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QMovie: fix quadratic behavior

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Repeatedly calling QList::erase(it) (via QMutableListIterator::remove())
results in quadratic runtime.

Use std::remove_if, which does exactly what the old code tried to do,
except in linear time.

Change-Id: I682e5e05f04953ae1c8788e5d66335241de39fee
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
This commit is contained in:
Marc Mutz 2015-12-03 13:47:27 +01:00
parent 5d44d17127
commit b566d670e5
1 changed files with 8 additions and 6 deletions
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14
src/gui/image/qmovie.cpp
View File

@ -965,14 +965,16 @@ void QMovie::setScaledSize(const QSize &size)
QList<QByteArray> QMovie::supportedFormats() QList<QByteArray> QMovie::supportedFormats()
{ {
QList<QByteArray> list = QImageReader::supportedImageFormats(); QList<QByteArray> list = QImageReader::supportedImageFormats();
QMutableListIterator<QByteArray> it(list);
QBuffer buffer; QBuffer buffer;
buffer.open(QIODevice::ReadOnly); buffer.open(QIODevice::ReadOnly);
while (it.hasNext()) {
QImageReader reader(&buffer, it.next()); const auto doesntSupportAnimation =
if (!reader.supportsAnimation()) [&buffer](const QByteArray &format) {
it.remove(); return !QImageReader(&buffer, format).supportsAnimation();
} };
list.erase(std::remove_if(list.begin(), list.end(), doesntSupportAnimation), list.end());
return list; return list;
} }