QWidget::mapTo/FromGlobal(): Fix transformation in case of QGraphicsItem::ItemIgnoresTransformations

Extract a helper returning the transform from
QGraphicsViewPrivate::mapToViewRect() and use that.

Fixes: QTBUG-128913
Change-Id: Idc31f653c23cd7d0e5bbb8af560f010f01ac4d4b
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
(cherry picked from commit deb4e08c1212aa3d43f62f9e7211bf69d3be0ada)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/graphicsview/qgraphicsview.cpp

@@ -885,16 +885,14 @@ void QGraphicsViewPrivate::populateSceneDragDropEvent(QGraphicsSceneDragDropEven
 /*!
     \internal
 */
-QRect QGraphicsViewPrivate::mapToViewRect(const QGraphicsItem *item, const QRectF &rect) const
+QTransform QGraphicsViewPrivate::mapToViewTransform(const QGraphicsItem *item) const
 {
     Q_Q(const QGraphicsView);
     if (dirtyScroll)
         const_cast<QGraphicsViewPrivate *>(this)->updateScroll();
 
-    if (item->d_ptr->itemIsUntransformable()) {
-        QTransform itv = item->deviceTransform(q->viewportTransform());
-        return itv.mapRect(rect).toAlignedRect();
-    }
+    if (item->d_ptr->itemIsUntransformable())
+        return item->deviceTransform(q->viewportTransform());
 
     // Translate-only
     // COMBINE
@@ -908,21 +906,20 @@ QRect QGraphicsViewPrivate::mapToViewRect(const QGraphicsItem *item, const QRect
         offset += itemd->pos;
     } while ((parentItem = itemd->parent));
 
-    QRectF baseRect = rect.translated(offset.x(), offset.y());
+    QTransform move = QTransform::fromTranslate(offset.x(), offset.y());
     if (!parentItem) {
-        if (identityMatrix) {
-            baseRect.translate(-scrollX, -scrollY);
-            return baseRect.toAlignedRect();
-        }
-        return matrix.mapRect(baseRect).translated(-scrollX, -scrollY).toAlignedRect();
+        move.translate(-scrollX, -scrollY);
+        return identityMatrix ? move : matrix * move;
     }
-
     QTransform tr = parentItem->sceneTransform();
     if (!identityMatrix)
         tr *= matrix;
-    QRectF r = tr.mapRect(baseRect);
-    r.translate(-scrollX, -scrollY);
-    return r.toAlignedRect();
+    return move * tr * QTransform::fromTranslate(-scrollX, -scrollY);
+}
+
+QRect QGraphicsViewPrivate::mapToViewRect(const QGraphicsItem *item, const QRectF &rect) const
+{
+    return mapToViewTransform(item).mapRect(rect).toAlignedRect();
 }
 
 /*!

src/widgets/graphicsview/qgraphicsview_p.h

@@ -139,6 +139,7 @@ public:
     void populateSceneDragDropEvent(QGraphicsSceneDragDropEvent *dest,
                                     QDropEvent *source);
 
+    QTransform mapToViewTransform(const QGraphicsItem *item) const;
     QRect mapToViewRect(const QGraphicsItem *item, const QRectF &rect) const;
     QRegion mapToViewRegion(const QGraphicsItem *item, const QRectF &rect) const;
     QRegion dirtyRegion;

src/widgets/kernel/qwidget.cpp

@@ -60,6 +60,7 @@
 #include "QtWidgets/qgraphicsproxywidget.h"
 #include "QtWidgets/qgraphicsscene.h"
 #include "private/qgraphicsproxywidget_p.h"
+#include "private/qgraphicsview_p.h"
 #endif
 #include "QtWidgets/qabstractscrollarea.h"
 #include "private/qabstractscrollarea_p.h"
@@ -12644,8 +12645,8 @@ static MapToGlobalTransformResult mapToGlobalTransform(const QWidget *w)
             if (const QGraphicsScene *scene = qgpw->scene()) {
                 const QList <QGraphicsView *> views = scene->views();
                 if (!views.isEmpty()) {
-                    result.transform *= qgpw->sceneTransform();
-                    result.transform *= views.first()->viewportTransform();
+                    auto *viewP = static_cast<QGraphicsViewPrivate *>(qt_widget_private(views.constFirst()));
+                    result.transform *= viewP->mapToViewTransform(qgpw);
                     w = views.first()->viewport();
                 }
             }

tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp

@@ -135,6 +135,7 @@ private slots:
     void QTBUG_6986_sendMouseEventToAlienWidget();
     void mapToGlobal();
     void mapToGlobalWithoutScene();
+    void mapToGlobalIgnoreTranformation();
     void QTBUG_43780_visibility();
 #if QT_CONFIG(wheelevent)
     void wheelEventPropagation();
@@ -3552,6 +3553,55 @@ void tst_QGraphicsProxyWidget::mapToGlobalWithoutScene() // QTBUG-44509
     QCOMPARE(embeddedWidget->mapFromGlobal(globalPos), localPos);
 }
 
+// QTBUG-128913,  QGraphicsProxyWidget with ItemIgnoresTransformations
+void tst_QGraphicsProxyWidget::mapToGlobalIgnoreTranformation()
+{
+    const QRect availableGeometry = QGuiApplication::primaryScreen()->availableGeometry();
+    const QSize size = availableGeometry.size() / 2;
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+    view.setWindowTitle(QLatin1StringView(QTest::currentTestFunction()));
+    view.setAlignment(Qt::AlignLeft | Qt::AlignTop);
+    view.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    view.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    view.setTransform(QTransform::fromScale(2, 2));
+    view.resize(size);
+    view.move(availableGeometry.bottomRight() - QPoint(size.width(), size.height())
+              - QPoint(100, 100));
+
+    static constexpr int labelWidth = 200;
+    static constexpr int labelHeight = 50;
+    auto *transforming = new QGraphicsProxyWidget();
+    auto *transformingLabel = new QLabel("Transforming"_L1);
+    transformingLabel->resize(labelWidth, labelHeight);
+    transforming->setWidget(transformingLabel);
+    transforming->setPos(0, 0);
+    scene.addItem(transforming);
+
+    auto *nonTransforming = new QGraphicsProxyWidget();
+    nonTransforming->setFlag(QGraphicsItem::ItemIgnoresTransformations);
+    auto *nonTransformingLabel = new QLabel("NonTransforming"_L1);
+    nonTransformingLabel->resize(labelWidth, labelHeight);
+    nonTransforming->setWidget(nonTransformingLabel);
+    nonTransforming->setPos(labelWidth, 0);
+    scene.addItem(nonTransforming);
+
+    view.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&view));
+
+    const QPoint labelCenter{ labelWidth / 2, labelHeight / 2 };
+    const QPoint topPos = view.geometry().topLeft() + view.viewport()->geometry().topLeft();
+    const QPoint transformingGlobal = transformingLabel->mapToGlobal(labelCenter);
+    const QPoint nonTransformingGlobal = nonTransformingLabel->mapToGlobal(labelCenter);
+
+    // Center of label at 0,0 scaled by 2 should match size
+    QCOMPARE(transformingGlobal - topPos, QPoint(labelWidth, labelHeight));
+
+    // Center of non-transforming label at 200 (scaled by 2), 0
+    QCOMPARE(nonTransformingGlobal - topPos,
+             QPoint(labelWidth * 2 + labelWidth / 2, labelHeight / 2));
+}
+
 // QTBUG_43780: Embedded widgets have isWindow()==true but showing them should not
 // trigger the top-level widget code path of show() that closes all popups
 // (for example combo popups).