如何将图像帧从C ++连续发送到QML

Question

我想将图像帧从C ++连续发送到我的QML文件中的插槽。在这里，我只进行C ++编码以从相机获取图像帧，但我需要使用某种方法（信号槽，注册表）将该图像帧发送到QML。我需要知道哪些QML元素可以连续接收我的图像帧并在屏幕上显示它们。

#include <QApplication>
#include <QDataStream>
#include <QString>
#include <QDebug>
#include <QBuffer>
#include <typeinfo>
#include "capturethread.h"
#include <iostream>
#include <QFile>
CaptureThread::CaptureThread(QWidget *parent) :
QThread(parent)
{
this->parent=(videowidget*)parent;
devam=false;
fd = -1;
}

void CaptureThread::run(){
fd = -1;
dev_name = "/dev/video0";
fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
if (fd < 0) {
       qDebug("Cannot open device");
       //exit(EXIT_FAILURE);
       return;
}
static struct v4lconvert_data *v4lconvert_data;
static struct v4l2_format src_fmt;
static unsigned char *dst_buf;
CLEAR(fmt);
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width       = 640;
fmt.fmt.pix.height      = 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
xioctl(fd, VIDIOC_S_FMT, &fmt);
if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_RGB24) {
       printf("Libv4l didn't accept RGB24 format. Can't proceed.\n");
       //exit(EXIT_FAILURE);
       return;
}
if ((fmt.fmt.pix.width != 640) || (fmt.fmt.pix.height != 480))
       printf("Warning: driver is sending image at %dx%d\n",
               fmt.fmt.pix.width, fmt.fmt.pix.height);

v4lconvert_data = v4lconvert_create(fd);
if (v4lconvert_data == NULL)
    qDebug("v4lconvert_create");
if (v4lconvert_try_format(v4lconvert_data, &fmt, &src_fmt) != 0)
    qDebug("v4lconvert_try_format");
xioctl(fd, VIDIOC_S_FMT, &src_fmt);
dst_buf = (unsigned char*)malloc(fmt.fmt.pix.sizeimage);

CLEAR(req);
req.count = 2;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
xioctl(fd, VIDIOC_REQBUFS, &req);

buffers = (buffer*)calloc(req.count, sizeof(*buffers));
for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
       CLEAR(buf);

       buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
       buf.memory      = V4L2_MEMORY_MMAP;
       buf.index       = n_buffers;

       xioctl(fd, VIDIOC_QUERYBUF, &buf);

       buffers[n_buffers].length = buf.length;
       buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
                     PROT_READ | PROT_WRITE, MAP_SHARED,
                     fd, buf.m.offset);

       if (MAP_FAILED == buffers[n_buffers].start) {
               qDebug("mmap");
               //exit(EXIT_FAILURE);
               return;
       }
}

for (int i = 0; i < n_buffers; ++i) {
       CLEAR(buf);
       buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
       buf.memory = V4L2_MEMORY_MMAP;
       buf.index = i;
       xioctl(fd, VIDIOC_QBUF, &buf);
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

xioctl(fd, VIDIOC_STREAMON, &type);

int di=0;
char header[]="P6\n640 480 255\n";
while(devam){
    /* bu döngü datanın birikmesini sağlıyor */
    do {
            FD_ZERO(&fds);
            FD_SET(fd, &fds);

            /* Timeout. */
            tv.tv_sec = 2;
            tv.tv_usec = 0;

            r = select(fd + 1, &fds, NULL, NULL, &tv);
    } while ((r == -1 && (errno = EINTR)));
    if (r == -1) {
            qDebug("select");
            //exit(1) ;
            return;
    }

    CLEAR(buf);
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory = V4L2_MEMORY_MMAP;
    xioctl(fd, VIDIOC_DQBUF, &buf);

    try{

    if (v4lconvert_convert(v4lconvert_data,
                            &src_fmt,
                            &fmt,
                            (unsigned char*)buffers[buf.index].start, buf.bytesused,
                            dst_buf, fmt.fmt.pix.sizeimage) < 0) {
            if (errno != EAGAIN)
                    qDebug("v4l_convert");

    }


    unsigned char* asil=(unsigned char*)malloc(fmt.fmt.pix.sizeimage+qstrlen(header));
    memmove(asil, dst_buf, fmt.fmt.pix.sizeimage);
    memmove(asil+qstrlen(header), asil, fmt.fmt.pix.sizeimage);
    memcpy(asil,header,qstrlen(header));

    QImage qq;//=new QImage(dst_buf,640,480,QImage::Format_RGB32);

    if(qq.loadFromData(asil,fmt.fmt.pix.sizeimage+qstrlen(header),"PPM")){
        if(parent->isVisible()){
            QImage q1(qq);
            qDebug()<<"qimage"<<q1;
            parent->img=q1;
            parent->update();
          //this->msleep(50);
        }
    //qApp->processEvents();
        if(asil)
            free(asil);
    }
    }catch(...){}
    xioctl(fd, VIDIOC_QBUF, &buf);
    di++;
}
try{
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
xioctl(fd, VIDIOC_STREAMOFF, &type);
for (int i = 0; i < n_buffers; ++i)
       v4l2_munmap(buffers[i].start, buffers[i].length);
    v4l2_close(fd);
}catch(...){}
}

上面的代码基于QThread类，我需要从QML调用线程并接收图像帧。