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  4. Signal/Slots doesn't work with QSlider and QDoubleSpinBox
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Signal/Slots doesn't work with QSlider and QDoubleSpinBox

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signals&slotsqsliderqdoublespinbox
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  • S SGaist
    16 May 2016, 21:41

    Hi,

    QDoubleSpinBox has no such slot, only setValue(double). Use the new Qt 5 notation for your connection, that will solve your problem.

    i.e.

    connect(sliderHeight, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
    
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    A Former User
    wrote on 17 May 2016, 08:48 last edited by
    #14

    @SGaist
    Thank you, it works!

    But how can do that:

    I have a chackbox. If the Checkbox is checked, the two spinboxes are Ratio. If i changed one slider, the other slider changed too. They both are Ratio to each other.

    Do you understand?

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    0
    • J Offline
      J Offline
      jsulm
      Lifetime Qt Champion
      wrote on 17 May 2016, 10:13 last edited by
      #15

      Not really. Should both QDoubleSpinbox have the same value if that checkbox is checked?

      https://forum.qt.io/topic/113070/qt-code-of-conduct

      ? 1 Reply Last reply 17 May 2016, 11:44
      0
      • J jsulm
        17 May 2016, 10:13

        Not really. Should both QDoubleSpinbox have the same value if that checkbox is checked?

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        A Former User
        wrote on 17 May 2016, 11:44 last edited by
        #16

        @jsulm
        They should have the value when:

        1. The Checkbox is checked and
        2. one slider is dragged. So than both checkboxes have the value from slider

        U understand?

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        • J Offline
          J Offline
          jsulm
          Lifetime Qt Champion
          wrote on 17 May 2016, 11:53 last edited by
          #17

          Unfortunately not:
          First version: "I have a chackbox. If the Checkbox is checked, the two spinboxes are Ratio. If i changed one slider, the other slider changed too. They both are Ratio to each other."

          Second version: "
          The Checkbox is checked and
          one slider is dragged. So than both checkboxes have the value from slider"

          In the first version you are talking about two spinboxes in the second version you are talking about two checkboxes. Sorry, but I'm lost...
          And you did not answer my question whether both spinboxes (I assume you really mean spinboxes) should have the same value if one of them is changed while checkbox is checked.

          https://forum.qt.io/topic/113070/qt-code-of-conduct

          ? 1 Reply Last reply 17 May 2016, 11:55
          0
          • J jsulm
            17 May 2016, 11:53

            Unfortunately not:
            First version: "I have a chackbox. If the Checkbox is checked, the two spinboxes are Ratio. If i changed one slider, the other slider changed too. They both are Ratio to each other."

            Second version: "
            The Checkbox is checked and
            one slider is dragged. So than both checkboxes have the value from slider"

            In the first version you are talking about two spinboxes in the second version you are talking about two checkboxes. Sorry, but I'm lost...
            And you did not answer my question whether both spinboxes (I assume you really mean spinboxes) should have the same value if one of them is changed while checkbox is checked.

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            A Former User
            wrote on 17 May 2016, 11:55 last edited by
            #18

            @jsulm
            Yes, sorry. I mean SpinBoxes...

            Your Question:

            Yes, both should have the same value when the ceckbox is checked:

               if (m_keepRatioCheckBox->isChecked())
               {
                  connect(sliderHeight, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
                  connect(sliderHeight, &QSlider::valueChanged, m_widthSpinBox, &QDoubleSpinBox::setValue);
                  connect(sliderWidth, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
                  connect(sliderWidth, &QSlider::valueChanged, m_widthSpinBox, &QDoubleSpinBox::setValue);
               }
            

            This won't work..

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            • J Offline
              J Offline
              jsulm
              Lifetime Qt Champion
              wrote on 17 May 2016, 12:01 last edited by
              #19

              What you could do: if, for example, sliderHeight is changed you do not set m_widthSpinBox directly, but instead you calculate the difference between m_hightSpinBox and its new value and add this difference (which can be negative) to m_widthSpinBox.
              You will need your own slots for that.

              https://forum.qt.io/topic/113070/qt-code-of-conduct

              ? 1 Reply Last reply 17 May 2016, 12:02
              0
              • J jsulm
                17 May 2016, 12:01

                What you could do: if, for example, sliderHeight is changed you do not set m_widthSpinBox directly, but instead you calculate the difference between m_hightSpinBox and its new value and add this difference (which can be negative) to m_widthSpinBox.
                You will need your own slots for that.

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                A Former User
                wrote on 17 May 2016, 12:02 last edited by
                #20

                @jsulm
                Can you make/Show an example, please?

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                • J Offline
                  J Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on 17 May 2016, 12:09 last edited by
                  #21

                  I did not test this code:

                  void MyClass::sliderHeightChanged(int value)
                  {
                      double diff = m_heightSpinBox->value - value;
                      m_heightSpinBox->setValue(value);
                      m_widthSpinBox->setValue(m_widthSpinBox->value + diff);
                  }
                  
                  void MyClass::sliderWidthChanged(int value)
                  {
                  
                      double diff = m_widthSpinBox->value - value;
                      m_widthSpinBox->setValue(value);
                      m_HeightSpinBox->setValue(m_heightSpinBox->value + diff);
                  }
                  
                  if (m_keepRatioCheckBox->isChecked())
                  {
                      connect(sliderHeight, &QSlider::valueChanged, this, &MyClass::sliderHeightChanged);
                      connect(sliderWidth, &QSlider::valueChanged, this, &MyClass::sliderWidthChanged);
                  }
                  

                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                  ? 3 Replies Last reply 17 May 2016, 12:54
                  0
                  • J jsulm
                    17 May 2016, 12:09

                    I did not test this code:

                    void MyClass::sliderHeightChanged(int value)
                    {
                        double diff = m_heightSpinBox->value - value;
                        m_heightSpinBox->setValue(value);
                        m_widthSpinBox->setValue(m_widthSpinBox->value + diff);
                    }
                    
                    void MyClass::sliderWidthChanged(int value)
                    {
                    
                        double diff = m_widthSpinBox->value - value;
                        m_widthSpinBox->setValue(value);
                        m_HeightSpinBox->setValue(m_heightSpinBox->value + diff);
                    }
                    
                    if (m_keepRatioCheckBox->isChecked())
                    {
                        connect(sliderHeight, &QSlider::valueChanged, this, &MyClass::sliderHeightChanged);
                        connect(sliderWidth, &QSlider::valueChanged, this, &MyClass::sliderWidthChanged);
                    }
                    
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                    A Former User
                    wrote on 17 May 2016, 12:54 last edited by
                    #22

                    @jsulm
                    I have written all the Code for the Dialog in a Header file..

                    1 Reply Last reply
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                    • J jsulm
                      17 May 2016, 12:09

                      I did not test this code:

                      void MyClass::sliderHeightChanged(int value)
                      {
                          double diff = m_heightSpinBox->value - value;
                          m_heightSpinBox->setValue(value);
                          m_widthSpinBox->setValue(m_widthSpinBox->value + diff);
                      }
                      
                      void MyClass::sliderWidthChanged(int value)
                      {
                      
                          double diff = m_widthSpinBox->value - value;
                          m_widthSpinBox->setValue(value);
                          m_HeightSpinBox->setValue(m_heightSpinBox->value + diff);
                      }
                      
                      if (m_keepRatioCheckBox->isChecked())
                      {
                          connect(sliderHeight, &QSlider::valueChanged, this, &MyClass::sliderHeightChanged);
                          connect(sliderWidth, &QSlider::valueChanged, this, &MyClass::sliderWidthChanged);
                      }
                      
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                      A Former User
                      wrote on 17 May 2016, 12:55 last edited by
                      #23

                      @jsulm
                      Where can i insert your Code?

                      class ResizeImageDialog : public QDialog
                      {
                      Q_OBJECT
                      
                      double         m_ratio;
                      
                      QLabel         *m_widthLabel;
                      QLabel         *m_hightLabel;
                      QDoubleSpinBox *m_widthSpinBox;
                      QDoubleSpinBox *m_hightSpinBox;
                      QRadioButton   *m_keepRatioCheckBox;
                      QPushButton    *m_okButton;
                      QPushButton    *m_cancelButton;
                      QSlider        *sliderWidth;
                      QSlider        *sliderHeight;
                      QHBoxLayout    *m_widthLayout;
                      QHBoxLayout    *m_hightLayout;
                      QHBoxLayout    *m_buttonLayout;
                      QVBoxLayout    *m_generalLayout;
                      
                      
                      public:
                      ResizeImageDialog(QWidget * parent = 0, double imageWidth = 100.0, double imageHight = 100.0) : QDialog(parent)
                      {
                         m_widthLabel = new QLabel("Breite");
                         m_hightLabel = new QLabel("Höhe");
                      
                         m_widthSpinBox = new QDoubleSpinBox;
                         m_widthSpinBox->setMaximum(1500);
                         m_widthSpinBox->setValue(imageWidth);
                      
                      
                         sliderHeight = new QSlider(Qt::Horizontal);
                         sliderHeight->setMaximum(1500);
                         sliderHeight->setMinimum(0);
                      
                      
                      
                      
                         sliderWidth = new QSlider(Qt::Horizontal);
                         sliderWidth->setMaximum(1500);
                         sliderWidth->setMinimum(0);
                      
                      
                         m_hightSpinBox = new QDoubleSpinBox;
                         m_hightSpinBox->setMaximum(1500);
                         m_hightSpinBox->setValue(imageHight);
                      
                         connect(sliderHeight, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
                         connect(sliderWidth, &QSlider::valueChanged, m_widthSpinBox, &QDoubleSpinBox::setValue);
                      
                         m_ratio = imageWidth / imageHight;
                      
                         m_keepRatioCheckBox = new QRadioButton("Keep ratio", this);
                         m_keepRatioCheckBox->setChecked(false);
                      
                      
                         if (m_keepRatioCheckBox->isChecked())
                         {
                            connect(sliderHeight, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
                            connect(sliderHeight, &QSlider::valueChanged, m_widthSpinBox, &QDoubleSpinBox::setValue);
                            connect(sliderWidth, &QSlider::valueChanged, m_hightSpinBox, &QDoubleSpinBox::setValue);
                            connect(sliderWidth, &QSlider::valueChanged, m_widthSpinBox, &QDoubleSpinBox::setValue);
                            m_hightSpinBox->setValue(25.8);
                         }
                      
                         
                         
                         
                         
                      
                         m_widthLayout = new QHBoxLayout;
                         m_widthLayout->addWidget(m_widthLabel);
                         m_widthLayout->addWidget(m_widthSpinBox);
                         m_widthLayout->addWidget(sliderWidth);
                      
                         m_hightLayout = new QHBoxLayout;
                         m_hightLayout->addWidget(m_hightLabel);
                         m_hightLayout->addWidget(m_hightSpinBox);
                         m_hightLayout->addWidget(sliderHeight);
                      
                         m_okButton = new QPushButton("Ok");
                         connect(m_okButton, SIGNAL(clicked()), this, SLOT(accept()));
                      
                         m_cancelButton = new QPushButton("Abbrechen");
                         connect(m_cancelButton, SIGNAL(clicked()), this, SLOT(reject()));
                      
                         m_buttonLayout = new QHBoxLayout;
                         m_buttonLayout->addStretch();
                         m_buttonLayout->addWidget(m_okButton);
                         m_buttonLayout->addWidget(m_cancelButton);
                      
                         m_generalLayout = new QVBoxLayout;
                         m_generalLayout->addLayout(m_widthLayout);
                         m_generalLayout->addLayout(m_hightLayout);
                         m_generalLayout->addWidget(m_keepRatioCheckBox);
                         m_generalLayout->addLayout(m_buttonLayout);
                         setLayout(m_generalLayout);
                      
                         setMaximumSize(500, 300);
                         resize(350, 100);
                         setModal(true);
                         //resize(670,630);
                         setWindowTitle(tr("Bildgröße ändern"));
                         setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
                      }
                      
                      static QPair<double, double> getNewSize(QWidget * parent = 0, double imageWidth = 100.0, double imageHight = 100.0)
                      {
                         ResizeImageDialog dlg(parent, imageWidth, imageHight);
                      
                         dlg.exec();
                      
                      
                      
                         QPair<double, double> size;
                         size.first  = dlg.m_widthSpinBox->value();
                         size.second = dlg.m_hightSpinBox->value();
                         return size;
                      }
                      };
                      
                      
                      #endif // PAGESTEXTEDIT_H
                      
                      
                      

                      A .cpp file is not there for the dialog

                      1 Reply Last reply
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                      • J jsulm
                        17 May 2016, 12:09

                        I did not test this code:

                        void MyClass::sliderHeightChanged(int value)
                        {
                            double diff = m_heightSpinBox->value - value;
                            m_heightSpinBox->setValue(value);
                            m_widthSpinBox->setValue(m_widthSpinBox->value + diff);
                        }
                        
                        void MyClass::sliderWidthChanged(int value)
                        {
                        
                            double diff = m_widthSpinBox->value - value;
                            m_widthSpinBox->setValue(value);
                            m_HeightSpinBox->setValue(m_heightSpinBox->value + diff);
                        }
                        
                        if (m_keepRatioCheckBox->isChecked())
                        {
                            connect(sliderHeight, &QSlider::valueChanged, this, &MyClass::sliderHeightChanged);
                            connect(sliderWidth, &QSlider::valueChanged, this, &MyClass::sliderWidthChanged);
                        }
                        
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                        A Former User
                        wrote on 17 May 2016, 12:57 last edited by
                        #24

                        @jsulm
                        Are there other methods for resizing an Image?

                        Maybe drag the Image in the Corners for resizing?

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                        0

                        23/24

                        17 May 2016, 12:55

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