[SDL] mousewheel partially broken on macOS 10.12, SDL hg

Eric Wasylishen ewasylishen at gmail.com
Wed Sep 21 10:47:56 PDT 2016

Posted to the bugtracker with a possible fix here:

On Wed, Sep 21, 2016 at 11:36 AM, Eric Wasylishen <ewasylishen at gmail.com> wrote:
> Hi,
> If I run the "testrelative" SDL demo with "--info all", I'm noticing
> that rolling the scroll wheel one "notch" doesn't generate a scroll
> event. If I keep rolling it, I will start to see scroll events logged.
> This is with a logitech G400, or a microsoft ergonomic mouse.
> What's happening is, in Cocoa_HandleMouseWheel the deltaY for
> scrolling the scroll wheel one notch is 0.00172424316. SDL adds 0.9 to
> that, and the resuting value is truncated to an int which results in
> 0.
> I don't think this happened in OS X 10.11.
> As an immediate fix, if the delta is non-zero, we could snap it to 1
> or -1. Maybe this needs a runtime macOS version check to avoid
> changing the scroll behaviour on previous mac versions?
> Eric

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