How to create any number of QGraphicsView Dynamically

dheerendra

show the code please.

R_Irudezu

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QGraphicsItem>
#include <QGraphicsView>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT


public:
    explicit Widget(QWidget *parent = nullptr);
    ~Widget();

    QGraphicsScene *scene;
    QTimeLine *timeline;
    QGraphicsView *gw;
    QGraphicsView *newGw;

    void drawNewGraphicsView
    (
        QGraphicsView *gw_func,
        uint16_t fixedHeight,
        uint16_t fixedWidth,
        uint16_t moveX,
        uint16_t moveY,
        uint16_t lifeTime
    );

private slots:
    void on_pushButton_clicked();

private:
    Ui::Widget *ui;
};

#endif // WIDGET_H

widget.cpp:

#include "widget.h"
#include "ui_widget.h"
#include <QTimeLine>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    timeline = new QTimeLine;
    gw = new QGraphicsView(ui->widget);
    drawNewGraphicsView(gw, 80, 80, 150, 150, 3);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::drawNewGraphicsView
(
    QGraphicsView *gw_func,
    uint16_t fixedHeight,
    uint16_t fixedWidth,
    uint16_t moveX,
    uint16_t moveY,
    uint16_t lifeTime
)
{
    timeline->setDuration (1000);
    timeline->setCurveShape (QTimeLine::CosineCurve);
    QObject::connect (timeline, SIGNAL(finished()), timeline, SLOT(deleteLater()));

    scene = new QGraphicsScene(this);

    newGw = gw_func;
    newGw->setScene(scene);
    newGw->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    newGw->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff );
    newGw->setStyleSheet("background-color: transparent; border: none;");
    newGw->setFixedHeight(fixedHeight);
    newGw->setFixedWidth(fixedWidth);
    newGw->move(moveX,moveY);
    newGw->setDisabled(true); //scrolling inactivate
    newGw->raise();
    newGw->show();

    scene->setSceneRect (-75, -75, 150, 150);
    setupRot (timeline, scene->addEllipse (rect(35), QPen (QBrush (QColor (0, 153, 255)), 2.4, Qt::DotLine)));
    timeline->setLoopCount (0); 
    timeline->start();
}

void Widget::on_pushButton_clicked()
{
    // adding new graphicview objects to randomly locations
    // lifetime 5 second and want to delete it
}

I couldn't do what i want. I'm gonna create them many, at least mean 3 graphicsView in one second, so i do now want to do memory leak.

dheerendra

I did not understand your response. Do you have issue still or not ?

R_Irudezu

@dheerendra Sir the issue is that graphicsView objects defined in header are in specific number. I do not want to declare them before compile, i want to create graphicsView objects at runtime:

you can see in the media, i created 3 graphicsView objects, second and third one is creating like that:

void Widget::on_pushButton_clicked()
{
    uint16_t x = (qrand() % 50)*3 ; qDebug() << x;
    uint16_t y = (qrand() % 35)*3 ; qDebug() << x;

    gw1 = new QGraphicsView(ui->widget);
    drawNewGraphicsView(gw1, 120, 120, x, x*2, 5);

    gw2 = new QGraphicsView(ui->widget);
    drawNewGraphicsView(gw2, 130, 160, y, y*2+5, 8);
}

void Widget::on_pushButton_2_clicked()
{
    delete gw1;
    delete gw2;
}

Like i said and like you see, these number of objects are specific, i do not want to specify number of its, what i want is creating how much i want to create of this objects at a (x)second, show them and delete them. Can you help me about that point?

dheerendra

How do you get the input on how many number of objects to create ? Is it based on some input ? How do you decide the number of GraphicsView object ?

R_Irudezu

@dheerendra it is exactly based on some outputs that an external library callback function gives me. I mean i got 3 * (x,y,w,h)
locations at one second and i have to show this graphic object (the blue cycle in the GIF ) at these locations.

dheerendra

when the callback happens store that value in some member variable. Use that member variable to decide on how many Views you need to create.

QGraphicsView **views; // Declare this as member variable in your class.

views = new QGraphicsView* [count]
for(int i=0; i<count;i++ {
    views[i] = new QGraphicsView(ui->widget);
    drawNewGraphicsView(views[i], 130, 160, y, y*2+5, 8);
}

Asperamanca

You could simply connect the finished() signal of your timeline to the deleteLater() slots of the QGraphicsScene and QGraphicsView. That way, they are automatically deleted when the timeline expires.

EDIT: No need to keep a pointer to those scenes, unless you need to access them at a later time in your code.

R_Irudezu

@Asperamanca It's seems logical about deleting objects after shown but is it possible to define a connect that valid for every QGraphicView object created?

R_Irudezu

So i wrote a sample based on @dheerendra and @Asperamanca 's replies.

    //in the header file defined 
    QGraphicsView **views;
    QTimeLine **timelineSet;

    // connect both view and scene objects' deleteLater slots to 
    // timeline's finished signal
    QGraphicsView::connect(timeline, SIGNAL(finished()), newGw, SLOT(deleteLater()));
    QGraphicsScene::connect(timeline, SIGNAL(finished()), scene, SLOT(deleteLater()));

    // in the callback
    views = new QGraphicsView* [5]; //specific 
    for(int i=0; i<5;i++)
    {
        y += 25 + i*12;
        views[i] = new QGraphicsView(ui->widget);
        timelineSet[i] = new QTimeLine();
        drawNewGraphicsView(views[i], 130, 160, y*2+5,  y*2+25, timelineSet[i], lifeT*i%3, 5);
    }

So it's okay now, just like i want. I'm creating objects, showing them for a couple of seconds and delete them automatically with deleteLater().

Thanks for any help :)