[Xcb] problem about fetching xcb_visualtype_t

[快乐迷宫]

 Hello, guys!
 I‘m now trying to use XCB instead of XLib of my program backend. And I'm trying to translate these few lines:

    XVisualInfo vinfo;
    XSetWindowAttributes attr;
    screen = DefaultScreen(display);
    XMatchVisualInfo(display, screen, 32, TrueColor, &vinfo);                                       //create a transparent window
    attr.colormap = XCreateColormap(display, rootwin, vinfo.visual, AllocNone);
    attr.override_redirect = 1;                                                                                        // ... and without the title-bar

I found a tutor on this web-page, but while I was trying to get the xcb_visualtype_t structure, function screen_of_display() didn't seem existed. I tried xcb_setup_roots_iterator() instead, and the result was, I got a NULL xcb_visualtype_t *...

--      screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
=>      screen = screen_of_display (c, screen_nbr);

So is there anyway I can create a transparent, no title-bar window and filling the window with cairo?
Thanks!

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happymaze
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