How to (re-)select previous row in a QTreeView?

soma_yarram

Hello,

I have a QTreeView with single column and multiple row (lets say 5 rows). What I want to achieve is that if I select a row, I want to re-select previous row on some condition.

Here is the code I have:

MyWidget.h

#ifndef MYWIDGET_H
#define MYWIDGET_H

#include <QWidget>
#include <QTreeView>
#include <QStandardItemModel>
#include <QStandardItem>
#include <QModelIndex>
#include <QHBoxLayout>

class MyWidget : public QWidget
{
	Q_OBJECT

public:
	MyWidget(QWidget *parent = 0);
	~MyWidget();

private slots:
	void _OnTreeViewCurrentRowChanged(const QModelIndex &rcqmiCurrIndex,
		const QModelIndex &rcqmiPrevIndex);

private:
	QHBoxLayout *_pLayout;

	QTreeView *_pTreeView;
	QStandardItemModel *_pStandardItemModel;
	QStandardItem *_pStandardItem;
};

#endif

MyWidget.cpp

#include "MyWidget.h"

static bool bCondition = false;

MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
	_pLayout = new QHBoxLayout(this);

	_pTreeView = new QTreeView(this);
	_pStandardItemModel = new QStandardItemModel(_pTreeView);
	_pStandardItem = new QStandardItem("Column A");

	_pLayout->addWidget(_pTreeView);

	_pStandardItemModel->setColumnCount(1);
	_pStandardItemModel->setHorizontalHeaderItem(0, _pStandardItem);

	_pTreeView->setModel(_pStandardItemModel);
	_pTreeView->setSelectionBehavior(QAbstractItemView::SelectRows);
	_pTreeView->setSelectionMode(QAbstractItemView::SingleSelection);
	_pTreeView->setEditTriggers(QAbstractItemView::NoEditTriggers);

	// add rows
	_pTreeView->selectionModel()->blockSignals(true);

	for (int i = 0; i < 5; ++i)
	{
		QStandardItem *pStandardItem = new QStandardItem(
			QString("Row: %1").arg(i + 1));

		_pStandardItemModel->appendRow(pStandardItem);
	}

	_pTreeView->selectionModel()->blockSignals(false);

	// update view
	_pTreeView->viewport()->update();

	connect(_pTreeView->selectionModel(),
		SIGNAL(currentRowChanged(const QModelIndex &, const QModelIndex &)),
		this, SLOT(_OnTreeViewCurrentRowChanged(const QModelIndex &,
		const QModelIndex &)));
}

MyWidget::~MyWidget()
{

}

void MyWidget::_OnTreeViewCurrentRowChanged(
	const QModelIndex &rcqmiCurrIndex, const QModelIndex &rcqmiPrevIndex)
{
	if (bCondition) // some condition
	{
		_pTreeView->selectionModel()->blockSignals(true);

		// select previous index
		_pTreeView->selectionModel()->setCurrentIndex(
			rcqmiPrevIndex, QItemSelectionModel::SelectCurrent);

		_pTreeView->selectionModel()->blockSignals(false);

		// update view
		_pTreeView->viewport()->update();
	}

	bCondition = !bCondition;
}

In _OnTreeViewCurrentRowChanged(...), I can see that "selection" of tree view's selection model is updated with QItemSelectionModel::setCurrentIndex(rcqmiPrevIndex, QItemSelectionModel::SelectCurrent); but the tree view's row selection is NOT updated, still the rcqmiCurrIndex is selected.

What am I missing here?

Any help is much appreciated. Thanks in advance.

mrjj

@soma_yarram said:

_pTreeView->selectionModel()->blockSignals(true);

Hi,
maybe the row selection depends on a signal and u block it:) ?

Jan-Willem

And perhaps the protected function of QTreeView might also be of use.
You will have to subclass it though.

virtual void  currentChanged(const QModelIndex &current, const QModelIndex &previous)