Fix global coordinate mapping for child widgets in QGraphicsView.

Move the code path handling widgets embedded in QGraphicsProxyWidget
into the loop moving up the parent hierarchy.

Add child widget to test.

Task-number: QTBUG-41135
Change-Id: Ibd86413faaa927145a85a2f5864f162979135053
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

2 files changed, 45 insertions, 26 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index e701eb07ba..88d7cdce76 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -12264,20 +12264,21 @@ QPaintEngine *QWidget::paintEngine() const
 */
 QPoint QWidget::mapToGlobal(const QPoint &pos) const
 {
-#ifndef QT_NO_GRAPHICSVIEW
-    Q_D(const QWidget);
-    if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
-        const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
-        if (!views.isEmpty()) {
-            const QPointF scenePos = d->extra->proxyWidget->mapToScene(pos);
-            const QPoint viewPortPos = views.first()->mapFromScene(scenePos);
-            return views.first()->viewport()->mapToGlobal(viewPortPos);
-        }
-    }
-#endif // !QT_NO_GRAPHICSVIEW
     int x = pos.x(), y = pos.y();
     const QWidget *w = this;
     while (w) {
+#ifndef QT_NO_GRAPHICSVIEW
+        const QWidgetPrivate *d = w->d_func();
+        if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
+            const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
+            if (!views.isEmpty()) {
+                const QPointF scenePos = d->extra->proxyWidget->mapToScene(QPoint(x, y));
+                const QPoint viewPortPos = views.first()->mapFromScene(scenePos);
+                return views.first()->viewport()->mapToGlobal(viewPortPos);
+            }
+        }
+#endif // !QT_NO_GRAPHICSVIEW
+
         QWindow *window = w->windowHandle();
         if (window && window->handle())
             return window->mapToGlobal(QPoint(x, y));
@@ -12299,20 +12300,21 @@ QPoint QWidget::mapToGlobal(const QPoint &pos) const
 */
 QPoint QWidget::mapFromGlobal(const QPoint &pos) const
 {
-#ifndef QT_NO_GRAPHICSVIEW
-    Q_D(const QWidget);
-    if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
-        const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
-        if (!views.isEmpty()) {
-            const QPoint viewPortPos = views.first()->viewport()->mapFromGlobal(pos);
-            const QPointF scenePos = views.first()->mapToScene(viewPortPos);
-            return d->extra->proxyWidget->mapFromScene(scenePos).toPoint();
-        }
-    }
-#endif // !QT_NO_GRAPHICSVIEW
     int x = pos.x(), y = pos.y();
     const QWidget *w = this;
     while (w) {
+#ifndef QT_NO_GRAPHICSVIEW
+        const QWidgetPrivate *d = w->d_func();
+        if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
+            const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
+            if (!views.isEmpty()) {
+                const QPoint viewPortPos = views.first()->viewport()->mapFromGlobal(QPoint(x, y));
+                const QPointF scenePos = views.first()->mapToScene(viewPortPos);
+                return d->extra->proxyWidget->mapFromScene(scenePos).toPoint();
+            }
+        }
+#endif // !QT_NO_GRAPHICSVIEW
+
         QWindow *window = w->windowHandle();
         if (window && window->handle())
             return window->mapFromGlobal(QPoint(x, y));
diff --git a/tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp b/tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp
index f8d852888c..cd40c5541c 100644
--- a/tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp
+++ b/tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp
@@ -3670,6 +3670,14 @@ void tst_QGraphicsProxyWidget::QTBUG_6986_sendMouseEventToAlienWidget()
     QTRY_COMPARE(scene.hoverButton->hoverLeaveReceived, true);
 }
 
+static QByteArray msgPointMismatch(const QPoint &actual, const QPoint &expected)
+{
+    QString result;
+    QDebug(&result) << actual << " != " << expected << " manhattanLength="
+        << (expected - actual).manhattanLength();
+    return result.toLocal8Bit();
+}
+
 void tst_QGraphicsProxyWidget::mapToGlobal() // QTBUG-41135
 {
     const QRect availableGeometry = QGuiApplication::primaryScreen()->availableGeometry();
@@ -3681,20 +3689,29 @@ void tst_QGraphicsProxyWidget::mapToGlobal() // QTBUG-41135
     view.move(availableGeometry.bottomRight() - QPoint(size.width(), size.height()) - QPoint(100, 100));
     QWidget *embeddedWidget = new QWidget;
     embeddedWidget->setFixedSize(size / 2);
+    QWidget *childWidget = new QWidget(embeddedWidget);
+    childWidget->setStyleSheet(QLatin1String("background-color: \"red\"; "));
+    childWidget->resize(embeddedWidget->size() / 2);
+    childWidget->move(embeddedWidget->width() / 4, embeddedWidget->height() / 4); // center in embeddedWidget
     scene.addWidget(embeddedWidget);
     QApplication::setActiveWindow(&view);
     view.show();
     QVERIFY(QTest::qWaitForWindowExposed(&view));
-    const QPoint embeddedCenter = embeddedWidget->geometry().center();
+    const QPoint embeddedCenter = embeddedWidget->rect().center();
     const QPoint embeddedCenterGlobal = embeddedWidget->mapToGlobal(embeddedCenter);
     QCOMPARE(embeddedWidget->mapFromGlobal(embeddedCenterGlobal), embeddedCenter);
     // This should be equivalent to the view center give or take rounding
     // errors due to odd window margins
     const QPoint viewCenter = view.geometry().center();
     QVERIFY2((viewCenter - embeddedCenterGlobal).manhattanLength() <= 2,
-             qPrintable(QStringLiteral("%1, %2 != %3, %4")
-                        .arg(viewCenter.x()).arg(viewCenter.y())
-                        .arg(embeddedCenterGlobal.x()).arg(embeddedCenterGlobal.y())));
+             msgPointMismatch(embeddedCenterGlobal, viewCenter).constData());
+
+    // Same test with child centered on embeddedWidget
+    const QPoint childCenter = childWidget->rect().center();
+    const QPoint childCenterGlobal = childWidget->mapToGlobal(childCenter);
+    QCOMPARE(childWidget->mapFromGlobal(childCenterGlobal), childCenter);
+    QVERIFY2((viewCenter - childCenterGlobal).manhattanLength() <= 4,
+             msgPointMismatch(childCenterGlobal, viewCenter).constData());
 }
 
 void tst_QGraphicsProxyWidget::mapToGlobalWithoutScene() // QTBUG-44509