src/ui/events/gesture_detection/gesture_detector.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // MSVC++ requires this to be set before any other includes to get M_PI.
   6 #define _USE_MATH_DEFINES
   7
   8 #include "ui/events/gesture_detection/gesture_detector.h"
   9
  10 #include <cmath>
  11
  12 #include "base/timer/timer.h"
  13 #include "ui/events/gesture_detection/gesture_listeners.h"
  14 #include "ui/events/gesture_detection/motion_event.h"
  15
  16 namespace ui {
  17 namespace {
  18
  19 // Using a small epsilon when comparing slop distances allows pixel perfect
  20 // slop determination when using fractional DIP coordinates (assuming the slop
  21 // region and DPI scale are reasonably proportioned).
  22 const float kSlopEpsilon = .05f;
  23
  24 // Minimum distance a scroll must have traveled from the last scroll/focal point
  25 // to trigger an |OnScroll| callback.
  26 const float kScrollEpsilon = .1f;
  27
  28 const float kDegreesToRadians = static_cast<float>(M_PI) / 180.0f;
  29
  30 // Constants used by TimeoutGestureHandler.
  31 enum TimeoutEvent {
  32   SHOW_PRESS = 0,
  33   LONG_PRESS,
  34   TAP,
  35   TIMEOUT_EVENT_COUNT
  36 };
  37
  38 }  // namespace
  39
  40 // Note: These constants were taken directly from the default (unscaled)
  41 // versions found in Android's ViewConfiguration.
  42 GestureDetector::Config::Config()
  43     : longpress_timeout(base::TimeDelta::FromMilliseconds(500)),
  44       showpress_timeout(base::TimeDelta::FromMilliseconds(180)),
  45       double_tap_timeout(base::TimeDelta::FromMilliseconds(300)),
  46       double_tap_min_time(base::TimeDelta::FromMilliseconds(40)),
  47       touch_slop(8),
  48       double_tap_slop(100),
  49       minimum_fling_velocity(50),
  50       maximum_fling_velocity(8000),
  51       swipe_enabled(false),
  52       minimum_swipe_velocity(20),
  53       maximum_swipe_deviation_angle(20.f),
  54       two_finger_tap_enabled(false),
  55       two_finger_tap_max_separation(300),
  56       two_finger_tap_timeout(base::TimeDelta::FromMilliseconds(700)),
  57       velocity_tracker_strategy(VelocityTracker::Strategy::STRATEGY_DEFAULT) {
  58 }
  59
  60 GestureDetector::Config::~Config() {}
  61
  62 class GestureDetector::TimeoutGestureHandler {
  63  public:
  64   TimeoutGestureHandler(const Config& config, GestureDetector* gesture_detector)
  65       : gesture_detector_(gesture_detector) {
  66     DCHECK(config.showpress_timeout <= config.longpress_timeout);
  67
  68     timeout_callbacks_[SHOW_PRESS] = &GestureDetector::OnShowPressTimeout;
  69     timeout_delays_[SHOW_PRESS] = config.showpress_timeout;
  70
  71     timeout_callbacks_[LONG_PRESS] = &GestureDetector::OnLongPressTimeout;
  72     timeout_delays_[LONG_PRESS] =
  73         config.longpress_timeout + config.showpress_timeout;
  74
  75     timeout_callbacks_[TAP] = &GestureDetector::OnTapTimeout;
  76     timeout_delays_[TAP] = config.double_tap_timeout;
  77   }
  78
  79   ~TimeoutGestureHandler() {
  80     Stop();
  81   }
  82
  83   void StartTimeout(TimeoutEvent event) {
  84     timeout_timers_[event].Start(FROM_HERE,
  85                                  timeout_delays_[event],
  86                                  gesture_detector_,
  87                                  timeout_callbacks_[event]);
  88   }
  89
  90   void StopTimeout(TimeoutEvent event) { timeout_timers_[event].Stop(); }
  91
  92   void Stop() {
  93     for (size_t i = SHOW_PRESS; i < TIMEOUT_EVENT_COUNT; ++i)
  94       timeout_timers_[i].Stop();
  95   }
  96
  97   bool HasTimeout(TimeoutEvent event) const {
  98     return timeout_timers_[event].IsRunning();
  99   }
 100
 101  private:
 102   typedef void (GestureDetector::*ReceiverMethod)();
 103
 104   GestureDetector* const gesture_detector_;
 105   base::OneShotTimer<GestureDetector> timeout_timers_[TIMEOUT_EVENT_COUNT];
 106   ReceiverMethod timeout_callbacks_[TIMEOUT_EVENT_COUNT];
 107   base::TimeDelta timeout_delays_[TIMEOUT_EVENT_COUNT];
 108 };
 109
 110 GestureDetector::GestureDetector(
 111     const Config& config,
 112     GestureListener* listener,
 113     DoubleTapListener* optional_double_tap_listener)
 114     : timeout_handler_(new TimeoutGestureHandler(config, this)),
 115       listener_(listener),
 116       double_tap_listener_(optional_double_tap_listener),
 117       touch_slop_square_(0),
 118       double_tap_touch_slop_square_(0),
 119       double_tap_slop_square_(0),
 120       two_finger_tap_distance_square_(0),
 121       min_fling_velocity_(1),
 122       max_fling_velocity_(1),
 123       min_swipe_velocity_(0),
 124       min_swipe_direction_component_ratio_(0),
 125       still_down_(false),
 126       defer_confirm_single_tap_(false),
 127       always_in_tap_region_(false),
 128       always_in_bigger_tap_region_(false),
 129       two_finger_tap_allowed_for_gesture_(false),
 130       is_double_tapping_(false),
 131       last_focus_x_(0),
 132       last_focus_y_(0),
 133       down_focus_x_(0),
 134       down_focus_y_(0),
 135       longpress_enabled_(true),
 136       showpress_enabled_(true),
 137       swipe_enabled_(false),
 138       two_finger_tap_enabled_(false),
 139       velocity_tracker_(config.velocity_tracker_strategy) {
 140   DCHECK(listener_);
 141   Init(config);
 142 }
 143
 144 GestureDetector::~GestureDetector() {}
 145
 146 bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
 147   const MotionEvent::Action action = ev.GetAction();
 148
 149   velocity_tracker_.AddMovement(ev);
 150
 151   const bool pointer_up = action == MotionEvent::ACTION_POINTER_UP;
 152   const int skip_index = pointer_up ? ev.GetActionIndex() : -1;
 153
 154   // Determine focal point.
 155   float sum_x = 0, sum_y = 0;
 156   const int count = static_cast<int>(ev.GetPointerCount());
 157   for (int i = 0; i < count; i++) {
 158     if (skip_index == i)
 159       continue;
 160     sum_x += ev.GetX(i);
 161     sum_y += ev.GetY(i);
 162   }
 163   const int div = pointer_up ? count - 1 : count;
 164   const float focus_x = sum_x / div;
 165   const float focus_y = sum_y / div;
 166
 167   bool handled = false;
 168
 169   switch (action) {
 170     case MotionEvent::ACTION_POINTER_DOWN: {
 171       down_focus_x_ = last_focus_x_ = focus_x;
 172       down_focus_y_ = last_focus_y_ = focus_y;
 173       // Cancel long press and taps.
 174       CancelTaps();
 175
 176       if (!two_finger_tap_allowed_for_gesture_)
 177         break;
 178
 179       const int action_index = ev.GetActionIndex();
 180       const float dx = ev.GetX(action_index) - current_down_event_->GetX();
 181       const float dy = ev.GetY(action_index) - current_down_event_->GetY();
 182
 183       if (ev.GetPointerCount() == 2 &&
 184           dx * dx + dy * dy < two_finger_tap_distance_square_) {
 185         secondary_pointer_down_event_ = ev.Clone();
 186       } else {
 187         two_finger_tap_allowed_for_gesture_ = false;
 188       }
 189     } break;
 190
 191     case MotionEvent::ACTION_POINTER_UP: {
 192       down_focus_x_ = last_focus_x_ = focus_x;
 193       down_focus_y_ = last_focus_y_ = focus_y;
 194
 195       // Check the dot product of current velocities.
 196       // If the pointer that left was opposing another velocity vector, clear.
 197       velocity_tracker_.ComputeCurrentVelocity(1000, max_fling_velocity_);
 198       const int up_index = ev.GetActionIndex();
 199       const int id1 = ev.GetPointerId(up_index);
 200       const float vx1 = velocity_tracker_.GetXVelocity(id1);
 201       const float vy1 = velocity_tracker_.GetYVelocity(id1);
 202       float vx_total = vx1;
 203       float vy_total = vy1;
 204       for (int i = 0; i < count; i++) {
 205         if (i == up_index)
 206           continue;
 207
 208         const int id2 = ev.GetPointerId(i);
 209         const float vx2 = velocity_tracker_.GetXVelocity(id2);
 210         const float vy2 = velocity_tracker_.GetYVelocity(id2);
 211         const float dot = vx1 * vx2 + vy1 * vy2;
 212         if (dot < 0) {
 213           vx_total = 0;
 214           vy_total = 0;
 215           velocity_tracker_.Clear();
 216           break;
 217         }
 218         vx_total += vx2;
 219         vy_total += vy2;
 220       }
 221
 222       handled = HandleSwipeIfNeeded(ev, vx_total / count, vy_total / count);
 223
 224       if (two_finger_tap_allowed_for_gesture_ && ev.GetPointerCount() == 2 &&
 225           (ev.GetEventTime() - secondary_pointer_down_event_->GetEventTime() <=
 226            two_finger_tap_timeout_)) {
 227         handled = listener_->OnTwoFingerTap(*current_down_event_, ev);
 228       }
 229       two_finger_tap_allowed_for_gesture_ = false;
 230     } break;
 231
 232     case MotionEvent::ACTION_DOWN:
 233       if (double_tap_listener_) {
 234         bool had_tap_message = timeout_handler_->HasTimeout(TAP);
 235         if (had_tap_message)
 236           timeout_handler_->StopTimeout(TAP);
 237         if (current_down_event_ && previous_up_event_ && had_tap_message &&
 238             IsConsideredDoubleTap(
 239                 *current_down_event_, *previous_up_event_, ev)) {
 240           // This is a second tap.
 241           is_double_tapping_ = true;
 242           // Give a callback with the first tap of the double-tap.
 243           handled |= double_tap_listener_->OnDoubleTap(*current_down_event_);
 244           // Give a callback with down event of the double-tap.
 245           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 246         } else {
 247           // This is a first tap.
 248           DCHECK(double_tap_timeout_ > base::TimeDelta());
 249           timeout_handler_->StartTimeout(TAP);
 250         }
 251       }
 252
 253       down_focus_x_ = last_focus_x_ = focus_x;
 254       down_focus_y_ = last_focus_y_ = focus_y;
 255       current_down_event_ = ev.Clone();
 256
 257       secondary_pointer_down_event_.reset();
 258       always_in_tap_region_ = true;
 259       always_in_bigger_tap_region_ = true;
 260       still_down_ = true;
 261       defer_confirm_single_tap_ = false;
 262       two_finger_tap_allowed_for_gesture_ = two_finger_tap_enabled_;
 263
 264       // Always start the SHOW_PRESS timer before the LONG_PRESS timer to ensure
 265       // proper timeout ordering.
 266       if (showpress_enabled_)
 267         timeout_handler_->StartTimeout(SHOW_PRESS);
 268       if (longpress_enabled_)
 269         timeout_handler_->StartTimeout(LONG_PRESS);
 270       handled |= listener_->OnDown(ev);
 271       break;
 272
 273     case MotionEvent::ACTION_MOVE:
 274       {
 275         const float scroll_x = last_focus_x_ - focus_x;
 276         const float scroll_y = last_focus_y_ - focus_y;
 277         if (is_double_tapping_) {
 278           // Give the move events of the double-tap.
 279           DCHECK(double_tap_listener_);
 280           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 281         } else if (always_in_tap_region_) {
 282           const float delta_x = focus_x - down_focus_x_;
 283           const float delta_y = focus_y - down_focus_y_;
 284           const float distance_square = delta_x * delta_x + delta_y * delta_y;
 285           if (distance_square > touch_slop_square_) {
 286             handled = listener_->OnScroll(
 287                 *current_down_event_, ev, scroll_x, scroll_y);
 288             last_focus_x_ = focus_x;
 289             last_focus_y_ = focus_y;
 290             always_in_tap_region_ = false;
 291             timeout_handler_->Stop();
 292           }
 293           if (distance_square > double_tap_touch_slop_square_)
 294             always_in_bigger_tap_region_ = false;
 295         } else if (std::abs(scroll_x) > kScrollEpsilon ||
 296                    std::abs(scroll_y) > kScrollEpsilon) {
 297           handled =
 298               listener_->OnScroll(*current_down_event_, ev, scroll_x, scroll_y);
 299           last_focus_x_ = focus_x;
 300           last_focus_y_ = focus_y;
 301         }
 302
 303         if (!two_finger_tap_allowed_for_gesture_)
 304           break;
 305
 306         // Two-finger tap should be prevented if either pointer exceeds its
 307         // (independent) slop region.
 308         const int id0 = current_down_event_->GetPointerId(0);
 309         const int ev_idx0 = ev.GetPointerId(0) == id0 ? 0 : 1;
 310
 311         // Check if the primary pointer exceeded the slop region.
 312         float dx = current_down_event_->GetX() - ev.GetX(ev_idx0);
 313         float dy = current_down_event_->GetY() - ev.GetY(ev_idx0);
 314         if (dx * dx + dy * dy > touch_slop_square_) {
 315           two_finger_tap_allowed_for_gesture_ = false;
 316           break;
 317         }
 318         if (ev.GetPointerCount() == 2) {
 319           // Check if the secondary pointer exceeded the slop region.
 320           const int ev_idx1 = ev_idx0 == 0 ? 1 : 0;
 321           const int idx1 = secondary_pointer_down_event_->GetActionIndex();
 322           dx = secondary_pointer_down_event_->GetX(idx1) - ev.GetX(ev_idx1);
 323           dy = secondary_pointer_down_event_->GetY(idx1) - ev.GetY(ev_idx1);
 324           if (dx * dx + dy * dy > touch_slop_square_)
 325             two_finger_tap_allowed_for_gesture_ = false;
 326         }
 327       }
 328       break;
 329
 330     case MotionEvent::ACTION_UP:
 331       still_down_ = false;
 332       {
 333         if (is_double_tapping_) {
 334           // Finally, give the up event of the double-tap.
 335           DCHECK(double_tap_listener_);
 336           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 337         } else if (always_in_tap_region_) {
 338           handled = listener_->OnSingleTapUp(ev);
 339           if (defer_confirm_single_tap_ && double_tap_listener_ != NULL) {
 340             double_tap_listener_->OnSingleTapConfirmed(ev);
 341           }
 342         } else {
 343
 344           // A fling must travel the minimum tap distance.
 345           const int pointer_id = ev.GetPointerId(0);
 346           velocity_tracker_.ComputeCurrentVelocity(1000, max_fling_velocity_);
 347           const float velocity_y = velocity_tracker_.GetYVelocity(pointer_id);
 348           const float velocity_x = velocity_tracker_.GetXVelocity(pointer_id);
 349
 350           if ((std::abs(velocity_y) > min_fling_velocity_) ||
 351               (std::abs(velocity_x) > min_fling_velocity_)) {
 352             handled = listener_->OnFling(
 353                 *current_down_event_, ev, velocity_x, velocity_y);
 354           }
 355
 356           handled |= HandleSwipeIfNeeded(ev, velocity_x, velocity_y);
 357         }
 358
 359         previous_up_event_ = ev.Clone();
 360
 361         velocity_tracker_.Clear();
 362         is_double_tapping_ = false;
 363         defer_confirm_single_tap_ = false;
 364         timeout_handler_->StopTimeout(SHOW_PRESS);
 365         timeout_handler_->StopTimeout(LONG_PRESS);
 366       }
 367       break;
 368
 369     case MotionEvent::ACTION_CANCEL:
 370       Cancel();
 371       break;
 372   }
 373
 374   return handled;
 375 }
 376
 377 void GestureDetector::SetDoubleTapListener(
 378     DoubleTapListener* double_tap_listener) {
 379   if (double_tap_listener == double_tap_listener_)
 380     return;
 381
 382   DCHECK(!is_double_tapping_);
 383
 384   // Null'ing the double-tap listener should flush an active tap timeout.
 385   if (!double_tap_listener) {
 386     if (timeout_handler_->HasTimeout(TAP)) {
 387       timeout_handler_->StopTimeout(TAP);
 388       OnTapTimeout();
 389     }
 390   }
 391
 392   double_tap_listener_ = double_tap_listener;
 393 }
 394
 395 void GestureDetector::Init(const Config& config) {
 396   DCHECK(listener_);
 397
 398   const float touch_slop = config.touch_slop + kSlopEpsilon;
 399   const float double_tap_touch_slop = touch_slop;
 400   const float double_tap_slop = config.double_tap_slop + kSlopEpsilon;
 401   touch_slop_square_ = touch_slop * touch_slop;
 402   double_tap_touch_slop_square_ = double_tap_touch_slop * double_tap_touch_slop;
 403   double_tap_slop_square_ = double_tap_slop * double_tap_slop;
 404   double_tap_timeout_ = config.double_tap_timeout;
 405   double_tap_min_time_ = config.double_tap_min_time;
 406   DCHECK(double_tap_min_time_ < double_tap_timeout_);
 407   min_fling_velocity_ = config.minimum_fling_velocity;
 408   max_fling_velocity_ = config.maximum_fling_velocity;
 409
 410   swipe_enabled_ = config.swipe_enabled;
 411   min_swipe_velocity_ = config.minimum_swipe_velocity;
 412   DCHECK_GT(config.maximum_swipe_deviation_angle, 0);
 413   DCHECK_LE(config.maximum_swipe_deviation_angle, 45);
 414   const float maximum_swipe_deviation_angle =
 415       std::min(45.f, std::max(0.001f, config.maximum_swipe_deviation_angle));
 416   min_swipe_direction_component_ratio_ =
 417       1.f / tan(maximum_swipe_deviation_angle * kDegreesToRadians);
 418
 419   two_finger_tap_enabled_ = config.two_finger_tap_enabled;
 420   two_finger_tap_distance_square_ = config.two_finger_tap_max_separation *
 421                                     config.two_finger_tap_max_separation;
 422   two_finger_tap_timeout_ = config.two_finger_tap_timeout;
 423 }
 424
 425 void GestureDetector::OnShowPressTimeout() {
 426   listener_->OnShowPress(*current_down_event_);
 427 }
 428
 429 void GestureDetector::OnLongPressTimeout() {
 430   timeout_handler_->StopTimeout(TAP);
 431   defer_confirm_single_tap_ = false;
 432   listener_->OnLongPress(*current_down_event_);
 433 }
 434
 435 void GestureDetector::OnTapTimeout() {
 436   if (!double_tap_listener_)
 437     return;
 438   if (!still_down_)
 439     double_tap_listener_->OnSingleTapConfirmed(*current_down_event_);
 440   else
 441     defer_confirm_single_tap_ = true;
 442 }
 443
 444 void GestureDetector::Cancel() {
 445   CancelTaps();
 446   velocity_tracker_.Clear();
 447   still_down_ = false;
 448 }
 449
 450 void GestureDetector::CancelTaps() {
 451   timeout_handler_->Stop();
 452   is_double_tapping_ = false;
 453   always_in_tap_region_ = false;
 454   always_in_bigger_tap_region_ = false;
 455   defer_confirm_single_tap_ = false;
 456 }
 457
 458 bool GestureDetector::IsConsideredDoubleTap(
 459     const MotionEvent& first_down,
 460     const MotionEvent& first_up,
 461     const MotionEvent& second_down) const {
 462   if (!always_in_bigger_tap_region_)
 463     return false;
 464
 465   const base::TimeDelta delta_time =
 466       second_down.GetEventTime() - first_up.GetEventTime();
 467   if (delta_time < double_tap_min_time_ || delta_time > double_tap_timeout_)
 468     return false;
 469
 470   const float delta_x = first_down.GetX() - second_down.GetX();
 471   const float delta_y = first_down.GetY() - second_down.GetY();
 472   return (delta_x * delta_x + delta_y * delta_y < double_tap_slop_square_);
 473 }
 474
 475 bool GestureDetector::HandleSwipeIfNeeded(const MotionEvent& up,
 476                                           float vx,
 477                                           float vy) {
 478   if (!swipe_enabled_ || (!vx && !vy))
 479     return false;
 480   float vx_abs = std::abs(vx);
 481   float vy_abs = std::abs(vy);
 482
 483   if (vx_abs < min_swipe_velocity_)
 484     vx_abs = vx = 0;
 485   if (vy_abs < min_swipe_velocity_)
 486     vy_abs = vy = 0;
 487
 488   // Note that the ratio will be 0 if both velocites are below the min.
 489   float ratio = vx_abs > vy_abs ? vx_abs / std::max(vy_abs, 0.001f)
 490                                 : vy_abs / std::max(vx_abs, 0.001f);
 491
 492   if (ratio < min_swipe_direction_component_ratio_)
 493     return false;
 494
 495   if (vx_abs > vy_abs)
 496     vy = 0;
 497   else
 498     vx = 0;
 499   return listener_->OnSwipe(*current_down_event_, up, vx, vy);
 500 }
 501
 502 }  // namespace ui