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/* -*- 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 */
* Code to notify things that animate before a refresh, at an appropriate
* refresh rate. (Perhaps temporary, until replaced by compositor.)
#include <functional>
#include "mozilla/Attributes.h"
#include "mozilla/TimeStamp.h"
#include "nsISupports.h"
class nsPresContext;
namespace mozilla {
class AnimationEventDispatcher;
class PendingFullscreenEvent;
class PresShell;
class RefreshDriverTimer;
} // namespace mozilla
* An abstract base class to be implemented by callers wanting to be
* notified at refresh times. When nothing needs to be painted, callers
* may not be notified.
class nsARefreshObserver {
// AddRef and Release signatures that match nsISupports. Implementors
// must implement reference counting, and those that do implement
// nsISupports will already have methods with the correct signature.
// The refresh driver does NOT hold references to refresh observers
// except while it is notifying them.
MOZ_CAN_RUN_SCRIPT virtual void WillRefresh(mozilla::TimeStamp aTime) = 0;
#ifdef DEBUG
// Count of the active registrations we currently have with nsRefreshDrivers.
// This is incremented in nsRefreshDriver::AddRefreshObserver, decremented in
// nsRefreshDriver::RemoveRefreshObserver. No other code should modify this.
// We expect this to be 0 when we're destructed.
int32_t mRegistrationCount = 0;
// Virtual destructor to enforce the mRegistrationCount invariant.
virtual ~nsARefreshObserver() {
MOZ_ASSERT(mRegistrationCount == 0,
"Refresh observer AddRefreshObserver/RemoveRefreshObserver "
"calls should have balanced out to zero");
#endif // DEBUG
* An abstract base class to be implemented by callers wanting to be notified
* that a refresh has occurred. Callers must ensure an observer is removed
* before it is destroyed.
class nsAPostRefreshObserver {
virtual void DidRefresh() = 0;
namespace mozilla {
* A wrapper for nsAPostRefreshObserver that's refcounted and might unregister
* itself after firing.
* Note, while the observer unregisters itself, the registering still needs to
* be done by the caller.
class ManagedPostRefreshObserver : public nsAPostRefreshObserver {
// Whether the post-refresh observer should be unregistered after it has
// fired.
enum class Unregister : bool { No, Yes };
using Action = std::function<Unregister(bool aWasCanceled)>;
ManagedPostRefreshObserver(nsPresContext*, Action&&);
explicit ManagedPostRefreshObserver(nsPresContext*);
void DidRefresh() override;
void Cancel();
virtual ~ManagedPostRefreshObserver();
RefPtr<nsPresContext> mPresContext;
Action mAction;
} // namespace mozilla