新建一个QT GUI程序，选择基类Widget，取消创建界面。修改main.cpp

#include "widget.h"#include 
    
     #include 
     
      #include 
      
       #include 
       
        int main(int argc, char *argv[]){    QApplication a(argc, argv);    QPainterPath path;    path.moveTo(30, 120);     //绘图的起点    path.cubicTo(80, 0, 50, 50, 80, 80);   //绘制贝塞尔曲线    QGraphicsScene scene;    scene.addPath(path, QPen(Qt::black), QBrush(Qt::green));    scene.addText("I love Qt programming", QFont("Times", 15, QFont::Bold));    QGraphicsView view(&scene);    view.setAlignment(Qt::AlignLeft | Qt::AlignTop);  //    view.show();    return a.exec();}