Re: notes on 320 CSS Pixels to inches

On 18/01/2018 05:12, Gregg Vanderheiden GPII wrote:
> *Can someone check the thinking - calculations here? *
> *thx*
> *Gregg*
> 
> *
> *
> *RE 320 pixels*
> 
>     A CSS pixel is .26 mm

I'll stop you right there to point out that on screen devices, 
everything is anchored on the ideal pixel. So when you start talking 
about converting CSS px to a measurement like mm, inch, etc, that still 
doesn't actually mean "as measured on the screen with a ruler", as 
devices/browsers do not actually know/care what the actual physical size 
of their display is.

>       x 320 CSS pixels = 83.2 mm  = 8.32 CM = 3.275591 inch

Case in point: most mobile phones, in portrait orientation, have a width 
of 320 CSS px. Now, there are a large variety of phones out there with 
varying actual physical dimensions...but they all have the same CSS 
pixel width. Take an actual ruler, measure the actual width of your 
phone's screen...and you're likely never to hit that exact measure in 
mm/cm/inches.

> *RE 40 CSS Pixels *
> 
>     and 40 CSS pixels would be  10mm or 1 CM
> 
>     that would be a HUGE button on a phone

Even assuming that this was always an actual 1cm as measured on screen 
(but as pointed out above, the actual dimension really varies), look at 
the actual size of a fingertip. Look at the area it covers when you tap 
somewhere. Look at the area it obscures while on a screen. While yes, 
the active "tip" of a finger can - with a lot of dexterity and control - 
touch a relatively small area, it gets tricky. Particularly if you then 
add any further factors like tremors or similar.

>     and it would be hard to put many of those on a screen -  or much
>     content on the screen with many links / buttons

Which is why, if you look at native apps on mobile for instance, you'll 
notice that indeed they usually don't feature such a high density of 
controls as traditional mouse-driven interfaces.

P
-- 
Patrick H. Lauke

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Received on Thursday, 18 January 2018 10:32:36 UTC