layout/base/nsRefreshObservers.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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * Code to notify things that animate before a refresh, at an appropriate
   9  * refresh rate.  (Perhaps temporary, until replaced by compositor.)
  10  */
  11
  12 #ifndef LAYOUT_BASE_NSREFRESHOBSERVERS_H_
  13 #define LAYOUT_BASE_NSREFRESHOBSERVERS_H_
  14
  15 #include <functional>
  16
  17 #include "mozilla/Attributes.h"
  18 #include "mozilla/TimeStamp.h"
  19 #include "nsISupports.h"
  20
  21 class nsPresContext;
  22
  23 namespace mozilla {
  24 class AnimationEventDispatcher;
  25 class PendingFullscreenEvent;
  26 class PresShell;
  27 class RefreshDriverTimer;
  28 }  // namespace mozilla
  29
  30 /**
  31  * An abstract base class to be implemented by callers wanting to be
  32  * notified at refresh times.  When nothing needs to be painted, callers
  33  * may not be notified.
  34  */
  35 class nsARefreshObserver {
  36  public:
  37   // AddRef and Release signatures that match nsISupports.  Implementors
  38   // must implement reference counting, and those that do implement
  39   // nsISupports will already have methods with the correct signature.
  40   //
  41   // The refresh driver does NOT hold references to refresh observers
  42   // except while it is notifying them.
  43   NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
  44
  45   MOZ_CAN_RUN_SCRIPT virtual void WillRefresh(mozilla::TimeStamp aTime) = 0;
  46
  47 #ifdef DEBUG
  48   // Count of the active registrations we currently have with nsRefreshDrivers.
  49   // This is incremented in nsRefreshDriver::AddRefreshObserver, decremented in
  50   // nsRefreshDriver::RemoveRefreshObserver. No other code should modify this.
  51   // We expect this to be 0 when we're destructed.
  52   int32_t mRegistrationCount = 0;
  53
  54   // Virtual destructor to enforce the mRegistrationCount invariant.
  55   virtual ~nsARefreshObserver() {
  56     MOZ_ASSERT(mRegistrationCount == 0,
  57                "Refresh observer AddRefreshObserver/RemoveRefreshObserver "
  58                "calls should have balanced out to zero");
  59   }
  60 #endif  // DEBUG
  61 };
  62
  63 /**
  64  * An abstract base class to be implemented by callers wanting to be notified
  65  * when the observing refresh driver updated mMostRecentRefresh due to active
  66  * timer changes. Callers must ensure an observer is removed before it is
  67  * destroyed.
  68  */
  69 class nsATimerAdjustmentObserver {
  70  public:
  71   virtual void NotifyTimerAdjusted(mozilla::TimeStamp aTime) = 0;
  72 };
  73
  74 /**
  75  * An abstract base class to be implemented by callers wanting to be notified
  76  * that a refresh has occurred. Callers must ensure an observer is removed
  77  * before it is destroyed.
  78  */
  79 class nsAPostRefreshObserver {
  80  public:
  81   virtual void DidRefresh() = 0;
  82 };
  83
  84 namespace mozilla {
  85
  86 /**
  87  * A wrapper for nsAPostRefreshObserver that's refcounted and might unregister
  88  * itself after firing.
  89  *
  90  * Note, while the observer unregisters itself, the registering still needs to
  91  * be done by the caller.
  92  */
  93 class ManagedPostRefreshObserver : public nsAPostRefreshObserver {
  94  public:
  95   // Whether the post-refresh observer should be unregistered after it has
  96   // fired.
  97   enum class Unregister : bool { No, Yes };
  98   using Action = std::function<Unregister(bool aWasCanceled)>;
  99   NS_INLINE_DECL_REFCOUNTING(ManagedPostRefreshObserver)
 100   ManagedPostRefreshObserver(nsPresContext*, Action&&);
 101   explicit ManagedPostRefreshObserver(nsPresContext*);
 102   void DidRefresh() override;
 103   void Cancel();
 104
 105  protected:
 106   virtual ~ManagedPostRefreshObserver();
 107   RefPtr<nsPresContext> mPresContext;
 108   Action mAction;
 109 };
 110
 111 }  // namespace mozilla
 112
 113 #endif