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Signal/Slots doesn't work with QSlider and QDoubleSpinBox

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signals&slotsqsliderqdoublespinbox
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  • JKSHJ Offline
    JKSHJ Offline
    JKSH
    Moderators
    wrote on last edited by
    #13

    See http://doc.qt.io/qt-5/signalsandslots-syntaxes.html#type-checking-and-implicit-type-conversions -- it uses exactly QSlider and QDoubleSpinBox in an example, and explains why it "doesn't work" with the old connection style.

    Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

    1 Reply Last reply
    3
    • SGaistS SGaist

      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);
      
      ? Offline
      ? Offline
      A Former User
      wrote on 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?

      1 Reply Last reply
      0
      • jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on 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
        0
        • jsulmJ jsulm

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

          ? Offline
          ? Offline
          A Former User
          wrote on 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?

          1 Reply Last reply
          0
          • jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on 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
            0
            • jsulmJ jsulm

              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.

              ? Offline
              ? Offline
              A Former User
              wrote on 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..

              1 Reply Last reply
              0
              • jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on 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
                0
                • jsulmJ jsulm

                  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.

                  ? Offline
                  ? Offline
                  A Former User
                  wrote on last edited by
                  #20

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

                  1 Reply Last reply
                  0
                  • jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on 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
                    0
                    • jsulmJ jsulm

                      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);
                      }
                      
                      ? Offline
                      ? Offline
                      A Former User
                      wrote on last edited by
                      #22

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

                      1 Reply Last reply
                      0
                      • jsulmJ jsulm

                        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);
                        }
                        
                        ? Offline
                        ? Offline
                        A Former User
                        wrote on 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
                        0
                        • jsulmJ jsulm

                          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);
                          }
                          
                          ? Offline
                          ? Offline
                          A Former User
                          wrote on last edited by
                          #24

                          @jsulm
                          Are there other methods for resizing an Image?

                          Maybe drag the Image in the Corners for resizing?

                          1 Reply Last reply
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