Bug 159668 – AX: Double tap to zoom breaks fullscreen web apps (in WKWebView)

• Component: Accessibility
• Status: NEW

[Nan Wang]

Ignoring user-scalable=no should only affect pinch to zoom on iOS.

<rdar://problem/27052950>

[Nan Wang]

Created attachment 283394 [details]
Initial patch

[Simon Fraser (smfr)]

Comment on attachment 283394 [details]
Initial patch

You need the radar number in the commit message and changelog.

[Nan Wang]

Created attachment 283428 [details]
patch with radar number

Added radar number in changelog

[Nan Wang]

(In reply to comment #2)
> Comment on attachment 283394 [details]
> Initial patch
> 
> You need the radar number in the commit message and changelog.

Uploaded a new patch.

[Simon Fraser (smfr)]

Comment on attachment 283394 [details]
Initial patch

View in context: https://bugs.webkit.org/attachment.cgi?id=283394&action=review

> Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm:1733
> +    if ([_configuration ignoresViewportScaleLimits])
> +        return NO;

Doesn't this mean that you've killed double-tap zoom on ALL pages, not just those with user-scalable=no?

[Simon Fraser (smfr)]

Comment on attachment 283428 [details]
patch with radar number

Doesn't this mean that you've killed double-tap zoom on ALL pages, not just those with user-scalable=no?

[Simon Fraser (smfr)]

Comment on attachment 283428 [details]
patch with radar number

View in context: https://bugs.webkit.org/attachment.cgi?id=283428&action=review

> Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm:1733
> +    if ([_configuration ignoresViewportScaleLimits])
> +        return NO;

Why is it OK to check this first, before the other conditions?

[Dean Jackson]

Why is this change necessary? Why is double tap to zoom different from pinch zoom?

[Dean Jackson]

As I commented in radar, the zooming gestures are an all or nothing option. Pinch and double tap zoom are either enabled together, or disabled together.

(That's not quite true, since our fast tap heuristics sometimes disable double tap temporarily)

[Nan Wang]

(In reply to comment #8)
> Why is this change necessary? Why is double tap to zoom different from pinch
> zoom?

I think in some web apps, develop will intentionally set userscaleble=no and override double tap gesture on app side.  But if we have ignoresViewportScaleLimits enabled the webpage might intercept the gesture.

[Nan Wang]

(In reply to comment #6)
> Comment on attachment 283428 [details]
> patch with radar number
> 
> Doesn't this mean that you've killed double-tap zoom on ALL pages, not just
> those with user-scalable=no?

I will work on the user-scalable=no check

[Simon Fraser (smfr)]

Also, if your patch didn't cause any test failures, please add tests to detect the things that you would have broken.

[Nan Wang]

Created attachment 283473 [details]
Patch

Added another check for user-scalable=no and added test cases.

[Simon Fraser (smfr)]

Still not clear if this is the right approach. Comments in the Radar.

[siim]

Still not fixed in iOS 16.4.1