We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

Bug 2110 - Debian bug report: libsdl2/X: false positives in mouse wheel code
Summary: Debian bug report: libsdl2/X: false positives in mouse wheel code
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: *don't know* (show other bugs)
Version: 2.0.0
Hardware: x86_64 Linux
: P2 normal
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-09-22 20:30 UTC by manuel.montezelo
Modified: 2013-09-28 06:37 UTC (History)
0 users

See Also:

Attachments
mouse-wheel-false-positives.diff (1.97 KB, patch)
2013-09-22 20:30 UTC, manuel.montezelo 		Details | Diff
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description manuel.montezelo 2013-09-22 20:30:21 UTC 
Created attachment 1335 [details]
mouse-wheel-false-positives.diff

This was reported in Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=723797

Patch suggested by Darren attached.  Please advise before we incorporate it in Debian.

-----------------------------------------------------------
Reported by: Darren Salt <bugspam@moreofthesa.me.uk>

I've noticed that one mouse button, which was fine with SDL 1.2, didn't
appear to be working when using SDL 2.0.

Some digging showed that it's a consequence of two things: how SDL2 detects
mouse wheel usage, and a kernel patch to work around a problem with the mouse
in question regarding that button.

Since the mouse does not generate a release event when that button is
released (this appears to be by design), release events need to be
synthesised in order to avoid confusing X into thinking that a drag operation
is in progress when that button is pressed. This causes press time == release
time, and tricks SDL2 into handling it as a wheel – but, since SDL2 ‘knows’
elsewhere that Button4 and Button5 are the only possible wheel buttons, the
event is effectively discarded (it is sent with wheel.y = 0 and the button
information is lost).

(While investigating this, I noticed that the horizontal wheel ISN'T picked
up as a mouse wheel and, consequently, works without problems with SDL2 – it
fails the press time == release time test so doesn't fall foul of SDL2's X11
code only knowing about the vertical scroll wheel.)
-----------------------------------------------------------
Comment 1 Sam Lantinga 2013-09-28 06:37:44 UTC 
Yes, this patch looks good and is in for the 2.0.1 release.
http://hg.libsdl.org/SDL/rev/6073ad385c9b

Thanks!