Cursor jumps when moving very slowly

[cesarizu]

When trying to reach to an exact pixel, when moving very slowly the cursor jumps 3-6 pixels. This only happens if I leave the cursor still for a bit and then move. If I move continuously the cursor doesn't jump.

[galexander1]

I think this is because the driver implements a bit of hysteresis. There is a heuristic in the mtrack driver that decides if input is signal or noise. If it hasn't detected signal in a while, then the weight of the assumption moves towards noise, and it requires a clear signal (a relatively larger movement with a consistent pressure and so on) before it will accept any input. But once you have convinced it the input is really coming from intentional movements of your finger, then it accepts even very small movements as input.

I find the status quo unsatisfying but as yet have not thought of anything better. :)

Cheers,

• Greg

On Wed, Nov 13, 2013 at 09:04:35AM -0800, César Izurieta wrote:

When trying to reach to an exact pixel, when moving very slowly the cursor jumps 3-6 pixels. This only happens if I leave the cursor still for a bit and then move. If I move continuously the cursor doesn't jump.

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Reply to this email directly or view it on GitHub: https://github.com/BlueDragonX/xf86-input-mtrack/issues/60

[cesarizu]

Hello Greg,

Thanks a lot for your reply. Could you point me where in the code this heuristic is? I would like to give it a shot and see if there's anything I can do.

Greetings, César

[rynbrd]

I don't have any such heuristics for noise built into the driver. Though I do experience the same behavior on my MBP Retina. What trackpad are you using?

[cesarizu]

I have a MBP retina as well.