Bug 88359 – [chromium] More than 8 fingers get ignored by touch

• Status: RESOLVED
• Resolution: FIXED
• Component: UI Events

[Eugene Girard]

WebTouchEvent::touchesLengthCap is set to 8.

On devices that support more than 8 touches, additional touches get ignored.  Bump this up to 12.

[Robert Kroeger]

Created attachment 145862 [details]
Patch

[Robert Kroeger]

I think this is sufficient. What do you think?

[WebKit Review Bot]

Please wait for approval from [e-mail], [e-mail], [e-mail], [e-mail] or [e-mail] before submitting, as this patch contains changes to the Chromium public API. See also https://trac.webkit.org/wiki/ChromiumWebKitAPI.

[Eugene Girard]

LGTM

[James Robinson]

Both of these numbers seem really arbitrary.  Is the use case here two-handed polydactylic users?

[Robert Kroeger]

fwiw: my justification for 12: it's 1 more than the best commonly available touchscreen hardware and as you observe: more than the normal human finger count.

[Eugene Girard]

Arbitrary, yes.  The justification is that we have ten fingers, so eight is clearly too low.  The Gesture Recognizer (part of Chromium) assumes 12 points.  The iPad supports 11, 3M reportedly makes a 30 touch screen, and my home brew device supports, well, an unlimited number of points.

12 seemed to be a good value since it's in line with the GR.

[James Robinson]

Comment on attachment 145862 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=145862&action=review

> Source/WebKit/chromium/public/WebInputEvent.h:388
> +    enum { touchesLengthCap = 12 };

Please document where this number is coming from (i.e. this is matching chromium's gesture recognition library).

[Robert Kroeger]

Created attachment 146599 [details]
Patch

[WebKit Review Bot]

Comment on attachment 146599 [details]
Patch

Clearing flags on attachment: 146599

Committed r119843: <http://trac.webkit.org/changeset/119843>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.

[Eric Seidel (no email)]

Comment on attachment 146599 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=146599&action=review

> Source/WebKit/chromium/public/WebInputEvent.h:389
> +    // Maximum number of simultaneous touches supported on
> +    // Ash/Aura.

Odd wrapping.  Odd names.