Shawn said:
> So maybe the best way to design the visual aspect of most applications
> is to use font-based units (like the em space) for physical sizes, but
> for touch UIs, to also use physical measurements as a minimum.
> e.g. width: Math.max(7mm, 3em) - will it be possible, or can we have
> nicer syntax? For example a button must be able to fit its text
> (unless it’s so long that the designer plans for it to be elided), but
> the button must also be at least 7mm in both dimensions to be
> touchable.
I think this means designers need to be specifying *bounds on* the sizes
of things, rather than the sizes themselves. This image shouldn't be
bigger, in either direction, than the screen; that button must be big
enough for a finger to hit it. The rendering engine is then left to
work out what *actual* size to make each thing.
Unfortunately, graphical design historically took for granted that the
designer knows the size of the page, hence also can control the size of
every thing on the page. That actually failed to work for folk with
poor visual accuity even when it was happening on the mashed carcasses
of trees, but it's how many designers still think. They just "have to"
adjust their design to several different sizes of page^W screen now; and
still think, for each page-size, that they should control the exact size
of everything on the page. Anyone who has learned TeX knows that's the
wrong way to think, but it's not a cultural lesson that's made much
progress into the graphical design community.
> The user should choose the text size,
Indeed - ideally as a device setup action that configures a
device-global parameter that all apps get to work with. All font sizes
should be specified in terms of the user-selected "comfortable size to
read" for a font. The screen size, measured in this font-sizes's em
unit, may be rather small for some users and significantly bigger for
other users. That's, to some degree, true today - different devices
have different-sized screens after all - but we'd need designers to
start taking it seriously and stop thinking they can "fix" this by
having the design respond to the "physical" size (in mm) of the screen.
As you point out, physical pixels are now so small they're irrelevant;
we used to care about them because pixelation was a visual wart of our
displays, but that's long since passed. Only virtual pixels, or some
equivalent unit (such as the "comfortable font size" - some suitable
fraction of which can be used as the virtual pixel size), are relevant
now.
Eddy.
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