content/renderer/input/input_handler_proxy.cc

   1 // Copyright 2013 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 #include "content/renderer/input/input_handler_proxy.h"
   6
   7 #include "base/auto_reset.h"
   8 #include "base/command_line.h"
   9 #include "base/logging.h"
  10 #include "base/metrics/histogram.h"
  11 #include "base/trace_event/trace_event.h"
  12 #include "content/common/input/did_overscroll_params.h"
  13 #include "content/common/input/web_input_event_traits.h"
  14 #include "content/public/common/content_switches.h"
  15 #include "content/renderer/input/input_handler_proxy_client.h"
  16 #include "content/renderer/input/input_scroll_elasticity_controller.h"
  17 #include "third_party/WebKit/public/platform/Platform.h"
  18 #include "third_party/WebKit/public/web/WebInputEvent.h"
  19 #include "ui/events/latency_info.h"
  20 #include "ui/gfx/frame_time.h"
  21 #include "ui/gfx/geometry/point_conversions.h"
  22
  23 using blink::WebFloatPoint;
  24 using blink::WebFloatSize;
  25 using blink::WebGestureEvent;
  26 using blink::WebInputEvent;
  27 using blink::WebMouseEvent;
  28 using blink::WebMouseWheelEvent;
  29 using blink::WebPoint;
  30 using blink::WebTouchEvent;
  31 using blink::WebTouchPoint;
  32
  33 namespace {
  34
  35 // Maximum time between a fling event's timestamp and the first |Animate| call
  36 // for the fling curve to use the fling timestamp as the initial animation time.
  37 // Two frames allows a minor delay between event creation and the first animate.
  38 const double kMaxSecondsFromFlingTimestampToFirstAnimate = 2. / 60.;
  39
  40 // Threshold for determining whether a fling scroll delta should have caused the
  41 // client to scroll.
  42 const float kScrollEpsilon = 0.1f;
  43
  44 // Minimum fling velocity required for the active fling and new fling for the
  45 // two to accumulate.
  46 const double kMinBoostFlingSpeedSquare = 350. * 350.;
  47
  48 // Minimum velocity for the active touch scroll to preserve (boost) an active
  49 // fling for which cancellation has been deferred.
  50 const double kMinBoostTouchScrollSpeedSquare = 150 * 150.;
  51
  52 // Timeout window after which the active fling will be cancelled if no scrolls
  53 // or flings of sufficient velocity relative to the current fling are received.
  54 // The default value on Android native views is 40ms, but we use a slightly
  55 // increased value to accomodate small IPC message delays.
  56 const double kFlingBoostTimeoutDelaySeconds = 0.045;
  57
  58 gfx::Vector2dF ToClientScrollIncrement(const WebFloatSize& increment) {
  59   return gfx::Vector2dF(-increment.width, -increment.height);
  60 }
  61
  62 double InSecondsF(const base::TimeTicks& time) {
  63   return (time - base::TimeTicks()).InSecondsF();
  64 }
  65
  66 bool ShouldSuppressScrollForFlingBoosting(
  67     const gfx::Vector2dF& current_fling_velocity,
  68     const WebGestureEvent& scroll_update_event,
  69     double time_since_last_boost_event) {
  70   DCHECK_EQ(WebInputEvent::GestureScrollUpdate, scroll_update_event.type);
  71
  72   gfx::Vector2dF dx(scroll_update_event.data.scrollUpdate.deltaX,
  73                     scroll_update_event.data.scrollUpdate.deltaY);
  74   if (gfx::DotProduct(current_fling_velocity, dx) <= 0)
  75     return false;
  76
  77   if (time_since_last_boost_event < 0.001)
  78     return true;
  79
  80   // TODO(jdduke): Use |scroll_update_event.data.scrollUpdate.velocity{X,Y}|.
  81   // The scroll must be of sufficient velocity to maintain the active fling.
  82   const gfx::Vector2dF scroll_velocity =
  83       gfx::ScaleVector2d(dx, 1. / time_since_last_boost_event);
  84   if (scroll_velocity.LengthSquared() < kMinBoostTouchScrollSpeedSquare)
  85     return false;
  86
  87   return true;
  88 }
  89
  90 bool ShouldBoostFling(const gfx::Vector2dF& current_fling_velocity,
  91                       const WebGestureEvent& fling_start_event) {
  92   DCHECK_EQ(WebInputEvent::GestureFlingStart, fling_start_event.type);
  93
  94   gfx::Vector2dF new_fling_velocity(
  95       fling_start_event.data.flingStart.velocityX,
  96       fling_start_event.data.flingStart.velocityY);
  97
  98   if (gfx::DotProduct(current_fling_velocity, new_fling_velocity) <= 0)
  99     return false;
 100
 101   if (current_fling_velocity.LengthSquared() < kMinBoostFlingSpeedSquare)
 102     return false;
 103
 104   if (new_fling_velocity.LengthSquared() < kMinBoostFlingSpeedSquare)
 105     return false;
 106
 107   return true;
 108 }
 109
 110 WebGestureEvent ObtainGestureScrollBegin(const WebGestureEvent& event) {
 111   WebGestureEvent scroll_begin_event = event;
 112   scroll_begin_event.type = WebInputEvent::GestureScrollBegin;
 113   scroll_begin_event.data.scrollBegin.deltaXHint = 0;
 114   scroll_begin_event.data.scrollBegin.deltaYHint = 0;
 115   return scroll_begin_event;
 116 }
 117
 118 void ReportInputEventLatencyUma(const WebInputEvent& event,
 119                                 const ui::LatencyInfo& latency_info) {
 120   if (!(event.type == WebInputEvent::GestureScrollBegin ||
 121         event.type == WebInputEvent::GestureScrollUpdate ||
 122         event.type == WebInputEvent::GesturePinchBegin ||
 123         event.type == WebInputEvent::GesturePinchUpdate ||
 124         event.type == WebInputEvent::GestureFlingStart)) {
 125     return;
 126   }
 127
 128   ui::LatencyInfo::LatencyMap::const_iterator it =
 129       latency_info.latency_components.find(std::make_pair(
 130           ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT, 0));
 131
 132   if (it == latency_info.latency_components.end())
 133     return;
 134
 135   base::TimeDelta delta = base::TimeTicks::Now() - it->second.event_time;
 136   for (size_t i = 0; i < it->second.event_count; ++i) {
 137     switch (event.type) {
 138       case blink::WebInputEvent::GestureScrollBegin:
 139         UMA_HISTOGRAM_CUSTOM_COUNTS(
 140             "Event.Latency.RendererImpl.GestureScrollBegin",
 141             delta.InMicroseconds(), 1, 1000000, 100);
 142         break;
 143       case blink::WebInputEvent::GestureScrollUpdate:
 144         UMA_HISTOGRAM_CUSTOM_COUNTS(
 145             // So named for historical reasons.
 146             "Event.Latency.RendererImpl.GestureScroll2",
 147             delta.InMicroseconds(), 1, 1000000, 100);
 148         break;
 149       case blink::WebInputEvent::GesturePinchBegin:
 150         UMA_HISTOGRAM_CUSTOM_COUNTS(
 151             "Event.Latency.RendererImpl.GesturePinchBegin",
 152             delta.InMicroseconds(), 1, 1000000, 100);
 153         break;
 154       case blink::WebInputEvent::GesturePinchUpdate:
 155         UMA_HISTOGRAM_CUSTOM_COUNTS(
 156             "Event.Latency.RendererImpl.GesturePinchUpdate",
 157             delta.InMicroseconds(), 1, 1000000, 100);
 158         break;
 159       case blink::WebInputEvent::GestureFlingStart:
 160         UMA_HISTOGRAM_CUSTOM_COUNTS(
 161             "Event.Latency.RendererImpl.GestureFlingStart",
 162             delta.InMicroseconds(), 1, 1000000, 100);
 163         break;
 164       default:
 165         NOTREACHED();
 166         break;
 167     }
 168   }
 169 }
 170
 171 }  // namespace
 172
 173 namespace content {
 174
 175 InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler,
 176                                      InputHandlerProxyClient* client)
 177     : client_(client),
 178       input_handler_(input_handler),
 179       deferred_fling_cancel_time_seconds_(0),
 180 #ifndef NDEBUG
 181       expect_scroll_update_end_(false),
 182 #endif
 183       gesture_scroll_on_impl_thread_(false),
 184       gesture_pinch_on_impl_thread_(false),
 185       fling_may_be_active_on_main_thread_(false),
 186       disallow_horizontal_fling_scroll_(false),
 187       disallow_vertical_fling_scroll_(false),
 188       has_fling_animation_started_(false),
 189       uma_latency_reporting_enabled_(base::TimeTicks::IsHighResolution()) {
 190   DCHECK(client);
 191   input_handler_->BindToClient(this);
 192   smooth_scroll_enabled_ = base::CommandLine::ForCurrentProcess()->HasSwitch(
 193       switches::kEnableSmoothScrolling);
 194   cc::ScrollElasticityHelper* scroll_elasticity_helper =
 195       input_handler_->CreateScrollElasticityHelper();
 196   if (scroll_elasticity_helper) {
 197     scroll_elasticity_controller_.reset(
 198         new InputScrollElasticityController(scroll_elasticity_helper));
 199   }
 200 }
 201
 202 InputHandlerProxy::~InputHandlerProxy() {}
 203
 204 void InputHandlerProxy::WillShutdown() {
 205   scroll_elasticity_controller_.reset();
 206   input_handler_ = NULL;
 207   client_->WillShutdown();
 208 }
 209
 210 InputHandlerProxy::EventDisposition
 211 InputHandlerProxy::HandleInputEventWithLatencyInfo(
 212     const WebInputEvent& event,
 213     ui::LatencyInfo* latency_info) {
 214   DCHECK(input_handler_);
 215
 216   if (uma_latency_reporting_enabled_)
 217     ReportInputEventLatencyUma(event, *latency_info);
 218
 219   TRACE_EVENT_FLOW_STEP0("input,benchmark",
 220                          "LatencyInfo.Flow",
 221                          TRACE_ID_DONT_MANGLE(latency_info->trace_id),
 222                          "HandleInputEventImpl");
 223
 224   scoped_ptr<cc::SwapPromiseMonitor> latency_info_swap_promise_monitor =
 225       input_handler_->CreateLatencyInfoSwapPromiseMonitor(latency_info);
 226   InputHandlerProxy::EventDisposition disposition = HandleInputEvent(event);
 227   return disposition;
 228 }
 229
 230 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleInputEvent(
 231     const WebInputEvent& event) {
 232   DCHECK(input_handler_);
 233   TRACE_EVENT1("input,benchmark", "InputHandlerProxy::HandleInputEvent",
 234                "type", WebInputEventTraits::GetName(event.type));
 235
 236   client_->DidReceiveInputEvent(event.type);
 237   if (FilterInputEventForFlingBoosting(event))
 238     return DID_HANDLE;
 239
 240   switch (event.type) {
 241     case WebInputEvent::MouseWheel:
 242       return HandleMouseWheel(static_cast<const WebMouseWheelEvent&>(event));
 243
 244     case WebInputEvent::GestureScrollBegin:
 245       return HandleGestureScrollBegin(
 246           static_cast<const WebGestureEvent&>(event));
 247
 248     case WebInputEvent::GestureScrollUpdate:
 249       return HandleGestureScrollUpdate(
 250           static_cast<const WebGestureEvent&>(event));
 251
 252     case WebInputEvent::GestureScrollEnd:
 253       return HandleGestureScrollEnd(static_cast<const WebGestureEvent&>(event));
 254
 255     case WebInputEvent::GesturePinchBegin: {
 256       DCHECK(!gesture_pinch_on_impl_thread_);
 257       const WebGestureEvent& gesture_event =
 258           static_cast<const WebGestureEvent&>(event);
 259       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad &&
 260           input_handler_->HaveWheelEventHandlersAt(
 261               gfx::Point(gesture_event.x, gesture_event.y))) {
 262         return DID_NOT_HANDLE;
 263       } else {
 264         input_handler_->PinchGestureBegin();
 265         gesture_pinch_on_impl_thread_ = true;
 266         return DID_HANDLE;
 267       }
 268     }
 269
 270     case WebInputEvent::GesturePinchEnd:
 271       if (gesture_pinch_on_impl_thread_) {
 272         gesture_pinch_on_impl_thread_ = false;
 273         input_handler_->PinchGestureEnd();
 274         return DID_HANDLE;
 275       } else {
 276         return DID_NOT_HANDLE;
 277       }
 278
 279     case WebInputEvent::GesturePinchUpdate: {
 280       if (gesture_pinch_on_impl_thread_) {
 281         const WebGestureEvent& gesture_event =
 282             static_cast<const WebGestureEvent&>(event);
 283         input_handler_->PinchGestureUpdate(
 284             gesture_event.data.pinchUpdate.scale,
 285             gfx::Point(gesture_event.x, gesture_event.y));
 286         return DID_HANDLE;
 287       } else {
 288         return DID_NOT_HANDLE;
 289       }
 290     }
 291
 292     case WebInputEvent::GestureFlingStart:
 293       return HandleGestureFlingStart(
 294           *static_cast<const WebGestureEvent*>(&event));
 295
 296     case WebInputEvent::GestureFlingCancel:
 297       if (CancelCurrentFling())
 298         return DID_HANDLE;
 299       else if (!fling_may_be_active_on_main_thread_)
 300         return DROP_EVENT;
 301       return DID_NOT_HANDLE;
 302
 303     case WebInputEvent::TouchStart:
 304       return HandleTouchStart(static_cast<const WebTouchEvent&>(event));
 305
 306     case WebInputEvent::MouseMove: {
 307       const WebMouseEvent& mouse_event =
 308           static_cast<const WebMouseEvent&>(event);
 309       // TODO(tony): Ignore when mouse buttons are down?
 310       // TODO(davemoore): This should never happen, but bug #326635 showed some
 311       // surprising crashes.
 312       CHECK(input_handler_);
 313       input_handler_->MouseMoveAt(gfx::Point(mouse_event.x, mouse_event.y));
 314       return DID_NOT_HANDLE;
 315     }
 316
 317     default:
 318       if (WebInputEvent::isKeyboardEventType(event.type)) {
 319         // Only call |CancelCurrentFling()| if a fling was active, as it will
 320         // otherwise disrupt an in-progress touch scroll.
 321         if (fling_curve_)
 322           CancelCurrentFling();
 323       }
 324       break;
 325   }
 326
 327   return DID_NOT_HANDLE;
 328 }
 329
 330 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleMouseWheel(
 331     const WebMouseWheelEvent& wheel_event) {
 332   InputHandlerProxy::EventDisposition result = DID_NOT_HANDLE;
 333   cc::InputHandlerScrollResult scroll_result;
 334
 335   if (wheel_event.scrollByPage) {
 336     // TODO(jamesr): We don't properly handle scroll by page in the compositor
 337     // thread, so punt it to the main thread. http://crbug.com/236639
 338     result = DID_NOT_HANDLE;
 339   } else if (!wheel_event.canScroll) {
 340     // Wheel events with |canScroll| == false will not trigger scrolling,
 341     // only event handlers.  Forward to the main thread.
 342     result = DID_NOT_HANDLE;
 343   } else if (smooth_scroll_enabled_) {
 344     cc::InputHandler::ScrollStatus scroll_status =
 345         input_handler_->ScrollAnimated(
 346             gfx::Point(wheel_event.x, wheel_event.y),
 347             gfx::Vector2dF(-wheel_event.deltaX, -wheel_event.deltaY));
 348     switch (scroll_status) {
 349       case cc::InputHandler::ScrollStarted:
 350         result = DID_HANDLE;
 351         break;
 352       case cc::InputHandler::ScrollIgnored:
 353         result = DROP_EVENT;
 354       default:
 355         result = DID_NOT_HANDLE;
 356         break;
 357     }
 358   } else {
 359     cc::InputHandler::ScrollStatus scroll_status = input_handler_->ScrollBegin(
 360         gfx::Point(wheel_event.x, wheel_event.y), cc::InputHandler::Wheel);
 361     switch (scroll_status) {
 362       case cc::InputHandler::ScrollStarted: {
 363         TRACE_EVENT_INSTANT2(
 364             "input", "InputHandlerProxy::handle_input wheel scroll",
 365             TRACE_EVENT_SCOPE_THREAD, "deltaX", -wheel_event.deltaX, "deltaY",
 366             -wheel_event.deltaY);
 367         gfx::Point scroll_point(wheel_event.x, wheel_event.y);
 368         gfx::Vector2dF scroll_delta(-wheel_event.deltaX, -wheel_event.deltaY);
 369         scroll_result = input_handler_->ScrollBy(scroll_point, scroll_delta);
 370         HandleOverscroll(scroll_point, scroll_result);
 371         input_handler_->ScrollEnd();
 372         result = scroll_result.did_scroll ? DID_HANDLE : DROP_EVENT;
 373         break;
 374       }
 375       case cc::InputHandler::ScrollIgnored:
 376         // TODO(jamesr): This should be DROP_EVENT, but in cases where we fail
 377         // to properly sync scrollability it's safer to send the event to the
 378         // main thread. Change back to DROP_EVENT once we have synchronization
 379         // bugs sorted out.
 380         result = DID_NOT_HANDLE;
 381         break;
 382       case cc::InputHandler::ScrollUnknown:
 383       case cc::InputHandler::ScrollOnMainThread:
 384         result = DID_NOT_HANDLE;
 385         break;
 386       case cc::InputHandler::ScrollStatusCount:
 387         NOTREACHED();
 388         break;
 389     }
 390   }
 391
 392   // Send the event and its disposition to the elasticity controller to update
 393   // the over-scroll animation. If the event is to be handled on the main
 394   // thread, the event and its disposition will be sent to the elasticity
 395   // controller after being handled on the main thread.
 396   if (scroll_elasticity_controller_ && result != DID_NOT_HANDLE) {
 397     // Note that the call to the elasticity controller is made asynchronously,
 398     // to minimize divergence between main thread and impl thread event
 399     // handling paths.
 400     base::MessageLoop::current()->PostTask(
 401         FROM_HERE,
 402         base::Bind(&InputScrollElasticityController::ObserveWheelEventAndResult,
 403                    scroll_elasticity_controller_->GetWeakPtr(), wheel_event,
 404                    scroll_result));
 405   }
 406   return result;
 407 }
 408
 409 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollBegin(
 410     const WebGestureEvent& gesture_event) {
 411   DCHECK(!gesture_scroll_on_impl_thread_);
 412 #ifndef NDEBUG
 413   DCHECK(!expect_scroll_update_end_);
 414   expect_scroll_update_end_ = true;
 415 #endif
 416   cc::InputHandler::ScrollStatus scroll_status = input_handler_->ScrollBegin(
 417       gfx::Point(gesture_event.x, gesture_event.y),
 418       cc::InputHandler::Gesture);
 419   UMA_HISTOGRAM_ENUMERATION("Renderer4.CompositorScrollHitTestResult",
 420                             scroll_status,
 421                             cc::InputHandler::ScrollStatusCount);
 422   switch (scroll_status) {
 423     case cc::InputHandler::ScrollStarted:
 424       TRACE_EVENT_INSTANT0("input",
 425                            "InputHandlerProxy::handle_input gesture scroll",
 426                            TRACE_EVENT_SCOPE_THREAD);
 427       gesture_scroll_on_impl_thread_ = true;
 428       return DID_HANDLE;
 429     case cc::InputHandler::ScrollUnknown:
 430     case cc::InputHandler::ScrollOnMainThread:
 431       return DID_NOT_HANDLE;
 432     case cc::InputHandler::ScrollIgnored:
 433       return DROP_EVENT;
 434     case cc::InputHandler::ScrollStatusCount:
 435       NOTREACHED();
 436       break;
 437   }
 438   return DID_NOT_HANDLE;
 439 }
 440
 441 InputHandlerProxy::EventDisposition
 442 InputHandlerProxy::HandleGestureScrollUpdate(
 443   const WebGestureEvent& gesture_event) {
 444 #ifndef NDEBUG
 445   DCHECK(expect_scroll_update_end_);
 446 #endif
 447
 448   if (!gesture_scroll_on_impl_thread_ && !gesture_pinch_on_impl_thread_)
 449     return DID_NOT_HANDLE;
 450
 451   gfx::Point scroll_point(gesture_event.x, gesture_event.y);
 452   gfx::Vector2dF scroll_delta(-gesture_event.data.scrollUpdate.deltaX,
 453                               -gesture_event.data.scrollUpdate.deltaY);
 454   cc::InputHandlerScrollResult scroll_result = input_handler_->ScrollBy(
 455       scroll_point, scroll_delta);
 456   HandleOverscroll(scroll_point, scroll_result);
 457   return scroll_result.did_scroll ? DID_HANDLE : DROP_EVENT;
 458 }
 459
 460 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollEnd(
 461   const WebGestureEvent& gesture_event) {
 462 #ifndef NDEBUG
 463   DCHECK(expect_scroll_update_end_);
 464   expect_scroll_update_end_ = false;
 465 #endif
 466   input_handler_->ScrollEnd();
 467   if (!gesture_scroll_on_impl_thread_)
 468     return DID_NOT_HANDLE;
 469   gesture_scroll_on_impl_thread_ = false;
 470   return DID_HANDLE;
 471 }
 472
 473 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureFlingStart(
 474     const WebGestureEvent& gesture_event) {
 475   cc::InputHandler::ScrollStatus scroll_status;
 476
 477   if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad) {
 478     scroll_status = input_handler_->ScrollBegin(
 479         gfx::Point(gesture_event.x, gesture_event.y),
 480         cc::InputHandler::NonBubblingGesture);
 481   } else {
 482     if (!gesture_scroll_on_impl_thread_)
 483       scroll_status = cc::InputHandler::ScrollOnMainThread;
 484     else
 485       scroll_status = input_handler_->FlingScrollBegin();
 486   }
 487
 488 #ifndef NDEBUG
 489   expect_scroll_update_end_ = false;
 490 #endif
 491
 492   switch (scroll_status) {
 493     case cc::InputHandler::ScrollStarted: {
 494       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad)
 495         input_handler_->ScrollEnd();
 496
 497       const float vx = gesture_event.data.flingStart.velocityX;
 498       const float vy = gesture_event.data.flingStart.velocityY;
 499       current_fling_velocity_ = gfx::Vector2dF(vx, vy);
 500       DCHECK(!current_fling_velocity_.IsZero());
 501       fling_curve_.reset(client_->CreateFlingAnimationCurve(
 502           gesture_event.sourceDevice,
 503           WebFloatPoint(vx, vy),
 504           blink::WebSize()));
 505       disallow_horizontal_fling_scroll_ = !vx;
 506       disallow_vertical_fling_scroll_ = !vy;
 507       TRACE_EVENT_ASYNC_BEGIN2("input",
 508                                "InputHandlerProxy::HandleGestureFling::started",
 509                                this,
 510                                "vx",
 511                                vx,
 512                                "vy",
 513                                vy);
 514       // Note that the timestamp will only be used to kickstart the animation if
 515       // its sufficiently close to the timestamp of the first call |Animate()|.
 516       has_fling_animation_started_ = false;
 517       fling_parameters_.startTime = gesture_event.timeStampSeconds;
 518       fling_parameters_.delta = WebFloatPoint(vx, vy);
 519       fling_parameters_.point = WebPoint(gesture_event.x, gesture_event.y);
 520       fling_parameters_.globalPoint =
 521           WebPoint(gesture_event.globalX, gesture_event.globalY);
 522       fling_parameters_.modifiers = gesture_event.modifiers;
 523       fling_parameters_.sourceDevice = gesture_event.sourceDevice;
 524       input_handler_->SetNeedsAnimate();
 525       return DID_HANDLE;
 526     }
 527     case cc::InputHandler::ScrollUnknown:
 528     case cc::InputHandler::ScrollOnMainThread: {
 529       TRACE_EVENT_INSTANT0("input",
 530                            "InputHandlerProxy::HandleGestureFling::"
 531                            "scroll_on_main_thread",
 532                            TRACE_EVENT_SCOPE_THREAD);
 533       fling_may_be_active_on_main_thread_ = true;
 534       return DID_NOT_HANDLE;
 535     }
 536     case cc::InputHandler::ScrollIgnored: {
 537       TRACE_EVENT_INSTANT0(
 538           "input",
 539           "InputHandlerProxy::HandleGestureFling::ignored",
 540           TRACE_EVENT_SCOPE_THREAD);
 541       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad) {
 542         // We still pass the curve to the main thread if there's nothing
 543         // scrollable, in case something
 544         // registers a handler before the curve is over.
 545         return DID_NOT_HANDLE;
 546       }
 547       return DROP_EVENT;
 548     }
 549     case cc::InputHandler::ScrollStatusCount:
 550       NOTREACHED();
 551       break;
 552   }
 553   return DID_NOT_HANDLE;
 554 }
 555
 556 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleTouchStart(
 557     const blink::WebTouchEvent& touch_event) {
 558   for (size_t i = 0; i < touch_event.touchesLength; ++i) {
 559     if (touch_event.touches[i].state != WebTouchPoint::StatePressed)
 560       continue;
 561     if (input_handler_->HaveTouchEventHandlersAt(
 562             gfx::Point(touch_event.touches[i].position.x,
 563                        touch_event.touches[i].position.y))) {
 564       return DID_NOT_HANDLE;
 565     }
 566   }
 567   return DROP_EVENT;
 568 }
 569
 570 bool InputHandlerProxy::FilterInputEventForFlingBoosting(
 571     const WebInputEvent& event) {
 572   if (!WebInputEvent::isGestureEventType(event.type))
 573     return false;
 574
 575   if (!fling_curve_) {
 576     DCHECK(!deferred_fling_cancel_time_seconds_);
 577     return false;
 578   }
 579
 580   const WebGestureEvent& gesture_event =
 581       static_cast<const WebGestureEvent&>(event);
 582   if (gesture_event.type == WebInputEvent::GestureFlingCancel) {
 583     if (gesture_event.data.flingCancel.preventBoosting)
 584       return false;
 585
 586     if (current_fling_velocity_.LengthSquared() < kMinBoostFlingSpeedSquare)
 587       return false;
 588
 589     TRACE_EVENT_INSTANT0("input",
 590                          "InputHandlerProxy::FlingBoostStart",
 591                          TRACE_EVENT_SCOPE_THREAD);
 592     deferred_fling_cancel_time_seconds_ =
 593         event.timeStampSeconds + kFlingBoostTimeoutDelaySeconds;
 594     return true;
 595   }
 596
 597   // A fling is either inactive or is "free spinning", i.e., has yet to be
 598   // interrupted by a touch gesture, in which case there is nothing to filter.
 599   if (!deferred_fling_cancel_time_seconds_)
 600     return false;
 601
 602   // Gestures from a different source should immediately interrupt the fling.
 603   if (gesture_event.sourceDevice != fling_parameters_.sourceDevice) {
 604     CancelCurrentFling();
 605     return false;
 606   }
 607
 608   switch (gesture_event.type) {
 609     case WebInputEvent::GestureTapCancel:
 610     case WebInputEvent::GestureTapDown:
 611       return false;
 612
 613     case WebInputEvent::GestureScrollBegin:
 614       if (!input_handler_->IsCurrentlyScrollingLayerAt(
 615               gfx::Point(gesture_event.x, gesture_event.y),
 616               fling_parameters_.sourceDevice == blink::WebGestureDeviceTouchpad
 617                   ? cc::InputHandler::NonBubblingGesture
 618                   : cc::InputHandler::Gesture)) {
 619         CancelCurrentFling();
 620         return false;
 621       }
 622
 623       // TODO(jdduke): Use |gesture_event.data.scrollBegin.delta{X,Y}Hint| to
 624       // determine if the ScrollBegin should immediately cancel the fling.
 625       ExtendBoostedFlingTimeout(gesture_event);
 626       return true;
 627
 628     case WebInputEvent::GestureScrollUpdate: {
 629       const double time_since_last_boost_event =
 630           event.timeStampSeconds - last_fling_boost_event_.timeStampSeconds;
 631       if (ShouldSuppressScrollForFlingBoosting(current_fling_velocity_,
 632                                                gesture_event,
 633                                                time_since_last_boost_event)) {
 634         ExtendBoostedFlingTimeout(gesture_event);
 635         return true;
 636       }
 637
 638       CancelCurrentFling();
 639       return false;
 640     }
 641
 642     case WebInputEvent::GestureScrollEnd:
 643       // Clear the last fling boost event *prior* to fling cancellation,
 644       // preventing insertion of a synthetic GestureScrollBegin.
 645       last_fling_boost_event_ = WebGestureEvent();
 646       CancelCurrentFling();
 647       return true;
 648
 649     case WebInputEvent::GestureFlingStart: {
 650       DCHECK_EQ(fling_parameters_.sourceDevice, gesture_event.sourceDevice);
 651
 652       bool fling_boosted =
 653           fling_parameters_.modifiers == gesture_event.modifiers &&
 654           ShouldBoostFling(current_fling_velocity_, gesture_event);
 655
 656       gfx::Vector2dF new_fling_velocity(
 657           gesture_event.data.flingStart.velocityX,
 658           gesture_event.data.flingStart.velocityY);
 659       DCHECK(!new_fling_velocity.IsZero());
 660
 661       if (fling_boosted)
 662         current_fling_velocity_ += new_fling_velocity;
 663       else
 664         current_fling_velocity_ = new_fling_velocity;
 665
 666       WebFloatPoint velocity(current_fling_velocity_.x(),
 667                              current_fling_velocity_.y());
 668       deferred_fling_cancel_time_seconds_ = 0;
 669       disallow_horizontal_fling_scroll_ = !velocity.x;
 670       disallow_vertical_fling_scroll_ = !velocity.y;
 671       last_fling_boost_event_ = WebGestureEvent();
 672       fling_curve_.reset(client_->CreateFlingAnimationCurve(
 673           gesture_event.sourceDevice,
 674           velocity,
 675           blink::WebSize()));
 676       fling_parameters_.startTime = gesture_event.timeStampSeconds;
 677       fling_parameters_.delta = velocity;
 678       fling_parameters_.point = WebPoint(gesture_event.x, gesture_event.y);
 679       fling_parameters_.globalPoint =
 680           WebPoint(gesture_event.globalX, gesture_event.globalY);
 681
 682       TRACE_EVENT_INSTANT2("input",
 683                            fling_boosted ? "InputHandlerProxy::FlingBoosted"
 684                                          : "InputHandlerProxy::FlingReplaced",
 685                            TRACE_EVENT_SCOPE_THREAD,
 686                            "vx",
 687                            current_fling_velocity_.x(),
 688                            "vy",
 689                            current_fling_velocity_.y());
 690
 691       // The client expects balanced calls between a consumed GestureFlingStart
 692       // and |DidStopFlinging()|. TODO(jdduke): Provide a count parameter to
 693       // |DidStopFlinging()| and only send after the accumulated fling ends.
 694       client_->DidStopFlinging();
 695       return true;
 696     }
 697
 698     default:
 699       // All other types of gestures (taps, presses, etc...) will complete the
 700       // deferred fling cancellation.
 701       CancelCurrentFling();
 702       return false;
 703   }
 704 }
 705
 706 void InputHandlerProxy::ExtendBoostedFlingTimeout(
 707     const blink::WebGestureEvent& event) {
 708   TRACE_EVENT_INSTANT0("input",
 709                        "InputHandlerProxy::ExtendBoostedFlingTimeout",
 710                        TRACE_EVENT_SCOPE_THREAD);
 711   deferred_fling_cancel_time_seconds_ =
 712       event.timeStampSeconds + kFlingBoostTimeoutDelaySeconds;
 713   last_fling_boost_event_ = event;
 714 }
 715
 716 void InputHandlerProxy::Animate(base::TimeTicks time) {
 717   if (scroll_elasticity_controller_)
 718     scroll_elasticity_controller_->Animate(time);
 719
 720   if (!fling_curve_)
 721     return;
 722
 723   double monotonic_time_sec = InSecondsF(time);
 724
 725   if (deferred_fling_cancel_time_seconds_ &&
 726       monotonic_time_sec > deferred_fling_cancel_time_seconds_) {
 727     CancelCurrentFling();
 728     return;
 729   }
 730
 731   client_->DidAnimateForInput();
 732
 733   if (!has_fling_animation_started_) {
 734     has_fling_animation_started_ = true;
 735     // Guard against invalid, future or sufficiently stale start times, as there
 736     // are no guarantees fling event and animation timestamps are compatible.
 737     if (!fling_parameters_.startTime ||
 738         monotonic_time_sec <= fling_parameters_.startTime ||
 739         monotonic_time_sec >= fling_parameters_.startTime +
 740                                   kMaxSecondsFromFlingTimestampToFirstAnimate) {
 741       fling_parameters_.startTime = monotonic_time_sec;
 742       input_handler_->SetNeedsAnimate();
 743       return;
 744     }
 745   }
 746
 747   bool fling_is_active =
 748       fling_curve_->apply(monotonic_time_sec - fling_parameters_.startTime,
 749                           this);
 750
 751   if (disallow_vertical_fling_scroll_ && disallow_horizontal_fling_scroll_)
 752     fling_is_active = false;
 753
 754   if (fling_is_active) {
 755     input_handler_->SetNeedsAnimate();
 756   } else {
 757     TRACE_EVENT_INSTANT0("input",
 758                          "InputHandlerProxy::animate::flingOver",
 759                          TRACE_EVENT_SCOPE_THREAD);
 760     CancelCurrentFling();
 761   }
 762 }
 763
 764 void InputHandlerProxy::MainThreadHasStoppedFlinging() {
 765   fling_may_be_active_on_main_thread_ = false;
 766   client_->DidStopFlinging();
 767 }
 768
 769 void InputHandlerProxy::ReconcileElasticOverscrollAndRootScroll() {
 770   if (scroll_elasticity_controller_)
 771     scroll_elasticity_controller_->ReconcileStretchAndScroll();
 772 }
 773
 774 void InputHandlerProxy::HandleOverscroll(
 775     const gfx::Point& causal_event_viewport_point,
 776     const cc::InputHandlerScrollResult& scroll_result) {
 777   DCHECK(client_);
 778   if (!scroll_result.did_overscroll_root)
 779     return;
 780
 781   TRACE_EVENT2("input",
 782                "InputHandlerProxy::DidOverscroll",
 783                "dx",
 784                scroll_result.unused_scroll_delta.x(),
 785                "dy",
 786                scroll_result.unused_scroll_delta.y());
 787
 788   DidOverscrollParams params;
 789   params.accumulated_overscroll = scroll_result.accumulated_root_overscroll;
 790   params.latest_overscroll_delta = scroll_result.unused_scroll_delta;
 791   params.current_fling_velocity =
 792       ToClientScrollIncrement(current_fling_velocity_);
 793   params.causal_event_viewport_point = causal_event_viewport_point;
 794
 795   if (fling_curve_) {
 796     static const int kFlingOverscrollThreshold = 1;
 797     disallow_horizontal_fling_scroll_ |=
 798         std::abs(params.accumulated_overscroll.x()) >=
 799         kFlingOverscrollThreshold;
 800     disallow_vertical_fling_scroll_ |=
 801         std::abs(params.accumulated_overscroll.y()) >=
 802         kFlingOverscrollThreshold;
 803   }
 804
 805   client_->DidOverscroll(params);
 806 }
 807
 808 bool InputHandlerProxy::CancelCurrentFling() {
 809   if (CancelCurrentFlingWithoutNotifyingClient()) {
 810     client_->DidStopFlinging();
 811     return true;
 812   }
 813   return false;
 814 }
 815
 816 bool InputHandlerProxy::CancelCurrentFlingWithoutNotifyingClient() {
 817   bool had_fling_animation = fling_curve_;
 818   if (had_fling_animation &&
 819       fling_parameters_.sourceDevice == blink::WebGestureDeviceTouchscreen) {
 820     input_handler_->ScrollEnd();
 821     TRACE_EVENT_ASYNC_END0(
 822         "input",
 823         "InputHandlerProxy::HandleGestureFling::started",
 824         this);
 825   }
 826
 827   TRACE_EVENT_INSTANT1("input",
 828                        "InputHandlerProxy::CancelCurrentFling",
 829                        TRACE_EVENT_SCOPE_THREAD,
 830                        "had_fling_animation",
 831                        had_fling_animation);
 832   fling_curve_.reset();
 833   has_fling_animation_started_ = false;
 834   gesture_scroll_on_impl_thread_ = false;
 835   current_fling_velocity_ = gfx::Vector2dF();
 836   fling_parameters_ = blink::WebActiveWheelFlingParameters();
 837
 838   if (deferred_fling_cancel_time_seconds_) {
 839     deferred_fling_cancel_time_seconds_ = 0;
 840
 841     WebGestureEvent last_fling_boost_event = last_fling_boost_event_;
 842     last_fling_boost_event_ = WebGestureEvent();
 843     if (last_fling_boost_event.type == WebInputEvent::GestureScrollBegin ||
 844         last_fling_boost_event.type == WebInputEvent::GestureScrollUpdate) {
 845       // Synthesize a GestureScrollBegin, as the original was suppressed.
 846       HandleInputEvent(ObtainGestureScrollBegin(last_fling_boost_event));
 847     }
 848   }
 849
 850   return had_fling_animation;
 851 }
 852
 853 bool InputHandlerProxy::TouchpadFlingScroll(
 854     const WebFloatSize& increment) {
 855   WebMouseWheelEvent synthetic_wheel;
 856   synthetic_wheel.type = WebInputEvent::MouseWheel;
 857   synthetic_wheel.deltaX = increment.width;
 858   synthetic_wheel.deltaY = increment.height;
 859   synthetic_wheel.hasPreciseScrollingDeltas = true;
 860   synthetic_wheel.x = fling_parameters_.point.x;
 861   synthetic_wheel.y = fling_parameters_.point.y;
 862   synthetic_wheel.globalX = fling_parameters_.globalPoint.x;
 863   synthetic_wheel.globalY = fling_parameters_.globalPoint.y;
 864   synthetic_wheel.modifiers = fling_parameters_.modifiers;
 865
 866   InputHandlerProxy::EventDisposition disposition =
 867       HandleInputEvent(synthetic_wheel);
 868   switch (disposition) {
 869     case DID_HANDLE:
 870       return true;
 871     case DROP_EVENT:
 872       break;
 873     case DID_NOT_HANDLE:
 874       TRACE_EVENT_INSTANT0("input",
 875                            "InputHandlerProxy::scrollBy::AbortFling",
 876                            TRACE_EVENT_SCOPE_THREAD);
 877       // If we got a DID_NOT_HANDLE, that means we need to deliver wheels on the
 878       // main thread. In this case we need to schedule a commit and transfer the
 879       // fling curve over to the main thread and run the rest of the wheels from
 880       // there. This can happen when flinging a page that contains a scrollable
 881       // subarea that we can't scroll on the thread if the fling starts outside
 882       // the subarea but then is flung "under" the pointer.
 883       client_->TransferActiveWheelFlingAnimation(fling_parameters_);
 884       fling_may_be_active_on_main_thread_ = true;
 885       CancelCurrentFlingWithoutNotifyingClient();
 886       break;
 887   }
 888
 889   return false;
 890 }
 891
 892 bool InputHandlerProxy::scrollBy(const WebFloatSize& increment,
 893                                  const WebFloatSize& velocity) {
 894   WebFloatSize clipped_increment;
 895   WebFloatSize clipped_velocity;
 896   if (!disallow_horizontal_fling_scroll_) {
 897     clipped_increment.width = increment.width;
 898     clipped_velocity.width = velocity.width;
 899   }
 900   if (!disallow_vertical_fling_scroll_) {
 901     clipped_increment.height = increment.height;
 902     clipped_velocity.height = velocity.height;
 903   }
 904
 905   current_fling_velocity_ = clipped_velocity;
 906
 907   // Early out if the increment is zero, but avoid early terimination if the
 908   // velocity is still non-zero.
 909   if (clipped_increment == WebFloatSize())
 910     return clipped_velocity != WebFloatSize();
 911
 912   TRACE_EVENT2("input",
 913                "InputHandlerProxy::scrollBy",
 914                "x",
 915                clipped_increment.width,
 916                "y",
 917                clipped_increment.height);
 918
 919   bool did_scroll = false;
 920
 921   switch (fling_parameters_.sourceDevice) {
 922     case blink::WebGestureDeviceTouchpad:
 923       did_scroll = TouchpadFlingScroll(clipped_increment);
 924       break;
 925     case blink::WebGestureDeviceTouchscreen: {
 926       clipped_increment = ToClientScrollIncrement(clipped_increment);
 927       cc::InputHandlerScrollResult scroll_result = input_handler_->ScrollBy(
 928           fling_parameters_.point, clipped_increment);
 929       HandleOverscroll(fling_parameters_.point, scroll_result);
 930       did_scroll = scroll_result.did_scroll;
 931     } break;
 932   }
 933
 934   if (did_scroll) {
 935     fling_parameters_.cumulativeScroll.width += clipped_increment.width;
 936     fling_parameters_.cumulativeScroll.height += clipped_increment.height;
 937   }
 938
 939   // It's possible the provided |increment| is sufficiently small as to not
 940   // trigger a scroll, e.g., with a trivial time delta between fling updates.
 941   // Return true in this case to prevent early fling termination.
 942   if (std::abs(clipped_increment.width) < kScrollEpsilon &&
 943       std::abs(clipped_increment.height) < kScrollEpsilon)
 944     return true;
 945
 946   return did_scroll;
 947 }
 948
 949 }  // namespace content