this in a simple linked list.
               */
              g_hash_table_insert (edges_to_be_freed, edge, edge);
            }
        }
    }

  /* Now free all the window edges (the key destroy function is g_free) */
  g_hash_table_destroy (edges_to_be_freed);

  /* Now free the arrays and data */
  g_array_free (edge_data->left_edges, TRUE);
  g_array_free (edge_data->right_edges, TRUE);
  g_array_free (edge_data->top_edges, TRUE);
  g_array_free (edge_data->bottom_edges, TRUE);
  edge_data->left_edges = NULL;
  edge_data->right_edges = NULL;
  edge_data->top_edges = NULL;
  edge_data->bottom_edges = NULL;

  /* Cleanup the timeouts */
  if (edge_data->left_data.timeout_setup   &&
      edge_data->left_data.timeout_id   != 0)
    g_source_remove (edge_data->left_data.timeout_id);
  if (edge_data->right_data.timeout_setup  &&
      edge_data->right_data.timeout_id  != 0)
    g_source_remove (edge_data->right_data.timeout_id);
  if (edge_data->top_data.timeout_setup    &&
      edge_data->top_data.timeout_id    != 0)
    g_source_remove (edge_data->top_data.timeout_id);
  if (edge_data->bottom_data.timeout_setup &&
      edge_data->bottom_data.timeout_id != 0)
    g_source_remove (edge_data->bottom_data.timeout_id);

  g_free (display->grab_edge_resistance_data);
  display->grab_edge_resistance_data = NULL;
}

static int
stupid_sort_requiring_extra_pointer_dereference (gconstpointer a,
                                                 gconstpointer b)
{
  const MetaEdge * const *a_edge = a;
  const MetaEdge * const *b_edge = b;
  return meta_rectangle_edge_cmp_ignore_type (*a_edge, *b_edge);
}

static void
cache_edges (MetaDisplay *display,
             GList *window_edges,
             GList *xinerama_edges,
             GList *screen_edges)
{
  MetaEdgeResistanceData *edge_data;
  GList *tmp;<--- Variable 'tmp' can be declared as pointer to const
  int num_left, num_right, num_top, num_bottom;
  int i;

  /*
   * 0th: Print debugging information to the log about the edges
   */
#ifdef WITH_VERBOSE_MODE
  if (meta_is_verbose())
    {
      int max_edges = MAX (MAX( g_list_length (window_edges),
                                g_list_length (xinerama_edges)),
                           g_list_length (screen_edges));
      char big_buffer[(EDGE_LENGTH+2)*max_edges];

      meta_rectangle_edge_list_to_string (window_edges, ", ", big_buffer);
      meta_topic (META_DEBUG_EDGE_RESISTANCE,
                  "Window edges for resistance  : %s\n", big_buffer);

      meta_rectangle_edge_list_to_string (xinerama_edges, ", ", big_buffer);
      meta_topic (META_DEBUG_EDGE_RESISTANCE,
                  "Xinerama edges for resistance: %s\n", big_buffer);

      meta_rectangle_edge_list_to_string (screen_edges, ", ", big_buffer);
      meta_topic (META_DEBUG_EDGE_RESISTANCE,
                  "Screen edges for resistance  : %s\n", big_buffer);
    }
#endif

  /*
   * 1st: Get the total number of each kind of edge
   */
  num_left = num_right = num_top = num_bottom = 0;
  for (i = 0; i < 3; i++)
    {
      tmp = NULL;
      switch (i)
        {
        case 0:
          tmp = window_edges;
          break;
        case 1:
          tmp = xinerama_edges;
          break;
        case 2:
          tmp = screen_edges;
          break;
        default:
          g_assert_not_reached ();
        }

      while (tmp)
        {
          MetaEdge *edge = tmp->data;<--- Variable 'edge' can be declared as pointer to const
          switch (edge->side_type)
            {
            case META_SIDE_LEFT:
              num_left++;
              break;
            case META_SIDE_RIGHT:
              num_right++;
              break;
            case META_SIDE_TOP:
              num_top++;
              break;
            case META_SIDE_BOTTOM:
              num_bottom++;
              break;
            default:
              g_assert_not_reached ();
            }
          tmp = tmp->next;
        }
    }

  /*
   * 2nd: Allocate the edges
   */
  g_assert (display->grab_edge_resistance_data == NULL);
  display->grab_edge_resistance_data = g_new (MetaEdgeResistanceData, 1);
  edge_data = display->grab_edge_resistance_data;
  edge_data->left_edges   = g_array_sized_new (FALSE,
                                               FALSE,
                                               sizeof(MetaEdge*),
                                               num_left + num_right);
  edge_data->right_edges  = g_array_sized_new (FALSE,
                                               FALSE,
                                               sizeof(MetaEdge*),
                                               num_left + num_right);
  edge_data->top_edges    = g_array_sized_new (FALSE,
                                               FALSE,
                                               sizeof(MetaEdge*),
                                               num_top + num_bottom);
  edge_data->bottom_edges = g_array_sized_new (FALSE,
                                               FALSE,
                                               sizeof(MetaEdge*),
                                               num_top + num_bottom);

  /*
   * 3rd: Add the edges to the arrays
   */
  for (i = 0; i < 3; i++)
    {
      tmp = NULL;
      switch (i)
        {
        case 0:
          tmp = window_edges;
          break;
        case 1:
          tmp = xinerama_edges;
          break;
        case 2:
          tmp = screen_edges;
          break;
        default:
          g_assert_not_reached ();
        }

      while (tmp)
        {
          MetaEdge *edge = tmp->data;
          switch (edge->side_type)
            {
            case META_SIDE_LEFT:
            case META_SIDE_RIGHT:
              g_array_append_val (edge_data->left_edges, edge);
              g_array_append_val (edge_data->right_edges, edge);
              break;
            case META_SIDE_TOP:
            case META_SIDE_BOTTOM:
              g_array_append_val (edge_data->top_edges, edge);
              g_array_append_val (edge_data->bottom_edges, edge);
              break;
            default:
              g_assert_not_reached ();
            }
          tmp = tmp->next;
        }
    }

  /*
   * 4th: Sort the arrays (FIXME: This is kinda dumb since the arrays were
   * individually sorted earlier and we could have done this faster and
   * avoided this sort by sticking them into the array with some simple
   * merging of the lists).
   */
  g_array_sort (display->grab_edge_resistance_data->left_edges,
                stupid_sort_requiring_extra_pointer_dereference);
  g_array_sort (display->grab_edge_resistance_data->right_edges,
                stupid_sort_requiring_extra_pointer_dereference);
  g_array_sort (display->grab_edge_resistance_data->top_edges,
                stupid_sort_requiring_extra_pointer_dereference);
  g_array_sort (display->grab_edge_resistance_data->bottom_edges,
                stupid_sort_requiring_extra_pointer_dereference);
}

static void
initialize_grab_edge_resistance_data (MetaDisplay *display)
{
  MetaEdgeResistanceData *edge_data = display->grab_edge_resistance_data;

  edge_data->left_data.timeout_setup   = FALSE;
  edge_data->right_data.timeout_setup  = FALSE;
  edge_data->top_data.timeout_setup    = FALSE;
  edge_data->bottom_data.timeout_setup = FALSE;

  edge_data->left_data.keyboard_buildup   = 0;
  edge_data->right_data.keyboard_buildup  = 0;
  edge_data->top_data.keyboard_buildup    = 0;
  edge_data->bottom_data.keyboard_buildup = 0;
}

static void
compute_resistance_and_snapping_edges (MetaDisplay *display)
{
  GList *stacked_windows;
  GList *cur_window_iter;
  GList *edges;
  /* Lists of window positions (rects) and their relative stacking positions */
  int stack_position;
  GSList *obscuring_windows, *window_stacking;
  /* The portions of the above lists that still remain at the stacking position
   * in the layer that we are working on
   */
  GSList *rem_windows, *rem_win_stacking;

  g_assert (display->grab_window != NULL);
  meta_topic (META_DEBUG_WINDOW_OPS,
              "Computing edges to resist-movement or snap-to for %s.\n",
              display->grab_window->desc);

  /*
   * 1st: Get the list of relevant windows, from bottom to top
   */
  stacked_windows =
    meta_stack_list_windows (display->grab_screen->stack,
                             display->grab_screen->active_workspace);

  /*
   * 2nd: we need to separate that stacked list into a list of windows that
   * can obscure other edges.  To make sure we only have windows obscuring
   * those below it instead of going both ways, we also need to keep a
   * counter list.  Messy, I know.
   */
  obscuring_windows = window_stacking = NULL;
  cur_window_iter = stacked_windows;
  stack_position = 0;
  while (cur_window_iter != NULL)
    {
      MetaWindow *cur_window = cur_window_iter->data;
      if (WINDOW_EDGES_RELEVANT (cur_window, display))
        {
          MetaRectangle *new_rect;
          new_rect = g_new (MetaRectangle, 1);
          meta_window_get_outer_rect (cur_window, new_rect);
          obscuring_windows = g_slist_prepend (obscuring_windows, new_rect);
          window_stacking =
            g_slist_prepend (window_stacking, GINT_TO_POINTER (stack_position));
        }

      stack_position++;
      cur_window_iter = cur_window_iter->next;
    }
  /* Put 'em in bottom to top order */
  rem_windows = obscuring_windows = g_slist_reverse (obscuring_windows);
  rem_win_stacking = window_stacking = g_slist_reverse (window_stacking);

  /*
   * 3rd: loop over the windows again, this time getting the edges from
   * them and removing intersections with the relevant obscuring_windows &
   * obscuring_docks.
   */
  edges = NULL;
  stack_position = 0;
  cur_window_iter = stacked_windows;
  while (cur_window_iter != NULL)
    {
      MetaRectangle  cur_rect;
      MetaWindow    *cur_window = cur_window_iter->data;
      meta_window_get_outer_rect (cur_window, &cur_rect);

      /* Check if we want to use this window's edges for edge
       * resistance (note that dock edges are considered screen edges
       * which are handled separately
       */
      if (WINDOW_EDGES_RELEVANT (cur_window, display) &&
          cur_window->type != META_WINDOW_DOCK)
        {
          GList *new_edges;
          MetaEdge *new_edge;
          MetaRectangle reduced;

          /* We don't care about snapping to any portion of the window that
           * is offscreen (we also don't care about parts of edges covered
           * by other windows or DOCKS, but that's handled below).
           */
          meta_rectangle_intersect (&cur_rect,
                                    &display->grab_screen->rect,
                                    &reduced);

          new_edges = NULL;

          /* Left side of this window is resistance for the right edge of
           * the window being moved.
           */
          new_edge = g_new (MetaEdge, 1);
          new_edge->rect = reduced;
          new_edge->rect.width = 0;
          new_edge->side_type = META_SIDE_RIGHT;
          new_edge->edge_type = META_EDGE_WINDOW;
          new_edges = g_list_prepend (new_edges, new_edge);

          /* Right side of this window is resistance for the left edge of
           * the window being moved.
           */
          new_edge = g_new (MetaEdge, 1);
          new_edge->rect = reduced;
          new_edge->rect.x += new_edge->rect.width;
          new_edge->rect.width = 0;
          new_edge->side_type = META_SIDE_LEFT;
          new_edge->edge_type = META_EDGE_WINDOW;
          new_edges = g_list_prepend (new_edges, new_edge);

          /* Top side of this window is resistance for the bottom edge of
           * the window being moved.
           */
          new_edge = g_new (MetaEdge, 1);
          new_edge->rect = reduced;
          new_edge->rect.height = 0;
          new_edge->side_type = META_SIDE_BOTTOM;
          new_edge->edge_type = META_EDGE_WINDOW;
          new_edges = g_list_prepend (new_edges, new_edge);

          /* Top side of this window is resistance for the bottom edge of
           * the window being moved.
           */
          new_edge = g_new (MetaEdge, 1);
          new_edge->rect = reduced;
          new_edge->rect.y += new_edge->rect.height;
          new_edge->rect.height = 0;
          new_edge->side_type = META_SIDE_TOP;
          new_edge->edge_type = META_EDGE_WINDOW;
          new_edges = g_list_prepend (new_edges, new_edge);

          /* Update the remaining windows to only those at a higher
           * stacking position than this one.
           */
          while (rem_win_stacking &&
                 stack_position >= GPOINTER_TO_INT (rem_win_stacking->data))
            {
              rem_windows      = rem_windows->next;
              rem_win_stacking = rem_win_stacking->next;
            }

          /* Remove edge portions overlapped by rem_windows and rem_docks */
          new_edges =
            meta_rectangle_remove_intersections_with_boxes_from_edges (
              new_edges,
              rem_windows);

          /* Save the new edges */
          edges = g_list_concat (new_edges, edges);
        }

      stack_position++;
      cur_window_iter = cur_window_iter->next;
    }

  /*
   * 4th: Free the extra memory not needed and sort the list
   */
  g_list_free (stacked_windows);
  /* Free the memory used by the obscuring windows/docks lists */
  g_slist_free (window_stacking);
  g_slist_free_full (obscuring_windows, g_free);

  /* Sort the list.  FIXME: Should I bother with this sorting?  I just
   * sort again later in cache_edges() anyway...
   */
  edges = g_list_sort (edges, meta_rectangle_edge_cmp);

  /*
   * 5th: Cache the combination of these edges with the onscreen and
   * xinerama edges in an array for quick access.  Free the edges since
   * they've been cached elsewhere.
   */
  cache_edges (display,
               edges,
               display->grab_screen->active_workspace->xinerama_edges,
               display->grab_screen->active_workspace->screen_edges);
  g_list_free (edges);

  /*
   * 6th: Initialize the resistance timeouts and buildups
   */
  initialize_grab_edge_resistance_data (display);
}

/* Note that old_[xy] and new_[xy] are with respect to inner positions of
 * the window.
 */
void
meta_window_edge_resistance_for_move (MetaWindow  *window,
                                      int          old_x,
                                      int          old_y,
                                      int         *new_x,
                                      int         *new_y,
                                      GSourceFunc  timeout_func,
                                      gboolean     snap,
                                      gboolean     is_keyboard_op)
{
  MetaRectangle old_outer, proposed_outer, new_outer;
  gboolean is_resize;

  if (window == window->display->grab_window &&
      window->display->grab_wireframe_active)
    {
      meta_window_get_xor_rect (window,
                                &window->display->grab_wireframe_rect,
                                &old_outer);
    }
  else
    {
      meta_window_get_outer_rect (window, &old_outer);
    }
  proposed_outer = old_outer;
  proposed_outer.x += (*new_x - old_x);
  proposed_outer.y += (*new_y - old_y);
  new_outer = proposed_outer;

  window->display->grab_last_user_action_was_snap = snap;
  is_resize = FALSE;
  if (apply_edge_resistance_to_each_side (window->display,
                                          window,
                                          &old_outer,
                                          &new_outer,
                                          timeout_func,
                                          snap,
                                          is_keyboard_op,
                                          is_resize))
    {
      /* apply_edge_resistance_to_each_side independently applies
       * resistance to both the right and left edges of new_outer as both
       * could meet areas of resistance.  But we don't want a resize, so we
       * just have both edges move according to the stricter of the
       * resistances.  Same thing goes for top & bottom edges.
       */
      MetaRectangle *reference;
      int left_change, right_change, smaller_x_change;
      int top_change, bottom_change, smaller_y_change;

      if (snap && !is_keyboard_op)
        reference = &proposed_outer;
      else
        reference = &old_outer;

      left_change  = BOX_LEFT (new_outer)  - BOX_LEFT (*reference);
      right_change = BOX_RIGHT (new_outer) - BOX_RIGHT (*reference);
      if (     snap && is_keyboard_op && left_change == 0)
        smaller_x_change = right_change;
      else if (snap && is_keyboard_op && right_change == 0)
        smaller_x_change = left_change;
      else if (ABS (left_change) < ABS (right_change))
        smaller_x_change = left_change;
      else
        smaller_x_change = right_change;

      top_change    = BOX_TOP (new_outer)    - BOX_TOP (*reference);
      bottom_change = BOX_BOTTOM (new_outer) - BOX_BOTTOM (*reference);
      if (     snap && is_keyboard_op && top_change == 0)
        smaller_y_change = bottom_change;
      else if (snap && is_keyboard_op && bottom_change == 0)
        smaller_y_change = top_change;
      else if (ABS (top_change) < ABS (bottom_change))
        smaller_y_change = top_change;
      else
        smaller_y_change = bottom_change;

      *new_x = old_x + smaller_x_change +
              (BOX_LEFT (*reference) - BOX_LEFT (old_outer));
      *new_y = old_y + smaller_y_change +
              (BOX_TOP (*reference) - BOX_TOP (old_outer));

      meta_topic (META_DEBUG_EDGE_RESISTANCE,
                  "outer x & y move-to coordinate changed from %d,%d to %d,%d\n",
                  proposed_outer.x, proposed_outer.y,
                  old_outer.x + (*new_x - old_x),
                  old_outer.y + (*new_y - old_y));
    }
}

/* Note that old_(width|height) and new_(width|height) are with respect to
 * sizes of the inner window.
 */
void
meta_window_edge_resistance_for_resize (MetaWindow  *window,
                                        int          old_width,
                                        int          old_height,
                                        int         *new_width,
                                        int         *new_height,
                                        int          gravity,
                                        GSourceFunc  timeout_func,
                                        gboolean     snap,
                                        gboolean     is_keyboard_op)
{
  MetaRectangle old_outer, new_outer;
  int proposed_outer_width, proposed_outer_height;
  gboolean is_resize;

  if (window == window->display->grab_window &&
      window->display->grab_wireframe_active)
    {
      meta_window_get_xor_rect (window,
                                &window->display->grab_wireframe_rect,
                                &old_outer);
    }
  else
    {
      meta_window_get_outer_rect (window, &old_outer);
    }
  proposed_outer_width  = old_outer.width  + (*new_width  - old_width);
  proposed_outer_height = old_outer.height + (*new_height - old_height);
  meta_rectangle_resize_with_gravity (&old_outer,
                                      &new_outer,
                                      gravity,
                                      proposed_outer_width,
                                      proposed_outer_height);

  window->display->grab_last_user_action_was_snap = snap;
  is_resize = TRUE;
  if (apply_edge_resistance_to_each_side (window->display,
                                          window,
                                          &old_outer,
                                          &new_outer,
                                          timeout_func,
                                          snap,
                                          is_keyboard_op,
                                          is_resize))
    {
      *new_width  = old_width  + (new_outer.width  - old_outer.width);
      *new_height = old_height + (new_outer.height - old_outer.height);

      meta_topic (META_DEBUG_EDGE_RESISTANCE,
                  "outer width & height got changed from %d,%d to %d,%d\n",
                  proposed_outer_width, proposed_outer_height,
                  new_outer.width, new_outer.height);
    }
}