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Diffstat (limited to 'accessible/base/NotificationController.h')
| -rw-r--r-- | accessible/base/NotificationController.h | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/accessible/base/NotificationController.h b/accessible/base/NotificationController.h new file mode 100644 index 0000000000..bc1a692c23 --- /dev/null +++ b/accessible/base/NotificationController.h @@ -0,0 +1,393 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* 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_a11y_NotificationController_h_ +#define mozilla_a11y_NotificationController_h_ + +#include "EventQueue.h" + +#include "nsClassHashtable.h" +#include "nsCycleCollectionParticipant.h" +#include "nsIFrame.h" +#include "nsRefreshObservers.h" +#include "nsTHashSet.h" + +#include <utility> + +#ifdef A11Y_LOG +# include "Logging.h" +#endif + +namespace mozilla { + +class PresShell; + +namespace a11y { + +class DocAccessible; + +/** + * Notification interface. + */ +class Notification { + public: + NS_INLINE_DECL_REFCOUNTING(mozilla::a11y::Notification) + + /** + * Process notification. + */ + virtual void Process() = 0; + + protected: + Notification() {} + + /** + * Protected destructor, to discourage deletion outside of Release(): + */ + virtual ~Notification() {} + + private: + Notification(const Notification&); + Notification& operator=(const Notification&); +}; + +/** + * Template class for generic notification. + * + * @note Instance is kept as a weak ref, the caller must guarantee it exists + * longer than the document accessible owning the notification controller + * that this notification is processed by. + */ +template <class Class, class... Args> +class TNotification : public Notification { + public: + typedef void (Class::*Callback)(Args*...); + + TNotification(Class* aInstance, Callback aCallback, Args*... aArgs) + : mInstance(aInstance), mCallback(aCallback), mArgs(aArgs...) {} + virtual ~TNotification() { mInstance = nullptr; } + + virtual void Process() override { + ProcessHelper(std::index_sequence_for<Args...>{}); + } + + private: + TNotification(const TNotification&); + TNotification& operator=(const TNotification&); + + template <size_t... Indices> + void ProcessHelper(std::index_sequence<Indices...>) { + (mInstance->*mCallback)(std::get<Indices>(mArgs)...); + } + + Class* mInstance; + Callback mCallback; + std::tuple<RefPtr<Args>...> mArgs; +}; + +/** + * Used to process notifications from core for the document accessible. + */ +class NotificationController final : public EventQueue, + public nsARefreshObserver { + public: + NotificationController(DocAccessible* aDocument, PresShell* aPresShell); + + NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; + NS_IMETHOD_(MozExternalRefCountType) Release(void) override; + + NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(NotificationController) + + /** + * Shutdown the notification controller. + */ + void Shutdown(); + + /** + * Add an accessible event into the queue to process it later. + */ + void QueueEvent(AccEvent* aEvent) { + if (PushEvent(aEvent)) { + ScheduleProcessing(); + } + } + + /** + * Queue a mutation event to emit if not coalesced away. Returns true if the + * event was queued and has not yet been coalesced. + */ + bool QueueMutationEvent(AccTreeMutationEvent* aEvent); + + /** + * Coalesce all queued mutation events. + */ + void CoalesceMutationEvents(); + + /** + * Schedule binding the child document to the tree of this document. + */ + void ScheduleChildDocBinding(DocAccessible* aDocument); + + /** + * Schedule the accessible tree update because of rendered text changes. + */ + inline void ScheduleTextUpdate(nsIContent* aTextNode) { + // Make sure we are not called with a node that is not in the DOM tree or + // not visible. + MOZ_ASSERT(aTextNode->GetParentNode(), "A text node is not in DOM"); + MOZ_ASSERT(aTextNode->GetPrimaryFrame(), + "A text node doesn't have a frame"); + MOZ_ASSERT(aTextNode->GetPrimaryFrame()->StyleVisibility()->IsVisible(), + "A text node is not visible"); + + mTextHash.Insert(aTextNode); + + ScheduleProcessing(); + } + + /** + * Pend accessible tree update for content insertion. + */ + void ScheduleContentInsertion(LocalAccessible* aContainer, + nsTArray<nsCOMPtr<nsIContent>>& aInsertions); + + /** + * Pend an accessible subtree relocation. + */ + void ScheduleRelocation(LocalAccessible* aOwner) { + if (!mRelocations.Contains(aOwner)) { + // XXX(Bug 1631371) Check if this should use a fallible operation as it + // pretended earlier, or change the return type to void. + mRelocations.AppendElement(aOwner); + ScheduleProcessing(); + } + } + + /** + * Start to observe refresh to make notifications and events processing after + * layout. + */ + void ScheduleProcessing(); + + /** + * Process the generic notification synchronously if there are no pending + * layout changes and no notifications are pending or being processed right + * now. Otherwise, queue it up to process asynchronously. + * + * @note The caller must guarantee that the given instance still exists when + * the notification is processed. + */ + template <class Class, class... Args> + inline void HandleNotification( + Class* aInstance, + typename TNotification<Class, Args...>::Callback aMethod, + Args*... aArgs) { + if (!IsUpdatePending()) { +#ifdef A11Y_LOG + if (mozilla::a11y::logging::IsEnabled( + mozilla::a11y::logging::eNotifications)) { + mozilla::a11y::logging::Text("sync notification processing"); + } +#endif + (aInstance->*aMethod)(aArgs...); + return; + } + + RefPtr<Notification> notification = + new TNotification<Class, Args...>(aInstance, aMethod, aArgs...); + if (notification) { + // XXX(Bug 1631371) Check if this should use a fallible operation as it + // pretended earlier. + mNotifications.AppendElement(notification); + ScheduleProcessing(); + } + } + + /** + * Schedule the generic notification to process asynchronously. + * + * @note The caller must guarantee that the given instance still exists when + * the notification is processed. + */ + template <class Class> + inline void ScheduleNotification( + Class* aInstance, typename TNotification<Class>::Callback aMethod) { + RefPtr<Notification> notification = + new TNotification<Class>(aInstance, aMethod); + if (notification) { + // XXX(Bug 1631371) Check if this should use a fallible operation as it + // pretended earlier. + mNotifications.AppendElement(notification); + ScheduleProcessing(); + } + } + + template <class Class, class Arg> + inline void ScheduleNotification( + Class* aInstance, typename TNotification<Class, Arg>::Callback aMethod, + Arg* aArg) { + RefPtr<Notification> notification = + new TNotification<Class, Arg>(aInstance, aMethod, aArg); + if (notification) { + // XXX(Bug 1631371) Check if this should use a fallible operation as it + // pretended earlier. + mNotifications.AppendElement(notification); + ScheduleProcessing(); + } + } + +#ifdef DEBUG + bool IsUpdating() const { + return mObservingState == eRefreshProcessingForUpdate; + } +#endif + + protected: + virtual ~NotificationController(); + + nsCycleCollectingAutoRefCnt mRefCnt; + NS_DECL_OWNINGTHREAD + + /** + * Return true if the accessible tree state update is pending. + */ + bool IsUpdatePending(); + + /** + * Return true if we should wait for processing from the parent before we can + * process our own queue. + */ + bool WaitingForParent(); + + private: + NotificationController(const NotificationController&); + NotificationController& operator=(const NotificationController&); + + // nsARefreshObserver + virtual void WillRefresh(mozilla::TimeStamp aTime) override; + + private: + /** + * Remove a specific hide event if it should not be propagated. + */ + void CoalesceHideEvent(AccHideEvent* aHideEvent); + + /** + * get rid of a mutation event that is no longer necessary. + */ + void DropMutationEvent(AccTreeMutationEvent* aEvent); + + /** + * Fire all necessary mutation events. + */ + void ProcessMutationEvents(); + + /** + * Indicates whether we're waiting on an event queue processing from our + * notification controller to flush events. + */ + enum eObservingState { + eNotObservingRefresh, + eRefreshObserving, + eRefreshProcessing, + eRefreshProcessingForUpdate + }; + eObservingState mObservingState; + + /** + * The presshell of the document accessible. + */ + PresShell* mPresShell; + + /** + * Child documents that needs to be bound to the tree. + */ + nsTArray<RefPtr<DocAccessible>> mHangingChildDocuments; + + /** + * Pending accessible tree update notifications for content insertions. + */ + nsClassHashtable<nsRefPtrHashKey<LocalAccessible>, + nsTArray<nsCOMPtr<nsIContent>>> + mContentInsertions; + + template <class T> + class nsCOMPtrHashKey : public PLDHashEntryHdr { + public: + typedef T* KeyType; + typedef const T* KeyTypePointer; + + explicit nsCOMPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {} + nsCOMPtrHashKey(nsCOMPtrHashKey<T>&& aOther) + : PLDHashEntryHdr(std::move(aOther)), mKey(std::move(aOther.mKey)) {} + ~nsCOMPtrHashKey() {} + + KeyType GetKey() const { return mKey; } + bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; } + + static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; } + static PLDHashNumber HashKey(KeyTypePointer aKey) { + return NS_PTR_TO_INT32(aKey) >> 2; + } + + enum { ALLOW_MEMMOVE = true }; + + protected: + nsCOMPtr<T> mKey; + }; + + /** + * Pending accessible tree update notifications for rendered text changes. + */ + nsTHashSet<nsCOMPtrHashKey<nsIContent>> mTextHash; + + /** + * Other notifications like DOM events. Don't make this an AutoTArray; we + * use SwapElements() on it. + */ + nsTArray<RefPtr<Notification>> mNotifications; + + /** + * Holds all scheduled relocations. + */ + nsTArray<RefPtr<LocalAccessible>> mRelocations; + + /** + * A list of all mutation events we may want to emit. Ordered from the first + * event that should be emitted to the last one to emit. + */ + RefPtr<AccTreeMutationEvent> mFirstMutationEvent; + RefPtr<AccTreeMutationEvent> mLastMutationEvent; + + /** + * A class to map an accessible and event type to an event. + */ + class EventMap { + public: + enum EventType { + ShowEvent = 0x0, + HideEvent = 0x1, + ReorderEvent = 0x2, + }; + + void PutEvent(AccTreeMutationEvent* aEvent); + AccTreeMutationEvent* GetEvent(LocalAccessible* aTarget, EventType aType); + void RemoveEvent(AccTreeMutationEvent* aEvent); + void Clear() { mTable.Clear(); } + + private: + EventType GetEventType(AccTreeMutationEvent* aEvent); + + nsRefPtrHashtable<nsUint64HashKey, AccTreeMutationEvent> mTable; + }; + + EventMap mMutationMap; + uint32_t mEventGeneration; +}; + +} // namespace a11y +} // namespace mozilla + +#endif // mozilla_a11y_NotificationController_h_ |