qml: replace context properties and code updates

Most of the qml code in the repository was outdated,
and followed bad practices, like context properties.
Complementary, after the major updates for Qt6
most of the code was not relying on the new ways of
register types (singletons, and using the decorator QmlElement).

Drop the context property usage in the following examples:
- signals/qmltopy1
- signals/qmltopy2
- signals/pytoqml2
- usingmodel
- quickcontrols2/gallery
- textproperties

Additionally:
- all the tests related to context properties
- tutorials/qmlapp
- tutorials/qmlsqlintegration
- Removing 'scrolling' example
- Fixing some flake8 warnings

Change-Id: I649248c0149876bf2bf94e78e27cef7110f42f1d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Keith Kyzivat <keith.kyzivat@qt.io>

2 files changed, 19 insertions, 11 deletions

diff --git a/examples/declarative/usingmodel/usingmodel.py b/examples/declarative/usingmodel/usingmodel.py
index bd1fa2eba..3d5a03964 100644
--- a/examples/declarative/usingmodel/usingmodel.py
+++ b/examples/declarative/usingmodel/usingmodel.py
@@ -1,7 +1,7 @@
 
 #############################################################################
 ##
-## Copyright (C) 2016 The Qt Company Ltd.
+## Copyright (C) 2021 The Qt Company Ltd.
 ## Contact: http://www.qt.io/licensing/
 ##
 ## This file is part of the Qt for Python examples of the Qt Toolkit.
@@ -45,6 +45,7 @@ import sys
 from PySide6.QtCore import QAbstractListModel, Qt, QUrl, QByteArray
 from PySide6.QtGui import QGuiApplication
 from PySide6.QtQuick import QQuickView
+from PySide6.QtQml import qmlRegisterSingletonType
 
 
 class PersonModel (QAbstractListModel):
@@ -75,9 +76,17 @@ class PersonModel (QAbstractListModel):
             return d['myrole']
         return None
 
-    def populate(self):
-        self._data.append({'name': 'Qt', 'myrole': 'role1'})
-        self._data.append({'name': 'PySide', 'myrole': 'role2'})
+    def populate(self, data=None):
+        for item in data:
+            self._data.append(item)
+
+
+def model_callback(engine):
+    my_model = PersonModel()
+    data = [{'name': 'Qt', 'myrole': 'role1'},
+            {'name': 'PySide', 'myrole': 'role2'}]
+    my_model.populate(data)
+    return my_model
 
 
 if __name__ == '__main__':
@@ -85,17 +94,15 @@ if __name__ == '__main__':
     view = QQuickView()
     view.setResizeMode(QQuickView.SizeRootObjectToView)
 
-    myModel = PersonModel()
-    myModel.populate()
-
-    view.rootContext().setContextProperty("myModel", myModel)
+    qmlRegisterSingletonType(PersonModel, "PersonModel", 1, 0, "MyModel", model_callback)
     qml_file = os.fspath(Path(__file__).resolve().parent / 'view.qml')
     view.setSource(QUrl.fromLocalFile(qml_file))
     if view.status() == QQuickView.Error:
         sys.exit(-1)
     view.show()
 
-    app.exec()
+    r = app.exec()
     # Deleting the view before it goes out of scope is required to make sure all child QML instances
     # are destroyed in the correct order.
     del view
+    sys.exit(r)
diff --git a/examples/declarative/usingmodel/view.qml b/examples/declarative/usingmodel/view.qml
index 8eb4f7f97..682723d27 100644
--- a/examples/declarative/usingmodel/view.qml
+++ b/examples/declarative/usingmodel/view.qml
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the Qt for Python examples of the Qt Toolkit.
@@ -39,12 +39,13 @@
 ****************************************************************************/
 
 import QtQuick 2.0
+import PersonModel 1.0
 
 ListView {
     width: 100
     height: 100
     anchors.fill: parent
-    model: myModel
+    model: MyModel
     delegate: Component {
         Rectangle {
             height: 25