mozRequestFullScreen While Zoomed Causes Unexpected Results in iframes




Firefox for Android
5 months ago
4 months ago


(Reporter: Kenneth Weaver, Unassigned)


54 Branch

Firefox Tracking Flags

(Not tracked)




5 months ago
User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Steps to reproduce:

*Tested in Firefox 54.0.1 on a Nexus 6 running Android version 7.0*

1. Pinch zoom the page over the cyan box (results section of the fiddle).

-Note that the page should have a good amount of space to scroll left and up, now.

2. Tap the cyan box (runs mozRequestFullScreen on the iframe's documentElement)

Actual results:

While the iframe is fullscreen, it will start out looking correct (cyan box sits in top-left corner while the rest of the screen is blue).

-Touching the cyan box at this point will not trigger a click/touch event, but instead click the jsfiddle page. You can even click within the jsfiddle code behind the fullscreen element and edit it!

-In order to trigger a click/touch event on the cyan box, you must first scroll the page all the way to the top left (note that it won't look like any scrolling is occurring). It seems that the fullscreen element is located at the top left, even though this isn't true, visually.

-If, while fullscreen, the page remains untouched for 10~20 seconds, the fullscreen element will jump to the top left of the page. Any scrolling will return the element to being at the top left of the screen.

Side note: mozRequestFullScreen on Firefox for Android doesn't reset the zoom level while zoomed, but does prevent further zooming in and out, which can be very counter-intuitive for a user experience. It should either force a specific zoom level (check same fiddle in chrome) or still allow zooming while fullscreen.

Expected results:

When an iframe requests fullscreen:

It should properly occupy the screen space and allow interaction (touch/click events).

The parent of the fullscreen element should not receive any touch/click interaction. 

The fullscreen element should either be at the default zoom level, or retain the ability to zoom in/out.
I can reproduce this on my device. It is pretty strange behaviour. We have some other related bugs with zooming and fullscreen, I think.
Ever confirmed: true
Priority: -- → P3
See Also: → bug 1296776
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