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[SOLVED] Extending widgets

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  • mrjjM mrjj

    @nitzan
    Yes, just a normal cpp and h file.
    Just make sure you type ClassName (of your widget) correctly as it don't validate it :)

    N Offline
    N Offline
    nitzan
    wrote on last edited by
    #5

    @mrjj

    thanks!
    that worked well, except for one problem.
    calling the setTest method seems to have no effect at all..
    I'm doing this:

    MyWidget::MyWidget(QWidget* parent) : QLabel(parent) {
    	qDebug() << "MyWidget ctor";
    	this->setText("hey there");
    	this->setAttribute(Qt::WA_Hover);
    }
    
    bool MyWidget::event(QEvent* event) {
    	switch (event->type()) {
    		case QEvent::HoverEnter:
    			this->setStyleSheet("color: rgb(255, 0, 0)");
    			break;
    
    		case QEvent::HoverLeave:
    			this->setStyleSheet("color: rgb(0, 0, 0)");
    			break;
    
    		default:
    			return QLabel::event(event);
    	}
    
    	return true;
    }
    

    And the label has no text in it.
    Any idea why?

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    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #6

      @nitzan said:

      this->setText(..)

      Have you tried SetText from outside, like via a button ?
      Sometimes I get fooled by stuff overwritten by the ui->setup which is run after
      your constructor.

      N 1 Reply Last reply
      0
      • mrjjM mrjj

        @nitzan said:

        this->setText(..)

        Have you tried SetText from outside, like via a button ?
        Sometimes I get fooled by stuff overwritten by the ui->setup which is run after
        your constructor.

        N Offline
        N Offline
        nitzan
        wrote on last edited by
        #7

        @mrjj
        but that creates coupling i would prefer to avoid..
        is there anyway to have that in the same class in a way that will be called after the ui->setup?

        mrjjM 1 Reply Last reply
        0
        • N nitzan

          @mrjj
          but that creates coupling i would prefer to avoid..
          is there anyway to have that in the same class in a way that will be called after the ui->setup?

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #8

          @nitzan
          It was just for testing.

          Have you tried to set it on the label you promote. ?
          And not call SetText at all in constructor.

          I get the text here. (from designer)

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          • mrjjM mrjj

            @nitzan
            It was just for testing.

            Have you tried to set it on the label you promote. ?
            And not call SetText at all in constructor.

            I get the text here. (from designer)

            N Offline
            N Offline
            nitzan
            wrote on last edited by
            #9

            @mrjj
            calling setText from outside the class works well, even if I do it from the event method it works, but not in the ctor.

            I can't set the text from the designer as the actual text I'm trying to put there is from font awesome (using QtAwesome), and so the actual code is:

            UserWidget::UserWidget(QWidget* parent) : QLabel(parent) {
            	qDebug() << "UserWidget ctor";
            	this->setText(QString(QChar(fa::user)).append(" login"));
            	this->setAttribute(Qt::WA_Hover);
            }
            
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            • Chris KawaC Online
              Chris KawaC Online
              Chris Kawa
              Lifetime Qt Champion
              wrote on last edited by Chris Kawa
              #10

              If you don't want the text overwritten by the text from designer then instead of promoting QLabel to your class promote a plain QWidget. It won't have the Text property in the editor so the generated setupUi code won't call setText and the value set in your constructor will be preserved.

              N 1 Reply Last reply
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              • Chris KawaC Chris Kawa

                If you don't want the text overwritten by the text from designer then instead of promoting QLabel to your class promote a plain QWidget. It won't have the Text property in the editor so the generated setupUi code won't call setText and the value set in your constructor will be preserved.

                N Offline
                N Offline
                nitzan
                wrote on last edited by
                #11

                @Chris-Kawa
                Sounds like a workaround, but I would like to understand why it's needed.

                As the ctor of QLabel is called before the code in my widget is executed, then the setupUi code should be executed before my code as well.
                Unless I'm missing something?

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                0
                • mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #12

                  Well its the setupui for the mainform/dialog.
                  It creates the Qlabel and set its text.
                  So calls setText after the constructor.

                  1 Reply Last reply
                  1
                  • Chris KawaC Online
                    Chris KawaC Online
                    Chris Kawa
                    Lifetime Qt Champion
                    wrote on last edited by Chris Kawa
                    #13

                    It's not a workaround. You should always promote from the "lowest" widget of which functionality you want to preserve. In this case you don't want to have the label's ability to edit text in the designer so you promote from a widget, not label.

                    As the ctor of QLabel is called before the code in my widget is executed, then the setupUi code should be executed before my code as well. Unless I'm missing something?

                    The code of the window widget's constructor usually looks something like this:

                    Foo::Foo(QWidget* parent) : QWidget(parent) {
                        ui->setupUi(this);
                    }
                    

                    which "expands" to something like this:

                    Foo::Foo(QWidget* parent) : QWidget(parent) {
                        ...
                        ui->someLabel = new YourLabel(this);
                        ui->someLabel->setText(whateverWasSetinTheDesigner);
                        ...
                    }
                    

                    so as you can see whatever you set in the constructor is immediately overwritten by what was set in the designer.
                    If you promote from a QWidget the designer doesn't "know" it's a label and it won't generate the setText() call.

                    N 1 Reply Last reply
                    1
                    • Chris KawaC Chris Kawa

                      It's not a workaround. You should always promote from the "lowest" widget of which functionality you want to preserve. In this case you don't want to have the label's ability to edit text in the designer so you promote from a widget, not label.

                      As the ctor of QLabel is called before the code in my widget is executed, then the setupUi code should be executed before my code as well. Unless I'm missing something?

                      The code of the window widget's constructor usually looks something like this:

                      Foo::Foo(QWidget* parent) : QWidget(parent) {
                          ui->setupUi(this);
                      }
                      

                      which "expands" to something like this:

                      Foo::Foo(QWidget* parent) : QWidget(parent) {
                          ...
                          ui->someLabel = new YourLabel(this);
                          ui->someLabel->setText(whateverWasSetinTheDesigner);
                          ...
                      }
                      

                      so as you can see whatever you set in the constructor is immediately overwritten by what was set in the designer.
                      If you promote from a QWidget the designer doesn't "know" it's a label and it won't generate the setText() call.

                      N Offline
                      N Offline
                      nitzan
                      wrote on last edited by
                      #14

                      Alright, promoting from QWidget indeed did the job and now it works well!
                      Thanks for the both of you.

                      1 Reply Last reply
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