I am making something in QT in C++.
However, when I am using a while(1) loop in the code, the window never appears. I tried many things, such as adding a QApplication::processEvents(); at the end of the loop, but it doesn't work. There is no window.
How do get the window to appear?
Example code:
MainWindow::MainWindow(QWidget * parent, Qt::WindowFlags flags) : QMainWindow(parent, flags) {
_ui.setupUi(this);
while(1){
}
}
Thanks
Every widget constructor should never block the main message loop!
The main message loop looks usually like this:
int main(int argc, char *argv[]) {
QApplication a(argc, argv);
MainWindow w(nullptr);
w.show();
int r = a.exec();
return r
}
In your case your MainWindow ctor never returns, so w.show() is never called and a.exec() (main messgae loop) is never executed.
Not only blocking may be a problem in main window ctor, but also signals that are generated before main message loop is executed gets never raised. For an example establishment of an TCP/IP connection within main window ctor will never raise the connected() signal and associated slots. *1
At least if the creation of the main window is before the main message loop is executed like in 99% the cases.
QMainWindow::show();before the loop andQApplication::processEvents();in the loop solves this problem, but the window doesn't close.