QHeaderView - resizeSection improvement

This patch improves the manual resizeSection a bit. Before we didn't
consider that the program could maybe resize other sections when the
user was resizing one section.

The main issue with that is that setOffset is so smart that it helps
moving the mouse cursor - however it really shouldn't do if the
program is trying to change something too.

Maybe this won't solve all (possible) problems at once - but it is
a fixed needed just to make something work - trying to make anything
work without this fix is horrible....

Change-Id: I3cefa375a9b8ee4c1ef1e08ba0900025c671e4c6
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

src/widgets/itemviews/qheaderview.cpp

@@ -456,7 +456,7 @@ void QHeaderView::setOffset(int newOffset)
         d->viewport->scroll(isRightToLeft() ? -ndelta : ndelta, 0);
     else
         d->viewport->scroll(0, ndelta);
-    if (d->state == QHeaderViewPrivate::ResizeSection) {
+    if (d->state == QHeaderViewPrivate::ResizeSection && !d->preventCursorChangeInSetOffset) {
         QPoint cursorPos = QCursor::pos();
         if (d->orientation == Qt::Horizontal)
             QCursor::setPos(cursorPos.x() + ndelta, cursorPos.y());
@@ -827,6 +827,9 @@ void QHeaderView::swapSections(int first, int second)
     ResizeMode secondMode = d->headerSectionResizeMode(second);
     int secondLogical = d->logicalIndex(second);
 
+    if (d->state == QHeaderViewPrivate::ResizeSection)
+        d->preventCursorChangeInSetOffset = true;
+
     d->createSectionItems(second, second, firstSize, firstMode);
     d->createSectionItems(first, first, secondSize, secondMode);
 
@@ -876,6 +879,9 @@ void QHeaderView::resizeSection(int logical, int size)
     if (visual == -1)
         return;
 
+    if (d->state == QHeaderViewPrivate::ResizeSection && !d->cascadingResizing && logical != d->section)
+        d->preventCursorChangeInSetOffset = true;
+
     int oldSize = d->headerSectionSize(visual);
     if (oldSize == size)
         return;
@@ -1716,6 +1722,9 @@ void QHeaderView::sectionsInserted(const QModelIndex &parent,
 
     d->invalidateCachedSizeHint();
 
+    if (d->state == QHeaderViewPrivate::ResizeSection)
+        d->preventCursorChangeInSetOffset = true;
+
     // add the new sections
     int insertAt = logicalFirst;
     int insertCount = logicalLast - logicalFirst + 1;
@@ -1849,6 +1858,9 @@ void QHeaderViewPrivate::_q_sectionsRemoved(const QModelIndex &parent,
     int oldCount = q->count();
     int changeCount = logicalLast - logicalFirst + 1;
 
+    if (state == QHeaderViewPrivate::ResizeSection)
+        preventCursorChangeInSetOffset = true;
+
     updateHiddenSections(logicalFirst, logicalLast);
 
     if (visualIndices.isEmpty() && logicalIndices.isEmpty()) {
@@ -2268,6 +2280,7 @@ void QHeaderView::mousePressEvent(QMouseEvent *e)
         d->originalSize = sectionSize(handle);
         d->state = QHeaderViewPrivate::ResizeSection;
         d->section = handle;
+        d->preventCursorChangeInSetOffset = false;
     }
 
     d->firstPos = pos;

src/widgets/itemviews/qheaderview_p.h

@@ -84,6 +84,7 @@ public:
           pressed(-1),
           hover(-1),
           length(0),
+          preventCursorChangeInSetOffset(false),
           movableSections(false),
           clickableSections(false),
           highlightSelected(false),
@@ -266,6 +267,7 @@ public:
     int hover;
 
     int length;
+    bool preventCursorChangeInSetOffset;
     bool movableSections;
     bool clickableSections;
     bool highlightSelected;

tests/manual/widgets/itemviews/qheaderview/qheaderviewtest.pro

@@ -0,0 +1,3 @@
+TEMPLATE = app
+SOURCES = qheaderviewtest1.cpp
+QT += widgets

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

@@ -0,0 +1,110 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Thorbjørn Lund Martsum - tmartsum[at]gmail.com
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** 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, Nokia gives you certain additional
+** rights. These rights are described in the Nokia 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtWidgets/QtWidgets>
+
+class SomeHandler : public QObject
+{
+    Q_OBJECT
+    QHeaderView *m_hv;
+    QTableView *m_tv;
+public:
+    SomeHandler(QHeaderView *hv, QTableView *tv);
+public slots:
+    void slotSectionResized(int, int, int);
+};
+
+SomeHandler::SomeHandler(QHeaderView *hv, QTableView *tv)
+{
+    m_hv = hv;
+    m_tv = tv;
+    m_tv->setHorizontalScrollMode(QAbstractItemView::ScrollPerPixel);
+    connect(hv, SIGNAL(sectionResized(int, int, int)), this, SLOT(slotSectionResized(int, int, int)));
+}
+void SomeHandler::slotSectionResized(int logsection, int oldsize, int newsize)
+{
+    int offset = m_hv->offset();
+    m_tv->setUpdatesEnabled(false);
+    // Do some manual resizing - lets make every section having the new size.
+    m_hv->blockSignals(true);
+    for (int u = 0; u < m_hv->count(); ++u)
+        m_hv->resizeSection(u, newsize);
+    m_hv->blockSignals(false);
+
+    // Adjust offset and scrollbar. Maybe it isn't 100% perfect
+    // but proof of concept
+    // The test has sense without the define, too.
+#define DO_CORRECT_OFFSET_AND_SB
+#ifdef  DO_CORRECT_OFFSET_AND_SB
+    int leftRemoved =  (m_hv->visualIndex(logsection)) * (oldsize - newsize);
+    int newoffset = offset - leftRemoved;
+    if (newoffset < 0)
+        newoffset = 0;
+
+    if (newoffset > 0 && newoffset >= m_hv->count() * newsize - m_tv->viewport()->width())
+        m_hv->setOffsetToLastSection();
+    else
+        m_hv->setOffset(newoffset);
+
+    m_tv->horizontalScrollBar()->blockSignals(true);
+    m_tv->horizontalScrollBar()->setRange(0, m_hv->count() * newsize - m_tv->viewport()->width() );
+    m_tv->horizontalScrollBar()->setValue(newoffset);
+    m_tv->horizontalScrollBar()->blockSignals(false);
+#endif
+    m_tv->setUpdatesEnabled(true);
+}
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    QTableView tv;
+    QStandardItemModel m;
+    m.setRowCount(10);
+    m.setColumnCount(36);
+    tv.setModel(&m);
+    SomeHandler handler(tv.horizontalHeader(), &tv);
+    tv.horizontalHeader()->setDefaultSectionSize(200);
+    tv.showMaximized();
+    tv.horizontalScrollBar()->setValue(tv.horizontalScrollBar()->maximum());
+    app.exec();
+}
+
+#include "qheaderviewtest1.moc"