Graphic view frame

Ideas

New scene 、 Primitives 、 And views .
Elements are added to the scene , The scene is associated with the view , View display .

Initial example

The header file

#include <QGraphicsScene> // scene ： Add elements  void addItem(QGraphicsItem *item)
#include <QGraphicsView> // View ; Show scene 
#include <QGraphicsItem> // Primitives 

main.cpp

    QGraphicsScene *scene = new QGraphicsScene;  // scene 
    QGraphicsRectItem *item = new QGraphicsRectItem(100,100,50,50);  // Rectangular item 
    scene->addItem(item);  // Add item to scene 
    QGraphicsView *view = new QGraphicsView; // View 
    view->setScene(scene);  // The view is associated with the scene 
    view->resize(500,500);
    view->show();  // Show view 

Specific operation

Create a new primitive class MyItem Inherit QGraphicsItem, You can implement customized element items

Note that you need to rewrite two virtual functions boundingRect() and paint(), Otherwise there will be errors in the compilation

myitem.h

#ifndef MYITEM_H
#define MYITEM_H
#include <QGraphicsItem>

class MyItem : public QGraphicsItem
{
    
public:
    MyItem();
    QRectF boundingRect() const override;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
   };

#endif // MYITEM_H

myitem.cpp

#include "myitem.h"
#include <QPainter>
MyItem::MyItem()
{
    

}

QRectF MyItem::boundingRect() const
{
    

    qreal penWidth = 1;// Pen width 
    return QRectF(0 - penWidth/2,0-penWidth/2,20+penWidth,20+penWidth);// Return rectangle border （ coordinate 、 Wide and high ）
}

void MyItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    

    // Indicates that the parameter is not used 
       Q_UNUSED(option)
       Q_UNUSED(widget)

       painter->setBrush(Qt::green);// With the green   Brush 
       painter->drawEllipse(0,0,50,50);// A circle 
}

effect 1： A green circle :：
main.cpp

#include "widget.h"
#include <QApplication>
#include "animation.h"
#include <QDebug>
#include "myitem.h"
int main(int argc, char *argv[])
{
    

    QApplication a(argc, argv);
// Widget w;
// w.show();

    QGraphicsScene *scene = new QGraphicsScene;  // scene 
   // QGraphicsRectItem *item = new QGraphicsRectItem(100,100,50,50); // Rectangular item 
    MyItem *item=new MyItem;// Create a new primitive class object 
    scene->addItem(item);  // Add item to scene 
    QGraphicsView *view = new QGraphicsView; // View 
    view->setScene(scene);  // The view is associated with the scene 
    view->resize(500,500);
    view->show();  // Show view 

    return a.exec();
}

effect 2： Two green circles
operation ： Then define a primitive class object , Remember to change the position of the second element （ Prevent coincidence with the first ）
main.cpp

#include "widget.h"
#include <QApplication>
#include "animation.h"
#include <QDebug>
#include "myitem.h"
int main(int argc, char *argv[])
{
    
   	QApplication a(argc, argv);
    QGraphicsScene *scene = new QGraphicsScene;  // scene 
   // QGraphicsRectItem *item = new QGraphicsRectItem(100,100,50,50); // Rectangular item 
    MyItem *item=new MyItem;
    MyItem *item1=new MyItem;
    scene->addItem(item);  // Add item to scene 
    scene->addItem(item1);
    item1->setPos(66,66);// Set the position of the second element 
    QGraphicsView *view = new QGraphicsView; // View 
    view->setScene(scene);  // The view is associated with the scene 
    view->resize(500,500);
    view->show();  // Show view 

    return a.exec();
}

Element movement

Definition advance Function to move , Need to bind timer

collision detection