From 4a35b05b852e6ce6102e92d67cf2edb545e1e7a4 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sun, 13 Oct 2013 23:06:00 +0200
Subject: QImageReader/Writer: replace dubious use of QSet<QByteArray> with
 QList

The code populated QSets with some strings and went
on to copy the values to QLists. Since QSet is unordered_set, those
lists were not sorted, so the code did that manually.

Since QSet is a node-based container and not even an ordered one,
the code pays a hefty price just for ensuring uniqueness of values
prior to sorting.

The new code just crams everything into lists, duplicates and all,
then sorts the lists and only then removes duplicates using
std::unique.

Saves 3376B in text size on Linux AMD64 GCC 4.9-trunk release
stripped QtGui.

Change-Id: Ifee931102c01b7505c712cebf4effc37e94165b0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
---
 src/gui/image/qimagewriter.cpp | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

(limited to 'src/gui/image/qimagewriter.cpp')

diff --git a/src/gui/image/qimagewriter.cpp b/src/gui/image/qimagewriter.cpp
index c12dbb6544..7b8af90357 100644
--- a/src/gui/image/qimagewriter.cpp
+++ b/src/gui/image/qimagewriter.cpp
@@ -678,7 +678,7 @@ bool QImageWriter::supportsOption(QImageIOHandler::ImageOption option) const
 #ifndef QT_NO_IMAGEFORMATPLUGIN
 void supportedImageHandlerFormats(QFactoryLoader *loader,
                                   QImageIOPlugin::Capability cap,
-                                  QSet<QByteArray> *result)
+                                  QList<QByteArray> *result)
 {
     typedef QMultiMap<int, QString> PluginKeyMap;
     typedef PluginKeyMap::const_iterator PluginKeyMapConstIterator;
@@ -687,6 +687,7 @@ void supportedImageHandlerFormats(QFactoryLoader *loader,
     const PluginKeyMapConstIterator cend = keyMap.constEnd();
     int i = -1;
     QImageIOPlugin *plugin = 0;
+    result->reserve(result->size() + keyMap.size());
     for (PluginKeyMapConstIterator it = keyMap.constBegin(); it != cend; ++it) {
         if (it.key() != i) {
             i = it.key();
@@ -694,13 +695,13 @@ void supportedImageHandlerFormats(QFactoryLoader *loader,
         }
         const QByteArray key = it.value().toLatin1();
         if (plugin && (plugin->capabilities(0, key) & cap) != 0)
-            result->insert(key);
+            result->append(key);
     }
 }
 
 void supportedImageHandlerMimeTypes(QFactoryLoader *loader,
                                     QImageIOPlugin::Capability cap,
-                                    QSet<QByteArray> *result)
+                                    QList<QByteArray> *result)
 {
     QList<QJsonObject> metaDataList = loader->metaData();
 
@@ -713,7 +714,7 @@ void supportedImageHandlerMimeTypes(QFactoryLoader *loader,
         const int keyCount = keys.size();
         for (int k = 0; k < keyCount; ++k) {
             if (plugin && (plugin->capabilities(0, keys.at(k).toString().toLatin1()) & cap) != 0)
-                result->insert(mimeTypes.at(k).toString().toLatin1());
+                result->append(mimeTypes.at(k).toString().toLatin1());
         }
     }
 }
@@ -746,7 +747,7 @@ void supportedImageHandlerMimeTypes(QFactoryLoader *loader,
 */
 QList<QByteArray> QImageWriter::supportedImageFormats()
 {
-    QSet<QByteArray> formats;
+    QList<QByteArray> formats;
 #ifndef QT_NO_IMAGEFORMAT_BMP
     formats << "bmp";
 #endif
@@ -770,12 +771,9 @@ QList<QByteArray> QImageWriter::supportedImageFormats()
     supportedImageHandlerFormats(loader(), QImageIOPlugin::CanWrite, &formats);
 #endif // QT_NO_IMAGEFORMATPLUGIN
 
-    QList<QByteArray> sortedFormats;
-    for (QSet<QByteArray>::ConstIterator it = formats.constBegin(); it != formats.constEnd(); ++it)
-        sortedFormats << *it;
-
-    std::sort(sortedFormats.begin(), sortedFormats.end());
-    return sortedFormats;
+    std::sort(formats.begin(), formats.end());
+    formats.erase(std::unique(formats.begin(), formats.end()), formats.end());
+    return formats;
 }
 
 /*!
@@ -788,7 +786,7 @@ QList<QByteArray> QImageWriter::supportedImageFormats()
 */
 QList<QByteArray> QImageWriter::supportedMimeTypes()
 {
-    QSet<QByteArray> mimeTypes;
+    QList<QByteArray> mimeTypes;
 #ifndef QT_NO_IMAGEFORMAT_BMP
     mimeTypes << "image/bmp";
 #endif
@@ -814,12 +812,9 @@ QList<QByteArray> QImageWriter::supportedMimeTypes()
     supportedImageHandlerMimeTypes(loader(), QImageIOPlugin::CanWrite, &mimeTypes);
 #endif // QT_NO_IMAGEFORMATPLUGIN
 
-    QList<QByteArray> sortedMimeTypes;
-    for (QSet<QByteArray>::ConstIterator it = mimeTypes.constBegin(); it != mimeTypes.constEnd(); ++it)
-        sortedMimeTypes << *it;
-
-    std::sort(sortedMimeTypes.begin(), sortedMimeTypes.end());
-    return sortedMimeTypes;
+    std::sort(mimeTypes.begin(), mimeTypes.end());
+    mimeTypes.erase(std::unique(mimeTypes.begin(), mimeTypes.end()), mimeTypes.end());
+    return mimeTypes;
 }
 
 QT_END_NAMESPACE
-- 
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