Regression: QGraphicsScene::render fails to render the entire scene correctly.

This only happened with items that had either negative width or height
(boundingRect().width()|height()). Problem was that in case of not having
an exposed region (drawing items from QGraphicsScene::render), we simply
checked whether the bounding rect was empty or not. This is fine, however
we have to normalize the rect first.
(Note that QRegion::intersects(rect) always normalizes the rect, so
that's why this use case broke only when calling QGraphicsScene::render).

Auto-test included.

Task-number: QTBUG-7775
Reviewed-by: yoann

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/auto/qgraphicsscene/tst_qgraphicsscene.cpp b/tests/auto/qgraphicsscene/tst_qgraphicsscene.cpp
index 469ded0..9d437d6 100644
--- a/tests/auto/qgraphicsscene/tst_qgraphicsscene.cpp
+++ b/tests/auto/qgraphicsscene/tst_qgraphicsscene.cpp
@@ -244,6 +244,7 @@ private slots:
 #endif
     void render_data();
     void render();
+    void renderItemsWithNegativeWidthOrHeight();
     void contextMenuEvent();
     void contextMenuEvent_ItemIgnoresTransformations();
     void update();
@@ -2750,6 +2751,41 @@ void tst_QGraphicsScene::render()
     }
 }
 
+void tst_QGraphicsScene::renderItemsWithNegativeWidthOrHeight()
+{
+    QGraphicsScene scene(0, 0, 150, 150);
+
+    // Add item with negative width.
+    QGraphicsRectItem *item1 = new QGraphicsRectItem(0, 0, -150, 50);
+    item1->setBrush(Qt::red);
+    item1->setPos(150, 50);
+    scene.addItem(item1);
+
+    // Add item with negative height.
+    QGraphicsRectItem *item2 = new QGraphicsRectItem(0, 0, 50, -150);
+    item2->setBrush(Qt::blue);
+    item2->setPos(50, 150);
+    scene.addItem(item2);
+
+    QGraphicsView view(&scene);
+    view.setFrameStyle(QFrame::NoFrame);
+    view.resize(150, 150);
+    view.show();
+    QCOMPARE(view.viewport()->size(), QSize(150, 150));
+
+    QImage expected(view.viewport()->size(), QImage::Format_RGB32);
+    view.viewport()->render(&expected);
+
+    // Make sure the scene background is the same as the viewport background.
+    scene.setBackgroundBrush(view.viewport()->palette().brush(view.viewport()->backgroundRole()));
+    QImage actual(150, 150, QImage::Format_RGB32);
+    QPainter painter(&actual);
+    scene.render(&painter);
+    painter.end();
+
+    QCOMPARE(actual, expected);
+}
+
 void tst_QGraphicsScene::contextMenuEvent()
 {
     QGraphicsScene scene;