layout/style/MediaQueryList.cpp

   1 /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /* implements DOM interface for querying and observing media queries */
   7
   8 #include "mozilla/dom/MediaQueryList.h"
   9 #include "nsPresContext.h"
  10 #include "nsIMediaList.h"
  11 #include "nsCSSParser.h"
  12 #include "nsIDocument.h"
  13
  14 namespace mozilla {
  15 namespace dom {
  16
  17 MediaQueryList::MediaQueryList(nsPresContext *aPresContext,
  18                                const nsAString &aMediaQueryList)
  19   : mPresContext(aPresContext),
  20     mMediaList(new nsMediaList),
  21     mMatchesValid(false)
  22 {
  23   PR_INIT_CLIST(this);
  24
  25   SetIsDOMBinding();
  26
  27   nsCSSParser parser;
  28   parser.ParseMediaList(aMediaQueryList, nullptr, 0, mMediaList, false);
  29 }
  30
  31 MediaQueryList::~MediaQueryList()
  32 {
  33   if (mPresContext) {
  34     PR_REMOVE_LINK(this);
  35   }
  36 }
  37
  38 NS_IMPL_CYCLE_COLLECTION_CLASS(MediaQueryList)
  39
  40 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(MediaQueryList)
  41   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPresContext)
  42   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCallbacks)
  43   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
  44 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
  45
  46 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(MediaQueryList)
  47   if (tmp->mPresContext) {
  48     PR_REMOVE_LINK(tmp);
  49     NS_IMPL_CYCLE_COLLECTION_UNLINK(mPresContext)
  50   }
  51   tmp->RemoveAllListeners();
  52   NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
  53 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
  54
  55 NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(MediaQueryList)
  56
  57 NS_INTERFACE_MAP_BEGIN(MediaQueryList)
  58   NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
  59   NS_INTERFACE_MAP_ENTRY(nsISupports)
  60   NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(MediaQueryList)
  61 NS_INTERFACE_MAP_END
  62
  63 NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaQueryList)
  64 NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaQueryList)
  65
  66 void
  67 MediaQueryList::GetMedia(nsAString &aMedia)
  68 {
  69   mMediaList->GetText(aMedia);
  70 }
  71
  72 bool
  73 MediaQueryList::Matches()
  74 {
  75   if (!mMatchesValid) {
  76     NS_ABORT_IF_FALSE(!HasListeners(),
  77                       "when listeners present, must keep mMatches current");
  78     RecomputeMatches();
  79   }
  80
  81   return mMatches;
  82 }
  83
  84 void
  85 MediaQueryList::AddListener(MediaQueryListListener& aListener)
  86 {
  87   if (!HasListeners()) {
  88     // When we have listeners, the pres context owns a reference to
  89     // this.  This is a cyclic reference that can only be broken by
  90     // cycle collection.
  91     NS_ADDREF_THIS();
  92   }
  93
  94   if (!mMatchesValid) {
  95     NS_ABORT_IF_FALSE(!HasListeners(),
  96                       "when listeners present, must keep mMatches current");
  97     RecomputeMatches();
  98   }
  99
 100   for (uint32_t i = 0; i < mCallbacks.Length(); ++i) {
 101     if (aListener == *mCallbacks[i]) {
 102       // Already registered
 103       return;
 104     }
 105   }
 106
 107   mCallbacks.AppendElement(&aListener);
 108   if (!HasListeners()) {
 109     // Append failed; undo the AddRef above.
 110     NS_RELEASE_THIS();
 111   }
 112 }
 113
 114 void
 115 MediaQueryList::RemoveListener(MediaQueryListListener& aListener)
 116 {
 117   for (uint32_t i = 0; i < mCallbacks.Length(); ++i) {
 118     if (aListener == *mCallbacks[i]) {
 119       mCallbacks.RemoveElementAt(i);
 120       if (!HasListeners()) {
 121         // See NS_ADDREF_THIS() in AddListener.
 122         NS_RELEASE_THIS();
 123       }
 124       break;
 125     }
 126   }
 127 }
 128
 129 void
 130 MediaQueryList::RemoveAllListeners()
 131 {
 132   bool hadListeners = HasListeners();
 133   mCallbacks.Clear();
 134   if (hadListeners) {
 135     // See NS_ADDREF_THIS() in AddListener.
 136     NS_RELEASE_THIS();
 137   }
 138 }
 139
 140 void
 141 MediaQueryList::RecomputeMatches()
 142 {
 143   if (!mPresContext) {
 144     return;
 145   }
 146
 147   mMatches = mMediaList->Matches(mPresContext, nullptr);
 148   mMatchesValid = true;
 149 }
 150
 151 void
 152 MediaQueryList::MediumFeaturesChanged(NotifyList &aListenersToNotify)
 153 {
 154   mMatchesValid = false;
 155
 156   if (HasListeners()) {
 157     bool oldMatches = mMatches;
 158     RecomputeMatches();
 159     if (mMatches != oldMatches) {
 160       for (uint32_t i = 0, i_end = mCallbacks.Length(); i != i_end; ++i) {
 161         HandleChangeData *d = aListenersToNotify.AppendElement();
 162         if (d) {
 163           d->mql = this;
 164           d->callback = mCallbacks[i];
 165         }
 166       }
 167     }
 168   }
 169 }
 170
 171 nsISupports*
 172 MediaQueryList::GetParentObject() const
 173 {
 174   if (!mPresContext) {
 175     return nullptr;
 176   }
 177   return mPresContext->Document();
 178 }
 179
 180 JSObject*
 181 MediaQueryList::WrapObject(JSContext* aCx)
 182 {
 183   return MediaQueryListBinding::Wrap(aCx, this);
 184 }
 185
 186 } // namespace dom
 187 } // namespace mozilla