[chimerax-users] mutitouch mac

[Tom Goddard]

Hi Edoardo,

We don’t have multitouch (2 and 3 finger drag) in ChimeraX currently.

A few years ago I used the Qt window toolkit to handle multitouch events. Qt 5.2(?) had multitouch disabled on Mac OS because it supposedly interfered with scrolling. I don't think I observed that scrolling problem. But I had to write some C++ code that called a native Mac OS method to get touch events, a pretty ugly hack to get it to work.

The current state in Qt 5.9 seems that multitouch events work with Qt widgets. But we need them to work on the graphics area which is a QWindow (for drawing OpenGL 3D graphics). The following Qt bug report (53874) from June 2016 indicates that getting multitouch events on Mac in a QWindow does not work despite the documentation saying it is supposed to work.

​https://bugreports.qt.io/browse/QTBUG-53874 <https://bugreports.qt.io/browse/QTBUG-53874>
A comment from the Qt developer Morten Sørvig assigned to this ticket indicates it still will require a C++ hack to get multitouch events. "Touch events need to be enabled on a per-QWindow basis on OS X. Widgets and Quick currently do this via the private function QCocoaNativeInterface::registerTouchWindow(). This means there is currently no way to get touch evens via QWindow::touchEvent() on OS X using public API only."

I think the same hack I used in the past can get by this problem. But I don't thick trackpad handling on Mac is important enough relative to other priorities to work on it right now.

Here is the ChimeraX ticket to monitor progress on this issue.  This URL is currently password protected but we are working to make the ChimeraX bug/feature database visible to the public.

	https://www.rbvi.ucsf.edu/trac/ChimeraX/ticket/427 <https://www.rbvi.ucsf.edu/trac/ChimeraX/ticket/427>

  Tom


> On Sep 15, 2017, at 3:39 AM, Edoardo Gianni <egianni at mrc-lmb.cam.ac.uk> wrote:
> 
> Hello,
> 
> I was wondering if multitouch was available on chimerax for mac, or if you had plans to implement it in the future.
> 
> Thanks and best wishes,
> Edoardo
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