Re: [PATCH v2] ui/gtk: Allow user to select monitor number to display qemu in full screen through new gtk display option

[Markus Armbruster <armbru@redhat.com>]

You neglected to cc: the Graphics maintainer.  I'm doing that for you
now.

sweeaun <swee.aun.khor@intel.com> writes:

>  -display gtk,monitor=<value>
>
> Signed-off-by: sweeaun <swee.aun.khor@intel.com>

Your commit message is formatted badly.  What about this:

    ui/gtk: New -display gtk parameter 'monitor'.

    This lets the user select monitor number to display QEMU in full
    screen with -display gtk,monitor=<value>.

Furthermore, you're Signed-off-by line may be off.  It should be of the
form

    Signed-off-by: REAL NAME <EMAIL>

Is "sweeaun" your real name?

> ---
>  qapi/ui.json    |  4 +++-
>  qemu-options.hx |  2 +-
>  ui/gtk.c        | 15 +++++++++++++++
>  3 files changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/ui.json b/qapi/ui.json
> index 1052ca9c38..1616f3ffbd 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -1035,13 +1035,15 @@
>  #               assuming the guest will resize the display to match
>  #               the window size then.  Otherwise it defaults to "off".
>  #               Since 3.1
> +# @monitor: Monitor number to display qemu in full screen.

We spell it QEMU.

Should "full screen" be "full-screen" or even "fullscreen"?

>  #
>  # Since: 2.12
>  #
>  ##
>  { 'struct'  : 'DisplayGTK',
>    'data'    : { '*grab-on-hover' : 'bool',
> -                '*zoom-to-fit'   : 'bool'  } }
> +                '*zoom-to-fit'   : 'bool',
> +                '*monitor' : 'int' } }

Best to make your addition "blend in" like this

   { 'struct'  : 'DisplayGTK',
     'data'    : { '*grab-on-hover' : 'bool',
                   '*zoom-to-fit'   : 'bool',
                   '*monitor'       : 'int' } }

>  
>  ##
>  # @DisplayEGLHeadless:
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 14258784b3..e4b89b6a72 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1787,7 +1787,7 @@ DEF("display", HAS_ARG, QEMU_OPTION_display,
>      "            [,window_close=on|off][,gl=on|core|es|off]\n"
>  #endif
>  #if defined(CONFIG_GTK)
> -    "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
> +    "-display gtk[,grab_on_hover=on|off][,gl=on|off][,monitor=<value>]\n"
>  #endif
>  #if defined(CONFIG_VNC)
>      "-display vnc=<display>[,<optargs>]\n"
> diff --git a/ui/gtk.c b/ui/gtk.c
> index 98046f577b..84da126611 100644
> --- a/ui/gtk.c
> +++ b/ui/gtk.c
> @@ -2268,6 +2268,21 @@ static void gtk_display_init(DisplayState *ds, DisplayOptions *opts)
>          gtk_menu_item_activate(GTK_MENU_ITEM(s->grab_on_hover_item));
>      }
>      gd_clipboard_init(s);
> +
> +    if (opts->u.gtk.has_monitor) {
> +        int n_monitor;
> +        n_monitor = gdk_display_get_n_monitors(window_display);

Terser:

           int n_monitor = gdk_display_get_n_monitors(window_display);

> +
> +        if ((opts->u.gtk.monitor <= n_monitor) &&
> +            (opts->u.gtk.monitor > 0)) {

Suggest to drop the superfluous parenthesis:

           if (opts->u.gtk.monitor <= n_monitor &&
               opts->u.gtk.monitor > 0) {

> +            GdkScreen *gdk_screen;
> +            gdk_screen = gdk_display_get_default_screen(window_display);
> +            gtk_window_fullscreen_on_monitor(GTK_WINDOW(s->window), gdk_screen,
> +                                             (opts->u.gtk.monitor - 1));

Drop the superfluous parenthesis around the last argument.

Your new option argument seems to count monitors from 1, while GTK
counts them from zero.  Why the difference?

Your documentation states that @monitor applies only "in full screen",
but this code is not guarded by if (opts->full_screen).  Why is that
okay?

From gdk_display_get_n_monitors()'s documentation: "The returned number
is valid until the next emission of the “monitor-added” or
“monitor-removed” signal."  This suggests monitors can come and go at
any time.  If they can, what happens when the monitor we're trying to
use here has gone away since we called gdk_display_get_n_monitors()?

> +        } else {
> +            fprintf(stderr, "Invalid GTK monitor argument\n");
> +        }
> +    }
>  }
>  
>  static void early_gtk_display_init(DisplayOptions *opts)