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/Document.h"
  11 #include "mozilla/dom/ResizeObserver.h"
  12 #include "mozilla/TimeStamp.h"
  13 #include "nsRefreshObservers.h"
  14 #include "nsTObserverArray.h"
  15
  16 class nsRefreshDriver;
  17
  18 namespace mozilla {
  19
  20 class PresShell;
  21
  22 namespace dom {
  23
  24 class ResizeObserverController;
  25
  26 /**
  27  * ResizeObserverNotificationHelper will trigger ResizeObserver notifications
  28  * by registering with the Refresh Driver.
  29  */
  30 class ResizeObserverNotificationHelper final : public nsARefreshObserver {
  31  public:
  32   NS_INLINE_DECL_REFCOUNTING(ResizeObserverNotificationHelper, override)
  33
  34   explicit ResizeObserverNotificationHelper(ResizeObserverController* aOwner)
  35       : mOwner(aOwner), mRegistered(false) {
  36     MOZ_ASSERT(mOwner, "Need a non-null owner");
  37   }
  38
  39   MOZ_CAN_RUN_SCRIPT void WillRefresh(TimeStamp aTime) override;
  40
  41   nsRefreshDriver* GetRefreshDriver() const;
  42
  43   void Register();
  44
  45   void Unregister();
  46
  47   bool IsRegistered() const { return mRegistered; }
  48
  49   void DetachFromOwner() { mOwner = nullptr; }
  50
  51  private:
  52   virtual ~ResizeObserverNotificationHelper();
  53
  54   ResizeObserverController* mOwner;
  55   bool mRegistered;
  56 };
  57
  58 /**
  59  * ResizeObserverController contains the list of ResizeObservers and controls
  60  * the flow of notification.
  61  */
  62 class ResizeObserverController final {
  63  public:
  64   explicit ResizeObserverController(Document* aDocument)
  65       : mDocument(aDocument),
  66         mResizeObserverNotificationHelper(
  67             new ResizeObserverNotificationHelper(this)) {
  68     MOZ_ASSERT(mDocument, "Need a non-null document");
  69   }
  70
  71   void AddSizeOfIncludingThis(nsWindowSizes&) const;
  72
  73   void ShellDetachedFromDocument();
  74   void AddResizeObserver(ResizeObserver& aObserver) {
  75     MOZ_ASSERT(!mResizeObservers.Contains(&aObserver));
  76     // Insert internal ResizeObservers before scripted ones, since they may have
  77     // observable side-effects and we don't want to expose the insertion time.
  78     if (aObserver.HasNativeCallback()) {
  79       mResizeObservers.InsertElementAt(0, &aObserver);
  80     } else {
  81       mResizeObservers.AppendElement(&aObserver);
  82     }
  83   }
  84
  85   void RemoveResizeObserver(ResizeObserver& aObserver) {
  86     MOZ_ASSERT(mResizeObservers.Contains(&aObserver));
  87     mResizeObservers.RemoveElement(&aObserver);
  88   }
  89
  90   /**
  91    * Schedule the notification via ResizeObserverNotificationHelper refresh
  92    * observer.
  93    */
  94   void ScheduleNotification();
  95
  96   /**
  97    * Notify all ResizeObservers by gathering and broadcasting all active
  98    * observations.
  99    */
 100   MOZ_CAN_RUN_SCRIPT void Notify();
 101
 102   PresShell* GetPresShell() const { return mDocument->GetPresShell(); }
 103
 104   ~ResizeObserverController();
 105
 106  private:
 107   /**
 108    * Calls GatherActiveObservations(aDepth) for all ResizeObservers in this
 109    * controller. All observations in each ResizeObserver with element's depth
 110    * more than aDepth will be gathered.
 111    */
 112   void GatherAllActiveObservations(uint32_t aDepth);
 113
 114   /**
 115    * Calls BroadcastActiveObservations() for all ResizeObservers in this
 116    * controller. It also returns the shallowest depth of observed target
 117    * elements with active observations from all ResizeObservers or
 118    * numeric_limits<uint32_t>::max() if there aren't any active observations
 119    * at all.
 120    */
 121   MOZ_CAN_RUN_SCRIPT uint32_t BroadcastAllActiveObservations();
 122
 123   /**
 124    * Returns whether there is any ResizeObserver that has active observations.
 125    */
 126   bool HasAnyActiveObservations() const;
 127
 128   /**
 129    * Returns whether there is any ResizeObserver that has skipped observations.
 130    */
 131   bool HasAnySkippedObservations() const;
 132
 133   // Raw pointer is OK because mDocument strongly owns us & hence must outlive
 134   // us.
 135   Document* const mDocument;
 136
 137   RefPtr<ResizeObserverNotificationHelper> mResizeObserverNotificationHelper;
 138   nsTArray<ResizeObserver*> mResizeObservers;
 139 };
 140
 141 }  // namespace dom
 142 }  // namespace mozilla
 143
 144 #endif  // mozilla_dom_ResizeObserverController_h