x11grab.c

mediastreamer2是开源的网络传输媒体流的库

        }
        *x = -1;
        *y = -1;
    }
}

/**
 * Mouse painting helper function that applies an 'and' and 'or' mask pair to
 * '*dst' pixel. It actually draws a mouse pointer pixel to grabbed frame.
 *
 * @param dst Destination pixel
 * @param and Part of the mask that must be applied using a bitwise 'and'
 *            operator
 * @param or  Part of the mask that must be applied using a bitwise 'or'
 *            operator
 * @param bits_per_pixel Bits per pixel used in the grabbed image
 */
static void inline
apply_masks(uint8_t *dst, int and, int or, int bits_per_pixel)
{
    switch (bits_per_pixel) {
    case 32:
        *(uint32_t*)dst = (*(uint32_t*)dst & and) | or;
        break;
    case 16:
        *(uint16_t*)dst = (*(uint16_t*)dst & and) | or;
        break;
    case 8:
        *dst = !!or;
        break;
    }
}

/**
 * Paints a mouse pointer in an X11 image.
 *
 * @param image Image where to paint the mouse pointer
 * @param s context used to retrieve original grabbing rectangle
 *          coordinates
 * @param x Mouse pointer coordinate
 * @param y Mouse pointer coordinate
 */
static void
paint_mouse_pointer(XImage *image, x11_grab_t *s, int x, int y)
{
    /* 16x20x1bpp bitmap for the black channel of the mouse pointer */
    static const uint16_t const mousePointerBlack[] =
        {
            0x0000, 0x0003, 0x0005, 0x0009, 0x0011,
            0x0021, 0x0041, 0x0081, 0x0101, 0x0201,
            0x03c1, 0x0049, 0x0095, 0x0093, 0x0120,
            0x0120, 0x0240, 0x0240, 0x0380, 0x0000
        };

    /* 16x20x1bpp bitmap for the white channel of the mouse pointer */
    static const uint16_t const mousePointerWhite[] =
        {
            0x0000, 0x0000, 0x0002, 0x0006, 0x000e,
            0x001e, 0x003e, 0x007e, 0x00fe, 0x01fe,
            0x003e, 0x0036, 0x0062, 0x0060, 0x00c0,
            0x00c0, 0x0180, 0x0180, 0x0000, 0x0000
        };

    int x_off = s->x_off;
    int y_off = s->y_off;
    int width = s->width;
    int height = s->height;

    if (   x - x_off >= 0 && x < width + x_off
        && y - y_off >= 0 && y < height + y_off) {
        uint8_t *im_data = (uint8_t*)image->data;
        int bytes_per_pixel;
        int line;
        int masks;

        /* Select correct masks and pixel size */
        if (image->bits_per_pixel == 8) {
            masks = 1;
        } else {
            masks = (image->red_mask|image->green_mask|image->blue_mask);
        }
        bytes_per_pixel = image->bits_per_pixel>>3;

        /* Shift to right line */
        im_data += image->bytes_per_line * (y - y_off);
        /* Shift to right pixel in the line */
        im_data += bytes_per_pixel * (x - x_off);

        /* Draw the cursor - proper loop */
        for (line = 0; line < FFMIN(20, (y_off + height) - y); line++) {
            uint8_t *cursor = im_data;
            int column;
            uint16_t bm_b;
            uint16_t bm_w;

            bm_b = mousePointerBlack[line];
            bm_w = mousePointerWhite[line];

            for (column = 0; column < FFMIN(16, (x_off + width) - x); column++) {
                apply_masks(cursor, ~(masks*(bm_b&1)), masks*(bm_w&1),
                            image->bits_per_pixel);
                cursor += bytes_per_pixel;
                bm_b >>= 1;
                bm_w >>= 1;
            }
            im_data += image->bytes_per_line;
        }
    }
}


/**
 * Reads new data in the image structure.
 *
 * @param dpy X11 display to grab from
 * @param d
 * @param image Image where the grab will be put
 * @param x Top-Left grabbing rectangle horizontal coordinate
 * @param y Top-Left grabbing rectangle vertical coordinate
 * @return 0 if error, !0 if successful
 */
static int
xget_zpixmap(Display *dpy, Drawable d, XImage *image, int x, int y)
{
    xGetImageReply rep;
    xGetImageReq *req;
    long nbytes;

    if (!image) {
        return 0;
    }

    LockDisplay(dpy);
    GetReq(GetImage, req);

    /* First set up the standard stuff in the request */
    req->drawable = d;
    req->x = x;
    req->y = y;
    req->width = image->width;
    req->height = image->height;
    req->planeMask = (unsigned int)AllPlanes;
    req->format = ZPixmap;

    if (!_XReply(dpy, (xReply *)&rep, 0, xFalse) || !rep.length) {
        UnlockDisplay(dpy);
        SyncHandle();
        return 0;
    }

    nbytes = (long)rep.length << 2;
    _XReadPad(dpy, image->data, nbytes);

    UnlockDisplay(dpy);
    SyncHandle();
    return 1;
}

/**
 * Grabs a frame from x11 (public device demuxer API).
 *
 * @param s1 Context from avformat core
 * @param pkt Packet holding the brabbed frame
 * @return frame size in bytes
 */
static int
x11grab_read_packet(AVFormatContext *s1, AVPacket *pkt)
{
    x11_grab_t *s = s1->priv_data;
    Display *dpy = s->dpy;
    XImage *image = s->image;
    int x_off = s->x_off;
    int y_off = s->y_off;

    int64_t curtime, delay;
    struct timespec ts;

    /* Calculate the time of the next frame */
    s->time_frame += INT64_C(1000000);

    /* wait based on the frame rate */
    for(;;) {
        curtime = av_gettime();
        delay = s->time_frame * av_q2d(s->time_base) - curtime;
        if (delay <= 0) {
            if (delay < INT64_C(-1000000) * av_q2d(s->time_base)) {
                s->time_frame += INT64_C(1000000);
            }
            break;
        }
        ts.tv_sec = delay / 1000000;
        ts.tv_nsec = (delay % 1000000) * 1000;
        nanosleep(&ts, NULL);
    }

    if (av_new_packet(pkt, s->frame_size) < 0) {
        return AVERROR(EIO);
    }

    pkt->pts = curtime;

    if(s->use_shm) {
        if (!XShmGetImage(dpy, RootWindow(dpy, DefaultScreen(dpy)), image, x_off, y_off, AllPlanes)) {
            av_log (s1, AV_LOG_INFO, "XShmGetImage() failed\n");
        }
    } else {
        if (!xget_zpixmap(dpy, RootWindow(dpy, DefaultScreen(dpy)), image, x_off, y_off)) {
            av_log (s1, AV_LOG_INFO, "XGetZPixmap() failed\n");
        }
    }

    {
        int pointer_x, pointer_y;
        get_pointer_coordinates(&pointer_x, &pointer_y, dpy, s1);
        paint_mouse_pointer(image, s, pointer_x, pointer_y);
    }


    /* XXX: avoid memcpy */
    memcpy(pkt->data, image->data, s->frame_size);
    return s->frame_size;
}

/**
 * Closes x11 frame grabber (public device demuxer API).
 *
 * @param s1 Context from avformat core
 * @return 0 success, !0 failure
 */
static int
x11grab_read_close(AVFormatContext *s1)
{
    x11_grab_t *x11grab = s1->priv_data;

    /* Detach cleanly from shared mem */
    if (x11grab->use_shm) {
        XShmDetach(x11grab->dpy, &x11grab->shminfo);
        shmdt(x11grab->shminfo.shmaddr);
        shmctl(x11grab->shminfo.shmid, IPC_RMID, NULL);
    }

    /* Destroy X11 image */
    if (x11grab->image) {
        XDestroyImage(x11grab->image);
        x11grab->image = NULL;
    }

    /* Free X11 display */
    XCloseDisplay(x11grab->dpy);
    return 0;
}

/** x11 grabber device demuxer declaration */
AVInputFormat x11_grab_device_demuxer =
{
    "x11grab",
    "X11grab",
    sizeof(x11_grab_t),
    NULL,
    x11grab_read_header,
    x11grab_read_packet,
    x11grab_read_close,
    .flags = AVFMT_NOFILE,
};