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highlight QGraphicsItem

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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
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    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 :-)

    U 1 Reply Last reply
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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
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        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

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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?

              U 1 Reply Last reply
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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.

                1 Reply Last reply
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                • K kenchan

                  @user4592357
                  And does you hovered flag actually get set?

                  U Offline
                  U Offline
                  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?

                      U 1 Reply Last reply
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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
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                          kenchan
                          wrote on last edited by
                          #20

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

                          U 1 Reply Last reply
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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?

                              1 Reply Last reply
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                              • U user4592357

                                @kenchan
                                yes

                                K Offline
                                K Offline
                                kenchan
                                wrote on last edited by
                                #23

                                @user4592357
                                you are still not reseting the hover flag in hoverleave so it is always on, right?

                                U 1 Reply Last reply
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                                • K kenchan

                                  @user4592357
                                  you are still not reseting the hover flag in hoverleave so it is always on, right?

                                  U Offline
                                  U Offline
                                  user4592357
                                  wrote on last edited by
                                  #24

                                  @kenchan
                                  i reset it after drawing the white line.
                                  it is drawing above red line instead of around it

                                  K 1 Reply Last reply
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                                  • U user4592357

                                    @kenchan
                                    i reset it after drawing the white line.
                                    it is drawing above red line instead of around it

                                    K Offline
                                    K Offline
                                    kenchan
                                    wrote on last edited by
                                    #25

                                    @user4592357
                                    Well I am sorry to say that i just made a test using the same ideas in C++ and it works just fine for me and I don't have to call update :-).
                                    So are we seeing a Python issue here or is it your paint function ?

                                    U 1 Reply Last reply
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                                    • K kenchan

                                      @user4592357
                                      Well I am sorry to say that i just made a test using the same ideas in C++ and it works just fine for me and I don't have to call update :-).
                                      So are we seeing a Python issue here or is it your paint function ?

                                      U Offline
                                      U Offline
                                      user4592357
                                      wrote on last edited by user4592357
                                      #26

                                      @kenchan
                                      can you please share the code? maybe i am missing something?

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                                      • U user4592357

                                        @kenchan
                                        can you please share the code? maybe i am missing something?

                                        K Offline
                                        K Offline
                                        kenchan
                                        wrote on last edited by kenchan
                                        #27

                                        @user4592357
                                        It is in an app for testing my QGraphicsItems but I can share the code for the subclass.
                                        As a matter of interest what settings do you use for the QGraphicsScene and View? maybe the drawing is being influenced by those settings?

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                                        • U user4592357

                                          @kenchan
                                          can you please share the code? maybe i am missing something?

                                          K Offline
                                          K Offline
                                          kenchan
                                          wrote on last edited by
                                          #28

                                          @user4592357
                                          Looking at your paint code, I think it is wrong. I think you should separate the line drawing into two if sections.

                                          One draws both lines when hovering and the other draws just one line when not. That is how my code is. I tried it your way and I only saw the the thick lines.

                                          1 Reply Last reply
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