Windows: Fix some widget tests to pass on High DPI screens

For tst_QFrame and tst_QOpenGLWidget, force scaling off
since they do screen captures which would fail with
scaling activated due to different device pixel ratios.

For tst_QGraphicsItem and tst_QHeaderView, force
scaling on for Windows since some tests otherwise fail
due to violation of the minimum size constraints of
framed windows on Windows.

The tests will then pass regardless of any environment
setting of the scaling variables on a developer
machine.

Change-Id: Iefa4e84b433f7e51dce4e416546a9eda8ee6d0f1
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

tests/auto/widgets/graphicsview/qgraphicsitem/tst_qgraphicsitem.cpp

@@ -272,6 +272,9 @@ class tst_QGraphicsItem : public QObject
 {
     Q_OBJECT
 
+public:
+    static void initMain();
+
 private slots:
     void construction();
     void constructionWithParent();
@@ -474,6 +477,14 @@ private:
     QTouchDevice *m_touchDevice = nullptr;
 };
 
+void tst_QGraphicsItem::initMain()
+{
+#ifdef Q_OS_WIN
+    // Ensure minimum size constraints of framed windows on High DPI screens
+    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+#endif
+}
+
 void tst_QGraphicsItem::construction()
 {
     for (int i = 0; i < 7; ++i) {

tests/auto/widgets/itemviews/qheaderview/tst_qheaderview.cpp

@@ -106,6 +106,7 @@ class tst_QHeaderView : public QObject
 
 public:
     tst_QHeaderView();
+    static void initMain();
 
 private slots:
     void initTestCase();
@@ -265,6 +266,14 @@ protected:
     QElapsedTimer timer;
 };
 
+void tst_QHeaderView::initMain()
+{
+#ifdef Q_OS_WIN
+    // Ensure minimum size constraints of framed windows on High DPI screens
+    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+#endif
+}
+
 class QtTestModel: public QAbstractTableModel
 {
 

tests/auto/widgets/widgets/qframe/tst_qframe.cpp

@@ -37,6 +37,10 @@
 class tst_QFrame : public QObject
 {
     Q_OBJECT
+
+public:
+    static void initMain() { QCoreApplication::setAttribute(Qt::AA_DisableHighDpiScaling); }
+
 private slots:
     void testDefaults();
     void testInitStyleOption_data();

tests/auto/widgets/widgets/qopenglwidget/tst_qopenglwidget.cpp

@@ -49,6 +49,9 @@ class tst_QOpenGLWidget : public QObject
 {
     Q_OBJECT
 
+public:
+    static void initMain() { QCoreApplication::setAttribute(Qt::AA_DisableHighDpiScaling); }
+
 private slots:
     void initTestCase();
     void create();