Qt 5.0 QTreeView. Prevent manual moving of the first section

This prevents the user of moving the leftmost column.

There will be no API to allow move of the tree-structure.
It is very weird to do that, so it shouldn't be a problem.

In case it is a big problem somewhere it can be hacked with:
QTableView unused;
unused.setVerticalHeader(tree->header());
tree->header()->setParent(tree);
unused.setVerticalHeader(new QHeaderView(Qt::Horizontal));

Task-number: QTBUG-332

Change-Id: I3a251c8d0fd472ec0ad7edb20a7f3e00af7e0da8
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

src/widgets/itemviews/qheaderview.cpp

@@ -2268,7 +2268,12 @@ void QHeaderView::mousePressEvent(QMouseEvent *e)
         d->pressed = logicalIndexAt(pos);
         if (d->clickableSections)
             emit sectionPressed(d->pressed);
-        if (d->movableSections) {
+
+        bool acceptMoveSection = d->movableSections;
+        if (acceptMoveSection && d->pressed == 0 && !d->allowUserMoveOfSection0)
+            acceptMoveSection = false; // Do not allow moving the tree nod
+
+        if (acceptMoveSection) {
             d->section = d->target = d->pressed;
             if (d->section == -1)
                 return;
@@ -2332,6 +2337,9 @@ void QHeaderView::mouseMoveEvent(QMouseEvent *e)
                 int visual = visualIndexAt(pos);
                 if (visual == -1)
                     return;
+                if (visual == 0 && logicalIndex(0) == 0 && !d->allowUserMoveOfSection0)
+                    return;
+
                 int posThreshold = d->headerSectionPosition(visual) - d->offset + d->headerSectionSize(visual) / 2;
                 int moving = visualIndex(d->section);
                 if (visual < moving) {

src/widgets/itemviews/qheaderview.h

@@ -240,6 +240,9 @@ protected:
     QRegion visualRegionForSelection(const QItemSelection &selection) const;
     void initStyleOption(QStyleOptionHeader *option) const;
 
+    friend class QTableView;
+    friend class QTreeView;
+
 private:
     Q_PRIVATE_SLOT(d_func(), void _q_sectionsRemoved(const QModelIndex &parent, int logicalFirst, int logicalLast))
     Q_PRIVATE_SLOT(d_func(), void _q_layoutAboutToBeChanged())

src/widgets/itemviews/qheaderview_p.h

@@ -91,6 +91,7 @@ public:
           stretchLastSection(false),
           cascadingResizing(false),
           resizeRecursionBlock(false),
+          allowUserMoveOfSection0(true), // will be false for QTreeView and true for QTableView
           stretchSections(0),
           contentsSections(0),
           minimumSectionSize(-1),
@@ -234,6 +235,10 @@ public:
         }
     }
 
+    inline void setAllowUserMoveOfSection0(bool b) {
+        allowUserMoveOfSection0 = b;
+    }
+
     void clear();
     void flipSortIndicator(int section);
     void cascadingResize(int visual, int newSize);
@@ -274,6 +279,7 @@ public:
     bool stretchLastSection;
     bool cascadingResizing;
     bool resizeRecursionBlock;
+    bool allowUserMoveOfSection0;
     int stretchSections;
     int contentsSections;
     int defaultSectionSize;

src/widgets/itemviews/qtableview.cpp

@@ -53,6 +53,7 @@
 #include <qscrollbar.h>
 #include <qabstractbutton.h>
 #include <private/qtableview_p.h>
+#include <private/qheaderview_p.h>
 #ifndef QT_NO_ACCESSIBILITY
 #include <qaccessible.h>
 #endif
@@ -1181,6 +1182,7 @@ void QTableView::setHorizontalHeader(QHeaderView *header)
         delete d->horizontalHeader;
     d->horizontalHeader = header;
     d->horizontalHeader->setParent(this);
+    d->horizontalHeader->d_func()->setAllowUserMoveOfSection0(true);
     if (!d->horizontalHeader->model()) {
         d->horizontalHeader->setModel(d->model);
         if (d->selectionModel)
@@ -1218,6 +1220,7 @@ void QTableView::setVerticalHeader(QHeaderView *header)
         delete d->verticalHeader;
     d->verticalHeader = header;
     d->verticalHeader->setParent(this);
+    d->verticalHeader->d_func()->setAllowUserMoveOfSection0(true);
     if (!d->verticalHeader->model()) {
         d->verticalHeader->setModel(d->model);
         if (d->selectionModel)

src/widgets/itemviews/qtreeview.cpp

@@ -58,6 +58,7 @@
 #endif
 
 #include <private/qtreeview_p.h>
+#include <private/qheaderview_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -313,6 +314,7 @@ void QTreeView::setHeader(QHeaderView *header)
         delete d->header;
     d->header = header;
     d->header->setParent(this);
+    d->header->d_func()->setAllowUserMoveOfSection0(false);
 
     if (!d->header->model()) {
         d->header->setModel(d->model);

tests/manual/widgets/itemviews/qheaderview/qheaderviewtest1.cpp

@@ -101,9 +101,9 @@ int main(int argc, char *argv[])
     m.setColumnCount(36);
     tv.setModel(&m);
     SomeHandler handler(tv.horizontalHeader(), &tv);
-    tv.horizontalHeader()->setDefaultSectionSize(200);
+    tv.horizontalHeader()->setDefaultSectionSize(50);
+    tv.horizontalHeader()->setSectionsMovable(true);
     tv.showMaximized();
-    tv.horizontalScrollBar()->setValue(tv.horizontalScrollBar()->maximum());
     app.exec();
 }
 

tests/manual/widgets/itemviews/qtreeview/main.cpp

@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#include <QtWidgets/QFileSystemModel>
+#include <QtWidgets/QtWidgets>
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    QFileSystemModel *model = new QFileSystemModel;
+    model->setRootPath(QDir::currentPath());
+    QTreeView *tree = new QTreeView();
+    tree->setModel(model);
+    tree->show();
+    app.exec();
+}

tests/manual/widgets/itemviews/qtreeview/qtreeviewtest.pro

@@ -0,0 +1,4 @@
+TEMPLATE = app
+SOURCES = main.cpp
+QT += widgets
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0