W3C home > Mailing lists > Public > www-svg@w3.org > February 2012

Re: path data attribute lacks units!

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 13 Feb 2012 11:35:15 -0800
Message-ID: <CAAWBYDCyUfjUFa0xf5a+PPYATY2RMvbNBmM0KMadeFzPh7dxiQ@mail.gmail.com>
To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
Cc: www-svg@w3.org
Let's not rehash this discussion. Dr. Hoffman doesn't understand the
reasoning behind the definition of the css units, but all the browsers do,
and there's no theoretical merit to his complaints. As you point out, Doug,
printers have the necessary resolution and information to faithfully render
units like 'in'. If they currently fail to, that's merely an implementation
bug.

~TJ
On Feb 13, 2012 1:55 AM, "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de> wrote:

> Doug Schepers:
>
> >Uncalibrated screens, or those running at variable resolutions, are not
> >expected to be absolute in terms of pixel size.
>
> Well, to get an absolute size correct on screens worked already for
> example in earlier versions of Geckos/Firefox pretty good, but was
> pessimised maybe related to the units obfuscation in CSS 2.1.
>
> >Print, on the other hand, can afford these real-world measurement units.
>
> Of course, this is possible for screens as well, because typically the
> operating systems knows the current resolution of the screen.
> At least for TFT-LCD monitors, not necessarily for CRT monitors,
> it is not useful anymore to change the resolution (device pixels per mm)
> anyway.
>
> According to my tests, not all typical viewers manage to generate
> a printing output of 10 cm if 10 cm is noted in a file.
> The obfuscation of CSS 2.1 is simply inherited for printing as well.
>
> >Thus, units in SVG are as useful as can be expected for screens, and as
> >useful as is necessary for print.
>
> In theory yes, in practice not reliable without further information for the
> user, not familiar with the CSS 2.1 units problem.
> For screens the situation is not as useful as can be expected, it is
> hopeless.
> And for printing it depends strongly on the program, if this inherits the
> CSS 2.1 units obfuscation to printing output as well or not.
> If you want to send a scale drawing to someone, at least you have to add
> an instruction, how to print it to get the intended size or how to
> determine
> a scaling factor for the screen to get it right for specific viewers.
>
> Therefore SVG ist much more useful for applications without absolute units
> in it.
>
>
> Olaf
>
>
Received on Monday, 13 February 2012 19:36:08 GMT

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