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/. */
7 #ifndef mozilla_AsyncEventDispatcher_h_
8 #define mozilla_AsyncEventDispatcher_h_
10 #include "mozilla/Attributes.h"
11 #include "mozilla/EventForwards.h"
12 #include "mozilla/RefPtr.h"
13 #include "mozilla/dom/Event.h"
15 #include "mozilla/dom/Document.h"
17 #include "nsThreadUtils.h"
24 * Use AsyncEventDispatcher to fire a DOM event that requires safe a stable DOM.
25 * For example, you may need to fire an event from within layout, but
26 * want to ensure that the event handler doesn't mutate the DOM at
27 * the wrong time, in order to avoid resulting instability.
30 class AsyncEventDispatcher
: public CancelableRunnable
{
33 * If aOnlyChromeDispatch is true, the event is dispatched to only
34 * chrome node. In that case, if aTarget is already a chrome node,
35 * the event is dispatched to it, otherwise the dispatch path starts
36 * at the first chrome ancestor of that target.
39 dom::EventTarget
* aTarget
, const nsAString
& aEventType
,
41 ChromeOnlyDispatch aOnlyChromeDispatch
= ChromeOnlyDispatch::eNo
,
42 Composed aComposed
= Composed::eDefault
)
43 : CancelableRunnable("AsyncEventDispatcher"),
45 mEventType(aEventType
),
46 mEventMessage(eUnidentifiedEvent
),
47 mCanBubble(aCanBubble
),
48 mOnlyChromeDispatch(aOnlyChromeDispatch
),
49 mComposed(aComposed
) {}
52 * If aOnlyChromeDispatch is true, the event is dispatched to only
53 * chrome node. In that case, if aTarget is already a chrome node,
54 * the event is dispatched to it, otherwise the dispatch path starts
55 * at the first chrome ancestor of that target.
57 AsyncEventDispatcher(nsINode
* aTarget
, mozilla::EventMessage aEventMessage
,
59 ChromeOnlyDispatch aOnlyChromeDispatch
)
60 : CancelableRunnable("AsyncEventDispatcher"),
62 mEventMessage(aEventMessage
),
63 mCanBubble(aCanBubble
),
64 mOnlyChromeDispatch(aOnlyChromeDispatch
) {
65 mEventType
.SetIsVoid(true);
66 MOZ_ASSERT(mEventMessage
!= eUnidentifiedEvent
);
69 AsyncEventDispatcher(dom::EventTarget
* aTarget
,
70 mozilla::EventMessage aEventMessage
,
72 : CancelableRunnable("AsyncEventDispatcher"),
74 mEventMessage(aEventMessage
),
75 mCanBubble(aCanBubble
) {
76 mEventType
.SetIsVoid(true);
77 MOZ_ASSERT(mEventMessage
!= eUnidentifiedEvent
);
81 * aEvent must have been created without Widget*Event and Internal*Event
82 * because this constructor assumes that it's safe to use aEvent
83 * asynchronously (i.e., after all objects allocated in the stack are
87 dom::EventTarget
* aTarget
, already_AddRefed
<dom::Event
> aEvent
,
88 ChromeOnlyDispatch aOnlyChromeDispatch
= ChromeOnlyDispatch::eNo
)
89 : CancelableRunnable("AsyncEventDispatcher"),
92 mEventMessage(eUnidentifiedEvent
),
93 mOnlyChromeDispatch(aOnlyChromeDispatch
) {
95 mEvent
->IsSafeToBeDispatchedAsynchronously(),
96 "The DOM event should be created without Widget*Event and "
98 "because if it needs to be safe to be dispatched asynchronously");
101 AsyncEventDispatcher(dom::EventTarget
* aTarget
, WidgetEvent
& aEvent
);
103 MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHOD
Run() override
;
104 nsresult
Cancel() override
;
105 nsresult
PostDOMEvent();
108 * Dispatch event immediately if it's safe to dispatch the event.
109 * Otherwise, posting the event into the queue to dispatch it when it's safe.
111 * Note that this method allows callers to call itself with unsafe aTarget
112 * because its lifetime is guaranteed by this method (in the case of
113 * synchronous dispatching) or AsyncEventDispatcher (in the case of
114 * asynchronous dispatching).
116 MOZ_CAN_RUN_SCRIPT_BOUNDARY
static void RunDOMEventWhenSafe(
117 dom::EventTarget
& aTarget
, const nsAString
& aEventType
,
118 CanBubble aCanBubble
,
119 ChromeOnlyDispatch aOnlyChromeDispatch
= ChromeOnlyDispatch::eNo
,
120 Composed aComposed
= Composed::eDefault
);
123 * Dispatch event immediately if it's safe to dispatch the event.
124 * Otherwise, posting the event into the queue to dispatch it when it's safe.
126 * NOTE: Only this is now marked as MOZ_CAN_RUN_SCRIPT because all callers
127 * have already had safe smart pointers for both aTarget and aEvent.
128 * If you need to use this in a hot path without smart pointers, you may need
129 * to create unsafe version of this method for avoiding the extra add/release
130 * refcount cost in the case of asynchronous dispatching.
132 MOZ_CAN_RUN_SCRIPT
static void RunDOMEventWhenSafe(
133 dom::EventTarget
& aTarget
, dom::Event
& aEvent
,
134 ChromeOnlyDispatch aOnlyChromeDispatch
= ChromeOnlyDispatch::eNo
);
137 * Dispatch event immediately if it's safe to dispatch the event.
138 * Otherwise, posting the event into the queue to dispatch it when it's safe.
140 * Note that this method allows callers to call itself with unsafe aTarget
141 * because its lifetime is guaranteed by EventDispatcher (in the case of
142 * synchronous dispatching) or AsyncEventDispatcher (in the case of
143 * asynchronous dispatching).
145 MOZ_CAN_RUN_SCRIPT_BOUNDARY
static nsresult
RunDOMEventWhenSafe(
146 nsINode
& aTarget
, WidgetEvent
& aEvent
,
147 nsEventStatus
* aEventStatus
= nullptr);
149 // Calling this causes the Run() method to check that
150 // mTarget->IsInComposedDoc(). mTarget must be an nsINode or else we'll
152 void RequireNodeInDocument();
154 // NOTE: The static version of this should be preferred when possible, because
155 // it avoids the allocation but this is useful when used in combination with
156 // LoadBlockingAsyncEventDispatcher.
157 void RunDOMEventWhenSafe();
160 MOZ_CAN_RUN_SCRIPT
static void DispatchEventOnTarget(
161 dom::EventTarget
* aTarget
, dom::Event
* aEvent
,
162 ChromeOnlyDispatch aOnlyChromeDispatch
, Composed aComposed
);
163 MOZ_CAN_RUN_SCRIPT
static void DispatchEventOnTarget(
164 dom::EventTarget
* aTarget
, const nsAString
& aEventType
,
165 CanBubble aCanBubble
, ChromeOnlyDispatch aOnlyChromeDispatch
,
169 nsCOMPtr
<dom::EventTarget
> mTarget
;
170 RefPtr
<dom::Event
> mEvent
;
171 // If mEventType is set, mEventMessage will be eUnidentifiedEvent.
172 // If mEventMessage is set, mEventType will be void.
173 // They can never both be set at the same time.
175 EventMessage mEventMessage
;
176 CanBubble mCanBubble
= CanBubble::eNo
;
177 ChromeOnlyDispatch mOnlyChromeDispatch
= ChromeOnlyDispatch::eNo
;
178 Composed mComposed
= Composed::eDefault
;
179 bool mCanceled
= false;
180 bool mCheckStillInDoc
= false;
183 class LoadBlockingAsyncEventDispatcher final
: public AsyncEventDispatcher
{
185 LoadBlockingAsyncEventDispatcher(nsINode
* aEventNode
,
186 const nsAString
& aEventType
,
188 ChromeOnlyDispatch aDispatchChromeOnly
)
189 : AsyncEventDispatcher(aEventNode
, aEventType
, aBubbles
,
190 aDispatchChromeOnly
),
191 mBlockedDoc(aEventNode
->OwnerDoc()) {
192 mBlockedDoc
->BlockOnload();
195 LoadBlockingAsyncEventDispatcher(nsINode
* aEventNode
,
196 already_AddRefed
<dom::Event
> aEvent
)
197 : AsyncEventDispatcher(aEventNode
, std::move(aEvent
)),
198 mBlockedDoc(aEventNode
->OwnerDoc()) {
199 mBlockedDoc
->BlockOnload();
202 ~LoadBlockingAsyncEventDispatcher() { mBlockedDoc
->UnblockOnload(true); }
205 RefPtr
<dom::Document
> mBlockedDoc
;
208 } // namespace mozilla
210 #endif // mozilla_AsyncEventDispatcher_h_