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implementing a dynamic display

  • There may be multiple products (of varying types) on the network. The user needs to know which one, by product name, he wishes to access. When he chooses one, I can then determine what UI components to display.

  • Lifetime Qt Champion

    So indeed, a plugin based architecture might be best suited for that.

  • Kind of an unrelated note.
    It sounds like the application is for specialist use only. Can you go and ask one of the end users what they really want to do and in what order they would like to do it?

    So the products broadcast or reply to a broadcast on the network, so they can be identified? This would make it much easier for the network case.

    From the architecture side, a plugin approach makes most sense, especially as you expect future additions and changes.

  • @tekojo I wish I could poll the user community on this matter -- I always like hearing from end-users before implementing an app. Unfortunately that option isn't available to me at this time.

    Regarding using plugins: that might be overkill, given that there are only two levels of user access, and only a few levels of app functionality. I also need to be concerned with distribution, and I'm not really familiar with plugins, but a plugin exists in a separate file, right? So can I still do a static build to create a monolithic distribution entity?

  • I've decided to implement the additional fields using a QDialog object. I created a second form for this dialog, but then realized I don't know how to access this form programmatically. Can someone point me to some directions on this? I've done some looking but haven't found anything that tells me how to connect up a second form.

    Clarification: I know that I want the form to be enabled when a button push delivers a signal, but I don't know how to "point to" this form programatically. I hope this makes sense; I've been struggling to find the right words to explain what I'm looking for.


  • Lifetime Qt Champion

    You usually subclass QDialog and give it the necessary API to access what you want. Depending on what you want to add, you can also simply hide what should not be used.

  • @SGaist so each form would then have its own subclass?

  • Lifetime Qt Champion

    Just to be sure we are talking about the same thing, what do you mean by form ?

  • @SGaist by "form" I mean an entry under "Forms" in the project file; ie, a file with a .ui extension that is generated by Designer.

  • Lifetime Qt Champion

    Then that's the most common use case. You create as many "Forms" you need and give them the API you need.

  • I see. So, when I created this project, I selected Qt Widgets Application, and Creator automatically set up the form and the class for me. Should I use that class as a model for my new form?

    I still don't quite understand how the program "knows" to use the .ui file. I don't see the connection anywhere in my code.

  • Lifetime Qt Champion

    It's just a starting point. Nothing forbids you to have several forms.

    The .uil file is processed by uic to generate code (a bit like moc for QObject based classes) then the ui.setupUi(this); line does the "magic" to setup everything you prepared with Designer.

  • I've tried to implement a new class (patterned after my main form)...obviously I don't understand something.

    Here's the header:

    #ifndef CREDENTIALS_H
    #define CREDENTIALS_H
    #include <QWidget>
    namespace Ui
        class Credentials;
    class Credentials : public QWidget
        explicit Credentials(QWidget *parent = nullptr);
        Ui::Credentials *uiCredentials;
    #endif // CREDENTIALS_H

    and here's the source:

    #include "credentials.h"
    #include "ui_credentials.h"
    Credentials::Credentials(QWidget *parent)
        : QWidget(parent),
          uiCredentials(new Ui::Credentials)

    I'm getting an error "invalid use of incomplete type 'class Ui::Credentials'. Why is it incomplete?

  • Moderators

    #include "ui_credentials_form_file_name.h"

  • I think I'm already doing that -- in the source file:

    #include "credentials.h"
     ***** #include "ui_credentials.h" *****
    Credentials::Credentials(QWidget *parent)


  • Lifetime Qt Champion

    Did you re-run qmake after adding your new form ?

  • @SGaist Yes. (I just tried it again to be sure.) I even did a clean/qmake/build...same results.

  • Moderators

    And is the root object of your form called "Credentials" (look for it when you open the form in the designer - in the right, in the object tree the first object's name)?

  • Aha! That did the trick. Thanks, kshegunov. It was simply called "Dialog."

    So, the step I missed was matching the name of the top-level object created in Designer with the new class I created manually to support it. I looked past this because the first form (and its supporting class) was created automatically when I started the project.

    Thanks again.

  • Lifetime Qt Champion

    Just as a note. you can add as many forms as you like and
    have them auto created like mainwindow is.

    It sounds you manually created Credentials ?

    To get a new form, simply right click top of project, select "Add new" and then
    alt text
    In next window, you can choose if it should be MainWindow, Dialog or Widget.

    This way you get .ui, cpp and h all ready to go.

    maybe i misunderstood but just in case :)

  • @mrjj oh, that's good to know about. I looked right past that and just created the form from the line below. Thanks, mrjj...I'll remember that for the (not so distant) future.

  • Lifetime Qt Champion

    Ah, yep that gives you just the ui file which is useful for hooking somes some interface up
    with existing code. But not so much for a brand new window/dialog. :)

  • Just as a note. you can add as many forms as you like and
    have them auto created like mainwindow is.


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