QSplashScreen Class

The QSplashScreen widget provides a splash screen that can be shown during application startup. More...

Header:	#include <QSplashScreen>
qmake:	QT += widgets
Inherits:	QWidget

• List of all members, including inherited members

Public Functions

	QSplashScreen(QWidget *parent, const QPixmap &pixmap = QPixmap(), Qt::WindowFlags f = Qt::WindowFlags())
	QSplashScreen(const QPixmap &pixmap = QPixmap(), Qt::WindowFlags f = Qt::WindowFlags())
virtual	~QSplashScreen()
void	finish(QWidget *mainWin)
QString	message() const
const QPixmap	pixmap() const
void	repaint()
void	setPixmap(const QPixmap &pixmap)

Public Slots

void	clearMessage()
void	showMessage(const QString &message, int alignment = Qt::AlignLeft, const QColor &color = Qt::black)

Signals

void	messageChanged(const QString &message)

Protected Functions

virtual void

drawContents(QPainter *painter)

Reimplemented Protected Functions

virtual bool	event(QEvent *e) override
virtual void	mousePressEvent(QMouseEvent *) override

Detailed Description

A splash screen is a widget that is usually displayed when an application is being started. Splash screens are often used for applications that have long start up times (e.g. database or networking applications that take time to establish connections) to provide the user with feedback that the application is loading.

The splash screen appears in the center of the screen. It may be useful to add the Qt::WindowStaysOnTopHint to the splash widget's window flags if you want to keep it above all the other windows on the desktop.

Some X11 window managers do not support the "stays on top" flag. A solution is to set up a timer that periodically calls raise() on the splash screen to simulate the "stays on top" effect.

The most common usage is to show a splash screen before the main widget is displayed on the screen. This is illustrated in the following code snippet in which a splash screen is displayed and some initialization tasks are performed before the application's main window is shown:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QPixmap pixmap(":/splash.png");
    QSplashScreen splash(pixmap);
    splash.show();
    app.processEvents();
    ...
    QMainWindow window;
    window.show();
    splash.finish(&window);
    return app.exec();
}

The user can hide the splash screen by clicking on it with the mouse. Since the splash screen is typically displayed before the event loop has started running, it is necessary to periodically call QCoreApplication::processEvents() to receive the mouse clicks.

It is sometimes useful to update the splash screen with messages, for example, announcing connections established or modules loaded as the application starts up:

QPixmap pixmap(":/splash.png");
QSplashScreen *splash = new QSplashScreen(pixmap);
splash->show();

... // Loading some items
splash->showMessage("Loaded modules");

qApp->processEvents();

... // Establishing connections
splash->showMessage("Established connections");

qApp->processEvents();

QSplashScreen supports this with the showMessage() function. If you wish to do your own drawing you can get a pointer to the pixmap used in the splash screen with pixmap(). Alternatively, you can subclass QSplashScreen and reimplement drawContents().

Member Function Documentation

QSplashScreen::QSplashScreen(QWidget *parent, const QPixmap &pixmap = QPixmap(), Qt::WindowFlags f = Qt::WindowFlags())

This is an overloaded function.

This function allows you to specify a parent for your splashscreen. The typical use for this constructor is if you have a multiple screens and prefer to have the splash screen on a different screen than your primary one. In that case pass the proper desktop() as the parent.

QSplashScreen::QSplashScreen(const QPixmap &pixmap = QPixmap(), Qt::WindowFlags f = Qt::WindowFlags())

Construct a splash screen that will display the pixmap.

There should be no need to set the widget flags, f, except perhaps Qt::WindowStaysOnTopHint.

[slot] void QSplashScreen::clearMessage()

Removes the message being displayed on the splash screen

See also showMessage().

[signal] void QSplashScreen::messageChanged(const QString &message)

This signal is emitted when the message on the splash screen changes. message is the new message and is a null-string when the message has been removed.

See also showMessage() and clearMessage().

[slot] void QSplashScreen::showMessage(const QString &message, int alignment = Qt::AlignLeft, const QColor &color = Qt::black)

Draws the message text onto the splash screen with color color and aligns the text according to the flags in alignment. This function calls repaint() to make sure the splash screen is repainted immediately. As a result the message is kept up to date with what your application is doing (e.g. loading files).

See also Qt::Alignment, clearMessage(), and message().

[virtual] QSplashScreen::~QSplashScreen()

Destructor.

[virtual protected] void QSplashScreen::drawContents(QPainter *painter)

Draw the contents of the splash screen using painter painter. The default implementation draws the message passed by showMessage(). Reimplement this function if you want to do your own drawing on the splash screen.

[override virtual protected] bool QSplashScreen::event(QEvent *e)

Reimplements: QWidget::event(QEvent *event).

void QSplashScreen::finish(QWidget *mainWin)

Makes the splash screen wait until the widget mainWin is displayed before calling close() on itself.

QString QSplashScreen::message() const

Returns the message that is currently displayed on the splash screen.

This function was introduced in Qt 5.2.

See also showMessage() and clearMessage().

[override virtual protected] void QSplashScreen::mousePressEvent(QMouseEvent *)

Reimplements: QWidget::mousePressEvent(QMouseEvent *event).

const QPixmap QSplashScreen::pixmap() const

Returns the pixmap that is used in the splash screen. The image does not have any of the text drawn by showMessage() calls.

See also setPixmap().

void QSplashScreen::repaint()

This overrides QWidget::repaint(). It differs from the standard repaint function in that it also calls QCoreApplication::processEvents() to ensure the updates are displayed, even when there is no event loop present.

void QSplashScreen::setPixmap(const QPixmap &pixmap)

Sets the pixmap that will be used as the splash screen's image to pixmap.

See also pixmap().