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. Do not change these default
  42 // values without explicitly consulting an OWNER.
  43 GestureDetector::Config::Config()
  44     : longpress_timeout(base::TimeDelta::FromMilliseconds(500)),
  45       showpress_timeout(base::TimeDelta::FromMilliseconds(180)),
  46       double_tap_timeout(base::TimeDelta::FromMilliseconds(300)),
  47       double_tap_min_time(base::TimeDelta::FromMilliseconds(40)),
  48       touch_slop(8),
  49       double_tap_slop(100),
  50       minimum_fling_velocity(50),
  51       maximum_fling_velocity(8000),
  52       swipe_enabled(false),
  53       minimum_swipe_velocity(20),
  54       maximum_swipe_deviation_angle(20.f),
  55       two_finger_tap_enabled(false),
  56       two_finger_tap_max_separation(300),
  57       two_finger_tap_timeout(base::TimeDelta::FromMilliseconds(700)),
  58       velocity_tracker_strategy(VelocityTracker::Strategy::STRATEGY_DEFAULT) {
  59 }
  60
  61 GestureDetector::Config::~Config() {}
  62
  63 class GestureDetector::TimeoutGestureHandler {
  64  public:
  65   TimeoutGestureHandler(const Config& config, GestureDetector* gesture_detector)
  66       : gesture_detector_(gesture_detector) {
  67     DCHECK(config.showpress_timeout <= config.longpress_timeout);
  68
  69     timeout_callbacks_[SHOW_PRESS] = &GestureDetector::OnShowPressTimeout;
  70     timeout_delays_[SHOW_PRESS] = config.showpress_timeout;
  71
  72     timeout_callbacks_[LONG_PRESS] = &GestureDetector::OnLongPressTimeout;
  73     timeout_delays_[LONG_PRESS] =
  74         config.longpress_timeout + config.showpress_timeout;
  75
  76     timeout_callbacks_[TAP] = &GestureDetector::OnTapTimeout;
  77     timeout_delays_[TAP] = config.double_tap_timeout;
  78   }
  79
  80   ~TimeoutGestureHandler() {
  81     Stop();
  82   }
  83
  84   void StartTimeout(TimeoutEvent event) {
  85     timeout_timers_[event].Start(FROM_HERE,
  86                                  timeout_delays_[event],
  87                                  gesture_detector_,
  88                                  timeout_callbacks_[event]);
  89   }
  90
  91   void StopTimeout(TimeoutEvent event) { timeout_timers_[event].Stop(); }
  92
  93   void Stop() {
  94     for (size_t i = SHOW_PRESS; i < TIMEOUT_EVENT_COUNT; ++i)
  95       timeout_timers_[i].Stop();
  96   }
  97
  98   bool HasTimeout(TimeoutEvent event) const {
  99     return timeout_timers_[event].IsRunning();
 100   }
 101
 102  private:
 103   typedef void (GestureDetector::*ReceiverMethod)();
 104
 105   GestureDetector* const gesture_detector_;
 106   base::OneShotTimer<GestureDetector> timeout_timers_[TIMEOUT_EVENT_COUNT];
 107   ReceiverMethod timeout_callbacks_[TIMEOUT_EVENT_COUNT];
 108   base::TimeDelta timeout_delays_[TIMEOUT_EVENT_COUNT];
 109 };
 110
 111 GestureDetector::GestureDetector(
 112     const Config& config,
 113     GestureListener* listener,
 114     DoubleTapListener* optional_double_tap_listener)
 115     : timeout_handler_(new TimeoutGestureHandler(config, this)),
 116       listener_(listener),
 117       double_tap_listener_(optional_double_tap_listener),
 118       touch_slop_square_(0),
 119       double_tap_touch_slop_square_(0),
 120       double_tap_slop_square_(0),
 121       two_finger_tap_distance_square_(0),
 122       min_fling_velocity_(1),
 123       max_fling_velocity_(1),
 124       min_swipe_velocity_(0),
 125       min_swipe_direction_component_ratio_(0),
 126       still_down_(false),
 127       defer_confirm_single_tap_(false),
 128       always_in_tap_region_(false),
 129       always_in_bigger_tap_region_(false),
 130       two_finger_tap_allowed_for_gesture_(false),
 131       is_double_tapping_(false),
 132       last_focus_x_(0),
 133       last_focus_y_(0),
 134       down_focus_x_(0),
 135       down_focus_y_(0),
 136       longpress_enabled_(true),
 137       showpress_enabled_(true),
 138       swipe_enabled_(false),
 139       two_finger_tap_enabled_(false),
 140       velocity_tracker_(config.velocity_tracker_strategy) {
 141   DCHECK(listener_);
 142   Init(config);
 143 }
 144
 145 GestureDetector::~GestureDetector() {}
 146
 147 bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
 148   const MotionEvent::Action action = ev.GetAction();
 149
 150   velocity_tracker_.AddMovement(ev);
 151
 152   const bool pointer_up = action == MotionEvent::ACTION_POINTER_UP;
 153   const int skip_index = pointer_up ? ev.GetActionIndex() : -1;
 154
 155   // Determine focal point.
 156   float sum_x = 0, sum_y = 0;
 157   const int count = static_cast<int>(ev.GetPointerCount());
 158   for (int i = 0; i < count; i++) {
 159     if (skip_index == i)
 160       continue;
 161     sum_x += ev.GetX(i);
 162     sum_y += ev.GetY(i);
 163   }
 164   const int div = pointer_up ? count - 1 : count;
 165   const float focus_x = sum_x / div;
 166   const float focus_y = sum_y / div;
 167
 168   bool handled = false;
 169
 170   switch (action) {
 171     case MotionEvent::ACTION_POINTER_DOWN: {
 172       down_focus_x_ = last_focus_x_ = focus_x;
 173       down_focus_y_ = last_focus_y_ = focus_y;
 174       // Cancel long press and taps.
 175       CancelTaps();
 176
 177       if (!two_finger_tap_allowed_for_gesture_)
 178         break;
 179
 180       const int action_index = ev.GetActionIndex();
 181       const float dx = ev.GetX(action_index) - current_down_event_->GetX();
 182       const float dy = ev.GetY(action_index) - current_down_event_->GetY();
 183
 184       if (ev.GetPointerCount() == 2 &&
 185           dx * dx + dy * dy < two_finger_tap_distance_square_) {
 186         secondary_pointer_down_event_ = ev.Clone();
 187       } else {
 188         two_finger_tap_allowed_for_gesture_ = false;
 189       }
 190     } break;
 191
 192     case MotionEvent::ACTION_POINTER_UP: {
 193       down_focus_x_ = last_focus_x_ = focus_x;
 194       down_focus_y_ = last_focus_y_ = focus_y;
 195
 196       // Check the dot product of current velocities.
 197       // If the pointer that left was opposing another velocity vector, clear.
 198       velocity_tracker_.ComputeCurrentVelocity(1000, max_fling_velocity_);
 199       const int up_index = ev.GetActionIndex();
 200       const int id1 = ev.GetPointerId(up_index);
 201       const float vx1 = velocity_tracker_.GetXVelocity(id1);
 202       const float vy1 = velocity_tracker_.GetYVelocity(id1);
 203       float vx_total = vx1;
 204       float vy_total = vy1;
 205       for (int i = 0; i < count; i++) {
 206         if (i == up_index)
 207           continue;
 208
 209         const int id2 = ev.GetPointerId(i);
 210         const float vx2 = velocity_tracker_.GetXVelocity(id2);
 211         const float vy2 = velocity_tracker_.GetYVelocity(id2);
 212         const float dot = vx1 * vx2 + vy1 * vy2;
 213         if (dot < 0) {
 214           vx_total = 0;
 215           vy_total = 0;
 216           velocity_tracker_.Clear();
 217           break;
 218         }
 219         vx_total += vx2;
 220         vy_total += vy2;
 221       }
 222
 223       handled = HandleSwipeIfNeeded(ev, vx_total / count, vy_total / count);
 224
 225       if (two_finger_tap_allowed_for_gesture_ && ev.GetPointerCount() == 2 &&
 226           (ev.GetEventTime() - secondary_pointer_down_event_->GetEventTime() <=
 227            two_finger_tap_timeout_)) {
 228         handled = listener_->OnTwoFingerTap(*current_down_event_, ev);
 229       }
 230       two_finger_tap_allowed_for_gesture_ = false;
 231     } break;
 232
 233     case MotionEvent::ACTION_DOWN:
 234       if (double_tap_listener_) {
 235         bool had_tap_message = timeout_handler_->HasTimeout(TAP);
 236         if (had_tap_message)
 237           timeout_handler_->StopTimeout(TAP);
 238         if (current_down_event_ && previous_up_event_ && had_tap_message &&
 239             IsConsideredDoubleTap(
 240                 *current_down_event_, *previous_up_event_, ev)) {
 241           // This is a second tap.
 242           is_double_tapping_ = true;
 243           // Give a callback with the first tap of the double-tap.
 244           handled |= double_tap_listener_->OnDoubleTap(*current_down_event_);
 245           // Give a callback with down event of the double-tap.
 246           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 247         } else {
 248           // This is a first tap.
 249           DCHECK(double_tap_timeout_ > base::TimeDelta());
 250           timeout_handler_->StartTimeout(TAP);
 251         }
 252       }
 253
 254       down_focus_x_ = last_focus_x_ = focus_x;
 255       down_focus_y_ = last_focus_y_ = focus_y;
 256       current_down_event_ = ev.Clone();
 257
 258       secondary_pointer_down_event_.reset();
 259       always_in_tap_region_ = true;
 260       always_in_bigger_tap_region_ = true;
 261       still_down_ = true;
 262       defer_confirm_single_tap_ = false;
 263       two_finger_tap_allowed_for_gesture_ = two_finger_tap_enabled_;
 264
 265       // Always start the SHOW_PRESS timer before the LONG_PRESS timer to ensure
 266       // proper timeout ordering.
 267       if (showpress_enabled_)
 268         timeout_handler_->StartTimeout(SHOW_PRESS);
 269       if (longpress_enabled_)
 270         timeout_handler_->StartTimeout(LONG_PRESS);
 271       handled |= listener_->OnDown(ev);
 272       break;
 273
 274     case MotionEvent::ACTION_MOVE:
 275       {
 276         const float scroll_x = last_focus_x_ - focus_x;
 277         const float scroll_y = last_focus_y_ - focus_y;
 278         if (is_double_tapping_) {
 279           // Give the move events of the double-tap.
 280           DCHECK(double_tap_listener_);
 281           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 282         } else if (always_in_tap_region_) {
 283           const float delta_x = focus_x - down_focus_x_;
 284           const float delta_y = focus_y - down_focus_y_;
 285           const float distance_square = delta_x * delta_x + delta_y * delta_y;
 286           if (distance_square > touch_slop_square_) {
 287             handled = listener_->OnScroll(
 288                 *current_down_event_, ev, scroll_x, scroll_y);
 289             last_focus_x_ = focus_x;
 290             last_focus_y_ = focus_y;
 291             always_in_tap_region_ = false;
 292             timeout_handler_->Stop();
 293           }
 294           if (distance_square > double_tap_touch_slop_square_)
 295             always_in_bigger_tap_region_ = false;
 296         } else if (std::abs(scroll_x) > kScrollEpsilon ||
 297                    std::abs(scroll_y) > kScrollEpsilon) {
 298           // We should eventually apply touch slop for multi-finger
 299           // scrolls as well as single finger scrolls. See
 300           // crbug.com/492185 for details.
 301           handled =
 302               listener_->OnScroll(*current_down_event_, ev, scroll_x, scroll_y);
 303           last_focus_x_ = focus_x;
 304           last_focus_y_ = focus_y;
 305         }
 306
 307         if (!two_finger_tap_allowed_for_gesture_)
 308           break;
 309
 310         // Two-finger tap should be prevented if either pointer exceeds its
 311         // (independent) slop region.
 312         const int id0 = current_down_event_->GetPointerId(0);
 313         const int ev_idx0 = ev.GetPointerId(0) == id0 ? 0 : 1;
 314
 315         // Check if the primary pointer exceeded the slop region.
 316         float dx = current_down_event_->GetX() - ev.GetX(ev_idx0);
 317         float dy = current_down_event_->GetY() - ev.GetY(ev_idx0);
 318         if (dx * dx + dy * dy > touch_slop_square_) {
 319           two_finger_tap_allowed_for_gesture_ = false;
 320           break;
 321         }
 322         if (ev.GetPointerCount() == 2) {
 323           // Check if the secondary pointer exceeded the slop region.
 324           const int ev_idx1 = ev_idx0 == 0 ? 1 : 0;
 325           const int idx1 = secondary_pointer_down_event_->GetActionIndex();
 326           dx = secondary_pointer_down_event_->GetX(idx1) - ev.GetX(ev_idx1);
 327           dy = secondary_pointer_down_event_->GetY(idx1) - ev.GetY(ev_idx1);
 328           if (dx * dx + dy * dy > touch_slop_square_)
 329             two_finger_tap_allowed_for_gesture_ = false;
 330         }
 331       }
 332       break;
 333
 334     case MotionEvent::ACTION_UP:
 335       still_down_ = false;
 336       {
 337         if (is_double_tapping_) {
 338           // Finally, give the up event of the double-tap.
 339           DCHECK(double_tap_listener_);
 340           handled |= double_tap_listener_->OnDoubleTapEvent(ev);
 341         } else if (always_in_tap_region_) {
 342           handled = listener_->OnSingleTapUp(ev);
 343           if (defer_confirm_single_tap_ && double_tap_listener_ != NULL) {
 344             double_tap_listener_->OnSingleTapConfirmed(ev);
 345           }
 346         } else {
 347
 348           // A fling must travel the minimum tap distance.
 349           const int pointer_id = ev.GetPointerId(0);
 350           velocity_tracker_.ComputeCurrentVelocity(1000, max_fling_velocity_);
 351           const float velocity_y = velocity_tracker_.GetYVelocity(pointer_id);
 352           const float velocity_x = velocity_tracker_.GetXVelocity(pointer_id);
 353
 354           if ((std::abs(velocity_y) > min_fling_velocity_) ||
 355               (std::abs(velocity_x) > min_fling_velocity_)) {
 356             handled = listener_->OnFling(
 357                 *current_down_event_, ev, velocity_x, velocity_y);
 358           }
 359
 360           handled |= HandleSwipeIfNeeded(ev, velocity_x, velocity_y);
 361         }
 362
 363         previous_up_event_ = ev.Clone();
 364
 365         velocity_tracker_.Clear();
 366         is_double_tapping_ = false;
 367         defer_confirm_single_tap_ = false;
 368         timeout_handler_->StopTimeout(SHOW_PRESS);
 369         timeout_handler_->StopTimeout(LONG_PRESS);
 370       }
 371       break;
 372
 373     case MotionEvent::ACTION_CANCEL:
 374       Cancel();
 375       break;
 376   }
 377
 378   return handled;
 379 }
 380
 381 void GestureDetector::SetDoubleTapListener(
 382     DoubleTapListener* double_tap_listener) {
 383   if (double_tap_listener == double_tap_listener_)
 384     return;
 385
 386   DCHECK(!is_double_tapping_);
 387
 388   // Null'ing the double-tap listener should flush an active tap timeout.
 389   if (!double_tap_listener) {
 390     if (timeout_handler_->HasTimeout(TAP)) {
 391       timeout_handler_->StopTimeout(TAP);
 392       OnTapTimeout();
 393     }
 394   }
 395
 396   double_tap_listener_ = double_tap_listener;
 397 }
 398
 399 void GestureDetector::Init(const Config& config) {
 400   DCHECK(listener_);
 401
 402   const float touch_slop = config.touch_slop + kSlopEpsilon;
 403   const float double_tap_touch_slop = touch_slop;
 404   const float double_tap_slop = config.double_tap_slop + kSlopEpsilon;
 405   touch_slop_square_ = touch_slop * touch_slop;
 406   double_tap_touch_slop_square_ = double_tap_touch_slop * double_tap_touch_slop;
 407   double_tap_slop_square_ = double_tap_slop * double_tap_slop;
 408   double_tap_timeout_ = config.double_tap_timeout;
 409   double_tap_min_time_ = config.double_tap_min_time;
 410   DCHECK(double_tap_min_time_ < double_tap_timeout_);
 411   min_fling_velocity_ = config.minimum_fling_velocity;
 412   max_fling_velocity_ = config.maximum_fling_velocity;
 413
 414   swipe_enabled_ = config.swipe_enabled;
 415   min_swipe_velocity_ = config.minimum_swipe_velocity;
 416   DCHECK_GT(config.maximum_swipe_deviation_angle, 0);
 417   DCHECK_LE(config.maximum_swipe_deviation_angle, 45);
 418   const float maximum_swipe_deviation_angle =
 419       std::min(45.f, std::max(0.001f, config.maximum_swipe_deviation_angle));
 420   min_swipe_direction_component_ratio_ =
 421       1.f / tan(maximum_swipe_deviation_angle * kDegreesToRadians);
 422
 423   two_finger_tap_enabled_ = config.two_finger_tap_enabled;
 424   two_finger_tap_distance_square_ = config.two_finger_tap_max_separation *
 425                                     config.two_finger_tap_max_separation;
 426   two_finger_tap_timeout_ = config.two_finger_tap_timeout;
 427 }
 428
 429 void GestureDetector::OnShowPressTimeout() {
 430   listener_->OnShowPress(*current_down_event_);
 431 }
 432
 433 void GestureDetector::OnLongPressTimeout() {
 434   timeout_handler_->StopTimeout(TAP);
 435   defer_confirm_single_tap_ = false;
 436   listener_->OnLongPress(*current_down_event_);
 437 }
 438
 439 void GestureDetector::OnTapTimeout() {
 440   if (!double_tap_listener_)
 441     return;
 442   if (!still_down_) {
 443     CHECK(previous_up_event_);
 444     double_tap_listener_->OnSingleTapConfirmed(*previous_up_event_);
 445   } else {
 446     defer_confirm_single_tap_ = true;
 447   }
 448 }
 449
 450 void GestureDetector::Cancel() {
 451   CancelTaps();
 452   velocity_tracker_.Clear();
 453   still_down_ = false;
 454 }
 455
 456 void GestureDetector::CancelTaps() {
 457   timeout_handler_->Stop();
 458   is_double_tapping_ = false;
 459   always_in_tap_region_ = false;
 460   always_in_bigger_tap_region_ = false;
 461   defer_confirm_single_tap_ = false;
 462 }
 463
 464 bool GestureDetector::IsConsideredDoubleTap(
 465     const MotionEvent& first_down,
 466     const MotionEvent& first_up,
 467     const MotionEvent& second_down) const {
 468   if (!always_in_bigger_tap_region_)
 469     return false;
 470
 471   const base::TimeDelta delta_time =
 472       second_down.GetEventTime() - first_up.GetEventTime();
 473   if (delta_time < double_tap_min_time_ || delta_time > double_tap_timeout_)
 474     return false;
 475
 476   const float delta_x = first_down.GetX() - second_down.GetX();
 477   const float delta_y = first_down.GetY() - second_down.GetY();
 478   return (delta_x * delta_x + delta_y * delta_y < double_tap_slop_square_);
 479 }
 480
 481 bool GestureDetector::HandleSwipeIfNeeded(const MotionEvent& up,
 482                                           float vx,
 483                                           float vy) {
 484   if (!swipe_enabled_ || (!vx && !vy))
 485     return false;
 486   float vx_abs = std::abs(vx);
 487   float vy_abs = std::abs(vy);
 488
 489   if (vx_abs < min_swipe_velocity_)
 490     vx_abs = vx = 0;
 491   if (vy_abs < min_swipe_velocity_)
 492     vy_abs = vy = 0;
 493
 494   // Note that the ratio will be 0 if both velocites are below the min.
 495   float ratio = vx_abs > vy_abs ? vx_abs / std::max(vy_abs, 0.001f)
 496                                 : vy_abs / std::max(vx_abs, 0.001f);
 497
 498   if (ratio < min_swipe_direction_component_ratio_)
 499     return false;
 500
 501   if (vx_abs > vy_abs)
 502     vy = 0;
 503   else
 504     vx = 0;
 505   return listener_->OnSwipe(*current_down_event_, up, vx, vy);
 506 }
 507
 508 }  // namespace ui