[mutter] remote-desktop: Document NotifyPointerAxis() more explicit

[Marge Bot <marge-bot src gnome org>]

commit 70769454888e5077694ebbbaee65a2473cd1fe1c
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Wed Feb 17 21:33:21 2021 +0100

    remote-desktop: Document NotifyPointerAxis() more explicit
    
    Currently, the documentation for NotifyPointerAxis() just mentions that
    a smooth scroll event is emitted.
    However, this is not entirely correct. For each NotifyPointerAxis(),
    mutter emits an emulated discrete scrolling event based on the
    submitted accumulated smooth scrolling deltas.
    Additionally, it doesn't mention how the motion deltas need to be
    interpreted.
    
    So, document the NotifyPointerAxis() notification better by mentioning
    the emulation of discrete scroll events, how these discrete scroll
    events are calculated and how the motion deltas need to be interpreted.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1727>

 src/org.gnome.Mutter.RemoteDesktop.xml | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)
---
diff --git a/src/org.gnome.Mutter.RemoteDesktop.xml b/src/org.gnome.Mutter.RemoteDesktop.xml
index 0b79f70a61..1f3857e57b 100644
--- a/src/org.gnome.Mutter.RemoteDesktop.xml
+++ b/src/org.gnome.Mutter.RemoteDesktop.xml
@@ -111,7 +111,20 @@
     <!--
        NotifyPointerAxis:
 
-       A smooth pointer axis event notification
+       A smooth pointer axis event notification. Relative motion deltas are to be
+       interpreted as pixel movement of a standardized mouse.
+
+       Additionally to the smooth pointer axis event notification, an emulated
+       discrete pointer axis event notification is emitted based on the submitted
+       accumulated smooth scrolling steps.
+       The base for these emulated discrete pointer axis event is the discrete step
+       with the value 10.0.
+       This means that for a delta dx (or dy) with the value 10.0 one emulated
+       discrete scrolling event is emitted.
+       For a high resolution smooth pointer axis event, a smaller value is submitted
+       for each scrolling step.
+       This means: For a double resolution mouse wheel one emulated discrete event
+       is emitted for 2 smooth pointer axis events with each having the value 5.0.
 
        Possible @flags:
          1: finish - scroll motion was finished (e.g. fingers lifted)