Add a trackpad twist speed preference setting

[olibclarke@…]

Begin forwarded message:

On Sep 29, 2021, at 12:42 PM, Oliver Clarke via ChimeraX-users <chimerax-users@…> wrote:

Hi,

In recent versions of ChimeraX (I don't think it always did this but can't be 100% sure), when one uses pinch-to-zoom on the trackpad to scale the view, this also changes orientation, causing quite a large and unintended rotation which can be a bit disconcerting. Comparing directly with Chimera using the same model, this does not happen in Chimera.

Is there some difference in how the Chimera vs X are interpreting competing trackpad gestures, and could this be adjusted in ChimeraX? Because two fingers can be used both to scale and rotate... Chimera seems to be able to figure out which the user is intending, while ChimeraX presently applies both at the same time.

Cheers
Oli

From: Tom Goddard via ChimeraX-users <chimerax-users@…>
Subject: Re: [chimerax-users] Trackpad scaling causes unintended rotation
Date: September 29, 2021 at 12:55:19 PM PDT
To: Oliver Clarke <olibclarke@…>
Cc: ChimeraX Users Help <chimerax-users@…>
Reply-To: Tom Goddard

Hi Oliver,

ChimeraX Mac trackpad pinch and two finger rotation both occur simultaneously. Chimera 1.15 seems to behave the same except that Chimera twist sensitivity is less. I see in the ChimeraX code the twist speed factor is 6, meaning one full twist rotation would cause the model to rotate 6 full turns. This was intentional to make twist rotation adjustments less cumbersome. The Chimera 1.15 twist speed factor seems to be 2. Currently there is no command or preference setting to change just the twist speed. There is a ChimeraX trackpad preference to change the overall sensitivity but it will effect both pinch zoom and twist so won't help you zoom without twisting.

Tom

[olibclarke@…]

Just to add to this ticket - I know it is unlikely to get much attention for a while, but I think what would actually be most useful would be a preference to turn off "twist" completely, while still allowing pinch to zoom. 

With the trackpad, in-plane rotation is easy and precise by clicking and dragging along the edges of the display window. Having both twist and zoom assigned to the same gesture means neither are precise enough to be useful, in my opinion. In Chimera this wasn't an issue because the twist sensitivity was low enough that it didn't substantially change the view when pinching to zoom, but in ChimeraX this is not the case.

Cheers
Oli

[Tom Goddard]

Ok, I added a trackpad twist speed option. Default value is 6, meaning the models rotate 6 times faster than your two finger twist rotation. You can set it to 0 or a smaller value to reduce twist sensitivity. The setting is in ChimeraX Preferences / Trackpad.

[Tom Goddard]

Added only in ChimeraX 1.4. Too late for 1.3 which is scheduled for release in a week.