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_ACCEL_NUMERATOR 1200.0
  32 #define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0
  33
  34 static inline int
  35 tp_hysteresis(int in, int center, int margin)
  36 {
  37         int diff = in - center;
  38         if (abs(diff) <= margin)
  39                 return center;
  40
  41         if (diff > margin)
  42                 return center + diff - margin;
  43         else
  44                 return center + diff + margin;
  45 }
  46
  47 static inline struct tp_motion *
  48 tp_motion_history_offset(struct tp_touch *t, int offset)
  49 {
  50         int offset_index =
  51                 (t->history.index - offset + TOUCHPAD_HISTORY_LENGTH) %
  52                 TOUCHPAD_HISTORY_LENGTH;
  53
  54         return &t->history.samples[offset_index];
  55 }
  56
  57 static void
  58 tp_filter_motion(struct tp_dispatch *tp,
  59                  double *dx, double *dy, uint64_t time)
  60 {
  61         struct motion_params motion;
  62
  63         motion.dx = *dx * tp->accel.x_scale_coeff;
  64         motion.dy = *dy * tp->accel.y_scale_coeff;
  65
  66         if (motion.dx != 0.0 || motion.dy != 0.0)
  67                 filter_dispatch(tp->filter, &motion, tp, time);
  68
  69         *dx = motion.dx;
  70         *dy = motion.dy;
  71 }
  72
  73 static inline void
  74 tp_motion_history_push(struct tp_touch *t)
  75 {
  76         int motion_index = (t->history.index + 1) % TOUCHPAD_HISTORY_LENGTH;
  77
  78         if (t->history.count < TOUCHPAD_HISTORY_LENGTH)
  79                 t->history.count++;
  80
  81         t->history.samples[motion_index].x = t->x;
  82         t->history.samples[motion_index].y = t->y;
  83         t->history.index = motion_index;
  84 }
  85
  86 static inline void
  87 tp_motion_hysteresis(struct tp_dispatch *tp,
  88                      struct tp_touch *t)
  89 {
  90         int x = t->x,
  91             y = t->y;
  92
  93         if (t->history.count == 0) {
  94                 t->hysteresis.center_x = t->x;
  95                 t->hysteresis.center_y = t->y;
  96         } else {
  97                 x = tp_hysteresis(x,
  98                                   t->hysteresis.center_x,
  99                                   tp->hysteresis.margin_x);
 100                 y = tp_hysteresis(y,
 101                                   t->hysteresis.center_y,
 102                                   tp->hysteresis.margin_y);
 103                 t->hysteresis.center_x = x;
 104                 t->hysteresis.center_y = y;
 105                 t->x = x;
 106                 t->y = y;
 107         }
 108 }
 109
 110 static inline void
 111 tp_motion_history_reset(struct tp_touch *t)
 112 {
 113         t->history.count = 0;
 114 }
 115
 116 static inline struct tp_touch *
 117 tp_current_touch(struct tp_dispatch *tp)
 118 {
 119         return &tp->touches[min(tp->slot, tp->ntouches - 1)];
 120 }
 121
 122 static inline struct tp_touch *
 123 tp_get_touch(struct tp_dispatch *tp, unsigned int slot)
 124 {
 125         assert(slot < tp->ntouches);
 126         return &tp->touches[slot];
 127 }
 128
 129 static inline void
 130 tp_begin_touch(struct tp_dispatch *tp, struct tp_touch *t)
 131 {
 132         if (t->state != TOUCH_UPDATE) {
 133                 tp_motion_history_reset(t);
 134                 t->dirty = true;
 135                 t->state = TOUCH_BEGIN;
 136                 t->pinned.is_pinned = false;
 137                 tp->nfingers_down++;
 138                 assert(tp->nfingers_down >= 1);
 139                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 140         }
 141 }
 142
 143 static inline void
 144 tp_end_touch(struct tp_dispatch *tp, struct tp_touch *t)
 145 {
 146         if (t->state == TOUCH_NONE)
 147                 return;
 148
 149         t->dirty = true;
 150         t->is_pointer = false;
 151         t->is_palm = false;
 152         t->state = TOUCH_END;
 153         t->pinned.is_pinned = false;
 154         assert(tp->nfingers_down >= 1);
 155         tp->nfingers_down--;
 156         tp->queued |= TOUCHPAD_EVENT_MOTION;
 157 }
 158
 159 static double
 160 tp_estimate_delta(int x0, int x1, int x2, int x3)
 161 {
 162         return (x0 + x1 - x2 - x3) / 4;
 163 }
 164
 165 void
 166 tp_get_delta(struct tp_touch *t, double *dx, double *dy)
 167 {
 168         if (t->history.count < 4) {
 169                 *dx = 0;
 170                 *dy = 0;
 171                 return;
 172         }
 173
 174         *dx = tp_estimate_delta(tp_motion_history_offset(t, 0)->x,
 175                                 tp_motion_history_offset(t, 1)->x,
 176                                 tp_motion_history_offset(t, 2)->x,
 177                                 tp_motion_history_offset(t, 3)->x);
 178         *dy = tp_estimate_delta(tp_motion_history_offset(t, 0)->y,
 179                                 tp_motion_history_offset(t, 1)->y,
 180                                 tp_motion_history_offset(t, 2)->y,
 181                                 tp_motion_history_offset(t, 3)->y);
 182 }
 183
 184 static void
 185 tp_process_absolute(struct tp_dispatch *tp,
 186                     const struct input_event *e,
 187                     uint64_t time)
 188 {
 189         struct tp_touch *t = tp_current_touch(tp);
 190
 191         switch(e->code) {
 192         case ABS_MT_POSITION_X:
 193                 t->x = e->value;
 194                 t->millis = time;
 195                 t->dirty = true;
 196                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 197                 break;
 198         case ABS_MT_POSITION_Y:
 199                 t->y = e->value;
 200                 t->millis = time;
 201                 t->dirty = true;
 202                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 203                 break;
 204         case ABS_MT_SLOT:
 205                 tp->slot = e->value;
 206                 break;
 207         case ABS_MT_TRACKING_ID:
 208                 t->millis = time;
 209                 if (e->value != -1)
 210                         tp_begin_touch(tp, t);
 211                 else
 212                         tp_end_touch(tp, t);
 213         }
 214 }
 215
 216 static void
 217 tp_process_absolute_st(struct tp_dispatch *tp,
 218                        const struct input_event *e,
 219                        uint64_t time)
 220 {
 221         struct tp_touch *t = tp_current_touch(tp);
 222
 223         switch(e->code) {
 224         case ABS_X:
 225                 t->x = e->value;
 226                 t->millis = time;
 227                 t->dirty = true;
 228                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 229                 break;
 230         case ABS_Y:
 231                 t->y = e->value;
 232                 t->millis = time;
 233                 t->dirty = true;
 234                 tp->queued |= TOUCHPAD_EVENT_MOTION;
 235                 break;
 236         }
 237 }
 238
 239 static void
 240 tp_process_fake_touch(struct tp_dispatch *tp,
 241                       const struct input_event *e,
 242                       uint64_t time)
 243 {
 244         struct tp_touch *t;
 245         unsigned int fake_touches;
 246         unsigned int nfake_touches;
 247         unsigned int i;
 248         unsigned int shift;
 249
 250         if (e->code != BTN_TOUCH &&
 251             (e->code < BTN_TOOL_DOUBLETAP || e->code > BTN_TOOL_QUADTAP))
 252                 return;
 253
 254         shift = e->code == BTN_TOUCH ? 0 : (e->code - BTN_TOOL_DOUBLETAP + 1);
 255
 256         if (e->value)
 257                 tp->fake_touches |= 1 << shift;
 258         else
 259                 tp->fake_touches &= ~(0x1 << shift);
 260
 261         fake_touches = tp->fake_touches;
 262         nfake_touches = 0;
 263         while (fake_touches) {
 264                 nfake_touches++;
 265                 fake_touches >>= 1;
 266         }
 267
 268         for (i = 0; i < tp->ntouches; i++) {
 269                 t = tp_get_touch(tp, i);
 270                 if (i >= nfake_touches) {
 271                         if (t->state != TOUCH_NONE) {
 272                                 tp_end_touch(tp, t);
 273                                 t->millis = time;
 274                         }
 275                 } else if (t->state != TOUCH_UPDATE &&
 276                            t->state != TOUCH_BEGIN) {
 277                         t->state = TOUCH_NONE;
 278                         tp_begin_touch(tp, t);
 279                         t->millis = time;
 280                         t->fake =true;
 281                 }
 282         }
 283
 284         assert(tp->nfingers_down == nfake_touches);
 285 }
 286
 287 static void
 288 tp_process_key(struct tp_dispatch *tp,
 289                const struct input_event *e,
 290                uint64_t time)
 291 {
 292         switch (e->code) {
 293                 case BTN_LEFT:
 294                 case BTN_MIDDLE:
 295                 case BTN_RIGHT:
 296                         tp_process_button(tp, e, time);
 297                         break;
 298                 case BTN_TOUCH:
 299                 case BTN_TOOL_DOUBLETAP:
 300                 case BTN_TOOL_TRIPLETAP:
 301                 case BTN_TOOL_QUADTAP:
 302                         if (!tp->has_mt)
 303                                 tp_process_fake_touch(tp, e, time);
 304                         break;
 305         }
 306 }
 307
 308 static void
 309 tp_unpin_finger(struct tp_dispatch *tp, struct tp_touch *t)
 310 {
 311         unsigned int xdist, ydist;
 312
 313         if (!t->pinned.is_pinned)
 314                 return;
 315
 316         xdist = abs(t->x - t->pinned.center_x);
 317         ydist = abs(t->y - t->pinned.center_y);
 318
 319         if (xdist * xdist + ydist * ydist >=
 320                         tp->buttons.motion_dist * tp->buttons.motion_dist) {
 321                 t->pinned.is_pinned = false;
 322                 tp_set_pointer(tp, t);
 323         }
 324 }
 325
 326 static void
 327 tp_pin_fingers(struct tp_dispatch *tp)
 328 {
 329         struct tp_touch *t;
 330
 331         tp_for_each_touch(tp, t) {
 332                 t->is_pointer = false;
 333                 t->pinned.is_pinned = true;
 334                 t->pinned.center_x = t->x;
 335                 t->pinned.center_y = t->y;
 336         }
 337 }
 338
 339 static int
 340 tp_touch_active(struct tp_dispatch *tp, struct tp_touch *t)
 341 {
 342         return (t->state == TOUCH_BEGIN || t->state == TOUCH_UPDATE) &&
 343                 !t->is_palm &&
 344                 !t->pinned.is_pinned && tp_button_touch_active(tp, t);
 345 }
 346
 347 void
 348 tp_set_pointer(struct tp_dispatch *tp, struct tp_touch *t)
 349 {
 350         struct tp_touch *tmp = NULL;
 351
 352         /* Only set the touch as pointer if we don't have one yet */
 353         tp_for_each_touch(tp, tmp) {
 354                 if (tmp->is_pointer)
 355                         return;
 356         }
 357
 358         if (tp_touch_active(tp, t))
 359                 t->is_pointer = true;
 360 }
 361
 362 static void
 363 tp_palm_detect(struct tp_dispatch *tp, struct tp_touch *t)
 364 {
 365         /* once a palm, always a palm */
 366         if (t->is_palm)
 367                 return;
 368
 369         /* palm must start in exclusion zone, it's ok to move into
 370            the zone without being a palm */
 371         if (t->state != TOUCH_BEGIN ||
 372             (t->x > tp->palm.left_edge && t->x < tp->palm.right_edge))
 373                 return;
 374
 375         /* don't detect palm in software button areas, it's
 376            likely that legitimate touches start in the area
 377            covered by the exclusion zone */
 378         if (tp->buttons.is_clickpad &&
 379             tp_button_is_inside_softbutton_area(tp, t))
 380                 return;
 381
 382         t->is_palm = true;
 383 }
 384
 385 static void
 386 tp_process_state(struct tp_dispatch *tp, uint64_t time)
 387 {
 388         struct tp_touch *t;
 389         struct tp_touch *first = tp_get_touch(tp, 0);
 390
 391         tp_for_each_touch(tp, t) {
 392                 if (!tp->has_mt && t != first && first->fake) {
 393                         t->x = first->x;
 394                         t->y = first->y;
 395                         if (!t->dirty)
 396                                 t->dirty = first->dirty;
 397                 } else if (!t->dirty) {
 398                         continue;
 399                 }
 400
 401                 tp_palm_detect(tp, t);
 402
 403                 tp_motion_hysteresis(tp, t);
 404                 tp_motion_history_push(t);
 405
 406                 tp_unpin_finger(tp, t);
 407         }
 408
 409         tp_button_handle_state(tp, time);
 410
 411         /*
 412          * We have a physical button down event on a clickpad. To avoid
 413          * spurious pointer moves by the clicking finger we pin all fingers.
 414          * We unpin fingers when they move more then a certain threshold to
 415          * to allow drag and drop.
 416          */
 417         if ((tp->queued & TOUCHPAD_EVENT_BUTTON_PRESS) &&
 418             tp->buttons.is_clickpad)
 419                 tp_pin_fingers(tp);
 420 }
 421
 422 static void
 423 tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
 424 {
 425         struct tp_touch *t;
 426
 427         tp_for_each_touch(tp, t) {
 428                 if (!t->dirty)
 429                         continue;
 430
 431                 if (t->state == TOUCH_END) {
 432                         t->state = TOUCH_NONE;
 433                         t->fake = false;
 434                 } else if (t->state == TOUCH_BEGIN)
 435                         t->state = TOUCH_UPDATE;
 436
 437                 t->dirty = false;
 438         }
 439
 440         tp->buttons.old_state = tp->buttons.state;
 441
 442         tp->queued = TOUCHPAD_EVENT_NONE;
 443 }
 444
 445 static void
 446 tp_post_twofinger_scroll(struct tp_dispatch *tp, uint64_t time)
 447 {
 448         struct tp_touch *t;
 449         int nchanged = 0;
 450         double dx = 0, dy =0;
 451         double tmpx, tmpy;
 452
 453         tp_for_each_touch(tp, t) {
 454                 if (tp_touch_active(tp, t) && t->dirty) {
 455                         nchanged++;
 456                         tp_get_delta(t, &tmpx, &tmpy);
 457
 458                         dx += tmpx;
 459                         dy += tmpy;
 460                 }
 461                 /* Stop spurious MOTION events at the end of scrolling */
 462                 t->is_pointer = false;
 463         }
 464
 465         if (nchanged == 0)
 466                 return;
 467
 468         dx /= nchanged;
 469         dy /= nchanged;
 470
 471         tp_filter_motion(tp, &dx, &dy, time);
 472
 473         /* Require at least five px scrolling to start */
 474         if (dy <= -5.0 || dy >= 5.0)
 475                 tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL);
 476
 477         if (dx <= -5.0 || dx >= 5.0)
 478                 tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL);
 479
 480         if (dy != 0.0 &&
 481             (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))) {
 482                 pointer_notify_axis(&tp->device->base,
 483                                     time,
 484                                     LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
 485                                     dy);
 486         }
 487
 488         if (dx != 0.0 &&
 489             (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))) {
 490                 pointer_notify_axis(&tp->device->base,
 491                                     time,
 492                                     LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
 493                                     dx);
 494         }
 495 }
 496
 497 static void
 498 tp_stop_scroll_events(struct tp_dispatch *tp, uint64_t time)
 499 {
 500         /* terminate scrolling with a zero scroll event */
 501         if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))
 502                 pointer_notify_axis(&tp->device->base,
 503                                     time,
 504                                     LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
 505                                     0);
 506         if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))
 507                 pointer_notify_axis(&tp->device->base,
 508                                     time,
 509                                     LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
 510                                     0);
 511
 512         tp->scroll.direction = 0;
 513 }
 514
 515 static int
 516 tp_post_scroll_events(struct tp_dispatch *tp, uint64_t time)
 517 {
 518         struct tp_touch *t;
 519         int nfingers_down = 0;
 520
 521         /* Only count active touches for 2 finger scrolling */
 522         tp_for_each_touch(tp, t) {
 523                 if (tp_touch_active(tp, t))
 524                         nfingers_down++;
 525         }
 526
 527         if (nfingers_down != 2) {
 528                 tp_stop_scroll_events(tp, time);
 529                 return 0;
 530         }
 531
 532         tp_post_twofinger_scroll(tp, time);
 533         return 1;
 534 }
 535
 536 static void
 537 tp_post_events(struct tp_dispatch *tp, uint64_t time)
 538 {
 539         struct tp_touch *t = tp_current_touch(tp);
 540         double dx, dy;
 541         int consumed = 0;
 542
 543         consumed |= tp_tap_handle_state(tp, time);
 544         consumed |= tp_post_button_events(tp, time);
 545
 546         if (consumed) {
 547                 tp_stop_scroll_events(tp, time);
 548                 return;
 549         }
 550
 551         if (tp_post_scroll_events(tp, time) != 0)
 552                 return;
 553
 554         if (!t->is_pointer) {
 555                 tp_for_each_touch(tp, t) {
 556                         if (t->is_pointer)
 557                                 break;
 558                 }
 559         }
 560
 561         if (!t->is_pointer ||
 562             !t->dirty ||
 563             t->history.count < TOUCHPAD_MIN_SAMPLES)
 564                 return;
 565
 566         tp_get_delta(t, &dx, &dy);
 567         tp_filter_motion(tp, &dx, &dy, time);
 568
 569         if (dx != 0.0 || dy != 0.0)
 570                 pointer_notify_motion(&tp->device->base, time, dx, dy);
 571 }
 572
 573 static void
 574 tp_process(struct evdev_dispatch *dispatch,
 575            struct evdev_device *device,
 576            struct input_event *e,
 577            uint64_t time)
 578 {
 579         struct tp_dispatch *tp =
 580                 (struct tp_dispatch *)dispatch;
 581
 582         switch (e->type) {
 583         case EV_ABS:
 584                 if (tp->has_mt)
 585                         tp_process_absolute(tp, e, time);
 586                 else
 587                         tp_process_absolute_st(tp, e, time);
 588                 break;
 589         case EV_KEY:
 590                 tp_process_key(tp, e, time);
 591                 break;
 592         case EV_SYN:
 593                 tp_process_state(tp, time);
 594                 tp_post_events(tp, time);
 595                 tp_post_process_state(tp, time);
 596                 break;
 597         }
 598 }
 599
 600 static void
 601 tp_destroy(struct evdev_dispatch *dispatch)
 602 {
 603         struct tp_dispatch *tp =
 604                 (struct tp_dispatch*)dispatch;
 605
 606         tp_destroy_tap(tp);
 607         tp_destroy_buttons(tp);
 608
 609         filter_destroy(tp->filter);
 610         free(tp->touches);
 611         free(tp);
 612 }
 613
 614 static struct evdev_dispatch_interface tp_interface = {
 615         tp_process,
 616         tp_destroy
 617 };
 618
 619 static void
 620 tp_init_touch(struct tp_dispatch *tp,
 621               struct tp_touch *t)
 622 {
 623         t->tp = tp;
 624 }
 625
 626 static int
 627 tp_init_slots(struct tp_dispatch *tp,
 628               struct evdev_device *device)
 629 {
 630         size_t i;
 631         const struct input_absinfo *absinfo;
 632
 633         absinfo = libevdev_get_abs_info(device->evdev, ABS_MT_SLOT);
 634         if (absinfo) {
 635                 tp->ntouches = absinfo->maximum + 1;
 636                 tp->slot = absinfo->value;
 637                 tp->has_mt = true;
 638         } else {
 639                 struct map {
 640                         unsigned int code;
 641                         int ntouches;
 642                 } max_touches[] = {
 643                         { BTN_TOOL_QUINTTAP, 5 },
 644                         { BTN_TOOL_QUADTAP, 4 },
 645                         { BTN_TOOL_TRIPLETAP, 3 },
 646                         { BTN_TOOL_DOUBLETAP, 2 },
 647                 };
 648                 struct map *m;
 649
 650                 tp->slot = 0;
 651                 tp->has_mt = false;
 652                 tp->ntouches = 1;
 653
 654                 ARRAY_FOR_EACH(max_touches, m) {
 655                         if (libevdev_has_event_code(device->evdev,
 656                                                     EV_KEY,
 657                                                     m->code)) {
 658                                 tp->ntouches = m->ntouches;
 659                                 break;
 660                         }
 661                 }
 662         }
 663         tp->touches = calloc(tp->ntouches,
 664                              sizeof(struct tp_touch));
 665         if (!tp->touches)
 666                 return -1;
 667
 668         for (i = 0; i < tp->ntouches; i++)
 669                 tp_init_touch(tp, &tp->touches[i]);
 670
 671         return 0;
 672 }
 673
 674 static int
 675 tp_init_accel(struct tp_dispatch *tp, double diagonal)
 676 {
 677         struct motion_filter *accel;
 678         int res_x, res_y;
 679
 680         if (tp->has_mt) {
 681                 res_x = libevdev_get_abs_resolution(tp->device->evdev,
 682                                                     ABS_MT_POSITION_X);
 683                 res_y = libevdev_get_abs_resolution(tp->device->evdev,
 684                                                     ABS_MT_POSITION_Y);
 685         } else {
 686                 res_x = libevdev_get_abs_resolution(tp->device->evdev,
 687                                                     ABS_X);
 688                 res_y = libevdev_get_abs_resolution(tp->device->evdev,
 689                                                     ABS_Y);
 690         }
 691
 692         /*
 693          * Not all touchpads report the same amount of units/mm (resolution).
 694          * Normalize motion events to a resolution of 15.74 units/mm
 695          * (== 400 dpi) as base (unaccelerated) speed. This also evens out any
 696          * differences in x and y resolution, so that a circle on the
 697          * touchpad does not turn into an elipse on the screen.
 698          *
 699          * We pick 400dpi as thats one of the many default resolutions
 700          * for USB mice, so we end up with a similar base speed on the device.
 701          */
 702         if (res_x > 1 && res_y > 1) {
 703                 tp->accel.x_scale_coeff = (400/25.4) / res_x;
 704                 tp->accel.y_scale_coeff = (400/25.4) / res_y;
 705         } else {
 706         /*
 707          * For touchpads where the driver does not provide resolution, fall
 708          * back to scaling motion events based on the diagonal size in units.
 709          */
 710                 tp->accel.x_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
 711                 tp->accel.y_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
 712         }
 713
 714         accel = create_pointer_accelator_filter(
 715                         pointer_accel_profile_smooth_simple);
 716         if (accel == NULL)
 717                 return -1;
 718
 719         tp->filter = accel;
 720
 721         return 0;
 722 }
 723
 724 static int
 725 tp_init_scroll(struct tp_dispatch *tp)
 726 {
 727         tp->scroll.direction = 0;
 728
 729         return 0;
 730 }
 731
 732 static int
 733 tp_init_palmdetect(struct tp_dispatch *tp,
 734                    struct evdev_device *device)
 735 {
 736         int width;
 737
 738         width = abs(device->abs.absinfo_x->maximum -
 739                     device->abs.absinfo_x->minimum);
 740
 741         /* palm edges are 5% of the width on each side */
 742         tp->palm.right_edge = device->abs.absinfo_x->maximum - width * 0.05;
 743         tp->palm.left_edge = device->abs.absinfo_x->minimum + width * 0.05;
 744
 745         return 0;
 746 }
 747
 748
 749 static int
 750 tp_init(struct tp_dispatch *tp,
 751         struct evdev_device *device)
 752 {
 753         int width, height;
 754         double diagonal;
 755
 756         tp->base.interface = &tp_interface;
 757         tp->device = device;
 758
 759         if (tp_init_slots(tp, device) != 0)
 760                 return -1;
 761
 762         width = abs(device->abs.absinfo_x->maximum -
 763                     device->abs.absinfo_x->minimum);
 764         height = abs(device->abs.absinfo_y->maximum -
 765                      device->abs.absinfo_y->minimum);
 766         diagonal = sqrt(width*width + height*height);
 767
 768         tp->hysteresis.margin_x =
 769                 diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
 770         tp->hysteresis.margin_y =
 771                 diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
 772
 773         if (tp_init_scroll(tp) != 0)
 774                 return -1;
 775
 776         if (tp_init_accel(tp, diagonal) != 0)
 777                 return -1;
 778
 779         if (tp_init_tap(tp) != 0)
 780                 return -1;
 781
 782         if (tp_init_buttons(tp, device) != 0)
 783                 return -1;
 784
 785         if (tp_init_palmdetect(tp, device) != 0)
 786                 return -1;
 787
 788         return 0;
 789 }
 790
 791 struct evdev_dispatch *
 792 evdev_mt_touchpad_create(struct evdev_device *device)
 793 {
 794         struct tp_dispatch *tp;
 795
 796         tp = zalloc(sizeof *tp);
 797         if (!tp)
 798                 return NULL;
 799
 800         if (tp_init(tp, device) != 0) {
 801                 tp_destroy(&tp->base);
 802                 return NULL;
 803         }
 804
 805         return  &tp->base;
 806 }