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| author | Peter Hutterer <peter.hutterer@who-t.net> | 2019-01-21 15:21:45 +1000 |
|---|---|---|
| committer | Peter Hutterer <peter.hutterer@who-t.net> | 2019-01-25 14:31:11 +1000 |
| commit | e7eafa199e9e60c15014a9d72d14efcbbf8e44ca (patch) | |
| tree | 9a9b66712ca03fc1a90f09c3e236e32c88d3fe24 | |
| parent | d13ab268bdf6eb589022c58ddc87c1211b49ac4c (diff) | |
| download | xorg-driver-xf86-input-libinput-e7eafa199e9e60c15014a9d72d14efcbbf8e44ca.tar.gz | |
Handle scroll wheel events with a discrete of 0
The driver currently assumes that any wheel event has a non-zero discrete
value of 1. This is incorrect, it just hasn't triggered yet with any device.
With the hi-res scroll patches in place in the kernel and libinput, we may get
wheel events with a discrete value of 0. We assume that if this ever happens,
the device has some sensible click angle set so all we need to do is ignore
the discrete 0 events and wait for the first discrete event to come.
Also add an explanatory comment too to make it clear the calculation is only
done once.
Fixes #19
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
| -rw-r--r-- | src/xf86libinput.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/xf86libinput.c b/src/xf86libinput.c index a3005ea..103e0a4 100644 --- a/src/xf86libinput.c +++ b/src/xf86libinput.c @@ -1564,6 +1564,10 @@ xf86libinput_handle_key(InputInfoPtr pInfo, struct libinput_event_keyboard *even * e.g. a 2 degree click angle requires 8 clicks before a legacy event is * sent, but each of those clicks will send XI2.1 smooth scroll data for * compatible clients. + * + * Starting with kernel v5.0 we should get REL_WHEEL_HI_RES from those + * devices for the fine-grained scrolling and REL_WHEEL for the normal one, + * so the use-case above shouldn't matter anymore. */ static inline double get_wheel_scroll_value(struct xf86libinput *driver_data, @@ -1589,9 +1593,22 @@ get_wheel_scroll_value(struct xf86libinput *driver_data, angle = libinput_event_pointer_get_axis_value(event, axis); discrete = libinput_event_pointer_get_axis_value_discrete(event, axis); + /* We only need to guess the fraction on the first set of + * scroll events until a discrete value arrives. Once known, we + * re-use the fraction until the device goes away. + */ if (s->fraction != 0.0) goto out; + /* if we get a discrete of 0, assume REL_WHEEL_HI_RES exists and + * normal scroll events are sent correctly, so skip all the + * guesswork. + */ + if (discrete == 0) { + s->fraction = 1.0; + goto out; + } + /* Calculate the angle per single scroll event */ angle /= discrete; |