Viewport scale properties are ignored when Accessibility Zoom is on in iOS
||Date Originated:||18-Feb-2011 11:19 PM|
||Resolved:||iOS 5.0 beta 1|
Summary: In Mobile Safari, the viewport meta element properties seem to be ignored when Accessibility Zoom has been turned on in iOS. This results in the scale factor not staying at 1.0 when the device orientation changes from portrait to landscape orientation, breaking web applications which require a 1:1 mapping between the viewport and the visible area in order to adjust the application layout.
Steps to Reproduce: 1. Make sure “Settings” > “General” >”Accessibility” > “Zoom” is set to “On”.
2. Go to http://stuff.vandervossen.net/temporary/orientation.html or open the uploaded test page.
3. Rotate the iOS device from landscape to portrait orientation.
Expected Results: The scale factor should stay at 1.0 so that a 1:1 mapping between the viewport and the visible area is maintained.
Actual Results: The scale factor increases so that part of the viewport is no longer visible.
Notes: This behavior breaks web applications which require a 1:1 mapping between the viewport and the visible area in order to adjust the application layout for orientation changes.
These web applications often prevent the default handling of the touchstart event (as done on this page) which means that even though the “maximum-scale=1“ and/or ”user-scalable=no” viewport properties seem to be ignored when Accessibility Zoom is on, the user is still unable to change the scale of the viewport using the pinch open, and pinch close gestures (try it).
Given these issues it would seem reasonable for the Accessibility Zoom feature to no longer override the viewport settings defined in the viewport meta element of a HTML page. This would follow the behavior of the native applications and would allow the 3-finger gestures of the Accessibility Zoom feature to be used for web applications in both portrait and landscape orientation.
The irony is that right now, these kind of web application are made less accessible; parts of their UI are not visible and can’t be accessed when Accessibility Zoom is on. The full UI can only be accessed when Accessibility Zoom has been turned off, but then the user can’t use the 3-finger gestures to magnify and move around the screen.
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