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How to create a line between 2 points with QLabel?

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  • F frnklu20

    I guess a custom widget will be better, but i don't have any ideia to do that

    I want is to deal with the line as an object and to be clickable, i want to click in any part of the line and my program recognizes it.

    What i thought was to use a CustomLabel class that it emits a signal when it is clicked and create an obect of this class between 2 points.
    So the way you said before, i create a line inside my QLabel but it becomes to big for being a rect

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by
    #6

    @frnklu20
    Well the image has to be as big as the points
    like 0,0 and 100,100 , the pixmap must be 100x100
    But if you want to click on it, an image is not so good as it
    has no idea where line is. so it needs the point anyway.

    Even with a custom widget, it must still be as big as the span between the points.

    So what should happen when you click the line at any part of it ?

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    • F Offline
      F Offline
      frnklu20
      wrote on last edited by
      #7

      It's not pretty yet, but that's what my program does
      I add objects on the screen and draw lines between then

      0_1557239421701_daede2d6-eb37-4671-887c-e4d02e0c4430-image.png

      but this line has to be treated as an object as well, when i click in any point of the line it should open a window with its data

      mrjjM 1 Reply Last reply
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      • F frnklu20

        It's not pretty yet, but that's what my program does
        I add objects on the screen and draw lines between then

        0_1557239421701_daede2d6-eb37-4671-887c-e4d02e0c4430-image.png

        but this line has to be treated as an object as well, when i click in any point of the line it should open a window with its data

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

        @frnklu20
        well you need to store the 2 points for each line and
        then use math to find out if the user hits a line on mousePressed.
        How is the lines stored now ? ( the points you use to draw it )

        This explains it well
        http://www.jeffreythompson.org/collision-detection/line-point.php

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #9

          Hi,

          Since you seem to want to interact and have things working dynamically, did you consider the Graphics View Framework ?

          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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          • F Offline
            F Offline
            frnklu20
            wrote on last edited by
            #10

            Exactly!

            Graphics View Framework would help me a lot, i guess

            Do you know some book or site that i can learn more about it?with some examples and everything

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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #11

              Did you check the Qt documentation and related examples ?

              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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              • F Offline
                F Offline
                frnklu20
                wrote on last edited by
                #12

                Yes!
                But i'm having a problem.

                I saw in a video a guy using the the graphic view framework in a QDialog

                That's the code:

                dialog.h

                class Dialog : public QDialog
                {
                    Q_OBJECT
                
                public:
                    explicit Dialog(QWidget *parent = nullptr);
                    ~Dialog();
                
                private:
                    Ui::Dialog *ui;
                    QGraphicsScene *scene;
                    QGraphicsEllipseItem *ellipse;
                    QGraphicsRectItem *rectangle;
                    
                };
                

                dialog.cpp

                    QDialog(parent),
                    ui(new Ui::Dialog)
                {
                    ui->setupUi(this);
                
                    scene= new QGraphicsScene(this);
                    ui->graphicsView->setScene(scene);////the problem is here!
                    QBrush redBrush(Qt::red);
                    QPen blackpen(Qt::black);
                
                    ellipse=scene->addEllipse(10,10,100,100,blackpen,redBrush);
                
                }
                

                It says that no member named 'graphicView' in Ui::Dialog, so how can i fix it?
                i want to use the application in qwidget or qdialog class

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #13

                  Did you add a QGraphicsView widget name graphicsView through designer to your dialog ?

                  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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                  • F Offline
                    F Offline
                    frnklu20
                    wrote on last edited by
                    #14

                    no, how can i do this?

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                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #15

                      Well, use designer as explained here.

                      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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