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Thread: Access widget inside the QMainWindow centralwidget

  1. #1
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    Default Access widget inside the QMainWindow centralwidget

    Hi
    I'm trying to connect a button that is inside a widget(myCentralWidget). This widget is set as the QMainWindow central widget.
    This is an example:
    Qt Code:
    1. #include "mainwindow.h"
    2. #include "ui_mainwindow.h"
    3.  
    4. MainWindow::MainWindow(QWidget *parent) :
    5. QMainWindow(parent),
    6. ui(new Ui::MainWindow)
    7. {
    8. ui->setupUi(this);
    9. widget = new myCentralWidget(this);
    10. setCentralWidget(widget);
    11. // ...
    12. }
    To copy to clipboard, switch view to plain text mode 

    All classes are created using Qt Designer Form class from Qt Creator: MainWindow and myCentralWidget.
    How do i connect a button that is inside the ui of the myCentralWidget to make something happen in the qmainwindow?
    Thanks

  2. #2
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    Default Re: Access widget inside the QMainWindow centralwidget

    The cleanest way is to forward the signal in myCentralWidget so that the myCentralWidget class has a signal you can connect to in MainWindow.

    So you declare a signal in myCentralWidget
    Qt Code:
    1. class myCentralWidget : public QWidget
    2. {
    3. Q_OBjECT
    4. public:
    5. // ...
    6.  
    7. signals:
    8. void someButtonClicked(); // or use a name that indicates that the user wants to do
    9. };
    To copy to clipboard, switch view to plain text mode 
    and forward the button's signal, e.g. in the constructor
    Qt Code:
    1. connect( ui->someButton, SIGNAL(clicked()), this, SIGNAL(someButtonClicked()) );
    To copy to clipboard, switch view to plain text mode 

    Cheers,
    _

  3. The following user says thank you to anda_skoa for this useful post:

    graciano (23rd January 2014)

  4. #3
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    Default Re: Access widget inside the QMainWindow centralwidget

    Still don't get it ... i will take a better look at this: https://qt-project.org/doc/qt-5/signalsandslots.html
    Never tried to forward a signal before

  5. #4
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    Default Re: Access widget inside the QMainWindow centralwidget

    When the button is clicked, it emits its clicked() signal.
    Due to the signal/signal connect the container widget's someButtonClicked() signal is now also emitted.

    In MainWindow you have the object of the container widget, so you can connect its someButtonClicked() signal just like if it where the button.

    Cheers,
    _

  6. The following user says thank you to anda_skoa for this useful post:

    graciano (23rd January 2014)

  7. #5
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    Default Re: Access widget inside the QMainWindow centralwidget

    I get it ... and it is simple after all.
    Thanks for the patience anda_skoa.
    I attach example: question.zip

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