How to Use QSettings: Difference between revisions
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{{DocLink|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. | {{DocLink|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 {{DocLink|qsettings|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 {{DocLink|qsettings|value}}. | |||
The value of a setting can be obtained using method | |||
== Example == | == Example == | ||
Line 29: | Line 25: | ||
namespace Ui { | namespace Ui { | ||
class MainWindow; | |||
} | } | ||
Line 37: | Line 33: | ||
public: | public: | ||
explicit MainWindow(QWidget | explicit MainWindow(QWidget *parent = 0); | ||
virtual ~MainWindow(); | virtual ~MainWindow(); | ||
Line 56: | Line 52: | ||
QString m_sSettingsFile; | QString m_sSettingsFile; | ||
QLabel | QLabel* m_pLabel; | ||
QLineEdit* m_pEdit; | QLineEdit* m_pEdit; | ||
QPushButton* m_pButton; | QPushButton* m_pButton; | ||
}; | }; | ||
#endif // MAINWINDOW_H | #endif // MAINWINDOW_H | ||
</code> | </code> | ||
Line 71: | Line 66: | ||
<code> | <code> | ||
#include "mainwindow.h" | #include "mainwindow.h" | ||
#include <QCoreApplication> | #include <QCoreApplication> | ||
#include <QSettings> | #include <QSettings> | ||
#include <QApplication> | #include <QApplication> | ||
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initGui(); | initGui(); | ||
m_sSettingsFile = QApplication::applicationDirPath().left(1) + ":/demosettings.ini"; | m_sSettingsFile = QApplication::applicationDirPath().left(1) + ":/demosettings.ini"; | ||
loadSettings(); | loadSettings(); | ||
if (m_pButton) | if (m_pButton) | ||
{ | { | ||
connect(m_pButton, SIGNAL (released()),this, SLOT (handleButton())); | |||
} | } | ||
} | } | ||
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if (m_pLabel) | if (m_pLabel) | ||
{ | { | ||
m_pLabel->setText(sText); | |||
} | } | ||
} | } | ||
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if (m_pLabel) | if (m_pLabel) | ||
{ | { | ||
m_pLabel->setText(sText); | |||
} | } | ||
} | } | ||
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QApplication app(argc, argv); | QApplication app(argc, argv); | ||
MainWindow mainWindow; | MainWindow mainWindow; | ||
mainWindow.showMaximized(); | mainWindow.showMaximized(); | ||
return app.exec(); | return app.exec(); | ||
} | } | ||
</code> |
Revision as of 17:12, 17 May 2017
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().left(1) + ":/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);
if (m_pLabel)
{
m_pLabel->setText(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();
}