On Tue, Jul 20, 2021 at 6:43 PM Dennis Wölfing <denniswoelfing@gmx.de>
wrote:

> To handle relative mouse input the event handler needs to move the mouse
> away from the screen edges. Failing to do so results in the mouse
> getting stuck at invisible walls. However the current implementation for
> this is broken on hosts with multiple monitors.
>
> With multiple monitors the mouse can be located outside of the current
> monitor which is not handled by the current code. Also the monitor
> itself might be located at coordinates different from (0, 0).
>
> Signed-off-by: Dennis Wölfing <denniswoelfing@gmx.de>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

---
> Changes in v2:
> Warp the mouse to the center of the monitor.
>
>  ui/gtk.c | 26 +++++++-------------------
>  1 file changed, 7 insertions(+), 19 deletions(-)
>
> diff --git a/ui/gtk.c b/ui/gtk.c
> index 376b4d528d..18542c7633 100644
> --- a/ui/gtk.c
> +++ b/ui/gtk.c
> @@ -865,37 +865,25 @@ static gboolean gd_motion_event(GtkWidget *widget,
> GdkEventMotion *motion,
>          GdkWindow *win = gtk_widget_get_window(widget);
>          GdkMonitor *monitor = gdk_display_get_monitor_at_window(dpy, win);
>          GdkRectangle geometry;
> -        int screen_width, screen_height;
>
>          int x = (int)motion->x_root;
>          int y = (int)motion->y_root;
>
>          gdk_monitor_get_geometry(monitor, &geometry);
> -        screen_width = geometry.width;
> -        screen_height = geometry.height;
>
>          /* In relative mode check to see if client pointer hit
> -         * one of the screen edges, and if so move it back by
> -         * 200 pixels. This is important because the pointer
> +         * one of the monitor edges, and if so move it back to the
> +         * center of the monitor. This is important because the pointer
>           * in the server doesn't correspond 1-for-1, and so
>           * may still be only half way across the screen. Without
>           * this warp, the server pointer would thus appear to hit
>           * an invisible wall */
> -        if (x == 0) {
> -            x += 200;
> -        }
> -        if (y == 0) {
> -            y += 200;
> -        }
> -        if (x == (screen_width - 1)) {
> -            x -= 200;
> -        }
> -        if (y == (screen_height - 1)) {
> -            y -= 200;
> -        }
> -
> -        if (x != (int)motion->x_root || y != (int)motion->y_root) {
> +        if (x <= geometry.x || x - geometry.x >= geometry.width - 1 ||
> +            y <= geometry.y || y - geometry.y >= geometry.height - 1) {
>              GdkDevice *dev = gdk_event_get_device((GdkEvent *)motion);
> +            x = geometry.x + geometry.width / 2;
> +            y = geometry.y + geometry.height / 2;
> +
>              gdk_device_warp(dev, screen, x, y);
>              s->last_set = FALSE;
>              return FALSE;
> --
> 2.32.0
>
>

-- 
Marc-André Lureau