Application with multiple windows in Qt

Question

What is a good way to create application with multiple windows in Qt? Something like GIMP. I have already read this answer and it is not what I need.

I have two windows, one with controls and one with OpenGL inside. Right now I have something like this:

int main() { // some code MainWindow mw; mw.show(); GLWindow gw; gw.show(); // ... }

I don't like this for two reasons. First reason is when I start my application, window with OpenGL will be on top (because it is last to call show()) but MainWindow will be buried somewhere under all opened windows. What I need is both windows in front of everything (like GIMP), preferably with focus on MainWindow (I guess I can bring them to front, so that is minor issue). Second reason I don't like this is that my application will be closed completely only when I close both windows.

So I was thinking of having a reference to GLWindow inside MainWindow, and creating it from MainWindow.

Would that be a good way to create application with several windows?

EDIT: GLWindow inherits from QOpenGLWindow.

Are you planning to share the controls window with multiple opengl views or a single one? — Damien LEFEVRE
– Damien LEFEVRE, Commented Jun 8, 2020 at 17:52
Is there a particular reason why you would choose a secondary QMainWindow over a floating dialog (non-modal)? .I'm not quite sure what you need to achieve so it's hard to advise :) but if possible I'd use that. Give the main window as parent for the dialog which would insure it would be on top. — Damien LEFEVRE
– Damien LEFEVRE, Commented Jun 8, 2020 at 18:17
It is not a secondary QMainWindow, this class GLWindow inherits from QOpenGLWindow. — dosvarog
– dosvarog, Commented Jun 8, 2020 at 18:35

Saeed Sayyadipour · Accepted Answer · 2020-06-09 04:16:38Z

You are doing right, but with the following simple tricks, you can resolve both issues that cause you do not like your right method:

To activate both windows, just do as follows:

 MainWindow mw; mw.show(); mw.activateWindow(); GLWindow gw; gw.show(); gw.activateWindow();

To resolve the quit problem, you have to override the closeEvent in both windows. To do that, add the following code into the header file of your both windows:

protected: void closeEvent(QCloseEvent *event) override;

and in the implementation of the closeEvent, just write qApp->quit();. This way once you close either window, your application will terminate completely.

MainWindow.cpp

void MainWindow::closeEvent(QCloseEvent *event) { qApp->quit(); }

and

GLWindow.cpp

void GLWindow::closeEvent(QCloseEvent *event) { qApp->quit(); }

G.M. · Accepted Answer · 2020-06-08 17:52:48Z

I'm not sure I completely understand the situation but, typically, you can make the 'secondary' widgets child dialogs of the QMainWindow. Given your example code that would be something like...

int main () { // some code MainWindow mw; mw.show(); /* * Secondary windows should be created with the QMainWindow mw * as their parent. */ GLWindow gw(&mw); /* * Set the Qt::Dlaog window flag to `encourage' the QMainWindow * and its children to behave as a group. */ gw.setWindowFlags(gw.windowFlags() | Qt::Dialog); gw.show(); // ... }

Now all widgets behave as a group (possibly subject to the window manager being used) and closing the QMainWindow will, by default, close the application.

I have added edit to my question. GLWindow inherits from QOpenGLWindow. This is where stuff regarding OpenGL happens. Other window is QMainWindow and there are controls. I hope that clarifies.
You said that you don't completely understand the situation, so I thought this would clarify it. GLWindow inherits from QOpenGLWindow, so it is of type QWindow. Main window is of type QMainWindow. So, I have two windows that should act as one application. I will try with your advice to "hint" at GLWindow with this flag.

Collectives™ on Stack Overflow

Application with multiple windows in Qt

2 Answers 2

Comments

3 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Linked

Related