summaryrefslogtreecommitdiffstats
path: root/dom/base/ResizeObserverController.cpp
blob: 924bba10d18abe49a07910b2ebd77038ca7b5e47 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
/* -*- 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 http://mozilla.org/MPL/2.0/. */

#include "mozilla/dom/ResizeObserverController.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/ErrorEvent.h"
#include "nsIPresShell.h"
#include "nsPresContext.h"

namespace mozilla {
namespace dom {

void
ResizeObserverNotificationHelper::WillRefresh(TimeStamp aTime)
{
  MOZ_ASSERT(mOwner, "Why is mOwner already dead when this RefreshObserver is still registered?");
  if (mOwner) {
    mOwner->Notify();
  }
}

nsRefreshDriver*
ResizeObserverNotificationHelper::GetRefreshDriver() const
{
  nsIPresShell* presShell = mOwner->GetShell();
  if (MOZ_UNLIKELY(!presShell)) {
    return nullptr;
  }

  nsPresContext* presContext = presShell->GetPresContext();
  if (MOZ_UNLIKELY(!presContext)) {
    return nullptr;
  }

  return presContext->RefreshDriver();
}

void
ResizeObserverNotificationHelper::Register()
{
  if (mRegistered) {
    return;
  }

  nsRefreshDriver* refreshDriver = GetRefreshDriver();
  if (!refreshDriver) {
    // We maybe navigating away from this page or currently in an iframe with
    // display: none. Just abort the Register(), no need to do notification.
    return;
  }

  refreshDriver->AddRefreshObserver(this, Flush_Display);
  mRegistered = true;
}

void
ResizeObserverNotificationHelper::Unregister()
{
  if (!mRegistered) {
    return;
  }

  nsRefreshDriver* refreshDriver = GetRefreshDriver();
  if (!refreshDriver) {
    // We can't access RefreshDriver now. Just abort the Unregister().
    return;
  }

  refreshDriver->RemoveRefreshObserver(this, Flush_Display);
  mRegistered = false;
}

void
ResizeObserverNotificationHelper::Disconnect()
{
  Unregister();
  // Our owner is dying. Clear our pointer to it, in case we outlive it.
  mOwner = nullptr;
}

ResizeObserverNotificationHelper::~ResizeObserverNotificationHelper()
{
  Unregister();
}

void
ResizeObserverController::Traverse(nsCycleCollectionTraversalCallback& aCb)
{
  ImplCycleCollectionTraverse(aCb, mResizeObservers, "mResizeObservers");
}

void
ResizeObserverController::Unlink()
{
  mResizeObservers.Clear();
}

void
ResizeObserverController::AddResizeObserver(ResizeObserver* aObserver)
{
  MOZ_ASSERT(aObserver, "AddResizeObserver() should never be called with "
                        "a null parameter");
  mResizeObservers.AppendElement(aObserver);
}

void
ResizeObserverController::Notify()
{
  if (mResizeObservers.IsEmpty()) {
    return;
  }

  uint32_t shallowestTargetDepth = 0;

  GatherAllActiveObservations(shallowestTargetDepth);

  while (HasAnyActiveObservations()) {
    DebugOnly<uint32_t> oldShallowestTargetDepth = shallowestTargetDepth;
    shallowestTargetDepth = BroadcastAllActiveObservations();
    NS_ASSERTION(oldShallowestTargetDepth < shallowestTargetDepth,
                 "shallowestTargetDepth should be getting strictly deeper");

    // Flush layout, so that any callback functions' style changes / resizes
    // get a chance to take effect.
    mDocument->FlushPendingNotifications(Flush_Layout);

    // To avoid infinite resize loop, we only gather all active observations
    // that have the depth of observed target element more than current
    // shallowestTargetDepth.
    GatherAllActiveObservations(shallowestTargetDepth);
  }

  mResizeObserverNotificationHelper->Unregister();

  // Per spec, we deliver an error if the document has any skipped observations.
  if (HasAnySkippedObservations()) {
    RootedDictionary<ErrorEventInit> init(RootingCx());

    init.mMessage.AssignLiteral("ResizeObserver loop completed with undelivered"
                                " notifications.");
    init.mCancelable = true;
    init.mBubbles = true;

    nsEventStatus status = nsEventStatus_eIgnore;

    nsCOMPtr<nsPIDOMWindowInner> window =
      mDocument->GetWindow()->GetCurrentInnerWindow();

    if (window) {
      nsCOMPtr<nsIScriptGlobalObject> sgo = do_QueryInterface(window);
      MOZ_ASSERT(sgo);

      if (NS_WARN_IF(NS_FAILED(sgo->HandleScriptError(init, &status)))) {
        status = nsEventStatus_eIgnore;
      }
    } else {
      // We don't fire error events at any global for non-window JS on the main
      // thread.
    }

    // We need to deliver pending notifications in next cycle.
    ScheduleNotification();
  }
}

void
ResizeObserverController::GatherAllActiveObservations(uint32_t aDepth)
{
  for (auto observer : mResizeObservers) {
    observer->GatherActiveObservations(aDepth);
  }
}

uint32_t
ResizeObserverController::BroadcastAllActiveObservations()
{
  uint32_t shallowestTargetDepth = UINT32_MAX;

  for (auto observer : mResizeObservers) {

    uint32_t targetDepth = observer->BroadcastActiveObservations();

    if (targetDepth < shallowestTargetDepth) {
      shallowestTargetDepth = targetDepth;
    }
  }

  return shallowestTargetDepth;
}

bool
ResizeObserverController::HasAnyActiveObservations() const
{
  for (auto observer : mResizeObservers) {
    if (observer->HasActiveObservations()) {
      return true;
    }
  }
  return false;
}

bool
ResizeObserverController::HasAnySkippedObservations() const
{
  for (auto observer : mResizeObservers) {
    if (observer->HasSkippedObservations()) {
      return true;
    }
  }
  return false;
}

void
ResizeObserverController::ScheduleNotification()
{
  mResizeObserverNotificationHelper->Register();
}

nsIPresShell*
ResizeObserverController::GetShell() const
{
  return mDocument->GetShell();
}

ResizeObserverController::~ResizeObserverController()
{
  mResizeObserverNotificationHelper->Disconnect();
}

} // namespace dom
} // namespace mozilla