Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. QGraphicsView 90 degree Rotation
Forum Updated to NodeBB v4.3 + New Features

QGraphicsView 90 degree Rotation

Scheduled Pinned Locked Moved Unsolved General and Desktop
25 Posts 4 Posters 11.6k Views 3 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • ? Offline
    ? Offline
    A Former User
    wrote on last edited by A Former User
    #4

    See example code below.

    customgraphicsview.h

    #ifndef CUSTOMGRAPHICSVIEW_H
    #define CUSTOMGRAPHICSVIEW_H
    
    #include <QGraphicsView>
    
    class CustomGraphicsView : public QGraphicsView
    {
        Q_OBJECT
    public:
        explicit CustomGraphicsView(QWidget *parent = nullptr);
        void reset();
    
    protected:
        void wheelEvent(QWheelEvent* event) override;
    
    private:
        void updateTransform();
        double m_scale = 1.0;
        double m_angle = 0.0;
    };
    
    #endif // CUSTOMGRAPHICSVIEW_H
    

    customgraphicsview.cpp

    #include "customgraphicsview.h"
    #include <QBrush>
    #include <QColor>
    #include <QWheelEvent>
    
    CustomGraphicsView::CustomGraphicsView(QWidget *parent)
        : QGraphicsView(parent)
    {
        setBackgroundBrush(QBrush(QColor("grey")));
    }
    
    void CustomGraphicsView::reset()
    {
        m_scale = 1.0;
        m_angle = 0.0;
        updateTransform();
    }
    
    void CustomGraphicsView::wheelEvent(QWheelEvent *event)
    {
        auto const delta = (event->delta() <0.0) ? -1.0 : 1.0;
        if (event->modifiers() & Qt::ShiftModifier)
            m_scale += 0.1 * delta;
        else
            m_angle += 15.0 * delta;
        updateTransform();
    }
    
    void CustomGraphicsView::updateTransform()
    {
        QTransform t;
        t.scale(m_scale, m_scale);
        t.rotate(m_angle);
        setTransform(t);
    }
    
    keksi venksiK 1 Reply Last reply
    4
    • ? A Former User

      See example code below.

      customgraphicsview.h

      #ifndef CUSTOMGRAPHICSVIEW_H
      #define CUSTOMGRAPHICSVIEW_H
      
      #include <QGraphicsView>
      
      class CustomGraphicsView : public QGraphicsView
      {
          Q_OBJECT
      public:
          explicit CustomGraphicsView(QWidget *parent = nullptr);
          void reset();
      
      protected:
          void wheelEvent(QWheelEvent* event) override;
      
      private:
          void updateTransform();
          double m_scale = 1.0;
          double m_angle = 0.0;
      };
      
      #endif // CUSTOMGRAPHICSVIEW_H
      

      customgraphicsview.cpp

      #include "customgraphicsview.h"
      #include <QBrush>
      #include <QColor>
      #include <QWheelEvent>
      
      CustomGraphicsView::CustomGraphicsView(QWidget *parent)
          : QGraphicsView(parent)
      {
          setBackgroundBrush(QBrush(QColor("grey")));
      }
      
      void CustomGraphicsView::reset()
      {
          m_scale = 1.0;
          m_angle = 0.0;
          updateTransform();
      }
      
      void CustomGraphicsView::wheelEvent(QWheelEvent *event)
      {
          auto const delta = (event->delta() <0.0) ? -1.0 : 1.0;
          if (event->modifiers() & Qt::ShiftModifier)
              m_scale += 0.1 * delta;
          else
              m_angle += 15.0 * delta;
          updateTransform();
      }
      
      void CustomGraphicsView::updateTransform()
      {
          QTransform t;
          t.scale(m_scale, m_scale);
          t.rotate(m_angle);
          setTransform(t);
      }
      
      keksi venksiK Offline
      keksi venksiK Offline
      keksi venksi
      wrote on last edited by keksi venksi
      #5

      @Wieland said in QGraphicsView 90 degree Rotation:

      void CustomGraphicsView::updateTransform()
      {
      QTransform t;
      t.scale(m_scale, m_scale);
      t.rotate(m_angle);
      setTransform(t);
      }

      Thanks for your kind reply with full code .
      When i try to apply this code the code scales the view in x direction . In my caes if i rotate my view 90 clockwise it should scale in Y direction .

      Means in normal mode when i try to zoom , the view should expand by width mean while when i rotate and zoom in that rotated view it should expand in height

      1 Reply Last reply
      0
      • keksi venksiK Offline
        keksi venksiK Offline
        keksi venksi
        wrote on last edited by keksi venksi
        #6

        A Short note to all regarding this issue .

        Currently I have achieved the 90 degree clockwise rotation thourgh

        QTransform transform1;
        transform1.rotate(90);
        // Set the Views transformation
        view()->setTransform(transform1);
        

        Rotation works fine

        I try to achieve zooming functionality using fitInView()

        Normal case
        fitInView(0,0,calcValue,viewRect.height())

        In this case , zooming works fine

        90 rotation case
        fitInView(0,0,viewRect.weight(),calcValue)

        In this case , zooming is not not achieved . Please help me .

        I dont want to use scale() method because I set some restrictions in zooming through calcValue depending on the delta of the wheelEvent

        1 Reply Last reply
        0
        • keksi venksiK Offline
          keksi venksiK Offline
          keksi venksi
          wrote on last edited by
          #7

          Please some one look into this issue . Timely helps are really appreciable .

          1 Reply Last reply
          0
          • ? Offline
            ? Offline
            A Former User
            wrote on last edited by
            #8

            Sry, I think I don't understand exactly what you want to do. Maybe you can draw a few pictures to help my imagination :)

            keksi venksiK 1 Reply Last reply
            0
            • keksi venksiK Offline
              keksi venksiK Offline
              keksi venksi
              wrote on last edited by keksi venksi
              #9

              I tried to add image in my post but i cant .
              Can you help me on it

              ? 1 Reply Last reply
              0
              • ? A Former User

                Sry, I think I don't understand exactly what you want to do. Maybe you can draw a few pictures to help my imagination :)

                keksi venksiK Offline
                keksi venksiK Offline
                keksi venksi
                wrote on last edited by keksi venksi
                #10

                @Wieland

                X Mode

                **-----------------------------|

                -----------------------------**
                Width

                This is how I locate my graphicsview at initial stage

                Im achieving zooming through wheel event .

                I have currentZoomingWidth level if the delta is +ve then i will increase the currentZoomingWidth level and if it is -ve then i will decrease the currentZoomingWidth
                So finally i find the width to expand (currentZoomingWidth )

                wheelvent()
                {
                fitInVieW(0,0,currentZoomingWidth ,view().geometry().height())
                }
                So zooming is achieved through fitInView()

                Y MODE
                | |
                | |
                | |
                | |
                | | Height
                | |
                | |

                Width

                Like same case im calculating the currentZoomingWidth depending upon the delta and applying it to fitInView() height

                wheelvent()
                {
                fitInVieW(0,0 ,view().geometry().width(),currentZoomingWidth)
                }

                In X mode i apply the calculated zoom factor to width and in Y mode I apply it to the height

                My problem is In X mode the fit in view works fine but in Y mode it works weird

                1 Reply Last reply
                0
                • keksi venksiK keksi venksi

                  I tried to add image in my post but i cant .
                  Can you help me on it

                  ? Offline
                  ? Offline
                  A Former User
                  wrote on last edited by
                  #11

                  @keksi-venksi said in QGraphicsView 90 degree Rotation:

                  I tried to add image in my post but i cant .
                  Can you help me on it

                  Hi! The image-upload feature on our forum is broken, you might see the picture but other users don't. Please upload your image to a image hoster of your choice (e.g. postimage.org) and embed the pic here with the following markup: ![alternate text](image-url). See also How to insert image on this forum and Hitchhiker's Visual Guide to the Qt Forum.

                  keksi venksiK 1 Reply Last reply
                  1
                  • ? A Former User

                    @keksi-venksi said in QGraphicsView 90 degree Rotation:

                    I tried to add image in my post but i cant .
                    Can you help me on it

                    Hi! The image-upload feature on our forum is broken, you might see the picture but other users don't. Please upload your image to a image hoster of your choice (e.g. postimage.org) and embed the pic here with the following markup: ![alternate text](image-url). See also How to insert image on this forum and Hitchhiker's Visual Guide to the Qt Forum.

                    keksi venksiK Offline
                    keksi venksiK Offline
                    keksi venksi
                    wrote on last edited by keksi venksi
                    #12

                    @Wieland

                    I have explained my query in my previous post . Please give your suggestions
                    graphicsview

                    Any how i have added the image here .This is how my graphicsview rotated .
                    Now i wanna apply zooming functionality using fitinview in this 90 degree rotated graphicsview .

                    This is how Y Mode looks

                    kshegunovK 1 Reply Last reply
                    0
                    • keksi venksiK keksi venksi

                      @Wieland

                      I have explained my query in my previous post . Please give your suggestions
                      graphicsview

                      Any how i have added the image here .This is how my graphicsview rotated .
                      Now i wanna apply zooming functionality using fitinview in this 90 degree rotated graphicsview .

                      This is how Y Mode looks

                      kshegunovK Offline
                      kshegunovK Offline
                      kshegunov
                      Moderators
                      wrote on last edited by
                      #13

                      Use two QTransform objects - one for rotation and one for scaling, then multiply them in the proper order (the order of multiplication matters as scaling and rotation don't commute). After that apply your transform to whatever you need.

                      Read and abide by the Qt Code of Conduct

                      keksi venksiK 1 Reply Last reply
                      0
                      • kshegunovK kshegunov

                        Use two QTransform objects - one for rotation and one for scaling, then multiply them in the proper order (the order of multiplication matters as scaling and rotation don't commute). After that apply your transform to whatever you need.

                        keksi venksiK Offline
                        keksi venksiK Offline
                        keksi venksi
                        wrote on last edited by
                        #14

                        @kshegunov
                        Thanks for your reply .
                        Can you give some example code .

                        kshegunovK 1 Reply Last reply
                        0
                        • keksi venksiK keksi venksi

                          @kshegunov
                          Thanks for your reply .
                          Can you give some example code .

                          kshegunovK Offline
                          kshegunovK Offline
                          kshegunov
                          Moderators
                          wrote on last edited by
                          #15
                          QTransform rotation;
                          rotation.rotate(90);
                          
                          QTransform scaling;
                          scaling.scale(0.5, 1);
                          
                          setTransform(rotation * scaling);
                          // Or
                          QVector2D vector;
                          vector = rotation * scaling * vector;
                          

                          Modify according to your needs.

                          Read and abide by the Qt Code of Conduct

                          keksi venksiK 1 Reply Last reply
                          1
                          • kshegunovK kshegunov
                            QTransform rotation;
                            rotation.rotate(90);
                            
                            QTransform scaling;
                            scaling.scale(0.5, 1);
                            
                            setTransform(rotation * scaling);
                            // Or
                            QVector2D vector;
                            vector = rotation * scaling * vector;
                            

                            Modify according to your needs.

                            keksi venksiK Offline
                            keksi venksiK Offline
                            keksi venksi
                            wrote on last edited by keksi venksi
                            #16

                            @kshegunov

                            Thanks for your reply .

                            In my case I dont want to use scale to zoom

                            I wish to use fitInView() to achieve zoom.

                            In short note after applying transform (rotate 90 degree) fitInView() does not works fine . I want fitInView() to do zoom

                            keksi venksiK 1 Reply Last reply
                            0
                            • keksi venksiK keksi venksi

                              @kshegunov

                              Thanks for your reply .

                              In my case I dont want to use scale to zoom

                              I wish to use fitInView() to achieve zoom.

                              In short note after applying transform (rotate 90 degree) fitInView() does not works fine . I want fitInView() to do zoom

                              keksi venksiK Offline
                              keksi venksiK Offline
                              keksi venksi
                              wrote on last edited by keksi venksi
                              #17

                              @keksi-venksi

                              Can any one help me on it .
                              Helps are really appreciable

                              keksi venksiK 1 Reply Last reply
                              0
                              • ? Offline
                                ? Offline
                                A Former User
                                wrote on last edited by
                                #18

                                customgraphicsview.h

                                #ifndef CUSTOMGRAPHICSVIEW_H
                                #define CUSTOMGRAPHICSVIEW_H
                                
                                #include <QGraphicsView>
                                
                                class CustomGraphicsView : public QGraphicsView
                                {
                                    Q_OBJECT
                                public:
                                    enum class Mode
                                    {
                                        x,
                                        y
                                    };
                                
                                    explicit CustomGraphicsView(QWidget *parent = nullptr);
                                    void reset();
                                    void fit();
                                    void setMode(Mode mode);
                                
                                protected:
                                    void wheelEvent(QWheelEvent* event) override;
                                
                                private:
                                    void updateTransform();
                                    Mode m_mode = Mode::x;
                                    double m_scale = 1.0;
                                };
                                
                                #endif // CUSTOMGRAPHICSVIEW_H
                                

                                customgraphicsview.cpp

                                #include "customgraphicsview.h"
                                #include <QBrush>
                                #include <QColor>
                                #include <QWheelEvent>
                                #include <QDebug>
                                
                                CustomGraphicsView::CustomGraphicsView(QWidget *parent)
                                    : QGraphicsView(parent)
                                {
                                    setBackgroundBrush(QBrush(QColor("grey")));
                                }
                                
                                void CustomGraphicsView::reset()
                                {
                                    m_mode = Mode::x;
                                    m_scale = 1.0;
                                    updateTransform();
                                }
                                
                                void CustomGraphicsView::fit()
                                {
                                    auto const r = scene()->itemsBoundingRect();
                                    switch (m_mode) {
                                    case Mode::x: {
                                        double f1 = width() / (r.width() + 2);
                                        double f2 = height() / (r.height() + 2);
                                        m_scale = qMin(f1,f2);
                                        updateTransform();
                                        break;
                                    }
                                    case Mode::y: {
                                        double f1 = height() / (r.width() + 2);
                                        double f2 = width() / (r.height() + 2);
                                        m_scale = qMin(f1,f2);
                                        updateTransform();
                                        break;
                                    }
                                    }
                                }
                                
                                void CustomGraphicsView::setMode(CustomGraphicsView::Mode mode)
                                {
                                    if (m_mode == mode)
                                        return;
                                    m_mode = mode;
                                    updateTransform();
                                }
                                
                                void CustomGraphicsView::wheelEvent(QWheelEvent *event)
                                {
                                    auto const delta = (event->delta() <0.0) ? -1.0 : 1.0;
                                    m_scale += 0.1 * delta;
                                    updateTransform();
                                }
                                
                                void CustomGraphicsView::updateTransform()
                                {
                                    QTransform t;
                                    if (m_mode == Mode::y)
                                        t.rotate(90);
                                    t.scale(m_scale, m_scale);
                                    setTransform(t);
                                }
                                
                                1 Reply Last reply
                                1
                                • keksi venksiK keksi venksi

                                  @keksi-venksi

                                  Can any one help me on it .
                                  Helps are really appreciable

                                  keksi venksiK Offline
                                  keksi venksiK Offline
                                  keksi venksi
                                  wrote on last edited by
                                  #19

                                  @keksi-venksi

                                  I would like to continue with this thread

                                  in the normal mode im using view->fitInView(rect.x(),0,rect.width(),30)

                                  in the 90 degree rotated mode im using view->fitInView(0,rect.y(),30,rect.height())

                                  I have tried with different combinations of fitInView for 90 degree rotataion Nothing works

                                  Can any one suggest me the coordinates for the fitInView() for the rotated view

                                  Help me on it

                                  ? 1 Reply Last reply
                                  0
                                  • keksi venksiK keksi venksi

                                    @keksi-venksi

                                    I would like to continue with this thread

                                    in the normal mode im using view->fitInView(rect.x(),0,rect.width(),30)

                                    in the 90 degree rotated mode im using view->fitInView(0,rect.y(),30,rect.height())

                                    I have tried with different combinations of fitInView for 90 degree rotataion Nothing works

                                    Can any one suggest me the coordinates for the fitInView() for the rotated view

                                    Help me on it

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

                                    @keksi-venksi Please try the code above that I just posted. If I understood you right, then it should meet your requirements :)

                                    keksi venksiK 1 Reply Last reply
                                    0
                                    • ? A Former User

                                      @keksi-venksi Please try the code above that I just posted. If I understood you right, then it should meet your requirements :)

                                      keksi venksiK Offline
                                      keksi venksiK Offline
                                      keksi venksi
                                      wrote on last edited by
                                      #21

                                      @Wieland
                                      @Wieland

                                      Thanks for your reply

                                      I am using fitInView in many places in my project to work stable . So I would like to get some suggestions for fitInView() coordinates

                                      ? 1 Reply Last reply
                                      0
                                      • keksi venksiK keksi venksi

                                        @Wieland
                                        @Wieland

                                        Thanks for your reply

                                        I am using fitInView in many places in my project to work stable . So I would like to get some suggestions for fitInView() coordinates

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

                                        @keksi-venksi said in QGraphicsView 90 degree Rotation:

                                        I am using fitInView in many places in my project to work stable . So I would like to get some suggestions for fitInView() coordinates

                                        This is probably my last posting here because I think I can't help you. Have you seen my code above? The fit() function? It does just what you want, look:

                                        1 Reply Last reply
                                        1
                                        • keksi venksiK Offline
                                          keksi venksiK Offline
                                          keksi venksi
                                          wrote on last edited by keksi venksi
                                          #23

                                          Hi

                                          Thanks for your reply

                                          In this example in fit method you are trying it to fit the view in the frame when we click a button but my case i have used fitInView() while zooming .So it should adjust the view with the zooming delta

                                          So when ever we zoom fitInView() should be adjusted accordingly to the scene and update the scene as well

                                          keksi venksiK 1 Reply Last reply
                                          0

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved