gecko/layout/style/nsDOMMediaQueryList.cpp
L. David Baron d1a53c3af7 Hold on to MediaQueryList objects that have listeners so that notification doesn't depend on GC timing. (Bug 716751) r=bzbarsky
Note:  This also fixes a crash (when notifications happen) from
calling mql.addListeners(null).

This also fixes test_media_query_list.html so that the initial set of
tests doesn't keep running through the later tests.

The test for the null-dereference has been confirmed to crash without
the patch and pass with the patch.

The test for the gc issue has been confirmed to fail without the patch
and pass with the patch.
2012-02-29 20:47:55 -08:00

198 lines
5.7 KiB
C++

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsDOMMediaQueryList.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2011
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/* implements DOM interface for querying and observing media queries */
#include "nsDOMMediaQueryList.h"
#include "nsPresContext.h"
#include "nsIMediaList.h"
#include "nsCSSParser.h"
#include "nsDOMClassInfoID.h" // DOMCI_DATA
nsDOMMediaQueryList::nsDOMMediaQueryList(nsPresContext *aPresContext,
const nsAString &aMediaQueryList)
: mPresContext(aPresContext),
mMediaList(new nsMediaList),
mMatchesValid(false)
{
PR_INIT_CLIST(this);
nsCSSParser parser;
parser.ParseMediaList(aMediaQueryList, nsnull, 0, mMediaList, false);
}
nsDOMMediaQueryList::~nsDOMMediaQueryList()
{
if (mPresContext) {
PR_REMOVE_LINK(this);
}
}
NS_IMPL_CYCLE_COLLECTION_CLASS(nsDOMMediaQueryList)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsDOMMediaQueryList)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mPresContext)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSTARRAY_OF_NSCOMPTR(mListeners)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDOMMediaQueryList)
if (tmp->mPresContext) {
PR_REMOVE_LINK(tmp);
NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mPresContext)
}
tmp->RemoveAllListeners();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
DOMCI_DATA(MediaQueryList, nsDOMMediaQueryList)
NS_INTERFACE_MAP_BEGIN(nsDOMMediaQueryList)
NS_INTERFACE_MAP_ENTRY(nsIDOMMediaQueryList)
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(nsDOMMediaQueryList)
NS_DOM_INTERFACE_MAP_ENTRY_CLASSINFO(MediaQueryList)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(nsDOMMediaQueryList)
NS_IMPL_CYCLE_COLLECTING_RELEASE(nsDOMMediaQueryList)
NS_IMETHODIMP
nsDOMMediaQueryList::GetMedia(nsAString &aMedia)
{
mMediaList->GetText(aMedia);
return NS_OK;
}
NS_IMETHODIMP
nsDOMMediaQueryList::GetMatches(bool *aMatches)
{
if (!mMatchesValid) {
NS_ABORT_IF_FALSE(!HasListeners(),
"when listeners present, must keep mMatches current");
RecomputeMatches();
}
*aMatches = mMatches;
return NS_OK;
}
NS_IMETHODIMP
nsDOMMediaQueryList::AddListener(nsIDOMMediaQueryListListener *aListener)
{
if (!aListener) {
return NS_OK;
}
if (!HasListeners()) {
// When we have listeners, the pres context owns a reference to
// this. This is a cyclic reference that can only be broken by
// cycle collection.
NS_ADDREF_THIS();
}
if (!mMatchesValid) {
NS_ABORT_IF_FALSE(!HasListeners(),
"when listeners present, must keep mMatches current");
RecomputeMatches();
}
if (!mListeners.Contains(aListener)) {
mListeners.AppendElement(aListener);
if (!HasListeners()) {
// Append failed; undo the AddRef above.
NS_RELEASE_THIS();
}
}
return NS_OK;
}
NS_IMETHODIMP
nsDOMMediaQueryList::RemoveListener(nsIDOMMediaQueryListListener *aListener)
{
bool removed = mListeners.RemoveElement(aListener);
NS_ABORT_IF_FALSE(!mListeners.Contains(aListener),
"duplicate occurrence of listeners");
if (removed && !HasListeners()) {
// See NS_ADDREF_THIS() in AddListener.
NS_RELEASE_THIS();
}
return NS_OK;
}
void
nsDOMMediaQueryList::RemoveAllListeners()
{
bool hadListeners = HasListeners();
mListeners.Clear();
if (hadListeners) {
// See NS_ADDREF_THIS() in AddListener.
NS_RELEASE_THIS();
}
}
void
nsDOMMediaQueryList::RecomputeMatches()
{
if (!mPresContext) {
return;
}
mMatches = mMediaList->Matches(mPresContext, nsnull);
mMatchesValid = true;
}
void
nsDOMMediaQueryList::MediumFeaturesChanged(NotifyList &aListenersToNotify)
{
mMatchesValid = false;
if (mListeners.Length()) {
bool oldMatches = mMatches;
RecomputeMatches();
if (mMatches != oldMatches) {
for (PRUint32 i = 0, i_end = mListeners.Length(); i != i_end; ++i) {
HandleChangeData *d = aListenersToNotify.AppendElement();
if (d) {
d->mql = this;
d->listener = mListeners[i];
}
}
}
}
}