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keyPressEvent - how to override?

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  • Ashok KumarA Ashok Kumar

    @jenya7 you can create textedit object and do

    textedit->installEventFilter(this);

    J Offline
    J Offline
    jenya7
    wrote on last edited by jenya7
    #9

    @Ashok-Kumar said in keyPressEvent - how to override?:

    @jenya7 you can create textedit object and do

    textedit->installEventFilter(this);

    In mainwindow.cpp I do

    bool eventFilter(QObject *obj, QEvent *event)
    {
        if (obj == textEditTerminalTx) 
        {
            if (event->type() == QEvent::KeyPress) 
            {
                QKeyEvent keyEvent = static_cast<QKeyEvent>(event);
                //qDebug() << keyEvent->key();
                return true;
            } 
            else 
            {
                return false;
            }
        } 
        else 
        {
            // pass the event on to the parent class
            return eventFilter(obj, event);
        }
    }
    

    On this line obj == textEditTerminalTx I get - error: use of undeclared identifier 'textEditTerminalTx'
    On this line QKeyEvent keyEvent = static_cast<QKeyEvent>(event); - I get error: no matching conversion for static_cast from 'QEvent *' to 'QKeyEvent'

    Ashok KumarA 1 Reply Last reply
    0
    • J jenya7

      @Ashok-Kumar said in keyPressEvent - how to override?:

      @jenya7 you can create textedit object and do

      textedit->installEventFilter(this);

      In mainwindow.cpp I do

      bool eventFilter(QObject *obj, QEvent *event)
      {
          if (obj == textEditTerminalTx) 
          {
              if (event->type() == QEvent::KeyPress) 
              {
                  QKeyEvent keyEvent = static_cast<QKeyEvent>(event);
                  //qDebug() << keyEvent->key();
                  return true;
              } 
              else 
              {
                  return false;
              }
          } 
          else 
          {
              // pass the event on to the parent class
              return eventFilter(obj, event);
          }
      }
      

      On this line obj == textEditTerminalTx I get - error: use of undeclared identifier 'textEditTerminalTx'
      On this line QKeyEvent keyEvent = static_cast<QKeyEvent>(event); - I get error: no matching conversion for static_cast from 'QEvent *' to 'QKeyEvent'

      Ashok KumarA Offline
      Ashok KumarA Offline
      Ashok Kumar
      wrote on last edited by
      #10

      @jenya7 instead of doing casting like u did above QKeyEvent keyEvent = static_cast<QKeyEvent>(event);

      instead u can do like this

      QKeyEvent keyEvent=(QKeyEvent*)(event);
      It will work

      J 1 Reply Last reply
      0
      • Ashok KumarA Ashok Kumar

        @jenya7 instead of doing casting like u did above QKeyEvent keyEvent = static_cast<QKeyEvent>(event);

        instead u can do like this

        QKeyEvent keyEvent=(QKeyEvent*)(event);
        It will work

        J Offline
        J Offline
        jenya7
        wrote on last edited by jenya7
        #11

        @Ashok-Kumar said in keyPressEvent - how to override?:

        @jenya7 instead of doing casting like u did above QKeyEvent keyEvent = static_cast<QKeyEvent>(event);

        instead u can do like this

        QKeyEvent keyEvent=(QKeyEvent*)(event);
        It will work

        This way I get - error: no viable conversion from 'QKeyEvent *' to 'QKeyEvent'

        Ah I see - QKeyEvent keyEvent = (QKeyEvent)(event); - the site editor removes a pointer star.

        And why the object not visible in the scope - if (obj == textEditTerminalTx) ?
        I tried if (obj == ui->textEditTerminalTx) but ui also not visible.

        Say in functions with MainWindow:: ui is visible like
        void MainWindow::on_ButtonCompileScript_clicked()
        {
        QString text = ui->textEditScriptIn->toPlainText();
        }

        OK.

        In mainwindow.h I added

        public:
            bool eventFilter(QObject *obj, QEvent *event);
        

        In mainwindow.cpp

        MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
        {
            ui->setupUi(this);
            ui->textEditTerminalTx->installEventFilter(this);
        }
        
        bool MainWindow::eventFilter(QObject *obj, QEvent *event)
        {
            QMessageBox mb;
            if (obj == ui->textEditTerminalTx)
            {
                if (event->type() == QEvent::KeyPress)
                {
                    QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                    if (keyEvent->key() == Qt::Key_Enter)
                    {
                        mb.setText("Enter");
                        mb.exec();
                    }
                    return true;
                }
                else
                    return false;
            }
            else
            {
                // pass the event on to the parent class
                return eventFilter(obj, event);
            }
        }
        

        But when I type - no char is typed in the widget and no reaction on Enter key.

        Ashok KumarA 1 Reply Last reply
        0
        • J jenya7

          @Ashok-Kumar said in keyPressEvent - how to override?:

          @jenya7 instead of doing casting like u did above QKeyEvent keyEvent = static_cast<QKeyEvent>(event);

          instead u can do like this

          QKeyEvent keyEvent=(QKeyEvent*)(event);
          It will work

          This way I get - error: no viable conversion from 'QKeyEvent *' to 'QKeyEvent'

          Ah I see - QKeyEvent keyEvent = (QKeyEvent)(event); - the site editor removes a pointer star.

          And why the object not visible in the scope - if (obj == textEditTerminalTx) ?
          I tried if (obj == ui->textEditTerminalTx) but ui also not visible.

          Say in functions with MainWindow:: ui is visible like
          void MainWindow::on_ButtonCompileScript_clicked()
          {
          QString text = ui->textEditScriptIn->toPlainText();
          }

          OK.

          In mainwindow.h I added

          public:
              bool eventFilter(QObject *obj, QEvent *event);
          

          In mainwindow.cpp

          MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
          {
              ui->setupUi(this);
              ui->textEditTerminalTx->installEventFilter(this);
          }
          
          bool MainWindow::eventFilter(QObject *obj, QEvent *event)
          {
              QMessageBox mb;
              if (obj == ui->textEditTerminalTx)
              {
                  if (event->type() == QEvent::KeyPress)
                  {
                      QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                      if (keyEvent->key() == Qt::Key_Enter)
                      {
                          mb.setText("Enter");
                          mb.exec();
                      }
                      return true;
                  }
                  else
                      return false;
              }
              else
              {
                  // pass the event on to the parent class
                  return eventFilter(obj, event);
              }
          }
          

          But when I type - no char is typed in the widget and no reaction on Enter key.

          Ashok KumarA Offline
          Ashok KumarA Offline
          Ashok Kumar
          wrote on last edited by
          #12

          @jenya7 If u r getting no viable conversion from QKeyEvent* to QKeyEvent. include <QKeyEvent> headerfile in the mainwindow class

          J 1 Reply Last reply
          0
          • Ashok KumarA Ashok Kumar

            @jenya7 If u r getting no viable conversion from QKeyEvent* to QKeyEvent. include <QKeyEvent> headerfile in the mainwindow class

            J Offline
            J Offline
            jenya7
            wrote on last edited by jenya7
            #13

            @Ashok-Kumar said in keyPressEvent - how to override?:

            @jenya7 If u r getting no viable conversion from QKeyEvent* to QKeyEvent. include <QKeyEvent> headerfile in the mainwindow class

            I do get the event. To test it I added

            if (event->type() == QEvent::KeyPress)
                    {
                        QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                        if (keyEvent->key() == Qt::Key_Return)
                        {
                            mb.setText("Enter");
                            mb.exec();
                        }
                        else
                        {
                            term_str += static_cast<char> (keyEvent->key());
                            ui->textEditTerminalTx->setText(term_str);
                        }
                        return true;
                    }
                    else
                        return false;
            

            When I type I get chars in the widget but it types also backspase and delete keys instead of action. And on Key_Return I see the message box.

            Ashok KumarA 1 Reply Last reply
            0
            • J jenya7

              @Ashok-Kumar said in keyPressEvent - how to override?:

              @jenya7 If u r getting no viable conversion from QKeyEvent* to QKeyEvent. include <QKeyEvent> headerfile in the mainwindow class

              I do get the event. To test it I added

              if (event->type() == QEvent::KeyPress)
                      {
                          QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                          if (keyEvent->key() == Qt::Key_Return)
                          {
                              mb.setText("Enter");
                              mb.exec();
                          }
                          else
                          {
                              term_str += static_cast<char> (keyEvent->key());
                              ui->textEditTerminalTx->setText(term_str);
                          }
                          return true;
                      }
                      else
                          return false;
              

              When I type I get chars in the widget but it types also backspase and delete keys instead of action. And on Key_Return I see the message box.

              Ashok KumarA Offline
              Ashok KumarA Offline
              Ashok Kumar
              wrote on last edited by
              #14

              @jenya7
              if u want only chars in the QTextedit then u can use try this

              if(keyevent->key()>=Qt::Key_0 && keyevent->key()<=Qt::Key_9)

              if u want only digits in the QTextedit then u can use try this

              if(keyevent->key()>=Qt::Key_A && keyevent->key()<=Qt::Key_Z)...

              If u create the QMessageBox object in the constructor then it will be shown in the beginning itself

              J 1 Reply Last reply
              0
              • Ashok KumarA Ashok Kumar

                @jenya7
                if u want only chars in the QTextedit then u can use try this

                if(keyevent->key()>=Qt::Key_0 && keyevent->key()<=Qt::Key_9)

                if u want only digits in the QTextedit then u can use try this

                if(keyevent->key()>=Qt::Key_A && keyevent->key()<=Qt::Key_Z)...

                If u create the QMessageBox object in the constructor then it will be shown in the beginning itself

                J Offline
                J Offline
                jenya7
                wrote on last edited by jenya7
                #15

                @Ashok-Kumar said in keyPressEvent - how to override?:

                @jenya7
                if u want only chars in the QTextedit then u can use try this

                if(keyevent->key()>=Qt::Key_0 && keyevent->key()<=Qt::Key_9)

                if u want only digits in the QTextedit then u can use try this

                if(keyevent->key()>=Qt::Key_A && keyevent->key()<=Qt::Key_Z)...

                If u create the QMessageBox object in the constructor then it will be shown in the beginning itself

                to get every possible key I did so

                if (keyEvent->key() != Qt::Key_Backspace && keyEvent->key() != Qt::Key_Delete)
                 {
                            term_str += static_cast<char> (keyEvent->key());
                           ui->textEditTerminalTx->setText(term_str);
                 }
                

                but the keys Backspace and Delete don't act as suppose to be - no action - it suppose to delete chars.
                Also it gets chars only in upper case ignoring CapsLock selection.

                This way it works

                bool MainWindow::eventFilter(QObject *obj, QEvent *event)
                {
                    QMessageBox mb;
                    if (obj == ui->textEditTerminalTx)
                    {
                        if (event->type() == QEvent::KeyPress)
                        {
                            QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                            if (keyEvent->key() == Qt::Key_Return)
                            {
                
                                mb.setText("Enter");
                                mb.exec();
                            }
                            else
                            {
                                //term_str += static_cast<char> (keyEvent->key());
                                return false;
                            }
                        }
                        else
                            return false;
                    }
                    else
                        // pass the event on to the parent class
                        return MainWindow::eventFilter(obj, event);
                }
                
                Ashok KumarA 1 Reply Last reply
                0
                • J jenya7

                  @Ashok-Kumar said in keyPressEvent - how to override?:

                  @jenya7
                  if u want only chars in the QTextedit then u can use try this

                  if(keyevent->key()>=Qt::Key_0 && keyevent->key()<=Qt::Key_9)

                  if u want only digits in the QTextedit then u can use try this

                  if(keyevent->key()>=Qt::Key_A && keyevent->key()<=Qt::Key_Z)...

                  If u create the QMessageBox object in the constructor then it will be shown in the beginning itself

                  to get every possible key I did so

                  if (keyEvent->key() != Qt::Key_Backspace && keyEvent->key() != Qt::Key_Delete)
                   {
                              term_str += static_cast<char> (keyEvent->key());
                             ui->textEditTerminalTx->setText(term_str);
                   }
                  

                  but the keys Backspace and Delete don't act as suppose to be - no action - it suppose to delete chars.
                  Also it gets chars only in upper case ignoring CapsLock selection.

                  This way it works

                  bool MainWindow::eventFilter(QObject *obj, QEvent *event)
                  {
                      QMessageBox mb;
                      if (obj == ui->textEditTerminalTx)
                      {
                          if (event->type() == QEvent::KeyPress)
                          {
                              QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                              if (keyEvent->key() == Qt::Key_Return)
                              {
                  
                                  mb.setText("Enter");
                                  mb.exec();
                              }
                              else
                              {
                                  //term_str += static_cast<char> (keyEvent->key());
                                  return false;
                              }
                          }
                          else
                              return false;
                      }
                      else
                          // pass the event on to the parent class
                          return MainWindow::eventFilter(obj, event);
                  }
                  
                  Ashok KumarA Offline
                  Ashok KumarA Offline
                  Ashok Kumar
                  wrote on last edited by
                  #16

                  @jenya7 What exactly is your problem. Which keys do you need to use in textedit . can u elaborate it .

                  J 1 Reply Last reply
                  0
                  • Ashok KumarA Ashok Kumar

                    @jenya7 What exactly is your problem. Which keys do you need to use in textedit . can u elaborate it .

                    J Offline
                    J Offline
                    jenya7
                    wrote on last edited by jenya7
                    #17

                    @Ashok-Kumar said in keyPressEvent - how to override?:

                    @jenya7 What exactly is your problem. Which keys do you need to use in textedit . can u elaborate it .

                    The last function's version solves the problem - I get all the chars and keys Backspase and Delete work.
                    Now - on Enter key - I'd like to take the line before the Enter key and send it. Looking how to get the line before the Enter key. Trivial things so difficult in Qt... :)

                    Ashok KumarA 1 Reply Last reply
                    0
                    • J jenya7

                      @Ashok-Kumar said in keyPressEvent - how to override?:

                      @jenya7 What exactly is your problem. Which keys do you need to use in textedit . can u elaborate it .

                      The last function's version solves the problem - I get all the chars and keys Backspase and Delete work.
                      Now - on Enter key - I'd like to take the line before the Enter key and send it. Looking how to get the line before the Enter key. Trivial things so difficult in Qt... :)

                      Ashok KumarA Offline
                      Ashok KumarA Offline
                      Ashok Kumar
                      wrote on last edited by
                      #18

                      @jenya7 If u want the text before the enter key then you have to emit signal with parameter as string and write a particular slot for that and there u can get that text...

                      signal:
                      void textBeforeEnter(QString);

                      slot :
                      void getText(QString);

                      connect(this,SIGNAL(textBeforeEnter(QString)),this,SLOT(getText(QString)));
                      emit textBeforeEnter(textedit.text);

                      void getText(QString text)
                      {
                      qDebug()<<"The text in textedit before pressing enter key is "<<text<<endl;
                      }

                      1 Reply Last reply
                      0

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