src/gui/painting/qpainter.cpp

@@ -293,6 +293,7 @@ bool QPainterPrivate::attachPainterPrivate(QPainter *q, QPaintDevice *pdev)
     // Update matrix.
     if (q->d_ptr->state->WxF) {
         q->d_ptr->state->redirectionMatrix = q->d_ptr->state->matrix;
+        q->d_ptr->state->redirectionMatrix *= q->d_ptr->hidpiScaleTransform().inverted();
         q->d_ptr->state->redirectionMatrix.translate(-offset.x(), -offset.y());
         q->d_ptr->state->worldMatrix = QTransform();
         q->d_ptr->state->WxF = false;

src/plugins/platforms/ios/qiosscreen.mm

@@ -136,7 +136,7 @@ QIOSScreen::QIOSScreen(unsigned int screenIndex)
 
     int unscaledDpi = 163; // Regular iPhone DPI
     if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad
-        && deviceIdentifier != QStringLiteral("iPad2,5") /* iPad Mini */) {
+        && !deviceIdentifier.contains(QRegularExpression("^iPad2,[567]$")) /* excluding iPad Mini */) {
         unscaledDpi = 132;
     };
 

src/plugins/platforms/ios/qioswindow.mm

@@ -150,7 +150,8 @@
 
 - (void)updateTouchList:(NSSet *)touches withState:(Qt::TouchPointState)state
 {
-    QRect applicationRect = fromCGRect(self.window.screen.applicationFrame);
+    QPlatformScreen *screen = QGuiApplication::primaryScreen()->handle();
+    QRect applicationRect = fromPortraitToPrimary(fromCGRect(self.window.screen.applicationFrame), screen);
 
     foreach (UITouch *uiTouch, m_activeTouches.keys()) {
         QWindowSystemInterface::TouchPoint &touchPoint = m_activeTouches[uiTouch];
@@ -163,8 +164,10 @@
             // Find the touch position relative to the window. Then calculate the screen
             // position by subtracting the position of the applicationRect (since UIWindow
             // does not take that into account when reporting its own frame):
-            QPoint touchPos = fromCGPoint([uiTouch locationInView:nil]);
-            touchPoint.area = QRectF(touchPos - applicationRect.topLeft(), QSize(0, 0));
+            QRect touchInWindow = QRect(fromCGPoint([uiTouch locationInView:nil]), QSize(0, 0));
+            QRect touchInScreen = fromPortraitToPrimary(touchInWindow, screen);
+            QPoint touchPos = touchInScreen.topLeft() - applicationRect.topLeft();
+            touchPoint.area = QRectF(touchPos, QSize(0, 0));
             touchPoint.normalPosition = QPointF(touchPos.x() / applicationRect.width(), touchPos.y() / applicationRect.height());
         }
     }

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -503,10 +503,14 @@ QWindowsWindow::WindowData
     const QWindowCreationContextPtr context(new QWindowCreationContext(w, rect, data.customMargins, style, exStyle));
     QWindowsContext::instance()->setWindowCreationContext(context);
 
-    if (context->frameX < 0)
-        context->frameX = 0;
-    if (context->frameY < 0)
-        context->frameY = 0;
+    QRect screenGeometry;
+    if (QScreen *screen = w->screen())
+        screenGeometry = screen->availableVirtualGeometry();
+
+    if (context->frameX < screenGeometry.left())
+        context->frameX = screenGeometry.left();
+    if (context->frameY < screenGeometry.top())
+        context->frameY = screenGeometry.top();
 
     if (QWindowsContext::verboseWindows)
         qDebug().nospace()

src/widgets/graphicsview/qgridlayoutengine.cpp

@@ -291,7 +291,7 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
 
                     int stretch = stretches[start + i];
                     if (sumStretches == 0) {
-                        if (hasIgnoreFlag) {
+                        if (hasIgnoreFlag || sizes[i] == 0.0) {
                             factors[i] = (stretch < 0) ? 1.0 : 0.0;
                         } else {
                             factors[i] = (stretch < 0) ? sizes[i] : 0.0;

tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp

@@ -1884,6 +1884,18 @@ void tst_QGraphicsGridLayout::defaultStretchFactors_data()
                                 << QSizeF(10,10) << QSizeF(10,10) << QSizeF(10,10)
                             );
 
+    QTest::newRow("preferredsizeIsZero") << (ItemList()
+                                    << ItemDesc(0,0)
+                                        .preferredSizeHint(QSizeF(0,10))
+                                    << ItemDesc(0,1)
+                                        .preferredSizeHint(QSizeF(10,10))
+                                        .maxSize(QSizeF(20, 10))
+                                )
+                            << QSizeF(30, 10)
+                            << (SizeList()
+                                << QSizeF(10,10) << QSizeF(20,10)
+                            );
+
     QTest::newRow("ignoreitem01") << (ItemList()
                                     << ItemDesc(0,0)
                                         .preferredSizeHint(QSizeF(10,10))