[Cin] Interesting confusion on X screens vs displays

[Phyllis Smith]

Andrew, could a procedure to get this working be detailed so Andrea could
add it to the Manual?

On Sat, Jan 7, 2023 at 9:40 PM Andrew Randrianasulu <randrianasulu at gmail.com>
wrote:

> I tried to test multi-monitor support by firing another, nested X server
>
> Xephyr :1 -screen 1024x768
>
> then Cin displays her windows on either DISPLAY :0 or :1 depend on
> preferences but I can\t set compositor to just one ...xserver.
>
> I looked into code :)
>
> in cwindowgui.C
>
> CWindowGUI::CWindowGUI(MWindow *mwindow, CWindow *cwindow)
>  : BC_Window(_(PROGRAM_NAME ": Compositor"),
>     mwindow->session->cwindow_x,
>     mwindow->session->cwindow_y,
>     mwindow->session->cwindow_w,
>     mwindow->session->cwindow_h,
>     xS(100), yS(100), 1, 1, 1,
>     BC_WindowBase::get_resources()->bg_color,
>     mwindow->get_cwindow_display())
>
> in mwindow.C
>
> char *MWindow::get_cwindow_display()
> {
>     char *x11_host = screens < 2 || session->window_config == 0 ?
>         session->a_x11_host : session->b_x11_host;
>     return *x11_host ? x11_host : 0;
> }
>
> and screens set in
>
> void MWindow::init_preferences()
> {
>     preferences = new Preferences;
>     preferences->load_defaults(defaults);
>     File::setenv_path("LV2_PATH",preferences->lv2_path, 1);
>     session = new MainSession(this);
>     session->load_defaults(defaults);
>     // set x11_host, screens, window_config
>     screens = session->set_default_x11_host();
>
> so into mainsession.C
>
> // set default x11 host, window_config, return screens
> int MainSession::set_default_x11_host(int win_config)
> {
>     if( win_config < 0 ) win_config = window_config;
>     const char *x11_host = win_config!=1 ? a_x11_host : b_x11_host;
>     BC_DisplayInfo display_info(x11_host,0);
>     int screen = display_info.get_screen();
>     if( screen < 0 && strcmp(a_x11_host, b_x11_host) ) {
>         win_config = win_config==1 ? 0 : 1;
>         x11_host = win_config!=1 ? a_x11_host : b_x11_host;
>         display_info.init_window(x11_host,0);
>         screen = display_info.get_screen();
>     }
>     if( screen < 0 ) {
>         x11_host = "";
>         display_info.init_window(x11_host,1);
>     }
>     int screens = 1;
>     if( display_info.get_screen_count() > 1 )
>         screens = strcmp(a_x11_host, b_x11_host) != 0 ? 2 : 1;
>     window_config = win_config;
>     BC_Window::set_default_x11_host(x11_host);
>     return screens;
> }
>
> and display_info lives in
>
> guicast/bcdisplayinfo.C and h
>
> in our case in h file
>
> int get_screen() { return scrnum; }
>
> and scrnum set to
>  scrnum = DefaultScreen(display);
>
> in void BC_DisplayInfo::init_window(const char *display_name, int
> show_error)
>
> so, it seems having two 'x11 hosts" as separate X servers to send
> Compositor to actually not supported... ? we query number of screens
> on specific display/host ...
>
> so :0.0 and :0.1 works, while :1.0 and :0.0 not ?
>
> also, 3 or more displays will not work?
>
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