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highlight QGraphicsItem

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  • mrjjM mrjj

    Hi
    What about just subclass QGraphicsItem and paint it yourself

    class SimpleItem : public QGraphicsItem
    {
    public:
           void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
                   QWidget *widget)
        {
        draw the lines / with or without highlight
        }
    };
    
    U Offline
    U Offline
    user4592357
    wrote on last edited by
    #3

    @mrjj
    there i draw without the highlight. it's okay.
    for hoverEnterEvent i need to draw WITH highlight

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #4

      Hi,

      You can trigger a repaint in the hoverEnterEvent.

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

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      • SGaistS SGaist

        Hi,

        You can trigger a repaint in the hoverEnterEvent.

        U Offline
        U Offline
        user4592357
        wrote on last edited by
        #5

        @SGaist
        yes, but how should i draw a "border" around the line?

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #6

          Paint a rectangle that is slightly bigger that the geometry of your widget.

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

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          • U user4592357

            @SGaist
            yes, but how should i draw a "border" around the line?

            K Offline
            K Offline
            kenchan
            wrote on last edited by
            #7

            @user4592357 the same draw function needs to know when it needs to draw the highlight or just the line... how you do that depends on details of your implementation which you have not shared with us yet. I am sure you can figure some way to do it though :-).

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            • K kenchan

              @user4592357 the same draw function needs to know when it needs to draw the highlight or just the line... how you do that depends on details of your implementation which you have not shared with us yet. I am sure you can figure some way to do it though :-).

              U Offline
              U Offline
              user4592357
              wrote on last edited by
              #8

              @kenchan
              it is in Python, sorry. my tries are in vain:

              class Item(QGraphicsItem):
              
                  def __init__(self, x, y):
                      super(ErrorItem, self).__init__()
                      self.__x = x
                      self.__y = y
              
                      self.__hovered = False
              
                      self.setAcceptHoverEvents(True)
              
                  def paint(self, painter, option, widget):
                      pen = QPen(Qt.red)
                      pen.setWidth(4)
                      painter.setPen(pen)
              
                      painter.drawLine(QPoint(0, 0), QPoint(100, 100))
                      painter.drawLine(QPoint(0, 100), QPoint(100, 0))
              
                      if self.__hovered:
                          # what should go here?
                          pen.setColor(Qt.white)
                          pen.setWidth(8)
                          self.__hovered = False
                          # painter.drawLine(QPoint(-50, -50), QPoint(103, 103))
              
                  def boundingRect(self):
                      return QRectF(0, 0, 100, 100)
              
                  def hoverEnterEvent(self, event):
                      # self.setGraphicsEffect(QGraphicsColorizeEffect())
                      self.__hovered = True
                      
                  def hoverLeaveEvent(self, event):
                      self.setGraphicsEffect(None)
              
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              • U user4592357

                @kenchan
                it is in Python, sorry. my tries are in vain:

                class Item(QGraphicsItem):
                
                    def __init__(self, x, y):
                        super(ErrorItem, self).__init__()
                        self.__x = x
                        self.__y = y
                
                        self.__hovered = False
                
                        self.setAcceptHoverEvents(True)
                
                    def paint(self, painter, option, widget):
                        pen = QPen(Qt.red)
                        pen.setWidth(4)
                        painter.setPen(pen)
                
                        painter.drawLine(QPoint(0, 0), QPoint(100, 100))
                        painter.drawLine(QPoint(0, 100), QPoint(100, 0))
                
                        if self.__hovered:
                            # what should go here?
                            pen.setColor(Qt.white)
                            pen.setWidth(8)
                            self.__hovered = False
                            # painter.drawLine(QPoint(-50, -50), QPoint(103, 103))
                
                    def boundingRect(self):
                        return QRectF(0, 0, 100, 100)
                
                    def hoverEnterEvent(self, event):
                        # self.setGraphicsEffect(QGraphicsColorizeEffect())
                        self.__hovered = True
                        
                    def hoverLeaveEvent(self, event):
                        self.setGraphicsEffect(None)
                
                K Offline
                K Offline
                kenchan
                wrote on last edited by kenchan
                #9

                @user4592357 Sorry I don't develop Qt with Python...
                Maybe you could put the line drawing bits after the if statement and make that just change the colour and the thickness?
                Since you can draw the line normally then that should work as before, right?
                The next issue will be if your hovered flag is getting changed when the event is fired. Can you debug that to check it?
                Finally i guess you will want to force the scene to redraw, if that is the problem you are seeing.
                I would have thought that the scene would be redrawn when the hover events happen?
                I believe the default implementation of hoveredEnterEvent() function just calls update(). Maybe you should call update() or something?
                I think you should reset the hovered flag to false in the hoverLeaveEvent so it only happens when you are actually hovering over it :-)

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                • K kenchan

                  @user4592357 Sorry I don't develop Qt with Python...
                  Maybe you could put the line drawing bits after the if statement and make that just change the colour and the thickness?
                  Since you can draw the line normally then that should work as before, right?
                  The next issue will be if your hovered flag is getting changed when the event is fired. Can you debug that to check it?
                  Finally i guess you will want to force the scene to redraw, if that is the problem you are seeing.
                  I would have thought that the scene would be redrawn when the hover events happen?
                  I believe the default implementation of hoveredEnterEvent() function just calls update(). Maybe you should call update() or something?
                  I think you should reset the hovered flag to false in the hoverLeaveEvent so it only happens when you are actually hovering over it :-)

                  U Offline
                  U Offline
                  user4592357
                  wrote on last edited by
                  #10

                  @kenchan
                  drawing the line thicker isn't a problem, but i don't know how to draw a red line (normal) + the highlight (outline) around it which is white

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                  • U user4592357

                    @kenchan
                    drawing the line thicker isn't a problem, but i don't know how to draw a red line (normal) + the highlight (outline) around it which is white

                    K Offline
                    K Offline
                    kenchan
                    wrote on last edited by
                    #11

                    @user4592357
                    if you can draw it one way you can draw it the other way right?
                    So what exactly is the problem now then, the events are not working? the events work but your draw functions is not getting called when expect?

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                    • K kenchan

                      @user4592357
                      if you can draw it one way you can draw it the other way right?
                      So what exactly is the problem now then, the events are not working? the events work but your draw functions is not getting called when expect?

                      U Offline
                      U Offline
                      user4592357
                      wrote on last edited by
                      #12

                      @kenchan
                      as you can see in code, i set a boolean in hover event and in paint() check - if it's hovered draw outline, but it doesn't. i also tried to call update() inside hoverEnterEvent - still no luck

                      K 2 Replies Last reply
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                      • U user4592357

                        @kenchan
                        drawing the line thicker isn't a problem, but i don't know how to draw a red line (normal) + the highlight (outline) around it which is white

                        K Offline
                        K Offline
                        kenchan
                        wrote on last edited by
                        #13

                        @user4592357
                        What don't you understand about how to draw it?
                        If you want an outline around a line the easiest way is to draw a thin line on top of a thicker line using the same two points.
                        You draw the thick one first then you draw the thin one on top. If you want to make absolutely sure that the thin one is on top you can set the z value of it to be above the thick one.

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                        • U user4592357

                          @kenchan
                          as you can see in code, i set a boolean in hover event and in paint() check - if it's hovered draw outline, but it doesn't. i also tried to call update() inside hoverEnterEvent - still no luck

                          K Offline
                          K Offline
                          kenchan
                          wrote on last edited by
                          #14

                          @user4592357
                          And does you hovered flag actually get set?

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                          • U user4592357

                            @kenchan
                            as you can see in code, i set a boolean in hover event and in paint() check - if it's hovered draw outline, but it doesn't. i also tried to call update() inside hoverEnterEvent - still no luck

                            K Offline
                            K Offline
                            kenchan
                            wrote on last edited by kenchan
                            #15

                            @user4592357
                            Are you adding the pen thickness to your bounding rect?
                            Also, I think you must call prepareGeometyChange() if you change the shape or size of the bounding box etc.
                            You usually call this in a setting function that results in a change in shape. In your case you probably want to do it in your event function.

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                            • K kenchan

                              @user4592357
                              And does you hovered flag actually get set?

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                              user4592357
                              wrote on last edited by
                              #16

                              @kenchan
                              z value of what? QLine?

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                              • U user4592357

                                @kenchan
                                z value of what? QLine?

                                K Offline
                                K Offline
                                kenchan
                                wrote on last edited by
                                #17

                                @user4592357
                                Ah, sorry that is a property of your graphics item :-) no, I think just the draw order should work for the painter.

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                                • U user4592357

                                  @kenchan
                                  z value of what? QLine?

                                  K Offline
                                  K Offline
                                  kenchan
                                  wrote on last edited by
                                  #18

                                  @user4592357
                                  So, did you have any luck with it yet?

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                                  • K kenchan

                                    @user4592357
                                    So, did you have any luck with it yet?

                                    U Offline
                                    U Offline
                                    user4592357
                                    wrote on last edited by
                                    #19

                                    @kenchan
                                    no this is what i get:

                                    no hover:
                                    alt text

                                    after hover:
                                    alt text

                                    code:

                                        def paint(self, painter, option, widget):
                                            pen = QPen(Qt.red)
                                            if self.__hovered:
                                                # what should go here?
                                                self.__hovered = False
                                                pen.setColor(Qt.white)
                                                pen.setWidth(8)
                                                painter.setPen(pen)
                                                painter.drawLine(QPoint(0, 0), QPoint(100, 100))
                                                painter.drawLine(QPoint(0, 100), QPoint(100, 0))
                                    
                                            pen.setWidth(4)
                                            painter.setPen(pen)
                                    
                                            line = QLine(QPoint(0, 0), QPoint(100, 100))
                                            painter.drawLine(line)
                                            painter.drawLine(QPoint(0, 100), QPoint(100, 0))
                                    
                                        def boundingRect(self):
                                            return QRectF(0, 0, 108, 108)
                                    
                                        def hoverEnterEvent(self, event):
                                            # self.setGraphicsEffect(QGraphicsColorizeEffect())
                                            self.__hovered = True
                                            self.update()
                                            self.prepareGeometryChange()
                                    
                                        def hoverLeaveEvent(self, event):
                                            self.setGraphicsEffect(None)
                                    
                                    K 1 Reply Last reply
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                                    • U user4592357

                                      @kenchan
                                      no this is what i get:

                                      no hover:
                                      alt text

                                      after hover:
                                      alt text

                                      code:

                                          def paint(self, painter, option, widget):
                                              pen = QPen(Qt.red)
                                              if self.__hovered:
                                                  # what should go here?
                                                  self.__hovered = False
                                                  pen.setColor(Qt.white)
                                                  pen.setWidth(8)
                                                  painter.setPen(pen)
                                                  painter.drawLine(QPoint(0, 0), QPoint(100, 100))
                                                  painter.drawLine(QPoint(0, 100), QPoint(100, 0))
                                      
                                              pen.setWidth(4)
                                              painter.setPen(pen)
                                      
                                              line = QLine(QPoint(0, 0), QPoint(100, 100))
                                              painter.drawLine(line)
                                              painter.drawLine(QPoint(0, 100), QPoint(100, 0))
                                      
                                          def boundingRect(self):
                                              return QRectF(0, 0, 108, 108)
                                      
                                          def hoverEnterEvent(self, event):
                                              # self.setGraphicsEffect(QGraphicsColorizeEffect())
                                              self.__hovered = True
                                              self.update()
                                              self.prepareGeometryChange()
                                      
                                          def hoverLeaveEvent(self, event):
                                              self.setGraphicsEffect(None)
                                      
                                      K Offline
                                      K Offline
                                      kenchan
                                      wrote on last edited by
                                      #20

                                      @user4592357
                                      Hmm so that red thing is your thin line version?

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                                      • K kenchan

                                        @user4592357
                                        Hmm so that red thing is your thin line version?

                                        U Offline
                                        U Offline
                                        user4592357
                                        wrote on last edited by
                                        #21

                                        @kenchan
                                        yes

                                        K 2 Replies Last reply
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                                        • U user4592357

                                          @kenchan
                                          yes

                                          K Offline
                                          K Offline
                                          kenchan
                                          wrote on last edited by
                                          #22

                                          @user4592357
                                          so, it is drawing it but in the wrong place?

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