examples/example7/OverlayWidget.cpp

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#include "OverlayWidget.h"

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#define X_UYVY 0x59565955

OverlayWidget::OverlayWidget(QWidget *parent) : QWidget(parent)  {
    initXv();

    /* Make QT do the work of keeping the overlay the magic color  */
    QWidget::setBackgroundRole(QPalette::Window); 
    QWidget::setAutoFillBackground(true); 
    QPalette overlayPalette = QWidget::palette(); 
    overlayPalette.setColor 
    (QPalette::Window,  
     colorKey()); 
    QWidget::setPalette(overlayPalette); 
}


void OverlayWidget::initXv() {
    unsigned int nAdaptors;
    XvAdaptorInfo *ai;

    dpy = x11Info().display();

    XvQueryAdaptors(dpy, 
            winId(),
            &nAdaptors, &ai);

    if (nAdaptors > 0) {
    // Use the first available port
    xv_port = ai[0].base_id;
    printf("Using port %d\n", xv_port);
    XvFreeAdaptorInfo(ai);
    } else {
    printf("Error: no available xv ports\n"); 
    xv_port = -1;
    return; 
    }
  
    gc = XCreateGC(dpy, winId(), 0, 0);     
  
    yuv_image = NULL;
    
    //XvSetPortAttribute(dpy, xv_port, XInternAtom(dpy, "XV_DOUBLE_BUFFER", True), 0);
    //XvSetPortAttribute(dpy, xv_port, XInternAtom(dpy, "XV_AUTOPAINT_COLORKEY", True), 1);
    //XvSetPortAttribute(dpy, xv_port, XInternAtom(dpy, "XV_DISABLE_COLORKEY", True), 1);
    //XvSetPortAttribute(dpy, xv_port, XInternAtom(dpy, "XV_OMAP_VSYNC", True), 1);

    // Set the XV color key
    QColor key = colorKey();
    int val = ((key.red() >> 3) << 11) | ((key.green() >> 2) << 5) | ((key.blue() >> 3));
    XvSetPortAttribute(dpy, xv_port, XInternAtom(dpy, "XV_COLORKEY", True), val);
}

void OverlayWidget::checkImageSize() {
    if (yuv_image == NULL ||
    width() != yuv_image->width ||
    height() != yuv_image->height) {
    
    printf("Creating new image\n"); fflush(stdout);

    if (yuv_image) XFree(yuv_image);

    yuv_image = XvShmCreateImage(dpy, xv_port, X_UYVY, 0, width(), height(), &yuv_shminfo);

    if (!yuv_image) {
        printf("XvShmCreateImage returned NULL\n");
        return;
    }
    yuv_shminfo.shmid = shmget(IPC_PRIVATE, yuv_image->data_size, IPC_CREAT | 0777);
    yuv_shminfo.shmaddr = yuv_image->data = (char *)shmat(yuv_shminfo.shmid, 0, 0);
    yuv_shminfo.readOnly = False;

    // Make an FCam image that's a weak reference to the Xv image
    // data.
    framebuffer_ = FCam::Image(width(), height(),
                   FCam::UYVY,
                   (unsigned char*)yuv_image->data);

    if (!XShmAttach(dpy, &yuv_shminfo)) {
        printf("XShmAttach failed !\n");
        return;
    }             

    }    
}

void OverlayWidget::paintEvent(QPaintEvent *) {
    if (!yuv_image) return;
    
    XvShmPutImage(dpy, xv_port, winId(), gc, yuv_image,
          0, 0, yuv_image->width, yuv_image->height,
          0, 0, width(), height(), false);  
}

FCam::Image OverlayWidget::framebuffer() {
    checkImageSize();
    return framebuffer_;
}

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