Fix QGraphicsView::render() regression, ensure the right device is passed.

If we pass the viewport widget as the widget pointer when rendering to
an arbitrary painter (e.g., onto a pixmap), we confuse the rendering
functions to thinking that it's the viewport's region we should render
into. So instead, when drawItems() is passed a painter that's different
from the view, we pass 0 for the widget.

2 files changed, 61 insertions, 2 deletions

diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index 166bcb9..e685f9b 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -3526,8 +3526,10 @@ void QGraphicsView::drawItems(QPainter *painter, int numItems,
                               const QStyleOptionGraphicsItem options[])
 {
     Q_D(QGraphicsView);
-    if (d->scene)
-        d->scene->drawItems(painter, numItems, items, options, viewport());
+    if (d->scene) {
+        QWidget *widget = painter->device() == viewport() ? viewport() : 0;
+        d->scene->drawItems(painter, numItems, items, options, widget);
+    }
 }
 
 /*!
diff --git a/tests/auto/qgraphicsview/tst_qgraphicsview.cpp b/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
index 718c8d6..5167682 100644
--- a/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
+++ b/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
@@ -191,6 +191,7 @@ private slots:
     void centerOnDirtyItem();
     void mouseTracking();
     void mouseTracking2();
+    void render();
 
     // task specific tests below me
     void task172231_untransformableItems();
@@ -3203,6 +3204,62 @@ void tst_QGraphicsView::mouseTracking2()
     QCOMPARE(spy.count(), 1);
 }
 
+class RenderTester : public QGraphicsRectItem
+{
+public:
+    RenderTester(const QRectF &rect)
+        : QGraphicsRectItem(rect), paints(0)
+    { }
+
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
+               QWidget *widget)
+    {
+        QGraphicsRectItem::paint(painter, option, widget);
+        ++paints;
+    }
+    
+    int paints;
+};
+
+void tst_QGraphicsView::render()
+{
+    // ### This test can be much more thorough - see QGraphicsScene::render.
+    QGraphicsScene scene;
+    RenderTester *r1 = new RenderTester(QRectF(0, 0, 50, 50));
+    RenderTester *r2 = new RenderTester(QRectF(50, 50, 50, 50));
+    RenderTester *r3 = new RenderTester(QRectF(0, 50, 50, 50));
+    RenderTester *r4 = new RenderTester(QRectF(50, 0, 50, 50));
+    scene.addItem(r1);
+    scene.addItem(r2);
+    scene.addItem(r3);
+    scene.addItem(r4);
+
+    QGraphicsView view(&scene);
+    view.setFrameStyle(0);
+    view.resize(200, 200);
+    view.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&view);
+#endif
+    QTest::qWait(200);
+
+    QCOMPARE(r1->paints, 1);
+    QCOMPARE(r2->paints, 1);
+    QCOMPARE(r3->paints, 1);
+    QCOMPARE(r4->paints, 1);
+
+    QPixmap pix(200, 200);
+    pix.fill(Qt::transparent);
+    QPainter painter(&pix);
+    view.render(&painter);
+    painter.end();
+
+    QCOMPARE(r1->paints, 2);
+    QCOMPARE(r2->paints, 2);
+    QCOMPARE(r3->paints, 2);
+    QCOMPARE(r4->paints, 2);
+}
+
 void tst_QGraphicsView::task253415_reconnectUpdateSceneOnSceneChanged()
 {
     QGraphicsView view;