[PATCH weston 09/25] libinput: do not switch output associations on disable

[Peter Hutterer]

On Fri, Mar 23, 2018 at 02:00:49PM +0200, Pekka Paalanen wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> If an input device is associated to an output that then gets disabled,
> there is no case where associating to a different output would be
> correct.

just a general note here, especially in light of Jason's comments:
this statement above isn't true for external tablet devices like
the Wacom Intuos series (the ones *not* integrated into a touchscreen).
There are workflows where the device is used in absolute mode and mapped to
a specific monitor even though it's external like a touchpad. In fact, IMO
it's the more sane mode for these devices as the only other alternative is
to have the tablet span all outputs, making everything a bit weird.

With those devices, unplugging an output should thus map the tablet to the
remaining one.

It's not yet something weston needs to worry about given the other things
that you need in place for this to work (specifically: tablet area ratio to
monitor ratio). But keep this filed away in the back of your head anyway.

Cheers,
   Peter

> 
> The output association is used for absolute positioned input devices,
> and an input device like a touchscreen cannot ever be automatically
> valid for more than one possible output - the touchscreen display
> device.
> 
> Therefore do not automatically reassing implicitly associated input
> devices to another output. This removes some log spam on shutdown.
> 
> In fact, if there can be more than one output at any time, absolute
> input devices must be explicitly configured to associate with the
> correct output, or the results are essentially undefined in any case.
> 
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> ---
>  libweston/libinput-device.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/libweston/libinput-device.c b/libweston/libinput-device.c
> index dbbaae32..e1738613 100644
> --- a/libweston/libinput-device.c
> +++ b/libweston/libinput-device.c
> @@ -434,16 +434,8 @@ notify_output_destroy(struct wl_listener *listener, void *data)
>  	struct evdev_device *device =
>  		container_of(listener,
>  			     struct evdev_device, output_destroy_listener);
> -	struct weston_compositor *c = device->seat->compositor;
> -	struct weston_output *output;
> -
> -	if (!device->output_name && !wl_list_empty(&c->output_list)) {
> -		output = container_of(c->output_list.next,
> -				      struct weston_output, link);
> -		evdev_device_set_output(device, output);
> -	} else {
> -		evdev_device_set_output(device, NULL);
> -	}
> +
> +	evdev_device_set_output(device, NULL);
>  }
>  
>  /**
> -- 
> 2.16.1
> 
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