On Mac OS X, translate the wrect to the coordinates on screen

In the following configuration, wrect was off-screen and the widget was
not painted:
-scroll area "A"
-contains another scrollarea "B" with 2*WRECT_MAX < size < XCOORD_MAX
-the widget contained in B has size > XCOORD_MAX
-A is scrolled to the the bottom

To fix the issue, wrect is moved to the area where the top level window
is in the widget coordinate.

Task-number: 144779
Reviewed-by: nrc

2 files changed, 51 insertions, 7 deletions

diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index b0531ec..48e174b 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -3823,7 +3823,6 @@ void QWidgetPrivate::setWSGeometry(bool dontShow, const QRect &oldRect)
       Qt coordinate system for parent
       X coordinate system for parent (relative to parent's wrect).
     */
-    QRect wrectRange(-WRECT_MAX,-WRECT_MAX, 2*WRECT_MAX, 2*WRECT_MAX);
     QRect wrect;
     //xrect is the X geometry of my X widget. (starts out in  parent's Qt coord sys, and ends up in parent's X coord sys)
     QRect xrect = data.crect;
@@ -3845,6 +3844,7 @@ void QWidgetPrivate::setWSGeometry(bool dontShow, const QRect &oldRect)
             parentWRect = QRect(tmpRect.origin.x, tmpRect.origin.y,
                                 tmpRect.size.width, tmpRect.size.height);
         } else {
+            const QRect wrectRange(-WRECT_MAX,-WRECT_MAX, 2*WRECT_MAX, 2*WRECT_MAX);
             parentWRect = wrectRange;
         }
     } else {
@@ -3900,15 +3900,24 @@ void QWidgetPrivate::setWSGeometry(bool dontShow, const QRect &oldRect)
             }
         }
 
-        if (xrect.height() > XCOORD_MAX || xrect.width() > XCOORD_MAX) {
+        const QRect validRange(-XCOORD_MAX,-XCOORD_MAX, 2*XCOORD_MAX, 2*XCOORD_MAX);
+        if (!validRange.contains(xrect)) {
             // we are too big, and must clip
-            xrect &=wrectRange;
+            QPoint screenOffset(0, 0); // offset of the part being on screen
+            const QWidget *parentWidget = q->parentWidget();
+            while (parentWidget) {
+                screenOffset -= parentWidget->data->crect.topLeft();
+                parentWidget = parentWidget->parentWidget();
+            }
+            QRect cropRect(screenOffset.x() - WRECT_MAX,
+                           screenOffset.y() - WRECT_MAX,
+                           2*WRECT_MAX,
+                           2*WRECT_MAX);
+
+            xrect &=cropRect;
             wrect = xrect;
-            wrect.translate(-data.crect.topLeft());
-            //parent's X coord system is equal to parent's Qt coord
-            //sys, so we don't need to map xrect.
+            wrect.translate(-data.crect.topLeft()); // translate wrect in my Qt coordinates
         }
-
     }
 
     // unmap if we are outside the valid window system coord system
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index 04ec77d..fa36496 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -353,6 +353,7 @@ private slots:
     void toplevelLineEditFocus();
 
     void focusWidget_task254563();
+    void rectOutsideCoordinatesLimit_task144779();
 
 private:
     bool ensureScreenSize(int width, int height);
@@ -9117,5 +9118,39 @@ void tst_QWidget::focusWidget_task254563()
     QVERIFY(top.focusWidget() != widget); //dangling pointer
 }
 
+void tst_QWidget::rectOutsideCoordinatesLimit_task144779()
+{
+    QWidget main;
+    QPalette palette;
+    palette.setColor(QPalette::Window, Qt::red);
+    main.setPalette(palette);
+    main.resize(400, 400);
+
+    QWidget *offsetWidget = new QWidget(&main);
+    offsetWidget->setGeometry(0, -14600, 400, 15000);
+
+    // big widget is too big for the coordinates, it must be limited by wrect
+    // if wrect is not at the right position because of offsetWidget, bigwidget
+    // is not painted correctly
+    QWidget *bigWidget = new QWidget(offsetWidget);
+    bigWidget->setGeometry(0, 0, 400, 50000);
+    palette.setColor(QPalette::Window, Qt::green);
+    bigWidget->setPalette(palette);
+    bigWidget->setAutoFillBackground(true);
+
+    main.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&main);
+#endif
+    QTest::qWait(100);
+    QPixmap pixmap = QPixmap::grabWindow(main.winId());
+
+    QPixmap correct(main.size());
+    correct.fill(Qt::green);
+
+    QRect center(100, 100, 200, 200); // to avoid the decorations
+    QCOMPARE(pixmap.toImage().copy(center), correct.toImage().copy(center));
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"