Qt中实现进程间通信的方法诸多,这里讲解比较简单的共享内存类QSharedMemory在这之前,先来看看这个类,其实函数不是很多,详细资料到官方文档查看

演示

下面代码注释写的比较清楚了

#include<QDebug>
//内存共享 标识符
#define MEM_KEY "_sharedMemKey_"
#include<QPixmap>
#include<QBuffer>
#define PIX_MAP "test.jpg"
Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    //设置内存标志 key
    sharedMemory=new QSharedMemory(this);
    sharedMemory->setKey(MEM_KEY);
}
Widget::~Widget()
{
    delete ui;
}
//载入图片到内存
void Widget::on_pushButton_clicked()
{
    //如果已经绑定,则分离
    if(sharedMemory->isAttached()){
        sharedMemory->detach();
    }
    QPixmap pmp;
    pmp.load(PIX_MAP);
    ui->label->setPixmap(pmp.scaled(ui->label->size()));
    //图像的数据(QPixmap)---> ( QDataStream )-->QBuffer
    QBuffer tmpBuffer;
    //打开 缓存区设备
    tmpBuffer.open(QIODevice::ReadWrite);
    //数据流与缓存区关联
    QDataStream dataOutstream(&tmpBuffer);
    //图像数据输入到数据流
    dataOutstream<<pmp;
    //获取缓存区(图像)字节大小
    int bufferSize=tmpBuffer.size();
    //创建共享内存
    if(sharedMemory->create(bufferSize)){
        //lock
        sharedMemory->lock();
        //memset(sharedMemory->data(),0,bufferSize);
        //获取图像数据
        const char *datasharedBuffer= tmpBuffer.data().data();
        //获取共享内存地址
        char *datasharedMemory=(char *)sharedMemory->data();
        //图像数据 拷贝到 共享内存中
        memcpy(datasharedMemory,datasharedBuffer,bufferSize);
        //unlock
        sharedMemory->unlock();
    }
    tmpBuffer.close();
}
//从共享内存获取图像数据
void Widget::on_pushButton_2_clicked()
{
    //进程与共享内存绑定!,,注意要设置好标识符 key
    if(sharedMemory->attach()){
        qDebug()<<"ok!";
        sharedMemory->lock();
        // 图像的数据(QPixmap) <--- ( QDataStream ) <--- QBuffer
        QBuffer buffer;
        char *dataSharedMem=(char*)sharedMemory->data();
        int dataSize =sharedMemory->size();
        //设置共享内存的数据到缓存区
        buffer.setData(QByteArray(dataSharedMem,dataSize));
        QPixmap pmp;
        buffer.open(QIODevice::ReadOnly);
        //关联缓存区数据到数据流
        QDataStream dataInStream(&buffer);
        dataInStream>>pmp;
        ui->label->setPixmap(pmp.scaled(ui->label->size()));
        //进程与共享内存分离
        sharedMemory->unlock();
        if(sharedMemory->isAttached()){
            sharedMemory->detach();
        }
        buffer.close();
    }
}