X11/GLX - Fullscreen mode?

Question

I am trying to create a Linux application - a screensaver, in this case - and it is proving remarkably difficult to find information on the simple task of making a wind

Answer 1

I found freeglut fullscreen works well, even when hosting shader based opengl application inside. Here the internal code that get called (X11 branch...). HTH

#define _NET_WM_STATE_TOGGLE    2
static int fghResizeFullscrToggle(void)
{
    XWindowAttributes attributes;

    if(glutGet(GLUT_FULL_SCREEN)) {
        /* restore original window size */
        SFG_Window *win = fgStructure.CurrentWindow;
        fgStructure.CurrentWindow->State.NeedToResize = GL_TRUE;
        fgStructure.CurrentWindow->State.Width  = win->State.OldWidth;
        fgStructure.CurrentWindow->State.Height = win->State.OldHeight;

    } else {
        /* resize the window to cover the entire screen */
        XGetWindowAttributes(fgDisplay.Display,
                fgStructure.CurrentWindow->Window.Handle,
                &attributes);

        /*
         * The "x" and "y" members of "attributes" are the window's coordinates
         * relative to its parent, i.e. to the decoration window.
         */
        XMoveResizeWindow(fgDisplay.Display,
                fgStructure.CurrentWindow->Window.Handle,
                -attributes.x,
                -attributes.y,
                fgDisplay.ScreenWidth,
                fgDisplay.ScreenHeight);
    }
    return 0;
}

static int fghEwmhFullscrToggle(void)
{
    XEvent xev;
    long evmask = SubstructureRedirectMask | SubstructureNotifyMask;

    if(!fgDisplay.State || !fgDisplay.StateFullScreen) {
        return -1;
    }

    xev.type = ClientMessage;
    xev.xclient.window = fgStructure.CurrentWindow->Window.Handle;
    xev.xclient.message_type = fgDisplay.State;
    xev.xclient.format = 32;
    xev.xclient.data.l[0] = _NET_WM_STATE_TOGGLE;
    xev.xclient.data.l[1] = fgDisplay.StateFullScreen;
    xev.xclient.data.l[2] = 0;  /* no second property to toggle */
    xev.xclient.data.l[3] = 1;  /* source indication: application */
    xev.xclient.data.l[4] = 0;  /* unused */

    if(!XSendEvent(fgDisplay.Display, fgDisplay.RootWindow, 0, evmask, &xev)) {
        return -1;
    }
    return 0;
}

static int fghToggleFullscreen(void)
{
    /* first try the EWMH (_NET_WM_STATE) method ... */
    if(fghEwmhFullscrToggle() != -1) {
        return 0;
    }

    /* fall back to resizing the window */
    if(fghResizeFullscrToggle() != -1) {
        return 0;
    }
    return -1;
}


#endif  /* TARGET_HOST_POSIX_X11 */