Fix for restoring dockwidget's size when it gets dragged.

When user drags a dockwidget out of the docking area, restore widget's
previous floating size and center it's titlebar under the mouse.

Task-number: QTBUG-2940
Change-Id: I004de36d649abc4c32420bdd46bb6c810ef98c64
Reviewed-by: Girish Ramakrishnan <girish.1.ramakrishnan@nokia.com>

2 files changed, 51 insertions, 6 deletions

diff --git a/src/gui/widgets/qdockwidget.cpp b/src/gui/widgets/qdockwidget.cpp
index 5b2d250..f6da240 100644
--- a/src/gui/widgets/qdockwidget.cpp
+++ b/src/gui/widgets/qdockwidget.cpp
@@ -690,6 +690,7 @@ void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
     if (state != 0)
         return;
 
+    Q_Q(QDockWidget);
     QMainWindow *win = qobject_cast<QMainWindow*>(parent);
     Q_ASSERT(win != 0);
     QMainWindowLayout *layout = qt_mainwindow_layout(win);
@@ -698,12 +699,23 @@ void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
         return;
 
     state = new QDockWidgetPrivate::DragState;
-    state->pressPos = pos;
     state->dragging = false;
     state->widgetItem = 0;
     state->ownWidgetItem = false;
     state->nca = nca;
     state->ctrlDrag = false;
+
+    if (!q->isFloating()) {
+        // When dragging the widget out of the docking area,
+        // use the middle of title area as pressPos
+        QDockWidgetLayout *dwlayout = qobject_cast<QDockWidgetLayout*>(q->layout());
+        Q_ASSERT(dwlayout != 0);
+        int width = undockedGeometry.isNull() ? q->width() : undockedGeometry.width();
+        state->pressPos.setY(dwlayout->titleArea().height() / 2);
+        state->pressPos.setX(width / 2);
+    } else {
+        state->pressPos = pos;
+    }
 }
 
 void QDockWidgetPrivate::startDrag()
@@ -987,11 +999,17 @@ void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
 void QDockWidgetPrivate::unplug(const QRect &rect)
 {
     Q_Q(QDockWidget);
-    QRect r = rect;
-    r.moveTopLeft(q->mapToGlobal(QPoint(0, 0)));
-    QDockWidgetLayout *dwLayout = qobject_cast<QDockWidgetLayout*>(layout);
-    if (dwLayout->nativeWindowDeco(true))
-        r.adjust(0, dwLayout->titleHeight(), 0, 0);
+    QRect r;
+    if (!undockedGeometry.isNull()) {
+        r = undockedGeometry;
+    } else {
+        r = rect;
+        r.moveTopLeft(q->mapToGlobal(QPoint(0, 0)));
+        QDockWidgetLayout *dwLayout = qobject_cast<QDockWidgetLayout*>(layout);
+        if (dwLayout->nativeWindowDeco(true))
+            r.adjust(0, dwLayout->titleHeight(), 0, 0);
+    }
+
     setWindowState(true, true, r);
 }
 
diff --git a/tests/auto/qdockwidget/tst_qdockwidget.cpp b/tests/auto/qdockwidget/tst_qdockwidget.cpp
index b3e3b31..6ac386f 100644
--- a/tests/auto/qdockwidget/tst_qdockwidget.cpp
+++ b/tests/auto/qdockwidget/tst_qdockwidget.cpp
@@ -97,6 +97,7 @@ private slots:
     void task258459_visibilityChanged();
     void taskQTBUG_1665_closableChanged();
 	void taskQTBUG_9758_undockedGeometry();
+    void taskQTBUG_2940_resizeAfterUndocking();
 };
 
 // Testing get/set functions
@@ -899,6 +900,32 @@ void tst_QDockWidget::taskQTBUG_9758_undockedGeometry()
     QVERIFY(dock1.y() >= 0);
 }
 
+void tst_QDockWidget::taskQTBUG_2940_resizeAfterUndocking()
+{
+    QMainWindow window;
+    QDockWidget dw("dw", &window);
+    window.setGeometry(window.x(), window.y(), 400, 400);
+    window.addDockWidget(Qt::TopDockWidgetArea, &dw);
+    window.show();
+    dw.setFloating(true);
+    dw.setGeometry(dw.x(), dw.y(), 100, 100);
+
+    // When docked, width should be the same than window's width
+    dw.setFloating(false);
+    QCOMPARE(dw.width(), window.width());
+
+    // Drag the dock widget out of the window
+    qApp->postEvent(&dw, new QMouseEvent(QEvent::MouseButtonPress,
+                    QPoint(10, 10), Qt::LeftButton, 0, 0));
+    qApp->postEvent(&dw, new QMouseEvent(QEvent::MouseMove,
+                    QPoint(100, 100), Qt::LeftButton,Qt::LeftButton, 0));
+    qApp->postEvent(&dw, new QMouseEvent(QEvent::MouseButtonRelease,
+                    QPoint(100, 100), Qt::LeftButton, 0, 0));
+    qApp->processEvents();
+
+    // When undocked, size should be the restored
+    QCOMPARE(dw.size(), QSize(100, 100));
+}
 
 
 QTEST_MAIN(tst_QDockWidget)