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Re: User Agents Do Not Implement Absolute Length Units, Places Responsive Design in Jeopardy

From: David Singer <singer@apple.com>
Date: Fri, 21 Oct 2011 14:47:12 -0700
To: W3C Style <www-style@w3.org>
Message-id: <1979F8F2-2B9C-4FCF-9E89-43CA43443DD5@apple.com>

On Oct 21, 2011, at 13:10 , Brian Blakely wrote:

> This is an idea I strongly believe should be a separate unit or solution path.
> 
> It's super-useful for something like Sony's wearable display, wherein the viewport is physically small but apparently (I haven't tried it) functionally equivalent to a big-screen display.
> 
> However, I feel that is a corner case, and in most cases authors will want to use linear physical data, to then arrive at their own design conclusions about legibility and appropriate use.

I'd really encourage you to scan the archives, if you haven't already, because we had a long discussion of this.  Basically, in days of yore, when computers were real computers etc., the web was browsed on computer screens at about the distance and size of a piece of paper.  Using physical measurements like 10pt etc. 'worked'.  10pt text is unreadable on a monitor at TV-distance viewing, and is excessively large on a hand-held device with a high-res screen capable of displaying crisp text at smaller sizes. It's meaningless on projection glasses, and unimplementable on jumbotrons (whose pixels tend to be of the size of inches).

The use cases for true physical seem to be when you're comparing or using the page as a physical embodiment; you're using your tablet as a carpentry template, for example, and that one-inch hole you're making in the door should really be one inch or the lock won't fit.

Whole-wall displays are also getting more common, which have a size not unlike a jumbotron, but a vastly different viewing distance, subtended angle, and usage.  Mere physical size would again be misleading, I think.

The old comforts are fast disappearing, I fear.

> 
> Cheers,
> -Brian
> 
> 
> On Fri, Oct 21, 2011 at 2:28 PM, David Singer <singer@apple.com> wrote:
> Perhaps size detection should be based on the angle subtended at the eye?  That's what we are basing other stuff on.  I think the linear size is much less relevant (and meaningless in some cases).
> 
> To do it well, you probably need to know "how much is subtended by the display" .  You probably should not need to know "what is the pixel count in that range" as the equipment designer should have made it that 'normal' sizes like 10pt text are, in fact, readable.
> 
> On Oct 5, 2011, at 10:28 , Boris Zbarsky wrote:
> 
> > On 10/5/11 1:21 PM, Brian Blakely wrote:
> >> The problem isn't resolution detection.  The problem is that we're using
> >> pixel resolution to do *size *detection.  Adjusting a layout for
> >> small-size displays is currently achieved by defining max-width MQs at
> >> about 640 *pixels*, when it really should be 3.5 *inches* (ballpark).
> >
> > The problem is that to be web-compatible, UAs more or less have to fix 1in == 96px.
> >
> > And again, just to be clear, are you trying to detect _linear_ size, or _angular_ size of the screen?
> >
> > -Boris
> >
> 
> David Singer
> Multimedia and Software Standards, Apple Inc.
> 
> 
> 

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Friday, 21 October 2011 21:47:42 GMT

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