path: root/gfx/layers/apz/util/APZEventState.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "APZEventState.h"

#include <utility>

#include "APZCCallbackHelper.h"
#include "ActiveElementManager.h"
#include "TouchManager.h"
#include "mozilla/Assertions.h"
#include "mozilla/BasicEvents.h"
#include "mozilla/dom/Document.h"
#include "mozilla/EventForwards.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/PositionedEventTargeting.h"
#include "mozilla/Preferences.h"
#include "mozilla/PresShell.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/StaticPrefs_ui.h"
#include "mozilla/ToString.h"
#include "mozilla/TouchEvents.h"
#include "mozilla/ViewportUtils.h"
#include "mozilla/dom/BrowserChild.h"
#include "mozilla/dom/MouseEventBinding.h"
#include "mozilla/layers/APZCCallbackHelper.h"
#include "mozilla/layers/APZUtils.h"
#include "mozilla/layers/IAPZCTreeManager.h"
#include "mozilla/widget/nsAutoRollup.h"
#include "nsCOMPtr.h"
#include "nsContentUtils.h"
#include "nsDocShell.h"
#include "nsIDOMWindowUtils.h"
#include "nsINamed.h"
#include "nsIScrollableFrame.h"
#include "nsIScrollbarMediator.h"
#include "nsIWeakReferenceUtils.h"
#include "nsIWidget.h"
#include "nsLayoutUtils.h"
#include "nsQueryFrame.h"

static mozilla::LazyLogModule sApzEvtLog("apz.eventstate");
#define APZES_LOG(...) MOZ_LOG(sApzEvtLog, LogLevel::Debug, (__VA_ARGS__))

// Static helper functions
namespace {

int32_t WidgetModifiersToDOMModifiers(mozilla::Modifiers aModifiers) {
  int32_t result = 0;
  if (aModifiers & mozilla::MODIFIER_SHIFT) {
    result |= nsIDOMWindowUtils::MODIFIER_SHIFT;
  }
  if (aModifiers & mozilla::MODIFIER_CONTROL) {
    result |= nsIDOMWindowUtils::MODIFIER_CONTROL;
  }
  if (aModifiers & mozilla::MODIFIER_ALT) {
    result |= nsIDOMWindowUtils::MODIFIER_ALT;
  }
  if (aModifiers & mozilla::MODIFIER_META) {
    result |= nsIDOMWindowUtils::MODIFIER_META;
  }
  if (aModifiers & mozilla::MODIFIER_ALTGRAPH) {
    result |= nsIDOMWindowUtils::MODIFIER_ALTGRAPH;
  }
  if (aModifiers & mozilla::MODIFIER_CAPSLOCK) {
    result |= nsIDOMWindowUtils::MODIFIER_CAPSLOCK;
  }
  if (aModifiers & mozilla::MODIFIER_FN) {
    result |= nsIDOMWindowUtils::MODIFIER_FN;
  }
  if (aModifiers & mozilla::MODIFIER_FNLOCK) {
    result |= nsIDOMWindowUtils::MODIFIER_FNLOCK;
  }
  if (aModifiers & mozilla::MODIFIER_NUMLOCK) {
    result |= nsIDOMWindowUtils::MODIFIER_NUMLOCK;
  }
  if (aModifiers & mozilla::MODIFIER_SCROLLLOCK) {
    result |= nsIDOMWindowUtils::MODIFIER_SCROLLLOCK;
  }
  if (aModifiers & mozilla::MODIFIER_SYMBOL) {
    result |= nsIDOMWindowUtils::MODIFIER_SYMBOL;
  }
  if (aModifiers & mozilla::MODIFIER_SYMBOLLOCK) {
    result |= nsIDOMWindowUtils::MODIFIER_SYMBOLLOCK;
  }
  return result;
}

}  // namespace

namespace mozilla {
namespace layers {

APZEventState::APZEventState(nsIWidget* aWidget,
                             ContentReceivedInputBlockCallback&& aCallback)
    : mWidget(nullptr)  // initialized in constructor body
      ,
      mActiveElementManager(new ActiveElementManager()),
      mContentReceivedInputBlockCallback(std::move(aCallback)),
      mPendingTouchPreventedResponse(false),
      mPendingTouchPreventedBlockId(0),
      mEndTouchState(apz::SingleTapState::NotClick),
      mFirstTouchCancelled(false),
      mTouchEndCancelled(false),
      mReceivedNonTouchStart(false),
      mTouchStartPrevented(false),
      mLastTouchIdentifier(0) {
  nsresult rv;
  mWidget = do_GetWeakReference(aWidget, &rv);
  MOZ_ASSERT(NS_SUCCEEDED(rv),
             "APZEventState constructed with a widget that"
             " does not support weak references. APZ will NOT work!");
}

APZEventState::~APZEventState() = default;

void APZEventState::ProcessSingleTap(const CSSPoint& aPoint,
                                     const CSSToLayoutDeviceScale& aScale,
                                     Modifiers aModifiers, int32_t aClickCount,
                                     uint64_t aInputBlockId) {
  APZES_LOG("Handling single tap at %s with %d\n", ToString(aPoint).c_str(),
            mTouchEndCancelled);

  RefPtr<nsIContent> touchRollup = GetTouchRollup();
  mTouchRollup = nullptr;

  nsCOMPtr<nsIWidget> widget = GetWidget();
  if (!widget) {
    return;
  }

  if (mTouchEndCancelled) {
    return;
  }

  nsCOMPtr<nsIWidget> localWidget = do_QueryReferent(mWidget);
  if (localWidget) {
    widget::nsAutoRollup rollup(touchRollup);
    APZCCallbackHelper::FireSingleTapEvent(aPoint * aScale, aModifiers,
                                           aClickCount, localWidget);
  }

  mActiveElementManager->ProcessSingleTap();
}

PreventDefaultResult APZEventState::FireContextmenuEvents(
    PresShell* aPresShell, const CSSPoint& aPoint,
    const CSSToLayoutDeviceScale& aScale, Modifiers aModifiers,
    const nsCOMPtr<nsIWidget>& aWidget) {
  // Suppress retargeting for mouse events generated by a long-press
  EventRetargetSuppression suppression;

  // Synthesize mousemove event for allowing users to emulate to move mouse
  // cursor over the element.  As a result, users can open submenu UI which
  // is opened when mouse cursor is moved over a link (i.e., it's a case that
  // users cannot stay in the page after tapping it).  So, this improves
  // accessibility in websites which are designed for desktop.
  // Note that we don't need to check whether mousemove event is consumed or
  // not because Chrome also ignores the result.
  APZCCallbackHelper::DispatchSynthesizedMouseEvent(
      eMouseMove, aPoint * aScale, aModifiers, 0 /* clickCount */, aWidget);

  // Converting the modifiers to DOM format for the DispatchMouseEvent call
  // is the most useless thing ever because nsDOMWindowUtils::SendMouseEvent
  // just converts them back to widget format, but that API has many callers,
  // including in JS code, so it's not trivial to change.
  CSSPoint point = CSSPoint::FromAppUnits(
      ViewportUtils::VisualToLayout(CSSPoint::ToAppUnits(aPoint), aPresShell));
  PreventDefaultResult preventDefaultResult =
      APZCCallbackHelper::DispatchMouseEvent(
          aPresShell, u"contextmenu"_ns, point, 2, 1,
          WidgetModifiersToDOMModifiers(aModifiers),
          dom::MouseEvent_Binding::MOZ_SOURCE_TOUCH,
          0 /* Use the default value here. */);

  APZES_LOG("Contextmenu event %s\n", ToString(preventDefaultResult).c_str());
  if (preventDefaultResult != PreventDefaultResult::No) {
    // If the contextmenu event was handled then we're showing a contextmenu,
    // and so we should remove any activation
    mActiveElementManager->ClearActivation();
#ifndef XP_WIN
  } else {
    // If the contextmenu wasn't consumed, fire the eMouseLongTap event.
    nsEventStatus status = APZCCallbackHelper::DispatchSynthesizedMouseEvent(
        eMouseLongTap, aPoint * aScale, aModifiers,
        /*clickCount*/ 1, aWidget);
    APZES_LOG("eMouseLongTap event %s\n", ToString(status).c_str());
#endif
  }

  return preventDefaultResult;
}

void APZEventState::ProcessLongTap(PresShell* aPresShell,
                                   const CSSPoint& aPoint,
                                   const CSSToLayoutDeviceScale& aScale,
                                   Modifiers aModifiers,
                                   uint64_t aInputBlockId) {
  APZES_LOG("Handling long tap at %s block id %" PRIu64 "\n",
            ToString(aPoint).c_str(), aInputBlockId);

  nsCOMPtr<nsIWidget> widget = GetWidget();
  if (!widget) {
    return;
  }

  // If the touch block is waiting for a content response, send one now.
  // Bug 1848736: Why is a content response needed here? Can it be removed?
  // However, do not clear |mPendingTouchPreventedResponse|, because APZ will
  // wait for an additional content response before processing touch-move
  // events (since the first touch-move could still be prevented, and that
  // should prevent the touch block from being processed).
  if (mPendingTouchPreventedResponse) {
    APZES_LOG("Sending response %d for pending guid: %s block id: %" PRIu64
              " due to long tap\n",
              false, ToString(mPendingTouchPreventedGuid).c_str(),
              mPendingTouchPreventedBlockId);
    mContentReceivedInputBlockCallback(mPendingTouchPreventedBlockId, false);
  }

#ifdef XP_WIN
  // On Windows, we fire the contextmenu events when the user lifts their
  // finger, in keeping with the platform convention. This happens in the
  // ProcessLongTapUp function. However, we still fire the eMouseLongTap event
  // at this time, because things like text selection or dragging may want
  // to know about it.
  APZCCallbackHelper::DispatchSynthesizedMouseEvent(
      eMouseLongTap, aPoint * aScale, aModifiers, /*clickCount*/ 1, widget);
#else
  PreventDefaultResult preventDefaultResult =
      FireContextmenuEvents(aPresShell, aPoint, aScale, aModifiers, widget);
#endif

  const bool contextmenuOpen =
#ifdef XP_WIN
      // On Windows context menu will never be opened by long tap events, the
      // menu will open after the user lifts their finger.
      false;
#elif defined(MOZ_WIDGET_ANDROID)
      // On Android, GeckoView calls preventDefault() in a JSActor
      // (ContentDelegateChild.sys.mjs) when opening context menu so that we can
      // tell whether contextmenu opens in response to the contextmenu event by
      // checking where preventDefault() got called.
      preventDefaultResult == PreventDefaultResult::ByChrome;
#else
      // On desktop platforms (other than Windows) unlike Android, context menu
      // can be opened anywhere even if, for example, there's no link under the
      // touch point. So we can assume that "not preventDefault" means a context
      // menu is open.
      preventDefaultResult == PreventDefaultResult::No;
#endif
  // Assuming that contextmenuOpen=true here means a context menu was opened, it
  // will be treated as "preventDefaulted" in APZ.
  mContentReceivedInputBlockCallback(aInputBlockId, contextmenuOpen);

  if (contextmenuOpen) {
    // Also send a touchcancel to content
    //  a) on Android if browser's contextmenu is open
    //  b) on desktop platforms other than Windows if browser's contextmenu is
    //     open
    // so that listeners that might be waiting for a touchend don't trigger.
    WidgetTouchEvent cancelTouchEvent(true, eTouchCancel, widget.get());
    cancelTouchEvent.mModifiers = aModifiers;
    auto ldPoint = LayoutDeviceIntPoint::Round(aPoint * aScale);
    cancelTouchEvent.mTouches.AppendElement(new mozilla::dom::Touch(
        mLastTouchIdentifier, ldPoint, LayoutDeviceIntPoint(), 0, 0));
    APZCCallbackHelper::DispatchWidgetEvent(cancelTouchEvent);
  }
}

void APZEventState::ProcessLongTapUp(PresShell* aPresShell,
                                     const CSSPoint& aPoint,
                                     const CSSToLayoutDeviceScale& aScale,
                                     Modifiers aModifiers) {
#ifdef XP_WIN
  nsCOMPtr<nsIWidget> widget = GetWidget();
  if (widget) {
    FireContextmenuEvents(aPresShell, aPoint, aScale, aModifiers, widget);
  }
#endif
}

void APZEventState::ProcessTouchEvent(
    const WidgetTouchEvent& aEvent, const ScrollableLayerGuid& aGuid,
    uint64_t aInputBlockId, nsEventStatus aApzResponse,
    nsEventStatus aContentResponse,
    nsTArray<TouchBehaviorFlags>&& aAllowedTouchBehaviors) {
  if (aEvent.mMessage == eTouchStart && aEvent.mTouches.Length() > 0) {
    mActiveElementManager->SetTargetElement(
        aEvent.mTouches[0]->GetOriginalTarget());
    mLastTouchIdentifier = aEvent.mTouches[0]->Identifier();
  }
  if (aEvent.mMessage == eTouchStart) {
    // We get the allowed touch behaviors on a touchstart, but may not actually
    // use them until the first touchmove, so we stash them in a member
    // variable.
    mTouchBlockAllowedBehaviors = std::move(aAllowedTouchBehaviors);
  }

  bool isTouchPrevented = aContentResponse == nsEventStatus_eConsumeNoDefault;
  bool mayNeedPointerCancelEvent = false;
  APZES_LOG("Handling event type %d isPrevented=%d\n", aEvent.mMessage,
            isTouchPrevented);
  switch (aEvent.mMessage) {
    case eTouchStart: {
      mTouchEndCancelled = false;
      mReceivedNonTouchStart = false;
      mTouchRollup = do_GetWeakReference(widget::nsAutoRollup::GetLastRollup());

      SendPendingTouchPreventedResponse(false);
      // The above call may have sent a message to APZ if we get two
      // TOUCH_STARTs in a row and just responded to the first one.

      // We're about to send a response back to APZ, but we should only do it
      // for events that went through APZ (which should be all of them).
      MOZ_ASSERT(aEvent.mFlags.mHandledByAPZ);

      // If the first touchstart event was preventDefaulted, ensure that any
      // subsequent additional touchstart events also get preventDefaulted. This
      // ensures that e.g. pinch zooming is prevented even if just the first
      // touchstart was prevented by content.
      if (mTouchCounter.GetActiveTouchCount() == 0) {
        mFirstTouchCancelled = isTouchPrevented;
      } else {
        if (mFirstTouchCancelled && !isTouchPrevented) {
          APZES_LOG(
              "Propagating prevent-default from first-touch for block %" PRIu64
              "\n",
              aInputBlockId);
        }
        isTouchPrevented |= mFirstTouchCancelled;
      }

      mTouchStartPrevented = isTouchPrevented;
      if (isTouchPrevented) {
        mContentReceivedInputBlockCallback(aInputBlockId, isTouchPrevented);
      } else {
        APZES_LOG("Event not prevented; pending response for %" PRIu64 " %s\n",
                  aInputBlockId, ToString(aGuid).c_str());
        mPendingTouchPreventedResponse = true;
        mPendingTouchPreventedGuid = aGuid;
        mPendingTouchPreventedBlockId = aInputBlockId;
      }
      break;
    }

    case eTouchEnd:
      if (isTouchPrevented) {
        mTouchEndCancelled = true;
        mEndTouchState = apz::SingleTapState::NotClick;
      }
      [[fallthrough]];
    case eTouchCancel:
      if (mActiveElementManager->HandleTouchEndEvent(mEndTouchState)) {
        mEndTouchState = apz::SingleTapState::NotClick;
      }
      [[fallthrough]];
    case eTouchMove: {
      if (!mReceivedNonTouchStart) {
        // In the case where `touchstart` was preventDefaulted,
        // pointercancel event should NOT be fired.
        mayNeedPointerCancelEvent = !isTouchPrevented && !mTouchStartPrevented;
        mReceivedNonTouchStart = true;
      }

      if (mPendingTouchPreventedResponse) {
        MOZ_ASSERT(aGuid == mPendingTouchPreventedGuid);
        if (aEvent.mMessage == eTouchCancel) {
          // If we received a touch-cancel and we were waiting for the
          // first touch-move to send a content response, make the content
          // response be preventDefault=true. This is the safer choice
          // because content might have prevented the first touch-move,
          // and even though the touch-cancel means any subsequent touch-moves
          // will not be processed, the content response still influences
          // the InputResult sent to GeckoView.
          isTouchPrevented = true;
        }
        mContentReceivedInputBlockCallback(aInputBlockId, isTouchPrevented);
        mPendingTouchPreventedResponse = false;
      }
      break;
    }

    default:
      MOZ_ASSERT_UNREACHABLE("Unknown touch event type");
      break;
  }

  mTouchCounter.Update(aEvent);
  if (mTouchCounter.GetActiveTouchCount() == 0) {
    mFirstTouchCancelled = false;
  }

  APZES_LOG("Pointercancel if %d %d %d %d\n", mayNeedPointerCancelEvent,
            !isTouchPrevented, aApzResponse == nsEventStatus_eConsumeDoDefault,
            MainThreadAgreesEventsAreConsumableByAPZ());
  // From https://w3c.github.io/pointerevents/#the-pointercancel-event;
  //  The user agent MUST fire a pointer event named pointercancel when it
  //  detects a scenario to suppress a pointer event stream.
  //
  // And "suppress a pointer event steam" is defined in
  // https://w3c.github.io/pointerevents/#suppressing-a-pointer-event-stream .
  //
  // There are four scenarios when the user agent fires a pointercancel event in
  // the spec. Below code corresponds to one of the scenarios (the third bullet
  // point);
  //  The pointer is subsequently used by the user agent to manipulate the page
  //  viewport (e.g. panning or zooming).
  if (mayNeedPointerCancelEvent &&
      aApzResponse == nsEventStatus_eConsumeDoDefault &&
      MainThreadAgreesEventsAreConsumableByAPZ()) {
    WidgetTouchEvent cancelEvent(aEvent);
    cancelEvent.mMessage = eTouchPointerCancel;
    cancelEvent.mFlags.mCancelable = false;  // mMessage != eTouchCancel;
    for (uint32_t i = 0; i < cancelEvent.mTouches.Length(); ++i) {
      if (mozilla::dom::Touch* touch = cancelEvent.mTouches[i]) {
        touch->convertToPointer = true;
      }
    }
    nsEventStatus status;
    cancelEvent.mWidget->DispatchEvent(&cancelEvent, status);
  }
}

bool APZEventState::MainThreadAgreesEventsAreConsumableByAPZ() const {
  // APZ errs on the side of saying it can consume touch events to perform
  // default user-agent behaviours. In particular it may say this if it hasn't
  // received accurate touch-action information. Here we double-check using
  // accurate touch-action information. This code is kinda-sorta the main
  // thread equivalent of AsyncPanZoomController::ArePointerEventsConsumable().

  switch (mTouchBlockAllowedBehaviors.Length()) {
    case 0:
      // If we don't have any touch-action (e.g. because it is disabled) then
      // APZ has no restrictions.
      return true;

    case 1: {
      // If there's one touch point in this touch block, then check the pan-x
      // and pan-y flags. If neither is allowed, then we disagree with APZ and
      // say that it can't do anything with this touch block. Note that it would
      // be even better if we could check the allowed scroll directions of the
      // scrollframe at this point and refine this further.
      TouchBehaviorFlags flags = mTouchBlockAllowedBehaviors[0];
      return (flags & AllowedTouchBehavior::HORIZONTAL_PAN) ||
             (flags & AllowedTouchBehavior::VERTICAL_PAN);
    }

    case 2: {
      // If there's two touch points in this touch block, check that they both
      // allow zooming.
      for (const auto& allowed : mTouchBlockAllowedBehaviors) {
        if (!(allowed & AllowedTouchBehavior::PINCH_ZOOM)) {
          return false;
        }
      }
      return true;
    }

    default:
      // More than two touch points? APZ shouldn't be doing anything with this,
      // so APZ shouldn't be consuming them.
      return false;
  }
}

void APZEventState::ProcessWheelEvent(const WidgetWheelEvent& aEvent,
                                      uint64_t aInputBlockId) {
  // If this event starts a swipe, indicate that it shouldn't result in a
  // scroll by setting defaultPrevented to true.
  bool defaultPrevented = aEvent.DefaultPrevented() || aEvent.TriggersSwipe();
  mContentReceivedInputBlockCallback(aInputBlockId, defaultPrevented);
}

void APZEventState::ProcessMouseEvent(const WidgetMouseEvent& aEvent,
                                      uint64_t aInputBlockId) {
  bool defaultPrevented = false;
  mContentReceivedInputBlockCallback(aInputBlockId, defaultPrevented);
}

void APZEventState::ProcessAPZStateChange(ViewID aViewId,
                                          APZStateChange aChange, int aArg,
                                          Maybe<uint64_t> aInputBlockId) {
  switch (aChange) {
    case APZStateChange::eTransformBegin: {
      nsIScrollableFrame* sf = nsLayoutUtils::FindScrollableFrameFor(aViewId);
      if (sf) {
        sf->SetTransformingByAPZ(true);
        sf->ScrollbarActivityStarted();
      }

      nsIContent* content = nsLayoutUtils::FindContentFor(aViewId);
      dom::Document* doc = content ? content->GetComposedDoc() : nullptr;
      nsCOMPtr<nsIDocShell> docshell(doc ? doc->GetDocShell() : nullptr);
      if (docshell && sf) {
        nsDocShell* nsdocshell = static_cast<nsDocShell*>(docshell.get());
        nsdocshell->NotifyAsyncPanZoomStarted();
      }
      break;
    }
    case APZStateChange::eTransformEnd: {
      nsIScrollableFrame* sf = nsLayoutUtils::FindScrollableFrameFor(aViewId);
      if (sf) {
        sf->SetTransformingByAPZ(false);
        sf->ScrollbarActivityStopped();
      }

      nsIContent* content = nsLayoutUtils::FindContentFor(aViewId);
      dom::Document* doc = content ? content->GetComposedDoc() : nullptr;
      nsCOMPtr<nsIDocShell> docshell(doc ? doc->GetDocShell() : nullptr);
      if (docshell && sf) {
        nsDocShell* nsdocshell = static_cast<nsDocShell*>(docshell.get());
        nsdocshell->NotifyAsyncPanZoomStopped();
      }
      break;
    }
    case APZStateChange::eStartTouch: {
      bool canBePanOrZoom = aArg;
      mActiveElementManager->HandleTouchStart(canBePanOrZoom);
      // If this is a non-scrollable content, set a timer for the amount of
      // time specified by ui.touch_activation.duration_ms to clear the
      // active element state.
      APZES_LOG("%s: can-be-pan-or-zoom=%d", __FUNCTION__, aArg);
      if (!canBePanOrZoom) {
        MOZ_ASSERT(aInputBlockId.isSome());
      }
      break;
    }
    case APZStateChange::eStartPanning: {
      // The user started to pan, so we don't want anything to be :active.
      mActiveElementManager->ClearActivation();
      break;
    }
    case APZStateChange::eEndTouch: {
      mEndTouchState = static_cast<apz::SingleTapState>(aArg);
      if (mActiveElementManager->HandleTouchEnd(mEndTouchState)) {
        mEndTouchState = apz::SingleTapState::NotClick;
      }
      break;
    }
  }
}

void APZEventState::Destroy() { mActiveElementManager->Destroy(); }

void APZEventState::SendPendingTouchPreventedResponse(bool aPreventDefault) {
  if (mPendingTouchPreventedResponse) {
    APZES_LOG("Sending response %d for pending guid: %s block id: %" PRIu64
              "\n",
              aPreventDefault, ToString(mPendingTouchPreventedGuid).c_str(),
              mPendingTouchPreventedBlockId);
    mContentReceivedInputBlockCallback(mPendingTouchPreventedBlockId,
                                       aPreventDefault);
    mPendingTouchPreventedResponse = false;
  }
}

already_AddRefed<nsIWidget> APZEventState::GetWidget() const {
  nsCOMPtr<nsIWidget> result = do_QueryReferent(mWidget);
  return result.forget();
}

already_AddRefed<nsIContent> APZEventState::GetTouchRollup() const {
  nsCOMPtr<nsIContent> result = do_QueryReferent(mTouchRollup);
  return result.forget();
}

}  // namespace layers
}  // namespace mozilla