Line is positioned above touch point on iPad/iOS

[robertbird]

Hi, this is a great library, thankyou so much for sharing this!!

This works perfectly in a browser but when I tested on the latest version of iOS (5.1.1) I noticed that the line being drawn is slightly above the point on the screen that you touch. (I've tested this with a pen too).

It's ok when you get used to it, but for new users it seems to result in the signature going up at an angle as the user tries to compensate.

This is definitely more obvious on an iPad, but also happens to a lesser extent on the iPhone too.

[dvdotsenko]

Would you say the slight shift up is a "problem" or a "feature" for an average finger-using user?

[robertbird]

Thanks for the response, unfortunately I would say this is a problem for the average user.

It's as if you could just subtract a fixed amount from the vertical position when on iOS and it would be spot-on.

[brinley]

Hi Robert,

I haven't got a chance to try this out on an iPad but can you try to add a position relative on the containing element of your jSignature element? As I have seen an issue in an earlier version of jSignature which was caused by an incorrect calculation of the offset due to the positioning.

Regards, Brinley

[dvdotsenko]

Nahh. This is not a bug Brinley. This is a feature in jSig2 called Fat Finger Compensation. jSig detects touch devices and shifts the drawing a few pixels up.

We tested this on users internally and people loved it. They can see the line they are drawing behind the finger. Without the shift we saw a lot of finger lifting to see if what they wanted to draw came out right.

Based on enough research, I tend to say we keep the fat finger shift on touch devices, just scale it down a bit, maybe. I'll do some trials on this. Until then, it's a feature. :)

Daniel On May 26, 2012 1:55 AM, "Brinley Ang" < reply@reply.github.com> wrote:

Hi Robert,

I haven't got a chance to try this out on an iPad but can you try to add a position relative on the containing element of your jSignature element? As I have seen an issue in an earlier version of jSignature which was caused by an incorrect calculation of the offset due to the positioning.

Regards, Brinley

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Reply to this email directly or view it on GitHub: https://github.com/brinley/jSignature/issues/12#issuecomment-5945581

[brinley]

Ah i see. In that case, why not add a configurable option to manage the offset with an overwritable default rather than fixing to 15?

[robertbird]

Ah ok, that makes sense. I can see that users would want to see the line they are drawing, but in my opinion it should be scaled down slightly. A configurable option would be ideal. Cheers for the explanation

[dvdotsenko]

Take a glance (with your preferred touch device) at demo here: http://willowsystems.github.com/jSignature/#/demo/

It's updated to have more modest Fat Finger Compensation shift.

There is also a new setting value you can yank around (as of commit https://github.com/willowsystems/jSignature/commit/4da181b5552645bccbd7fae15db5d07cc9301b9c ) - minFatFingerCompensation

Set it to 0 (zero) to disable the shift, which is still "ON" by default, but less rabid.

If the solution is acceptable, will push it to mainline repo.

[brinley]

I think its perfect! Merge it

[robertbird]

Wow, thanks for such a quick turnaround! It's perfect, exactly what I was after!

[dvdotsenko]

merged.