Restore the mainwindow size on last open

[prabhatjha]

Hello Everyone,

I just want to restore the size of window of last open window. suppose i have open a window and its size is (500,500) and i have resize it to (600,600).
I have closed the window and again open the project this time window size should be (600,600).
Any help will be appreciable

[d_stranz]

Use QSettings to save / retrieve the size and position of your window. Override the QWidget::showEvent() and QWidget::closeEvent() methods for your window class and save and restore the setting there:

// Helper class
 
// QtSettingsHelper.h
 
#include <QVariant>
 
class QString;
 
class CQtSettingsHelper
{
private:
	virtual ~CQtSettingsHelper() = 0;
 
public:
	static QVariant	ReadValue( const QString & group, const QString & key, const QVariant & defValue = QVariant() );
	static void	WriteValue( const QString & group, const QString & key, const QVariant & value );
};
 
// QtSettingsHelper.cpp
 
#include "SAQtSettingsHelper.h"
 
#include <QCoreApplication>
#include <QSettings>
 
QVariant CQtSettingsHelper::ReadValue( const QString & group, const QString & key, const QVariant & defValue )
{
	QSettings	settings( QSettings::IniFormat, QSettings::UserScope, QCoreApplication::organizationName(), QCoreApplication::applicationName() );
 
	settings.beginGroup( group );
	QVariant value = settings.value( key, defValue );
	settings.endGroup();
 
	return value;
}
 
void CQtSettingsHelper::WriteValue( const QString & group, const QString & key, const QVariant & value )
{
	QSettings	settings( QSettings::IniFormat, QSettings::UserScope, QCoreApplication::organizationName(), QCoreApplication::applicationName() );
 
	settings.beginGroup( group );
	settings.setValue( key, value );
	settings.endGroup();
}
 
// Example how to use to save / restore window sizes
 
// Mainindow.h:
 
class CMainWindow 
	: public QMainWindow
{
	Q_OBJECT
 
public:
	CMainWindow(  QWidget * pParent = 0 );
	~CMainWindow();
 
protected:
	virtual void	closeEvent( QCloseEvent * pEvent );
	virtual void	showEvent( QShowEvent * pEvent );
 
private:
	void	restoreSettings();
	void	saveSettings();
};
 
// MainWindow.cpp
 
void CMainWindow::closeEvent( QCloseEvent * pEvent )
{
	saveSettings();
	pEvent->accept();
}
 
void CMainWindow::showEvent( QShowEvent * pEvent )
{
	restoreSettings();
	pEvent->accept();
 
}
 
static const int	sStateVersion = 1000;  // Used for versioning state information
 
 
void CMainWindow::restoreSettings()
{
	QString path = QStandardPaths::writableLocation( QStandardPaths::DocumentsLocation );
 
	resize( CQtSettingsHelper::ReadValue( "MainWindow", "Size", QSize( 800, 800 ) ).toSize() );
	move( CQtSettingsHelper::ReadValue( "MainWindow", "Position", QPoint( 50, 50 ) ).toPoint() );
	restoreState( CQtSettingsHelper::ReadValue( "MainWindow", "State" ).toByteArray(), sStateVersion );
 
}
 
void CMainWindow::saveSettings()
{
	CQtSettingsHelper::WriteValue( "MainWindow", "Size", size() );
	CQtSettingsHelper::WriteValue( "MainWindow", "Position", pos() );
	CQtSettingsHelper::WriteValue( "MainWindow", "State", saveState( sStateVersion ) );
}

// Helper class

// QtSettingsHelper.h

#include <QVariant>

class QString;

class CQtSettingsHelper
{
private:
	virtual ~CQtSettingsHelper() = 0;

public:
	static QVariant	ReadValue( const QString & group, const QString & key, const QVariant & defValue = QVariant() );
	static void	WriteValue( const QString & group, const QString & key, const QVariant & value );
};

// QtSettingsHelper.cpp

#include "SAQtSettingsHelper.h"

#include <QCoreApplication>
#include <QSettings>

QVariant CQtSettingsHelper::ReadValue( const QString & group, const QString & key, const QVariant & defValue )
{
	QSettings	settings( QSettings::IniFormat, QSettings::UserScope, QCoreApplication::organizationName(), QCoreApplication::applicationName() );

	settings.beginGroup( group );
	QVariant value = settings.value( key, defValue );
	settings.endGroup();

	return value;
}

void CQtSettingsHelper::WriteValue( const QString & group, const QString & key, const QVariant & value )
{
	QSettings	settings( QSettings::IniFormat, QSettings::UserScope, QCoreApplication::organizationName(), QCoreApplication::applicationName() );

	settings.beginGroup( group );
	settings.setValue( key, value );
	settings.endGroup();
}

// Example how to use to save / restore window sizes

// Mainindow.h:

class CMainWindow 
	: public QMainWindow
{
	Q_OBJECT

public:
	CMainWindow(  QWidget * pParent = 0 );
	~CMainWindow();

protected:
	virtual void	closeEvent( QCloseEvent * pEvent );
	virtual void	showEvent( QShowEvent * pEvent );

private:
	void	restoreSettings();
	void	saveSettings();
};

// MainWindow.cpp

void CMainWindow::closeEvent( QCloseEvent * pEvent )
{
	saveSettings();
	pEvent->accept();
}

void CMainWindow::showEvent( QShowEvent * pEvent )
{
	restoreSettings();
	pEvent->accept();

}

static const int	sStateVersion = 1000;  // Used for versioning state information


void CMainWindow::restoreSettings()
{
	QString path = QStandardPaths::writableLocation( QStandardPaths::DocumentsLocation );

	resize( CQtSettingsHelper::ReadValue( "MainWindow", "Size", QSize( 800, 800 ) ).toSize() );
	move( CQtSettingsHelper::ReadValue( "MainWindow", "Position", QPoint( 50, 50 ) ).toPoint() );
	restoreState( CQtSettingsHelper::ReadValue( "MainWindow", "State" ).toByteArray(), sStateVersion );

}

void CMainWindow::saveSettings()
{
	CQtSettingsHelper::WriteValue( "MainWindow", "Size", size() );
	CQtSettingsHelper::WriteValue( "MainWindow", "Position", pos() );
	CQtSettingsHelper::WriteValue( "MainWindow", "State", saveState( sStateVersion ) );
}

To copy to clipboard, switch view to plain text mode 

In this code, I am saving not only the size and position of my main window, but also the state, which contains information on the layout of menu, tab, and status bars as well as any dock widgets. Since saveState() and restoreState() and QMainWindow methods, they will not work for other QWidget classes.

The helper class makes it easier to pass arguments to QSettings for save or restore.