Qt wiki will be updated on October 12th 2023 starting at 11:30 AM (EEST) and the maintenance will last around 2-3 hours. During the maintenance the site will be unavailable.

How to Use QSettings

From Qt Wiki
Revision as of 15:32, 2 May 2023 by Henrik Jensen (talk | contribs) (Syntax highlight fix)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

En Ar Bg De El Es Fa Fi Fr Hi Hu It Ja Kn Ko Ms Nl Pl Pt Ru Sq Th Tr Uk Zh

QSettings class provides platform-independent application settings. The following example shows how to save and load settings to an ini file. The instance of QSettings will take care of writing and reading the settings from the ini file.

Method setValue should be used to save a value of a key (aka the name of the setting).

The value of a setting can be obtained using the method value.

Example

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

#include <QLabel>
#include <QLineEdit>
#include <QPushButton>

namespace Ui {
  class MainWindow;
}

class MainWindow : public QMainWindow
{
 Q_OBJECT
public:

 explicit MainWindow(QWidget *parent = 0);
 virtual ~MainWindow();

private:

 void initGui();

 void loadSettings();

 void saveSettings();

private slots:

 void handleButton();

private:

 QString m_sSettingsFile;

 QLabel* m_pLabel;

 QLineEdit* m_pEdit;

 QPushButton* m_pButton;
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include <QCoreApplication>
#include <QSettings>
#include <QApplication>

MainWindow::MainWindow(QWidget *parent)
 : QMainWindow(parent),
 m_pLabel(NULL),
 m_pEdit(NULL),
 m_pButton(NULL)
{
 initGui();

 m_sSettingsFile = QApplication::applicationDirPath() + "/demosettings.ini";
 loadSettings();

if (m_pButton)
 {
  connect(m_pButton, SIGNAL (released()),this, SLOT (handleButton()));
 }
}

void MainWindow::initGui()
{
 m_pLabel = new QLabel("", this);
 m_pLabel->setGeometry(0,0, 200,40);
 m_pEdit = new QLineEdit("", this);
 m_pEdit->setGeometry(0,40, 200,40);
 m_pButton = new QPushButton("OK", this);
 m_pButton->setGeometry(0,80, 200,40);
}

void MainWindow::loadSettings()
{
 QSettings settings(m_sSettingsFile, QSettings::NativeFormat);
 QString sText = settings.value("text", "").toString();
 if (m_pLabel)
 {
  m_pLabel->setText(sText);
 }
}

void MainWindow::saveSettings()
{
 QSettings settings(m_sSettingsFile, QSettings::NativeFormat);
 QString sText = (m_pEdit) ? m_pEdit->text() : "";
 settings.setValue("text", sText);
}

void MainWindow::handleButton()
{
 saveSettings();
}

MainWindow::~MainWindow()
{

}

main.cpp

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
 QApplication app(argc, argv);

 MainWindow mainWindow;
 mainWindow.showMaximized();
 return app.exec();
}