Add QMainWindow::GroupedDragging DockOption

If this setting is enabled, the entire group of docked tabs will
be draggable by the title bar of the group and and individual dock
can be dragged by dragging the tab.

When tabs are detached, the docks that are contained are reparented to
a QDockWidgetGroupWindow.

[ChangeLog][QtWidgets][QMainWindow] Added GroupedDragging as a DockOption
which allow users to drag all the tabs together when dragging the
title of a QDockWidget which is tabbed with others.

Change-Id: I5285685b129770498eb3e4fd5f4556e41225a595
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@theqtcompany.com>

1 files changed, 60 insertions, 22 deletions

diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index af0f2515fe..bc2259ce90 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2015 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -1854,20 +1855,6 @@ static Qt::DockWidgetArea toDockWidgetArea(QInternal::DockPosition pos)
     return Qt::NoDockWidgetArea;
 }
 
-static QRect constrainedRect(QRect rect, const QRect &desktop)
-{
-    if (desktop.isValid()) {
-        rect.setWidth(qMin(rect.width(), desktop.width()));
-        rect.setHeight(qMin(rect.height(), desktop.height()));
-        rect.moveLeft(qMax(rect.left(), desktop.left()));
-        rect.moveTop(qMax(rect.top(), desktop.top()));
-        rect.moveRight(qMin(rect.right(), desktop.right()));
-        rect.moveBottom(qMin(rect.bottom(), desktop.bottom()));
-    }
-
-    return rect;
-}
-
 bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*> &widgets, bool testing)
 {
     uchar marker;
@@ -1958,11 +1945,7 @@ bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*>
 #endif
                     if (!testing) {
                         QRect r(x, y, w, h);
-                        QDesktopWidget *desktop = QApplication::desktop();
-                        if (desktop->isVirtualDesktop())
-                            r = constrainedRect(r, desktop->screenGeometry(desktop->screenNumber(r.topLeft())));
-                        else
-                            r = constrainedRect(r, desktop->screenGeometry(widget));
+                        r = QDockAreaLayout::constrainedRect(r, widget);
                         widget->move(r.topLeft());
                         widget->resize(r.size());
                     }
@@ -2075,6 +2058,36 @@ void QDockAreaLayoutInfo::updateSeparatorWidgets() const
 #endif //QT_NO_TABBAR
 
 #ifndef QT_NO_TABBAR
+/*! \internal
+    reparent all the widgets contained in this layout portion to the
+    specified parent. This is used to reparent dock widgets and tabbars
+    to the floating window or the main window
+ */
+void QDockAreaLayoutInfo::reparentWidgets(QWidget *parent)
+{
+    if (tabBar)
+        tabBar->setParent(parent);
+
+    for (int i = 0; i < item_list.count(); ++i) {
+        const QDockAreaLayoutItem &item = item_list.at(i);
+        if (item.flags & QDockAreaLayoutItem::GapItem)
+            continue;
+        if (item.skip())
+            continue;
+        if (item.subinfo)
+            item.subinfo->reparentWidgets(parent);
+        if (item.widgetItem) {
+            QWidget *w = item.widgetItem->widget();
+            if (w->parent() != parent) {
+                bool hidden = w->isHidden();
+                w->setParent(parent);
+                if (!hidden)
+                    w->show();
+            }
+        }
+    }
+}
+
 //returns whether the tabbar is visible or not
 bool QDockAreaLayoutInfo::updateTabBar() const
 {
@@ -2981,6 +2994,33 @@ QSize QDockAreaLayout::minimumSize() const
     return QSize(qMax(row1, row2, row3), qMax(col1, col2, col3));
 }
 
+/*! \internal
+    Try to fit the given rectangle \a rect on the screen which contains
+    the window \a widget.
+    Used to compute the geometry of a dragged a dock widget that should
+    be shown with \a rect, but needs to be visible on the screen
+ */
+QRect QDockAreaLayout::constrainedRect(QRect rect, QWidget* widget)
+{
+    QRect desktop;
+    QDesktopWidget *desktopW = QApplication::desktop();
+    if (desktopW->isVirtualDesktop())
+        desktop = desktopW->screenGeometry(rect.topLeft());
+    else
+        desktop = desktopW->screenGeometry(widget);
+
+    if (desktop.isValid()) {
+        rect.setWidth(qMin(rect.width(), desktop.width()));
+        rect.setHeight(qMin(rect.height(), desktop.height()));
+        rect.moveLeft(qMax(rect.left(), desktop.left()));
+        rect.moveTop(qMax(rect.top(), desktop.top()));
+        rect.moveRight(qMin(rect.right(), desktop.right()));
+        rect.moveBottom(qMin(rect.bottom(), desktop.bottom()));
+    }
+
+    return rect;
+}
+
 bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
 {
     QList<int> index = indexOfPlaceHolder(dockWidget->objectName());
@@ -2994,9 +3034,7 @@ bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
     item.widgetItem = new QDockWidgetItem(dockWidget);
 
     if (placeHolder->window) {
-        const QRect screenGeometry =
-            QApplication::desktop()->screenGeometry(placeHolder->topLevelRect.center());
-        const QRect r = constrainedRect(placeHolder->topLevelRect, screenGeometry);
+        const QRect r = constrainedRect(placeHolder->topLevelRect, dockWidget);
         dockWidget->d_func()->setWindowState(true, true, r);
     }
     dockWidget->setVisible(!placeHolder->hidden);