Fix rubberband selection in rotated GraphicsView

Selection rectangle was incorrectly mapped to scene space when the
view was rotated. It became a rotated rectangle instead of the correct
polygon (rhombus).

Task-number: QTBUG-42008
Change-Id: Ib7b366bec7e1f83109e03c434268ad6897138f30
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

2 files changed, 44 insertions, 1 deletions

diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index 88d5e52204..5484ecb96e 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -765,7 +765,7 @@ void QGraphicsViewPrivate::updateRubberBand(const QMouseEvent *event)
     }
             // Set the new selection area
     QPainterPath selectionArea;
-    selectionArea.addPolygon(mapToScene(rubberBandRect));
+    selectionArea.addPolygon(q->mapToScene(rubberBandRect));
     selectionArea.closeSubpath();
     if (scene)
         scene->setSelectionArea(selectionArea, rubberBandSelectionMode, q->viewportTransform());
diff --git a/tests/auto/widgets/graphicsview/qgraphicsview/tst_qgraphicsview.cpp b/tests/auto/widgets/graphicsview/qgraphicsview/tst_qgraphicsview.cpp
index d38bb86487..afd8be71e8 100644
--- a/tests/auto/widgets/graphicsview/qgraphicsview/tst_qgraphicsview.cpp
+++ b/tests/auto/widgets/graphicsview/qgraphicsview/tst_qgraphicsview.cpp
@@ -160,6 +160,7 @@ private slots:
     void dragMode_scrollHand();
     void dragMode_rubberBand();
     void rubberBandSelectionMode();
+    void rotated_rubberBand();
     void backgroundBrush();
     void foregroundBrush();
     void matrix();
@@ -935,6 +936,48 @@ void tst_QGraphicsView::rubberBandSelectionMode()
     QCOMPARE(scene.selectedItems(), QList<QGraphicsItem *>() << rect);
 }
 
+void tst_QGraphicsView::rotated_rubberBand()
+{
+    QWidget toplevel;
+    setFrameless(&toplevel);
+
+    QGraphicsScene scene;
+    const int dim = 3;
+    for (int i = 0; i < dim; i++) {
+        for (int j = 0; j < dim; j ++) {
+            QGraphicsRectItem *rect = new QGraphicsRectItem(i * 20, j * 20, 10, 10);
+            rect->setFlag(QGraphicsItem::ItemIsSelectable);
+            rect->setData(0, (i == j));
+            scene.addItem(rect);
+        }
+    }
+
+    QGraphicsView view(&scene, &toplevel);
+    QCOMPARE(view.rubberBandSelectionMode(), Qt::IntersectsItemShape);
+    view.setDragMode(QGraphicsView::RubberBandDrag);
+    view.resize(120, 120);
+    view.rotate(45);
+    toplevel.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&toplevel));
+
+    // Disable mouse tracking to prevent the window system from sending mouse
+    // move events to the viewport while we are synthesizing events. If
+    // QGraphicsView gets a mouse move event with no buttons down, it'll
+    // terminate the rubber band.
+    view.viewport()->setMouseTracking(false);
+
+    QCOMPARE(scene.selectedItems(), QList<QGraphicsItem *>());
+    int midWidth = view.viewport()->width() / 2;
+    sendMousePress(view.viewport(), QPoint(midWidth - 2, 0), Qt::LeftButton);
+    sendMouseMove(view.viewport(), QPoint(midWidth + 2, view.viewport()->height()),
+                  Qt::LeftButton, Qt::LeftButton);
+    QCOMPARE(scene.selectedItems().count(), dim);
+    foreach (const QGraphicsItem *item, scene.items()) {
+        QCOMPARE(item->isSelected(), item->data(0).toBool());
+    }
+    sendMouseRelease(view.viewport(), QPoint(), Qt::LeftButton);
+}
+
 void tst_QGraphicsView::backgroundBrush()
 {
     QGraphicsScene scene;