Best Practise for GUI development for vanilla C++ application

Question

I want to know about developing of gui to vanilla C++ application. I have experience in mostly in command line application. My experience in C++ gui till now is cout and cin. I have some experience in WPF (just to mention that I do have some gui experience) I hope this will describe my level of experience with gui. Now,I want to develop an application which needs separate GUI with possibility of 3D display. Of course, one of the choice for GUI API is Qt.Also,after reading lots of stuff on internet, i think code separation would be really helpful in future.

So, here goes my question: Is it possible if I keep my logic as generic as possible (not using winapi or qt in my logic) and make only GUI part API specific (say winapi or qt). Or I will need to add some code in my logic section, say for synchronization between logic and GUI. One can say signal and slot from qt is possible but as far as i know signals and slots are qt specific. they are not standard C++.

In summery,my question is can i make my logic in standard C++ (to stay platform/ framework independent) and only design platform specific GUI? If yes, could you please suggest a link or tutorial or book. A sample code or implementation would be 'a wish come true'. Also, some insights in code separation tactics would be quite helpful.

Regards!!

EDIT:: I will elaborate my problem. I have an application which has separate GUI and Logic section. The gui uses WinAPI and as the communication mode used is windows messages, previous user has created a HWND object in Logic which communicates to GUI. So, there is a HWND in Logic and HWND in GUI. I don't find this approach satisfying. One of the reason is that Logic part will be edited by non-programmers in later stage (not much. just modification of constants or changing implementation of function without changing para or return value). So, I just want to keep logic part in standard format (as much as possible). So once again, could anyone help me in designing business logic in C++ and GUI in any API.

Answer 1

After reading some threads, I found that answering own question is not a bad practice. So I will share the answer I have got.

There is no standard way to build a C++ gui application without using external dependencies. The synchronization between gui and logic part is always framework specific. So, if I want to develop a C++ gui application, I cannot put logic part in standard C++. It must have some code from external framework which will communicate the logic part and gui part. Having said that, I have found my way in by following method. I am going to put my logic part inside a static lib and then I will attach this lib to gui part. It will increase coding in gui section, but it will keep the base functions in standard c++. This way (a function lib in standard C++ and machine operation in framework specific code) will work for me. I hope I am on right track. :)

Answer 2

I think that by default, you should aim to separate business logic from presentation (GUI) code. In web development, the most commonly used pattern is MVC, and it's principles apply equally to native applications.

However, this separation might be more difficult to achieve in native applications. Mainly because there are no frameworks such as Symfony, which have already solved these architectural problems, and make it easy to keep UI and business code separate by following the established conventions. I have't used Qt but from what I know it's mainly a GUI toolkit - models, views and controllers are not as well-defined and integrated.

Depending on the nature of the needed interface, a simple OpenGL GUI might suffice. This is what I did for a simple uni project. The project needed to display a shapefile colored according to statistics in an XML file. I created a number of GUI widgets - button, label etc, and a custom map widget which encapsulates "business logic". Perhaps I should have "cleansed" the map widget, making it as generic as possible, and move all business logic to a separate library, but considering the business layer was very thin I thought the added complexity would outweigh the benefits.

Another factor is your skill-set - current, and areas which you want to improve. I was more interested in OpenGL and freeglut, then in learning Qt. If I had known Qt, I would have used that.

Answer 3

I have done some projects with vanilla C++ and a QT GUI. The idea of not mixing any QT code into the pure C++ stuff is always good but takes a lot of fun out of it. Usually you end up with a much more elaborate GUI than you expected and would often like to connect it better/easier to your code. Signals and Slots are a really great way to let the GUI interact with your code, but then you start mixing...

TLDR: Think really hard about why you don't want to mix your code with e.g. QT. It would not meand mixing GUI and Logic, no way, but your life could be a lot easier using QT classes like QStrings, QProcesses or QThreads...

If you manage to do all the interactions using QTs Signal & Slot mechanism, at some point you might even change you native QT GUI to a QT Quick (QML) one, which is highly customizable, has nice looks and animations and whatnot.

This is just my opinion.

Answer 4

You can to a large extent write completely separate logic and GUI code in Qt. However you will be able to create a much more useful GUI if you allow the logic and GUI code to interact. Qt has it's own classes for a lot of things (QString, QVector<> etc.) but you're free to ignore these for the most part and use the standard library instead if you'd prefer.

However, I do not think that it is worth trying to separate Qt from the logic code entirely because, as mentioned before, you will be able to build a much better GUI if they interact. For a simple example you could write a very simple Qt GUI with just a window and a button; press that button and some logic code is run. However with more interaction you could use signals and slots to update a progress bar on the GUI to let the user know how far the logic code had got. Also Qt is very portable, allowing you to build your program for Windows, Mac and at least some Linux distros.

Also for your 3D display requirement I recently found myself trying to do a similar thing and found this example very useful - http://qt-project.org/doc/qt-5.0/qtgui/openglwindow.html.