[processing] fix app freeze when closing options dialog (fixes #15550)

(cherry picked from commit 3dcf487)

Author: nirvn

python/plugins/processing/core/ProcessingConfig.py

@@ -268,16 +268,15 @@ def setValue(self, value):
         self.validator(value)
         self.value = value
 
-    def read(self):
-        qsettings = QSettings()
+    def read(self, qsettings=QSettings()):
         value = qsettings.value(self.qname, None)
         if value is not None:
             if isinstance(self.value, bool):
                 value = unicode(value).lower() == unicode(True).lower()
             self.value = value
 
-    def save(self):
-        QSettings().setValue(self.qname, self.value)
+    def save(self, qsettings=QSettings()):
+        qsettings.setValue(self.qname, self.value)
 
     def __str__(self):
         return self.name + '=' + unicode(self.value)

python/plugins/processing/gui/ConfigDialog.py

@@ -30,7 +30,7 @@
 
 from PyQt4 import uic
 from PyQt4.QtCore import Qt, QEvent, QPyNullVariant
-from PyQt4.QtGui import (QFileDialog, QDialog, QIcon, QStyle,
+from PyQt4.QtGui import (QFileDialog, QDialog, QIcon, QStyle, QSettings,
                          QStandardItemModel, QStandardItem, QMessageBox, QStyledItemDelegate,
                          QLineEdit, QWidget, QToolButton, QHBoxLayout,
                          QComboBox)
@@ -139,6 +139,7 @@ def fillTree(self):
         self.adjustColumns()
 
     def accept(self):
+        qsettings = QSettings()
         for setting in self.items.keys():
             if isinstance(setting.value, bool):
                 setting.setValue(self.items[setting].checkState() == Qt.Checked)
@@ -149,7 +150,7 @@ def accept(self):
                     QMessageBox.warning(self, self.tr('Wrong value'),
                                         self.tr('Wrong value for parameter "%s":\n\n%s' % (setting.description, unicode(e))))
                     return
-            setting.save()
+            setting.save(qsettings)
         Processing.updateAlgsList()
 
         QDialog.accept(self)