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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include <QtGui>
// This example demonstrates how the standard Qt main()
// pattern works on Emscripten/WebAssambly, where exec()
// does not return.
class ClickWindow: public QRasterWindow
{
public:
ClickWindow() {
qDebug() << "ClickWindow constructor";
}
~ClickWindow() {
qDebug() << "ClickWindow destructor";
}
void paintEvent(QPaintEvent *ev) override {
QPainter p(this);
p.fillRect(ev->rect(), QColorConstants::Svg::deepskyblue);
p.drawText(50, 100, "Application has started. See the developer tools console for debug output");
}
void mousePressEvent(QMouseEvent *) override {
qDebug() << "mousePressEvent(): calling QGuiApplication::quit()";
QGuiApplication::quit();
}
};
int main(int argc, char **argv)
{
qDebug() << "main(): Creating QGuiApplication object";
QGuiApplication app(argc, argv);
QObject::connect(&app, &QCoreApplication::aboutToQuit, [](){
qDebug() << "QCoreApplication::aboutToQuit";
});
ClickWindow window;
window.show();
qDebug() << "main(): calling exec()";
app.exec();
// The exec() call above never returns; instead, a JavaScript exception
// is thrown such that control returns to the browser while preserving
// the C++ stack.
// This means that the window object above is not destroyed, and that
// shutdown code after exec() does not run.
qDebug() << "main(): after exit"; // <- will not be printed
}
// Global variables are created before main() as usual, but not destroyed
class Global
{
public:
Global() {
qDebug() << "Global constructor";
}
~Global() {
qDebug() << "Global destructor"; // <- will not be printed
}
};
Global global;
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