Re: [fltk.coredev] Gesture progress for 1.4?

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Re: Gesture progress for 1.4? Albrecht Schlosser 02:41 Oct 12 top right image
On 10/12/21 9:41 AM imacarthur wrote:

On Saturday, 9 October 2021 at 21:58:37 UTC+1 Albrecht Schlosser wrote:

Note that the two WM_MOUSEHWHEEL messages at the beginning of the log are really that. However, I don't know where exactly the other ewo interspersed WM_MOUSEHWHEEL messages came from. I think that's a Windows "feature", some gestures are sent as normal mousewheel events for backwards compatibility (more tests required).

Yes, from the subsequent discussion, it does seem very likely that the WM_MOUSEWHEEL events embedded in the GID_ZOOM stream may well be there to support legacy applications.
And therefore... do we need to do something analogous in our gesture event handling...?

Yes, I think so.

Windows gesture support in general is documented here:

The MS docs on "Legacy Support" can be found on the same page:

Interesting part: "The pan gesture maps to using the scroll wheel: WM_VSCROLL, WM_HSCROLL".

We don't handle these messages currently but I'm pretty sure I saw (vertical) WM_MOUSEWHEEL and (horizontal) WM_MOUSEHWHEEL messages originating from pan gestures. I'll check that out.

On macOS the system handles the pan gestures by sending  "mousewheel" events but, as Rob discovered and proposed in his patch, you can distinguish pan gestures from real mousewheel events and you *can* create different FLTK events. I think we need to keep the "legacy" behavior (FL_MOUSEWHEEL) but we can maybe add a flag so user programs know the origin (if necessary).

Another possibility would be to call an FLTK method that sets an option how to deal with such messages. Old programs that don't call this would get the "legacy" messages, new programs could opt in to use the "new" (gesture) messages. Or something like that. However, I wouldn't want to do that and I'm looking for a better way.

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