dom/base/ResizeObserverController.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_ResizeObserverController_h
   8 #define mozilla_dom_ResizeObserverController_h
   9
  10 #include "mozilla/dom/ResizeObserver.h"
  11 #include "mozilla/TimeStamp.h"
  12 #include "nsRefreshDriver.h"
  13 #include "nsTObserverArray.h"
  14
  15 namespace mozilla {
  16
  17 class PresShell;
  18
  19 namespace dom {
  20
  21 class Document;
  22 class ResizeObserverController;
  23
  24 /**
  25  * ResizeObserverNotificationHelper will trigger ResizeObserver notifications
  26  * by registering with the Refresh Driver.
  27  */
  28 class ResizeObserverNotificationHelper final : public nsARefreshObserver {
  29  public:
  30   NS_INLINE_DECL_REFCOUNTING(ResizeObserverNotificationHelper, override)
  31
  32   explicit ResizeObserverNotificationHelper(ResizeObserverController* aOwner)
  33       : mOwner(aOwner), mRegistered(false) {
  34     MOZ_ASSERT(mOwner, "Need a non-null owner");
  35   }
  36
  37   MOZ_CAN_RUN_SCRIPT void WillRefresh(TimeStamp aTime) override;
  38
  39   nsRefreshDriver* GetRefreshDriver() const;
  40
  41   void Register();
  42
  43   void Unregister();
  44
  45   bool IsRegistered() const { return mRegistered; }
  46
  47   void DetachFromOwner() { mOwner = nullptr; }
  48
  49  private:
  50   virtual ~ResizeObserverNotificationHelper();
  51
  52   ResizeObserverController* mOwner;
  53   bool mRegistered;
  54 };
  55
  56 /**
  57  * ResizeObserverController contains the list of ResizeObservers and controls
  58  * the flow of notification.
  59  */
  60 class ResizeObserverController final {
  61  public:
  62   explicit ResizeObserverController(Document* aDocument)
  63       : mDocument(aDocument),
  64         mResizeObserverNotificationHelper(
  65             new ResizeObserverNotificationHelper(this)) {
  66     MOZ_ASSERT(mDocument, "Need a non-null document");
  67   }
  68
  69   // Methods for supporting cycle-collection
  70   void Traverse(nsCycleCollectionTraversalCallback& aCb);
  71   void Unlink();
  72
  73   void ShellDetachedFromDocument();
  74   void AddResizeObserver(ResizeObserver* aObserver);
  75
  76   /**
  77    * Schedule the notification via ResizeObserverNotificationHelper refresh
  78    * observer.
  79    */
  80   void ScheduleNotification();
  81
  82   /**
  83    * Notify all ResizeObservers by gathering and broadcasting all active
  84    * observations.
  85    */
  86   MOZ_CAN_RUN_SCRIPT void Notify();
  87
  88   PresShell* GetPresShell() const { return mDocument->GetPresShell(); }
  89
  90   ~ResizeObserverController();
  91
  92  private:
  93   /**
  94    * Calls GatherActiveObservations(aDepth) for all ResizeObservers in this
  95    * controller. All observations in each ResizeObserver with element's depth
  96    * more than aDepth will be gathered.
  97    */
  98   void GatherAllActiveObservations(uint32_t aDepth);
  99
 100   /**
 101    * Calls BroadcastActiveObservations() for all ResizeObservers in this
 102    * controller. It also returns the shallowest depth of observed target
 103    * elements with active observations from all ResizeObservers or
 104    * numeric_limits<uint32_t>::max() if there aren't any active observations
 105    * at all.
 106    */
 107   MOZ_CAN_RUN_SCRIPT uint32_t BroadcastAllActiveObservations();
 108
 109   /**
 110    * Returns whether there is any ResizeObserver that has active observations.
 111    */
 112   bool HasAnyActiveObservations() const;
 113
 114   /**
 115    * Returns whether there is any ResizeObserver that has skipped observations.
 116    */
 117   bool HasAnySkippedObservations() const;
 118
 119   // Raw pointer is OK because mDocument strongly owns us & hence must outlive
 120   // us.
 121   Document* const mDocument;
 122
 123   RefPtr<ResizeObserverNotificationHelper> mResizeObserverNotificationHelper;
 124   nsTObserverArray<RefPtr<ResizeObserver>> mResizeObservers;
 125 };
 126
 127 }  // namespace dom
 128 }  // namespace mozilla
 129
 130 #endif  // mozilla_dom_ResizeObserverController_h