[PATCH libinput] Add libinput_device_touch_get_touch_count()

[Peter Hutterer]

On Fri, Mar 02, 2018 at 06:16:34PM +1000, Peter Hutterer wrote:
> This makes it possible for callers to detect whether a touch device is
> single or multitouch (or even check for things like dual-touch vs real
> multi-touch) and adjust the interface accordingly.
> 
> Note that this is for touch devices only, not touchpads that are just pointer
> devices.

ping? as a general rule, I don't add new APIs unless the people who need it
review the patches...

Cheers,
   Peter

> https://bugs.freedesktop.org/show_bug.cgi?id=104867
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/evdev.c       | 22 ++++++++++++++++++++++
>  src/evdev.h       |  3 +++
>  src/libinput.c    |  6 ++++++
>  src/libinput.h    | 14 ++++++++++++++
>  src/libinput.sym  |  4 ++++
>  test/test-touch.c | 23 +++++++++++++++++++++++
>  6 files changed, 72 insertions(+)
> 
> diff --git a/src/evdev.c b/src/evdev.c
> index 257824aa..629d4e2f 100644
> --- a/src/evdev.c
> +++ b/src/evdev.c
> @@ -2224,6 +2224,28 @@ evdev_device_has_key(struct evdev_device *device, uint32_t code)
>  	return libevdev_has_event_code(device->evdev, EV_KEY, code);
>  }
>  
> +int
> +evdev_device_get_touch_count(struct evdev_device *device)
> +{
> +	int ntouches;
> +
> +	if (!(device->seat_caps & EVDEV_DEVICE_TOUCH))
> +		return -1;
> +
> +	ntouches = libevdev_get_num_slots(device->evdev);
> +	if (ntouches == -1) {
> +		/* mtdev device have multitouch but we don't know
> +		 * how many. Otherwise, any touch device with num_slots of
> +		 * -1 is a single-touch device */
> +		if (device->mtdev)
> +			ntouches = 0;
> +		else
> +			ntouches = 1;
> +	}
> +
> +	return ntouches;
> +}
> +
>  int
>  evdev_device_has_switch(struct evdev_device *device,
>  			enum libinput_switch sw)
> diff --git a/src/evdev.h b/src/evdev.h
> index 162adecb..e732e693 100644
> --- a/src/evdev.h
> +++ b/src/evdev.h
> @@ -459,6 +459,9 @@ evdev_device_has_button(struct evdev_device *device, uint32_t code);
>  int
>  evdev_device_has_key(struct evdev_device *device, uint32_t code);
>  
> +int
> +evdev_device_get_touch_count(struct evdev_device *device);
> +
>  int
>  evdev_device_has_switch(struct evdev_device *device,
>  			enum libinput_switch sw);
> diff --git a/src/libinput.c b/src/libinput.c
> index 8fb0ba92..5e675dd9 100644
> --- a/src/libinput.c
> +++ b/src/libinput.c
> @@ -2941,6 +2941,12 @@ libinput_device_keyboard_has_key(struct libinput_device *device, uint32_t code)
>  	return evdev_device_has_key((struct evdev_device *)device, code);
>  }
>  
> +LIBINPUT_EXPORT int
> +libinput_device_touch_get_touch_count(struct libinput_device *device)
> +{
> +	return evdev_device_get_touch_count((struct evdev_device *)device);
> +}
> +
>  LIBINPUT_EXPORT int
>  libinput_device_switch_has_switch(struct libinput_device *device,
>  				  enum libinput_switch sw)
> diff --git a/src/libinput.h b/src/libinput.h
> index 759bce91..d9f74d2f 100644
> --- a/src/libinput.h
> +++ b/src/libinput.h
> @@ -3713,6 +3713,20 @@ int
>  libinput_device_keyboard_has_key(struct libinput_device *device,
>  				 uint32_t code);
>  
> +/**
> + * @ingroup device
> + *
> + * Check how many touches a @ref LIBINPUT_DEVICE_CAP_TOUCH device supports
> + * simultaneously.
> + *
> + * @param device A current input device
> + *
> + * @return The number of simultaneous touches or 0 if unknown, -1
> + * on error.
> + */
> +int
> +libinput_device_touch_get_touch_count(struct libinput_device *device);
> +
>  /**
>   * @ingroup device
>   *
> diff --git a/src/libinput.sym b/src/libinput.sym
> index bb283407..aa2794e9 100644
> --- a/src/libinput.sym
> +++ b/src/libinput.sym
> @@ -293,3 +293,7 @@ LIBINPUT_1.7 {
>  LIBINPUT_1.9 {
>  	libinput_device_switch_has_switch;
>  } LIBINPUT_1.7;
> +
> +LIBINPUT_1.11 {
> +	libinput_device_touch_get_touch_count;
> +} LIBINPUT_1.9;
> diff --git a/test/test-touch.c b/test/test-touch.c
> index b3a6d0a0..a14bcf4b 100644
> --- a/test/test-touch.c
> +++ b/test/test-touch.c
> @@ -945,6 +945,26 @@ START_TEST(touch_release_on_unplug)
>  }
>  END_TEST
>  
> +START_TEST(touch_count_st)
> +{
> +	struct litest_device *dev = litest_current_device();
> +	struct libinput_device *device = dev->libinput_device;
> +
> +	ck_assert_int_eq(libinput_device_touch_get_touch_count(device), 1);
> +}
> +END_TEST
> +
> +START_TEST(touch_count_mt)
> +{
> +	struct litest_device *dev = litest_current_device();
> +	struct libinput_device *device = dev->libinput_device;
> +	struct libevdev *evdev = dev->evdev;
> +
> +	ck_assert_int_eq(libinput_device_touch_get_touch_count(device),
> +			 libevdev_get_num_slots(evdev));
> +}
> +END_TEST
> +
>  void
>  litest_setup_tests_touch(void)
>  {
> @@ -980,4 +1000,7 @@ litest_setup_tests_touch(void)
>  	litest_add_for_device("touch:fuzz", touch_fuzz, LITEST_MULTITOUCH_FUZZ_SCREEN);
>  
>  	litest_add_no_device("touch:release", touch_release_on_unplug);
> +
> +	litest_add("touch:count", touch_count_st, LITEST_SINGLE_TOUCH, LITEST_TOUCHPAD);
> +	litest_add("touch:count", touch_count_mt, LITEST_TOUCH, LITEST_SINGLE_TOUCH);
>  }
> -- 
> 2.14.3