Sent by Richard Mason on 13 August 2009 06:06
On Wed, 12 Aug 2009, Felix Miata wrote
>On 2009/08/13 10:59 (GMT+1200) Richard Mason composed:
>
>> ... On paper inches are physical inches. On a screen inches are
>> logical inches. Logical inches and physical inches are not the same
>> thing as I explain here:
>> http://www.emdpi.com/screendpi.html
>
>Your second and third sentences need a qualifier. Logical inches need not be
>different in size from physical inches.
Indeed, but I never said they had to be. Windows allows one to manually
change the screen dpi (pixels in a logical inch) so that on a particular
monitor a logical inch matches a physical inch but why, generally, would
anyone want to do that? A monitor is not a sheet of paper and the
distance and orientation one reads text on paper is quite different to
that at which one reads text a screen.
>Non-broken computer displays have
>been reporting both size and resolution for quite some time.[1]
Just because something is reported you can't assume it's accurate!
http://www.emdpi.com/screenppi.html.
To quote myself:
"The screen width values that Windows has retrieved for the LCD screens
are near enough to those obtained by measuring screens with a ruler, but
are way out for the CRT and Laptop screens. You can see there's a
problem. A programmer can't rely on Windows to get actual screen
dimensions, and if you don't know the real physical size of the screen
then you can't draw physical lengths on the screen that match those on a
ruler."
But you don't _need_ to draw lengths on a screen so that they match
those on a ruler.
> That most
>computer desktop environments do not use that information to adjust logical
>inches to equal physical inches does not mean it is not possible.
Seeing as in Windows there is no way, programmatically, of:
1. Both reliably and accurately getting the screen size for any type of
monitor.
2. Adjusting the screen dpi.
Then I would say it is not possible. If anyone knows differently then I
would be happy to see the data.
--
Richard Mason
http://www.emdpi.com
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