CTRL++ zoom disorients iframe content




4 years ago
2 years ago


(Reporter: Dan Jacobson, Unassigned)


({helpwanted, testcase-wanted})

27 Branch
helpwanted, testcase-wanted

Firefox Tracking Flags

(Not tracked)




4 years ago
User Agent: Mozilla/5.0 (X11; Linux i686; rv:27.0) Gecko/20100101 Firefox/27.0 Iceweasel/27.0a2 (Beta/Release)
Build ID: 20131115004004

Steps to reproduce:

Plopped the below into an .html file and browsed it. Then hit CTRL++++++

<p><iframe width="640" height="480" frameborder="0" scrolling="no"
 marginheight="0" marginwidth="0" src=
 <a href=

Actual results:

The planes zoomed differently than the map, ending up in the water.

Expected results:

The planes and map should have zoomed at the same pace, just like they do in Google Chrome.
I can reproduce this issue with latest Aurora (build ID: 20131117004001) on Ubuntu 12.04 32-bit.
Ever confirmed: true


4 years ago
Component: Untriaged → Layout
Product: Firefox → Core
When you change the zoom you'll see the map update first, and then the planes get updated a little bit after. This would be consistent with the page updating the position of the planes. There are differences in the way that full zoom (control + corresponds to full zoom on Firefox, not text zoom as the bug title says) is handled in Firefox and Chrome. So my suspicion is that this will come down to one of those differences.


4 years ago
Summary: Text zoom disorients iframe content → CTRL++ zoom disorients iframe content


4 years ago
Priority: -- → P4
It would be appreciated if someone could dissect how the scripts at flightradar24.com
calculates the screen coordinates for the planes.
Keywords: helpwanted, testcase-wanted
Or perhaps someone wants to contact the affected website about this for them to look into.
This seems equally broken on all the browsers I've tried it on. Interestingly, Edge has some rounding errors that nicely show what look like layer boundaries or some kind of tiling within the canvas. Those boundaries happen to be exactly where the planes tend to have glitching issues when zooming.

Also, the zooming issues we were able to observe occurred when viewing the page directly too, not just when in an embedded iframe.

I'm not sure there's anything actionable to do here on our end.
Flags: needinfo?(mats)
I don't think it's possible to tell before someone has analyzed how this site works.
But yeah, it's unlikely a bug on our end if other UAs have similar glitches.
Flags: needinfo?(mats)
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