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Items in QGraphicsScene are not movable

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  • sanojsubranS Offline
    sanojsubranS Offline
    sanojsubran
    wrote on last edited by sanojsubran
    #4

    Hi,

    ellipse = scene->addEllipse(100,100,100,100,blackpen,bluebrush);
    ellipse->setFlags(QGraphicsItem::ItemIsMovable);
    rect = scene->addRect(-10,50,100,100,blackpen,redbrush);
    rect->setFlags(QGraphicsItem::ItemIsMovable);

    I added these items to a custom graphics scene and the move operation works perfectly for me.

    Could you please share more info/code ?
    Also are you overriding the mouse events for the graphics scene class?

    Regards,
    San

    1 Reply Last reply
    1
    • faiszalkhanF Offline
      faiszalkhanF Offline
      faiszalkhan
      wrote on last edited by
      #5

      Hi, Yes I am overriding the mousePressEvent as follows. Whereas the constructor is empty.

      void Canvas::mousePressEvent(QGraphicsSceneMouseEvent *gevent)
      {

      /* Get the position of the mouse clicked */
      QPointF pressedPosition(gevent->scenePos());
      

      #ifdef DEBUG
      qDebug("Mouse has been pressed");

        qreal temp_x = gevent->scenePos().x();
        qDebug("The value of the Xcordinate for the mouse clicked is");
        qDebug()<<temp_x;
      
        qreal temp_y = gevent->scenePos().y();
        qDebug("The value of the Ycordinate for the mouse clicked is");
        qDebug()<<temp_y;
      

      #endif

      /* Create the state here */
      srstate = new StateItem(pressedPosition);
      mainWindowPtr->scene->addItem(srstate);
      srstate->setFlags(QGraphicsItem::ItemIsMovable);
      

      }

      Thanks!

      1 Reply Last reply
      0
      • sanojsubranS Offline
        sanojsubranS Offline
        sanojsubran
        wrote on last edited by
        #6

        Try adding the statement QGraphicsScene::mousePressEvent( event ); before the end of the function

        faiszalkhanF 1 Reply Last reply
        3
        • sanojsubranS sanojsubran

          Try adding the statement QGraphicsScene::mousePressEvent( event ); before the end of the function

          faiszalkhanF Offline
          faiszalkhanF Offline
          faiszalkhan
          wrote on last edited by
          #7

          @sanojsubran I tried that but it results in a compilation error.

          mrjjM 1 Reply Last reply
          0
          • faiszalkhanF faiszalkhan

            @sanojsubran I tried that but it results in a compilation error.

            mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by
            #8

            @faiszalkhan
            Hi
            Can you list that error ?
            Since its the base class that do the actual moving,
            its critical to call it so lets find out what was wrong ?

            faiszalkhanF 1 Reply Last reply
            1
            • mrjjM mrjj

              @faiszalkhan
              Hi
              Can you list that error ?
              Since its the base class that do the actual moving,
              its critical to call it so lets find out what was wrong ?

              faiszalkhanF Offline
              faiszalkhanF Offline
              faiszalkhan
              wrote on last edited by faiszalkhan
              #9

              @mrjj @sanojsubran It was my bad. The solution worked. However I'm not very sure as to what we did there :(

              1 Reply Last reply
              0
              • faiszalkhanF Offline
                faiszalkhanF Offline
                faiszalkhan
                wrote on last edited by faiszalkhan
                #10

                The problem is not completely solved. StateItem is a custom graphics item which inherits QGraphicsItem.
                The constructor of StateItem is as shown below,

                StateItem::StateItem(QPointF pos)
                {
                /* Get the position from the caller */
                drawPos = new QPointF(pos.x(), pos.y());

                //TODO: Set item as movable
                setFlags(QGraphicsItem::ItemIsMovable);

                }

                This graphics Item is displayed on the scene but still is not movable.

                Please help!
                Thanks!

                1 Reply Last reply
                0
                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #11

                  Hi,

                  Your original problem was that by not calling the base class method implementation, you don't get the behaviour from the base class.

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  2
                  • faiszalkhanF Offline
                    faiszalkhanF Offline
                    faiszalkhan
                    wrote on last edited by
                    #12

                    Since I am inheriting the QGraphicsItem in StateItem to create custom shape. Am I missing out something for setFlags(QGraphicsItem::ItemIsMovable); in the constructor to not work ?

                    Thanks

                    1 Reply Last reply
                    0
                    • mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #13

                      Hi
                      You might need
                      setFlag(QGraphicsItem::ItemIsMovable);
                      setFlag(QGraphicsItem::ItemIsSelectable);

                      If we look at
                      http://doc.qt.io/qt-5/qtwidgets-graphicsview-diagramscene-example.html

                      It all it does to flag the items.

                      faiszalkhanF 1 Reply Last reply
                      1
                      • mrjjM mrjj

                        Hi
                        You might need
                        setFlag(QGraphicsItem::ItemIsMovable);
                        setFlag(QGraphicsItem::ItemIsSelectable);

                        If we look at
                        http://doc.qt.io/qt-5/qtwidgets-graphicsview-diagramscene-example.html

                        It all it does to flag the items.

                        faiszalkhanF Offline
                        faiszalkhanF Offline
                        faiszalkhan
                        wrote on last edited by
                        #14

                        @mrjj said in Items in QGraphicsScene are not movable:

                        setFlag(QGraphicsItem::ItemIsMovable);
                        setFlag(QGraphicsItem::ItemIsSelectable);

                        Hi @mrjj , tried the same but still not working.

                        1 Reply Last reply
                        0
                        • mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #15

                          Ok. cant tell what is wrong then.
                          You might have overridden a virtual and forgot to call base class.

                          Have a look at the diagram sample and see if can spot anything you
                          did different.

                          Or try the StateItem in a default scene/view.

                          faiszalkhanF 1 Reply Last reply
                          0
                          • mrjjM mrjj

                            Ok. cant tell what is wrong then.
                            You might have overridden a virtual and forgot to call base class.

                            Have a look at the diagram sample and see if can spot anything you
                            did different.

                            Or try the StateItem in a default scene/view.

                            faiszalkhanF Offline
                            faiszalkhanF Offline
                            faiszalkhan
                            wrote on last edited by
                            #16

                            @mrjj I just have the constructor, paint function and bounding rect. The file is as follows,

                            StateItem::StateItem(QPointF pos)
                            {

                            /* Get the position from the caller */
                            drawPos = new QPointF(pos.x(), pos.y());
                            
                            //TODO: Set item as movable
                            

                            // setFlags(QGraphicsItem::ItemIsFocusable);
                            // setFlags(QGraphicsItem::ItemIsSelectable);
                            setFlags(QGraphicsItem::ItemIsMovable);

                            // QGraphicsItem::QGraphicsItem();
                            }

                            QRectF StateItem::boundingRect() const
                            {
                            //TODO: Return a rectangle of calculated size
                            qreal penWidth = 1;
                            return QRectF(-10 - penWidth / 2, -10 - penWidth / 2,
                            20 + penWidth, 20 + penWidth);

                            }

                            /* Explicit call to this function is not required */
                            void StateItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget widget)
                            {
                            /
                            Set the pen */
                            QPen blackpen(Qt::black);
                            blackpen.setWidth(2);
                            painter->setPen(blackpen);

                            /* Set colour of the state */
                            QColor statecolor(229,231,233);
                            QBrush statebrush(statecolor);
                            painter->setBrush(statebrush);
                            
                            /* Draw state item */
                            painter->drawRoundedRect(drawPos->x(),drawPos->y(),100,50,8,8); //x,y,width,height,xradius,yradius
                            
                            QPoint p(drawPos->x(),(drawPos->y() + 10));
                            QPoint q((drawPos->x() + 100), (drawPos->y() + 10));
                            QLine stateLine(p,q);
                            painter->drawLine(stateLine);
                            

                            // QGraphicsItem::paint(painter,option,widget);

                            }

                            1 Reply Last reply
                            0
                            • mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by
                              #17

                              Hi
                              Dont it need to be selectable to be moveable ?
                              It all seems fine
                              try use the DiagramTextItem from the diagram sample (its available directly in Creator)

                              If that cant move, it means its your view or scene.

                              //! [0]
                              DiagramTextItem::DiagramTextItem(QGraphicsItem *parent)
                                  : QGraphicsTextItem(parent)
                              {
                                  setFlag(QGraphicsItem::ItemIsMovable); // BOTH 
                                  setFlag(QGraphicsItem::ItemIsSelectable);
                              }
                              //! [0]
                              
                              //! [1]
                              QVariant DiagramTextItem::itemChange(GraphicsItemChange change,
                                                   const QVariant &value)
                              {
                                  if (change == QGraphicsItem::ItemSelectedHasChanged)
                                      emit selectedChange(this);
                                  return value;
                              }
                              //! [1]
                              
                              //! [2]
                              void DiagramTextItem::focusOutEvent(QFocusEvent *event)
                              {
                                  setTextInteractionFlags(Qt::NoTextInteraction);
                                  emit lostFocus(this);
                                  QGraphicsTextItem::focusOutEvent(event);
                              }
                              //! [2]
                              
                              //! [5]
                              void DiagramTextItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event)
                              {
                                  if (textInteractionFlags() == Qt::NoTextInteraction)
                                      setTextInteractionFlags(Qt::TextEditorInteraction);
                                  QGraphicsTextItem::mouseDoubleClickEvent(event);
                              }
                              
                              faiszalkhanF 1 Reply Last reply
                              0
                              • mrjjM mrjj

                                Hi
                                Dont it need to be selectable to be moveable ?
                                It all seems fine
                                try use the DiagramTextItem from the diagram sample (its available directly in Creator)

                                If that cant move, it means its your view or scene.

                                //! [0]
                                DiagramTextItem::DiagramTextItem(QGraphicsItem *parent)
                                    : QGraphicsTextItem(parent)
                                {
                                    setFlag(QGraphicsItem::ItemIsMovable); // BOTH 
                                    setFlag(QGraphicsItem::ItemIsSelectable);
                                }
                                //! [0]
                                
                                //! [1]
                                QVariant DiagramTextItem::itemChange(GraphicsItemChange change,
                                                     const QVariant &value)
                                {
                                    if (change == QGraphicsItem::ItemSelectedHasChanged)
                                        emit selectedChange(this);
                                    return value;
                                }
                                //! [1]
                                
                                //! [2]
                                void DiagramTextItem::focusOutEvent(QFocusEvent *event)
                                {
                                    setTextInteractionFlags(Qt::NoTextInteraction);
                                    emit lostFocus(this);
                                    QGraphicsTextItem::focusOutEvent(event);
                                }
                                //! [2]
                                
                                //! [5]
                                void DiagramTextItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event)
                                {
                                    if (textInteractionFlags() == Qt::NoTextInteraction)
                                        setTextInteractionFlags(Qt::TextEditorInteraction);
                                    QGraphicsTextItem::mouseDoubleClickEvent(event);
                                }
                                
                                faiszalkhanF Offline
                                faiszalkhanF Offline
                                faiszalkhan
                                wrote on last edited by
                                #18

                                @mrjj Dont it need to be selectable to be moveable ?

                                No, Only setting it as moveable also works. I have standard QGraphicsRectItem and QGraphicsEllipseItem also in the same scene which are moving. So I don't think its the view or the scene.

                                :'(

                                mrjjM 1 Reply Last reply
                                0
                                • faiszalkhanF faiszalkhan

                                  @mrjj Dont it need to be selectable to be moveable ?

                                  No, Only setting it as moveable also works. I have standard QGraphicsRectItem and QGraphicsEllipseItem also in the same scene which are moving. So I don't think its the view or the scene.

                                  :'(

                                  mrjjM Offline
                                  mrjjM Offline
                                  mrjj
                                  Lifetime Qt Champion
                                  wrote on last edited by
                                  #19

                                  @faiszalkhan
                                  Ok, there is something i dont see then. :)
                                  if you provide both StateItem.h and cpp
                                  i can try run it and see.

                                  faiszalkhanF 1 Reply Last reply
                                  0
                                  • sanojsubranS Offline
                                    sanojsubranS Offline
                                    sanojsubran
                                    wrote on last edited by
                                    #20

                                    Hi,

                                    Comment your overriden paint method for StateItem and check whether it is working.

                                    Also please tell how you are updating the variable "drawPos".

                                    Regards,
                                    San

                                    1 Reply Last reply
                                    0
                                    • mrjjM mrjj

                                      @faiszalkhan
                                      Ok, there is something i dont see then. :)
                                      if you provide both StateItem.h and cpp
                                      i can try run it and see.

                                      faiszalkhanF Offline
                                      faiszalkhanF Offline
                                      faiszalkhan
                                      wrote on last edited by faiszalkhan
                                      #21
                                      This post is deleted!
                                      1 Reply Last reply
                                      0
                                      • faiszalkhanF Offline
                                        faiszalkhanF Offline
                                        faiszalkhan
                                        wrote on last edited by
                                        #22
                                        This post is deleted!
                                        1 Reply Last reply
                                        0
                                        • faiszalkhanF Offline
                                          faiszalkhanF Offline
                                          faiszalkhan
                                          wrote on last edited by
                                          #23

                                          I had previously given a static bounding rect value as the previous implementation was static. Now that the value is dynamic I had not changed the contents of the bounding rect as the size has not changed from the previous implementation.

                                          Making the changes in the bounding rect solved the problem.

                                          Thanks a lot to @mrjj @sanojsubran @SGaist !

                                          1 Reply Last reply
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