QT笔记 -- (5) 实现QWidget的paintEvent函数，在widget上画背景图形

 

如图，想在界面上画个弧线和直线，于是继承QWidget得到类MainContainer，并实现了paintEvent函数。然后用类MainContainer定义centralWidget。

MainContainer.h

#pragma once
#include "qwidget.h"
#include <QPainter>

class MainContainer : public QWidget{
    Q_OBJECT
public:
    MainContainer(QWidget *parent = 0) :QWidget(parent){};
    ~MainContainer();
    void addGeometry(int type,QRectF rect){
        if (type == 0) arcList.push_back(rect);
        else if (type == 1) rectList.push_back(rect);
    }
private:
    QPainter *painter;
    std::vector<QRectF> rectList;
    std::vector<QRectF> arcList;
    void paintEvent(QPaintEvent*){
        painter = new QPainter;
        painter->begin(this);
        painter->setPen(QPen(Qt::green,2,Qt::DashLine));
        //painter->setBrush(QBrush(Qt::red,Qt::SolidPattern));
        for (auto rect : arcList){
            painter->drawArc(rect, 30*16, 120*16);
        }
        for (auto rect : rectList){
            painter->drawRoundRect(rect);
        }
        painter->end();
    };
};

MainContainer.cpp

#include "MainContainer.h"

MainContainer::~MainContainer()
{
}