qt-creator/src/libs/utils/treewidgetcolumnstretcher.cpp

#include "treewidgetcolumnstretcher.h"
#include <QtGui/QTreeWidget>
#include <QtGui/QHideEvent>
#include <QtGui/QHeaderView>
using namespace Core::Utils;

TreeWidgetColumnStretcher::TreeWidgetColumnStretcher(QTreeWidget *treeWidget, int columnToStretch)
        : QObject(treeWidget->header()), m_columnToStretch(columnToStretch)
{
    parent()->installEventFilter(this);
    QHideEvent fake;
    TreeWidgetColumnStretcher::eventFilter(parent(), &fake);
}

bool TreeWidgetColumnStretcher::eventFilter(QObject *obj, QEvent *ev)
{
    if (obj == parent()) {
        if (ev->type() == QEvent::Show) {
            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
            for (int i = 0; i < hv->count(); ++i)
                hv->setResizeMode(i, QHeaderView::Interactive);
        } else if (ev->type() == QEvent::Hide) {
            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
            for (int i = 0; i < hv->count(); ++i)
                hv->setResizeMode(i, i == m_columnToStretch ? QHeaderView::Stretch : QHeaderView::ResizeToContents);
        } else if (ev->type() == QEvent::Resize) {
            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
            if (hv->resizeMode(m_columnToStretch) == QHeaderView::Interactive) {
                QResizeEvent *re = static_cast<QResizeEvent*>(ev);
                int diff = re->size().width() - re->oldSize().width() ;
                hv->resizeSection(m_columnToStretch, qMax(32, hv->sectionSize(1) + diff));
            }
        }
    }
    return false;
}