PointerEventHandler.h

/* -*- 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/. */

#ifndef mozilla_PointerEventHandler_h
#define mozilla_PointerEventHandler_h

#include "mozilla/EventForwards.h"
#include "mozilla/MouseEvents.h"
#include "mozilla/TouchEvents.h"
#include "mozilla/WeakPtr.h"

// XXX Avoid including this here by moving function bodies to the cpp file
#include "mozilla/dom/Document.h"
#include "mozilla/dom/Element.h"

class nsIFrame;
class nsIContent;
class nsPresContext;

namespace mozilla {

class PresShell;

namespace dom {
class BrowserParent;
class Document;
class Element;
};  // namespace dom

class PointerCaptureInfo final {
 public:
  RefPtr<dom::Element> mPendingElement;
  RefPtr<dom::Element> mOverrideElement;

  explicit PointerCaptureInfo(dom::Element* aPendingElement)
      : mPendingElement(aPendingElement) {
    MOZ_COUNT_CTOR(PointerCaptureInfo);
  }

  MOZ_COUNTED_DTOR(PointerCaptureInfo)

  bool Empty() { return !(mPendingElement || mOverrideElement); }
};

class PointerInfo final {
 public:
  uint16_t mPointerType;
  bool mActiveState;
  bool mPrimaryState;
  bool mPreventMouseEventByContent;
  WeakPtr<dom::Document> mActiveDocument;
  explicit PointerInfo(bool aActiveState, uint16_t aPointerType,
                       bool aPrimaryState, dom::Document* aActiveDocument)
      : mPointerType(aPointerType),
        mActiveState(aActiveState),
        mPrimaryState(aPrimaryState),
        mPreventMouseEventByContent(false),
        mActiveDocument(aActiveDocument) {}
};

class PointerEventHandler final {
 public:
  // Called in nsLayoutStatics::Initialize/Shutdown to initialize pointer event
  // related static variables.
  static void InitializeStatics();
  static void ReleaseStatics();

  // Return the preference value of implicit capture.
  static bool IsPointerEventImplicitCaptureForTouchEnabled();

  // Called in ESM::PreHandleEvent to update current active pointers in a hash
  // table.
  static void UpdateActivePointerState(WidgetMouseEvent* aEvent,
                                       nsIContent* aTargetContent = nullptr);

  // Request/release pointer capture of the specified pointer by the element.
  static void RequestPointerCaptureById(uint32_t aPointerId,
                                        dom::Element* aElement);
  static void ReleasePointerCaptureById(uint32_t aPointerId);
  static void ReleaseAllPointerCapture();

  // Set/release pointer capture of the specified pointer by the remote target.
  // Should only be called in parent process.
  static bool SetPointerCaptureRemoteTarget(uint32_t aPointerId,
                                            dom::BrowserParent* aBrowserParent);
  static void ReleasePointerCaptureRemoteTarget(
      dom::BrowserParent* aBrowserParent);
  static void ReleasePointerCaptureRemoteTarget(uint32_t aPointerId);
  static void ReleaseAllPointerCaptureRemoteTarget();

  // Get the pointer capturing remote target of the specified pointer.
  static dom::BrowserParent* GetPointerCapturingRemoteTarget(
      uint32_t aPointerId);

  // Get the pointer captured info of the specified pointer.
  static PointerCaptureInfo* GetPointerCaptureInfo(uint32_t aPointerId);

  // Return the PointerInfo if the pointer with aPointerId is situated in device
  // , nullptr otherwise.
  static const PointerInfo* GetPointerInfo(uint32_t aPointerId);

  // CheckPointerCaptureState checks cases, when got/lostpointercapture events
  // should be fired.
  MOZ_CAN_RUN_SCRIPT
  static void MaybeProcessPointerCapture(WidgetGUIEvent* aEvent);
  MOZ_CAN_RUN_SCRIPT
  static void ProcessPointerCaptureForMouse(WidgetMouseEvent* aEvent);
  MOZ_CAN_RUN_SCRIPT
  static void ProcessPointerCaptureForTouch(WidgetTouchEvent* aEvent);
  MOZ_CAN_RUN_SCRIPT
  static void CheckPointerCaptureState(WidgetPointerEvent* aEvent);

  // Implicitly get and release capture of current pointer for touch.
  static void ImplicitlyCapturePointer(nsIFrame* aFrame, WidgetEvent* aEvent);
  MOZ_CAN_RUN_SCRIPT
  static void ImplicitlyReleasePointerCapture(WidgetEvent* aEvent);

  /**
   * GetPointerCapturingContent returns a target element which captures the
   * pointer. It's applied to mouse or pointer event (except mousedown and
   * pointerdown). When capturing, return the element. Otherwise, nullptr.
   *
   * @param aEvent               A mouse event or pointer event which may be
   *                             captured.
   *
   * @return                     Target element for aEvent.
   */
  static dom::Element* GetPointerCapturingElement(WidgetGUIEvent* aEvent);

  static dom::Element* GetPointerCapturingElement(uint32_t aPointerId);

  // Release pointer capture if captured by the specified content or it's
  // descendant. This is called to handle the case that the pointer capturing
  // content or it's parent is removed from the document.
  static void ReleaseIfCaptureByDescendant(nsIContent* aContent);

  /*
   * This function handles the case when content had called preventDefault on
   * the active pointer. In that case we have to prevent firing subsequent mouse
   * to content. We check the flag PointerInfo::mPreventMouseEventByContent and
   * call PreventDefault(false) to stop default behaviors and stop firing mouse
   * events to content and chrome.
   *
   * note: mouse transition events are excluded
   * note: we have to clean mPreventMouseEventByContent on pointerup for those
   *       devices support hover
   * note: we don't suppress firing mouse events to chrome and system group
   *       handlers because they may implement default behaviors
   */
  static void PreHandlePointerEventsPreventDefault(
      WidgetPointerEvent* aPointerEvent, WidgetGUIEvent* aMouseOrTouchEvent);

  /*
   * This function handles the preventDefault behavior of pointerdown. When user
   * preventDefault on pointerdown, We have to mark the active pointer to
   * prevent sebsequent mouse events (except mouse transition events) and
   * default behaviors.
   *
   * We add mPreventMouseEventByContent flag in PointerInfo to represent the
   * active pointer won't firing compatible mouse events. It's set to true when
   * content preventDefault on pointerdown
   */
  static void PostHandlePointerEventsPreventDefault(
      WidgetPointerEvent* aPointerEvent, WidgetGUIEvent* aMouseOrTouchEvent);

  MOZ_CAN_RUN_SCRIPT
  static void DispatchPointerFromMouseOrTouch(
      PresShell* aShell, nsIFrame* aFrame, nsIContent* aContent,
      WidgetGUIEvent* aEvent, bool aDontRetargetEvents, nsEventStatus* aStatus,
      nsIContent** aTargetContent);

  static void InitPointerEventFromMouse(WidgetPointerEvent* aPointerEvent,
                                        WidgetMouseEvent* aMouseEvent,
                                        EventMessage aMessage);

  static void InitPointerEventFromTouch(WidgetPointerEvent& aPointerEvent,
                                        const WidgetTouchEvent& aTouchEvent,
                                        const mozilla::dom::Touch& aTouch,
                                        bool aIsPrimary);

  static bool ShouldGeneratePointerEventFromMouse(WidgetGUIEvent* aEvent) {
    return aEvent->mMessage == eMouseDown || aEvent->mMessage == eMouseUp ||
           aEvent->mMessage == eMouseMove ||
           aEvent->mMessage == eMouseExitFromWidget;
  }

  static bool ShouldGeneratePointerEventFromTouch(WidgetGUIEvent* aEvent) {
    return aEvent->mMessage == eTouchStart || aEvent->mMessage == eTouchMove ||
           aEvent->mMessage == eTouchEnd || aEvent->mMessage == eTouchCancel ||
           aEvent->mMessage == eTouchPointerCancel;
  }

  static MOZ_ALWAYS_INLINE int32_t GetSpoofedPointerIdForRFP() {
    return sSpoofedPointerId.valueOr(0);
  }

  static void NotifyDestroyPresContext(nsPresContext* aPresContext);

  static bool IsDragAndDropEnabled(WidgetMouseEvent& aEvent);

 private:
  // Set pointer capture of the specified pointer by the element.
  static void SetPointerCaptureById(uint32_t aPointerId,
                                    dom::Element* aElement);

  // GetPointerType returns pointer type like mouse, pen or touch for pointer
  // event with pointerId. The return value must be one of
  // MouseEvent_Binding::MOZ_SOURCE_*
  static uint16_t GetPointerType(uint32_t aPointerId);

  // GetPointerPrimaryState returns state of attribute isPrimary for pointer
  // event with pointerId
  static bool GetPointerPrimaryState(uint32_t aPointerId);

  MOZ_CAN_RUN_SCRIPT
  static void DispatchGotOrLostPointerCaptureEvent(
      bool aIsGotCapture, const WidgetPointerEvent* aPointerEvent,
      dom::Element* aCaptureTarget);

  // The cached spoofed pointer ID for fingerprinting resistance. We will use a
  // mouse pointer id for desktop. For mobile, we should use the touch pointer
  // id as the spoofed one, and this work will be addressed in Bug 1492775.
  static Maybe<int32_t> sSpoofedPointerId;

  // A helper function to cache the pointer id of the spoofed interface, we
  // would only cache the pointer id once. After that, we would always stick to
  // that pointer id for fingerprinting resistance.
  static void MaybeCacheSpoofedPointerID(uint16_t aInputSource,
                                         uint32_t aPointerId);
};

}  // namespace mozilla

#endif  // mozilla_PointerEventHandler_h