- From: Alastair Campbell <acampbell@nomensa.com>
- Date: Mon, 5 Sep 2016 15:36:38 +0000
- To: David MacDonald <david100@sympatico.ca>
- CC: "public-mobile-a11y-tf@w3.org" <public-mobile-a11y-tf@w3.org>
> “Buttons in study were 20mm = 75px with spacing of 6.35mm = 24 px (conversion here https://css-tricks.com/the-lengths-of-css/ ) This was based on research listed below.“ You have to be careful converting from physical to CSS units when you don’t have the digital sizing specified. They were using a 10.1 inch tablet, with 1200x800 resolution. For the Galaxy Tab 10.1 the device-pixels = CSS pixels, so ~150 pixels per inch. http://dpi.lv/#800×1280@10.1″ As 1 inch=25.4mm, so 6px per mm on the tablet, although that is 2D which I think means 2.5px per non-square mm. Therefore 20mm wide = 50px on that device. It is a shame they don’t actually specify the sizing from a programming point of view, but I think 50px is more realistic and wouldn’t look odd. I’ve some (expensive?) reading to do, but presumably it is a sliding scale kind of thing? Obviously bigger is easier, but then you get to the point of having one button on a screen, where do we draw the line? I suspect that if we specified more than the platform guidelines, we’re looking at a triple-A level criterial that might be better done on the user-agent side anyway... Cheers, -Alastair
Received on Monday, 5 September 2016 15:37:10 UTC