[PATCH libinput] Add libinput_device_touch_get_touch_count()

[Johannes Pointner]

Hello Peter,

I'm really sorry. I somehow completely missed your email.

I have now tested your patch with the 1.10-branch of libinput and
xf86-input-libinput-0.27.1 (the current versions used on my Arch Linux
PC).
Therefore I patched xf86-input-libinput.c like that:
diff --git a/src/xf86libinput.c b/src/xf86libinput.c
index f9ed8ba..dfbde9f 100644
--- a/src/xf86libinput.c
+++ b/src/xf86libinput.c
@@ -1058,11 +1058,13 @@ xf86libinput_init_touch(InputInfoPtr pInfo)
 {
  DeviceIntPtr dev = pInfo->dev;
  struct xf86libinput *driver_data = pInfo->private;
+ struct libinput_device *device = driver_data->shared_device->device;
  int min, max, res;
  unsigned char btnmap[MAX_BUTTONS + 1];
  Atom btnlabels[MAX_BUTTONS];
  Atom axislabels[TOUCHPAD_NUM_AXES];
  int nbuttons = 7;
+ int ntouches;

  init_button_map(btnmap, ARRAY_SIZE(btnmap));
  init_button_labels(btnlabels, ARRAY_SIZE(btnlabels));
@@ -1086,7 +1088,8 @@ xf86libinput_init_touch(InputInfoPtr pInfo)
  xf86InitValuatorAxisStruct(dev, 1,
             XIGetKnownProperty(AXIS_LABEL_PROP_ABS_MT_POSITION_Y),
     min, max, res * 1000, 0, res * 1000, Absolute);
- InitTouchClassDeviceStruct(dev, TOUCH_MAX_SLOTS, XIDirectTouch, 2);
+ ntouches = libinput_device_touch_get_touch_count(device);
+ InitTouchClassDeviceStruct(dev, ntouches, XIDirectTouch, 2);

As a result I was able to get the actual number of touch points from
Chromium through
https://developer.mozilla.org/en-US/docs/Web/API/Navigator/maxTouchPoints.

Cheers,
Hannes

On Mon, Mar 19, 2018 at 5:41 AM, Peter Hutterer
<peter.hutterer at who-t.net> wrote:
> 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