src/evdev-mt-touchpad.c

   1 /*
   2  * Copyright © 2014 Red Hat, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and
   5  * its documentation for any purpose is hereby granted without fee, provided
   6  * that the above copyright notice appear in all copies and that both that
   7  * copyright notice and this permission notice appear in supporting
   8  * documentation, and that the name of the copyright holders not be used in
   9  * advertising or publicity pertaining to distribution of the software
  10  * without specific, written prior permission.  The copyright holders make
  11  * no representations about the suitability of this software for any
  12  * purpose.  It is provided "as is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
  15  * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
  16  * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
  17  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
  18  * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
  19  * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  20  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  21  */
  22
  23 #include "config.h"
  24
  25 #include <assert.h>
  26 #include <math.h>
  27 #include <stdbool.h>
  28
  29 #include "evdev-mt-touchpad.h"
  30
  31 #define DEFAULT_CONSTANT_ACCEL_NUMERATOR 100
  32 #define DEFAULT_MIN_ACCEL_FACTOR 0.20
  33 #define DEFAULT_MAX_ACCEL_FACTOR 0.40
  34 #define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0
  35
  36 static inline int
  37 tp_hysteresis(int in, int center, int margin)
  38 {
  39         int diff = in - center;
  40         if (abs(diff) <= margin)
  41                 return center;
  42
  43         if (diff > margin)
  44                 return center + diff - margin;
  45         else if (diff < -margin)
  46                 return center + diff + margin;
  47         return center + diff;
  48 }
  49
  50 static double
  51 tp_accel_profile(struct motion_filter *filter,
  52                  void *data,
  53                  double velocity,
  54                  uint64_t time)
  55 {
  56         struct tp_dispatch *tp =
  57                 (struct tp_dispatch *) data;
  58
  59         double accel_factor;
  60
  61         accel_factor = velocity * tp->accel.constant_factor;
  62
  63         if (accel_factor > tp->accel.max_factor)
  64                 accel_factor = tp->accel.max_factor;
  65         else if (accel_factor < tp->accel.min_factor)
  66                 accel_factor = tp->accel.min_factor;
  67
  68         return accel_factor;
  69 }
  70
  71 static inline struct tp_motion *
  72 tp_motion_history_offset(struct tp_touch *t, int offset)
  73 {
  74         int offset_index =
  75                 (t->history.index - offset + TOUCHPAD_HISTORY_LENGTH) %
  76                 TOUCHPAD_HISTORY_LENGTH;
  77
  78         return &t->history.samples[offset_index];
  79 }
  80
  81 static void
  82 tp_filter_motion(struct tp_dispatch *tp,
  83                  double *dx, double *dy, uint64_t time)
  84 {
  85         struct motion_params motion;
  86
  87         motion.dx = *dx * tp->accel.x_scale_coeff;
  88         motion.dy = *dy * tp->accel.y_scale_coeff;
  89
  90         filter_dispatch(tp->filter, &motion, tp, time);
  91
  92         *dx = motion.dx;
  93         *dy = motion.dy;
  94 }
  95
  96 static inline void
  97 tp_motion_history_push(struct tp_touch *t)
  98 {
  99         int motion_index = (t->history.index + 1) % TOUCHPAD_HISTORY_LENGTH;
 100
 101         if (t->history.count < TOUCHPAD_HISTORY_LENGTH)
 102                 t->history.count++;
 103
 104         t->history.samples[motion_index].x = t->x;
 105         t->history.samples[motion_index].y = t->y;
 106         t->history.index = motion_index;
 107 }
 108
 109 static inline void
 110 tp_motion_hysteresis(struct tp_dispatch *tp,
 111                      struct tp_touch *t)
 112 {
 113         int x = t->x,
 114             y = t->y;
 115
 116         if (t->history.count == 0) {
 117                 t->hysteresis.center_x = t->x;
 118                 t->hysteresis.center_y = t->y;
 119         } else {
 120                 x = tp_hysteresis(x,
 121                                   t->hysteresis.center_x,
 122                                   tp->hysteresis.margin_x);
 123                 y = tp_hysteresis(y,
 124                                   t->hysteresis.center_y,
 125                                   tp->hysteresis.margin_y);
 126                 t->hysteresis.center_x = x;
 127                 t->hysteresis.center_y = y;
 128                 t->x = x;
 129                 t->y = y;
 130         }
 131 }
 132
 133 static inline void
 134 tp_motion_history_reset(struct tp_touch *t)
 135 {
 136         t->history.count = 0;
 137 }
 138
 139 static inline struct tp_touch *
 140 tp_current_touch(struct tp_dispatch *tp)
 141 {
 142         return &tp->touches[min(tp->slot, tp->ntouches - 1)];
 143 }
 144
 145 static inline struct tp_touch *
 146 tp_get_touch(struct tp_dispatch *tp, unsigned int slot)
 147 {
 148         assert(slot < tp->ntouches);
 149         return &tp->touches[slot];
 150 }
 151
 152 static inline void
 153 tp_begin_touch(struct tp_dispatch *tp, struct tp_touch *t)
 154 {
 155         if (t->state != TOUCH_UPDATE) {
 156                 tp_motion_history_reset(t);
 157                 t->dirty = true;
 158                 t->state = TOUCH_BEGIN;
 159                 t->pinned.is_pinned = false;
 160                 tp->nfingers_down++;
 161                 assert(tp->nfingers_down >= 1);
 162                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 163         }
 164 }
 165
 166 static inline void
 167 tp_end_touch(struct tp_dispatch *tp, struct tp_touch *t)
 168 {
 169         if (t->state == TOUCH_NONE)
 170                 return;
 171
 172         t->dirty = true;
 173         t->is_pointer = false;
 174         t->state = TOUCH_END;
 175         t->pinned.is_pinned = false;
 176         assert(tp->nfingers_down >= 1);
 177         tp->nfingers_down--;
 178         tp->queued |= TOUCHPAD_EVENT_MOTION;
 179 }
 180
 181 static double
 182 tp_estimate_delta(int x0, int x1, int x2, int x3)
 183 {
 184         return (x0 + x1 - x2 - x3) / 4;
 185 }
 186
 187 void
 188 tp_get_delta(struct tp_touch *t, double *dx, double *dy)
 189 {
 190         if (t->history.count < 4) {
 191                 *dx = 0;
 192                 *dy = 0;
 193                 return;
 194         }
 195
 196         *dx = tp_estimate_delta(tp_motion_history_offset(t, 0)->x,
 197                                 tp_motion_history_offset(t, 1)->x,
 198                                 tp_motion_history_offset(t, 2)->x,
 199                                 tp_motion_history_offset(t, 3)->x);
 200         *dy = tp_estimate_delta(tp_motion_history_offset(t, 0)->y,
 201                                 tp_motion_history_offset(t, 1)->y,
 202                                 tp_motion_history_offset(t, 2)->y,
 203                                 tp_motion_history_offset(t, 3)->y);
 204 }
 205
 206 static void
 207 tp_process_absolute(struct tp_dispatch *tp,
 208                     const struct input_event *e,
 209                     uint64_t time)
 210 {
 211         struct tp_touch *t = tp_current_touch(tp);
 212
 213         switch(e->code) {
 214         case ABS_MT_POSITION_X:
 215                 t->x = e->value;
 216                 t->millis = time;
 217                 t->dirty = true;
 218                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 219                 break;
 220         case ABS_MT_POSITION_Y:
 221                 t->y = e->value;
 222                 t->millis = time;
 223                 t->dirty = true;
 224                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 225                 break;
 226         case ABS_MT_SLOT:
 227                 tp->slot = e->value;
 228                 break;
 229         case ABS_MT_TRACKING_ID:
 230                 t->millis = time;
 231                 if (e->value != -1)
 232                         tp_begin_touch(tp, t);
 233                 else
 234                         tp_end_touch(tp, t);
 235         }
 236 }
 237
 238 static void
 239 tp_process_absolute_st(struct tp_dispatch *tp,
 240                        const struct input_event *e,
 241                        uint64_t time)
 242 {
 243         struct tp_touch *t = tp_current_touch(tp);
 244
 245         switch(e->code) {
 246         case ABS_X:
 247                 t->x = e->value;
 248                 t->millis = time;
 249                 t->dirty = true;
 250                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 251                 break;
 252         case ABS_Y:
 253                 t->y = e->value;
 254                 t->millis = time;
 255                 t->dirty = true;
 256                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 257                 break;
 258         }
 259 }
 260
 261 static void
 262 tp_process_fake_touch(struct tp_dispatch *tp,
 263                       const struct input_event *e,
 264                       uint64_t time)
 265 {
 266         struct tp_touch *t;
 267         unsigned int fake_touches;
 268         unsigned int nfake_touches;
 269         unsigned int i;
 270         unsigned int shift;
 271
 272         if (e->code != BTN_TOUCH &&
 273             (e->code < BTN_TOOL_DOUBLETAP || e->code > BTN_TOOL_QUADTAP))
 274                 return;
 275
 276         shift = e->code == BTN_TOUCH ? 0 : (e->code - BTN_TOOL_DOUBLETAP + 1);
 277
 278         if (e->value)
 279                 tp->fake_touches |= 1 << shift;
 280         else
 281                 tp->fake_touches &= ~(0x1 << shift);
 282
 283         fake_touches = tp->fake_touches;
 284         nfake_touches = 0;
 285         while (fake_touches) {
 286                 nfake_touches++;
 287                 fake_touches >>= 1;
 288         }
 289
 290         for (i = 0; i < tp->ntouches; i++) {
 291                 t = tp_get_touch(tp, i);
 292                 if (i >= nfake_touches) {
 293                         if (t->state != TOUCH_NONE) {
 294                                 tp_end_touch(tp, t);
 295                                 t->millis = time;
 296                         }
 297                 } else if (t->state != TOUCH_UPDATE &&
 298                            t->state != TOUCH_BEGIN) {
 299                         t->state = TOUCH_NONE;
 300                         tp_begin_touch(tp, t);
 301                         t->millis = time;
 302                         t->fake =true;
 303                 }
 304         }
 305
 306         assert(tp->nfingers_down == nfake_touches);
 307 }
 308
 309 static void
 310 tp_process_key(struct tp_dispatch *tp,
 311                const struct input_event *e,
 312                uint64_t time)
 313 {
 314         switch (e->code) {
 315                 case BTN_LEFT:
 316                 case BTN_MIDDLE:
 317                 case BTN_RIGHT:
 318                         tp_process_button(tp, e, time);
 319                         break;
 320                 case BTN_TOUCH:
 321                 case BTN_TOOL_DOUBLETAP:
 322                 case BTN_TOOL_TRIPLETAP:
 323                 case BTN_TOOL_QUADTAP:
 324                         if (!tp->has_mt)
 325                                 tp_process_fake_touch(tp, e, time);
 326                         break;
 327         }
 328 }
 329
 330 static void
 331 tp_unpin_finger(struct tp_dispatch *tp, struct tp_touch *t)
 332 {
 333         unsigned int xdist, ydist;
 334
 335         if (!t->pinned.is_pinned)
 336                 return;
 337
 338         xdist = abs(t->x - t->pinned.center_x);
 339         ydist = abs(t->y - t->pinned.center_y);
 340
 341         if (xdist * xdist + ydist * ydist >=
 342                         tp->buttons.motion_dist * tp->buttons.motion_dist) {
 343                 t->pinned.is_pinned = false;
 344                 tp_set_pointer(tp, t);
 345         }
 346 }
 347
 348 static void
 349 tp_pin_fingers(struct tp_dispatch *tp)
 350 {
 351         struct tp_touch *t;
 352
 353         tp_for_each_touch(tp, t) {
 354                 t->is_pointer = false;
 355                 t->pinned.is_pinned = true;
 356                 t->pinned.center_x = t->x;
 357                 t->pinned.center_y = t->y;
 358         }
 359 }
 360
 361 static int
 362 tp_touch_active(struct tp_dispatch *tp, struct tp_touch *t)
 363 {
 364         return (t->state == TOUCH_BEGIN || t->state == TOUCH_UPDATE) &&
 365                 !t->pinned.is_pinned && tp_button_touch_active(tp, t);
 366 }
 367
 368 void
 369 tp_set_pointer(struct tp_dispatch *tp, struct tp_touch *t)
 370 {
 371         struct tp_touch *tmp = NULL;
 372
 373         /* Only set the touch as pointer if we don't have one yet */
 374         tp_for_each_touch(tp, tmp) {
 375                 if (tmp->is_pointer)
 376                         return;
 377         }
 378
 379         if (tp_touch_active(tp, t))
 380                 t->is_pointer = true;
 381 }
 382
 383 static void
 384 tp_process_state(struct tp_dispatch *tp, uint64_t time)
 385 {
 386         struct tp_touch *t;
 387         struct tp_touch *first = tp_get_touch(tp, 0);
 388
 389         tp_for_each_touch(tp, t) {
 390                 if (!tp->has_mt && t != first && first->fake) {
 391                         t->x = first->x;
 392                         t->y = first->y;
 393                         if (!t->dirty)
 394                                 t->dirty = first->dirty;
 395                 } else if (!t->dirty)
 396                         continue;
 397
 398                 tp_motion_hysteresis(tp, t);
 399                 tp_motion_history_push(t);
 400
 401                 tp_unpin_finger(tp, t);
 402         }
 403
 404         tp_button_handle_state(tp, time);
 405
 406         /*
 407          * We have a physical button down event on a clickpad. To avoid
 408          * spurious pointer moves by the clicking finger we pin all fingers.
 409          * We unpin fingers when they move more then a certain threshold to
 410          * to allow drag and drop.
 411          */
 412         if ((tp->queued & TOUCHPAD_EVENT_BUTTON_PRESS) &&
 413             tp->buttons.is_clickpad)
 414                 tp_pin_fingers(tp);
 415 }
 416
 417 static void
 418 tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
 419 {
 420         struct tp_touch *t;
 421
 422         tp_for_each_touch(tp, t) {
 423                 if (!t->dirty)
 424                         continue;
 425
 426                 if (t->state == TOUCH_END) {
 427                         t->state = TOUCH_NONE;
 428                         t->fake = false;
 429                 } else if (t->state == TOUCH_BEGIN)
 430                         t->state = TOUCH_UPDATE;
 431
 432                 t->dirty = false;
 433         }
 434
 435         tp->buttons.old_state = tp->buttons.state;
 436
 437         tp->queued = TOUCHPAD_EVENT_NONE;
 438 }
 439
 440 static void
 441 tp_post_twofinger_scroll(struct tp_dispatch *tp, uint64_t time)
 442 {
 443         struct tp_touch *t;
 444         int nchanged = 0;
 445         double dx = 0, dy =0;
 446         double tmpx, tmpy;
 447
 448         tp_for_each_touch(tp, t) {
 449                 if (tp_touch_active(tp, t) && t->dirty) {
 450                         nchanged++;
 451                         tp_get_delta(t, &tmpx, &tmpy);
 452
 453                         dx += tmpx;
 454                         dy += tmpy;
 455                 }
 456                 /* Stop spurious MOTION events at the end of scrolling */
 457                 t->is_pointer = false;
 458         }
 459
 460         if (nchanged == 0)
 461                 return;
 462
 463         dx /= nchanged;
 464         dy /= nchanged;
 465
 466         tp_filter_motion(tp, &dx, &dy, time);
 467
 468         /* Require at least three px scrolling to start */
 469         if (dy <= -3.0 || dy >= 3.0)
 470                 tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL);
 471
 472         if (dx <= -3.0 || dx >= 3.0)
 473                 tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL);
 474
 475         if (dy != 0.0 &&
 476             (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))) {
 477                 pointer_notify_axis(&tp->device->base,
 478                                     time,
 479                                     LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
 480                                     dy);
 481         }
 482
 483         if (dx != 0.0 &&
 484             (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))) {
 485                 pointer_notify_axis(&tp->device->base,
 486                                     time,
 487                                     LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
 488                                     dx);
 489         }
 490 }
 491
 492 static void
 493 tp_stop_scroll_events(struct tp_dispatch *tp, uint64_t time)
 494 {
 495         /* terminate scrolling with a zero scroll event */
 496         if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))
 497                 pointer_notify_axis(&tp->device->base,
 498                                     time,
 499                                     LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
 500                                     0);
 501         if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))
 502                 pointer_notify_axis(&tp->device->base,
 503                                     time,
 504                                     LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
 505                                     0);
 506
 507         tp->scroll.direction = 0;
 508 }
 509
 510 static int
 511 tp_post_scroll_events(struct tp_dispatch *tp, uint64_t time)
 512 {
 513         struct tp_touch *t;
 514         int nfingers_down = 0;
 515
 516         /* Only count active touches for 2 finger scrolling */
 517         tp_for_each_touch(tp, t) {
 518                 if (tp_touch_active(tp, t))
 519                         nfingers_down++;
 520         }
 521
 522         if (nfingers_down != 2) {
 523                 tp_stop_scroll_events(tp, time);
 524                 return 0;
 525         }
 526
 527         tp_post_twofinger_scroll(tp, time);
 528         return 1;
 529 }
 530
 531 static void
 532 tp_post_events(struct tp_dispatch *tp, uint64_t time)
 533 {
 534         struct tp_touch *t = tp_current_touch(tp);
 535         double dx, dy;
 536         int consumed = 0;
 537
 538         consumed |= tp_tap_handle_state(tp, time);
 539         consumed |= tp_post_button_events(tp, time);
 540
 541         if (consumed) {
 542                 tp_stop_scroll_events(tp, time);
 543                 return;
 544         }
 545
 546         if (tp_post_scroll_events(tp, time) != 0)
 547                 return;
 548
 549         if (t->history.count >= TOUCHPAD_MIN_SAMPLES) {
 550                 if (!t->is_pointer) {
 551                         tp_for_each_touch(tp, t) {
 552                                 if (t->is_pointer)
 553                                         break;
 554                         }
 555                 }
 556
 557                 if (!t->is_pointer)
 558                         return;
 559
 560                 tp_get_delta(t, &dx, &dy);
 561                 tp_filter_motion(tp, &dx, &dy, time);
 562
 563                 if (dx != 0.0 || dy != 0.0)
 564                         pointer_notify_motion(&tp->device->base, time, dx, dy);
 565         }
 566 }
 567
 568 static void
 569 tp_process(struct evdev_dispatch *dispatch,
 570            struct evdev_device *device,
 571            struct input_event *e,
 572            uint64_t time)
 573 {
 574         struct tp_dispatch *tp =
 575                 (struct tp_dispatch *)dispatch;
 576
 577         switch (e->type) {
 578         case EV_ABS:
 579                 if (tp->has_mt)
 580                         tp_process_absolute(tp, e, time);
 581                 else
 582                         tp_process_absolute_st(tp, e, time);
 583                 break;
 584         case EV_KEY:
 585                 tp_process_key(tp, e, time);
 586                 break;
 587         case EV_SYN:
 588                 tp_process_state(tp, time);
 589                 tp_post_events(tp, time);
 590                 tp_post_process_state(tp, time);
 591                 break;
 592         }
 593 }
 594
 595 static void
 596 tp_destroy(struct evdev_dispatch *dispatch)
 597 {
 598         struct tp_dispatch *tp =
 599                 (struct tp_dispatch*)dispatch;
 600
 601         tp_destroy_tap(tp);
 602         tp_destroy_buttons(tp);
 603
 604         motion_filter_destroy(tp->filter);
 605         free(tp->touches);
 606         free(tp);
 607 }
 608
 609 static struct evdev_dispatch_interface tp_interface = {
 610         tp_process,
 611         tp_destroy
 612 };
 613
 614 static void
 615 tp_init_touch(struct tp_dispatch *tp,
 616               struct tp_touch *t)
 617 {
 618         t->tp = tp;
 619 }
 620
 621 static int
 622 tp_init_slots(struct tp_dispatch *tp,
 623               struct evdev_device *device)
 624 {
 625         size_t i;
 626         const struct input_absinfo *absinfo;
 627
 628         absinfo = libevdev_get_abs_info(device->evdev, ABS_MT_SLOT);
 629         if (absinfo) {
 630                 tp->ntouches = absinfo->maximum + 1;
 631                 tp->slot = absinfo->value;
 632                 tp->has_mt = true;
 633         } else {
 634                 struct map {
 635                         unsigned int code;
 636                         int ntouches;
 637                 } max_touches[] = {
 638                         { BTN_TOOL_QUINTTAP, 5 },
 639                         { BTN_TOOL_QUADTAP, 4 },
 640                         { BTN_TOOL_TRIPLETAP, 3 },
 641                         { BTN_TOOL_DOUBLETAP, 2 },
 642                 };
 643                 struct map *m;
 644
 645                 tp->slot = 0;
 646                 tp->has_mt = false;
 647                 tp->ntouches = 1;
 648
 649                 ARRAY_FOR_EACH(max_touches, m) {
 650                         if (libevdev_has_event_code(device->evdev,
 651                                                     EV_KEY,
 652                                                     m->code)) {
 653                                 tp->ntouches = m->ntouches;
 654                                 break;
 655                         }
 656                 }
 657         }
 658         tp->touches = calloc(tp->ntouches,
 659                              sizeof(struct tp_touch));
 660         if (!tp->touches)
 661                 return -1;
 662
 663         for (i = 0; i < tp->ntouches; i++)
 664                 tp_init_touch(tp, &tp->touches[i]);
 665
 666         return 0;
 667 }
 668
 669 static void
 670 calculate_scale_coefficients(struct tp_dispatch *tp)
 671 {
 672         int res_x, res_y;
 673
 674         if (tp->has_mt) {
 675                 res_x = libevdev_get_abs_resolution(tp->device->evdev,
 676                                                     ABS_MT_POSITION_X);
 677                 res_y = libevdev_get_abs_resolution(tp->device->evdev,
 678                                                     ABS_MT_POSITION_Y);
 679         } else {
 680                 res_x = libevdev_get_abs_resolution(tp->device->evdev,
 681                                                     ABS_X);
 682                 res_y = libevdev_get_abs_resolution(tp->device->evdev,
 683                                                     ABS_Y);
 684         }
 685
 686         if (res_x <= 0 || res_y <= 0) {
 687                 tp->accel.x_scale_coeff = 1.0;
 688                 tp->accel.y_scale_coeff = 1.0;
 689         } else if (res_x > res_y) {
 690                 tp->accel.x_scale_coeff = res_y / (double) res_x;
 691                 tp->accel.y_scale_coeff = 1.0f;
 692         } else {
 693                 tp->accel.y_scale_coeff = res_x / (double) res_y;
 694                 tp->accel.x_scale_coeff = 1.0f;
 695         }
 696 }
 697
 698 static int
 699 tp_init_accel(struct tp_dispatch *touchpad, double diagonal)
 700 {
 701         struct motion_filter *accel;
 702
 703         calculate_scale_coefficients(touchpad);
 704
 705         touchpad->accel.constant_factor =
 706                 DEFAULT_CONSTANT_ACCEL_NUMERATOR / diagonal;
 707         touchpad->accel.min_factor = DEFAULT_MIN_ACCEL_FACTOR;
 708         touchpad->accel.max_factor = DEFAULT_MAX_ACCEL_FACTOR;
 709
 710         accel = create_pointer_accelator_filter(tp_accel_profile);
 711         if (accel == NULL)
 712                 return -1;
 713
 714         touchpad->filter = accel;
 715
 716         return 0;
 717 }
 718
 719 static int
 720 tp_init_scroll(struct tp_dispatch *tp)
 721 {
 722         tp->scroll.direction = 0;
 723
 724         return 0;
 725 }
 726
 727 static int
 728 tp_init(struct tp_dispatch *tp,
 729         struct evdev_device *device)
 730 {
 731         int width, height;
 732         double diagonal;
 733
 734         tp->base.interface = &tp_interface;
 735         tp->device = device;
 736
 737         if (tp_init_slots(tp, device) != 0)
 738                 return -1;
 739
 740         width = abs(device->abs.absinfo_x->maximum -
 741                     device->abs.absinfo_x->minimum);
 742         height = abs(device->abs.absinfo_y->maximum -
 743                      device->abs.absinfo_y->minimum);
 744         diagonal = sqrt(width*width + height*height);
 745
 746         tp->hysteresis.margin_x =
 747                 diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
 748         tp->hysteresis.margin_y =
 749                 diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
 750
 751         if (tp_init_scroll(tp) != 0)
 752                 return -1;
 753
 754         if (tp_init_accel(tp, diagonal) != 0)
 755                 return -1;
 756
 757         if (tp_init_tap(tp) != 0)
 758                 return -1;
 759
 760         if (tp_init_buttons(tp, device) != 0)
 761                 return -1;
 762
 763         return 0;
 764 }
 765
 766 struct evdev_dispatch *
 767 evdev_mt_touchpad_create(struct evdev_device *device)
 768 {
 769         struct tp_dispatch *tp;
 770
 771         tp = zalloc(sizeof *tp);
 772         if (!tp)
 773                 return NULL;
 774
 775         if (tp_init(tp, device) != 0) {
 776                 tp_destroy(&tp->base);
 777                 return NULL;
 778         }
 779
 780         return  &tp->base;
 781 }