C++绘制QML图像

#ifndef CUSTIMAGE_H
#define CUSTIMAGE_H

#include <QObject>
#include <QQuickPaintedItem>
#include <QPainter>
#include <QImage>

//继承自基于QML可绘制项
class CustImage : public QQuickPaintedItem
{
    Q_OBJECT
public:
    //构造
    CustImage(QQuickItem *parent = 0);
    //析构
    ~CustImage();
    //单例
    static CustImage *getInst();
    //更新图像
    void UpdateImage(QImage _image);
    //QML调用函数
    //初始化
    Q_INVOKABLE void init();
    //清空图像
    Q_INVOKABLE void clear();

public:
    //接口重写
    void paint(QPainter *painter);

signals:

private slots:

private:
    QImage m_baseImage{nullptr};//图像对象
    int m_Width{1920};
    int m_Height{1080};
};

#endif // CUSTIMAGE_H

#include "custimage.h"

//全局对象
static CustImage *_inst;

//构造
CustImage::CustImage(QQuickItem *parent) : QQuickPaintedItem(parent)
{
    _inst = this;
    init();
}

//析构
CustImage::~CustImage()
{

}

//单例
CustImage *CustImage::getInst()
{
    if(nullptr==_inst){
        _inst = new CustImage;
    }
    return _inst;
}

//更新图像
void CustImage::UpdateImage(QImage _image)
{
    this->m_baseImage = _image;
    update();
}

//初始化
void CustImage::init()
{
    m_baseImage = QImage(m_Width,m_Height,QImage::Format_ARGB32);
    if(this->m_baseImage.load(":/test.jpg")){
        update();
    }else{
        m_baseImage.fill(Qt::black);
    }
}

//清空图像
void CustImage::clear()
{
    this->init();
}

//绘制图像
void CustImage::paint(QPainter *painter)
{
    painter->drawImage(
        QRectF(0,0,m_baseImage.width()*0.5,m_baseImage.width()*0.5),//绘制区域
        m_baseImage.copy()); //图像
}

import QtQuick 2.15
import QtQuick.Window 2.15
import CppImage.CustImage 1.0

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("CustImage Draw From CPP")
    Rectangle{
        anchors.fill: parent
        color:"red"
        Rectangle{
            anchors.centerIn: parent
            color: "blue"
            width: parent.width*0.9
            height: parent.height*0.9
            CustImage{
                id:custImg
                anchors.centerIn: parent
                width: parent.width*0.9
                height: parent.height*0.9
            }
        }
    }
}