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Re: Making pt a non-physical unit

From: L. David Baron <dbaron@dbaron.org>
Date: Sun, 10 Jan 2010 18:26:29 -0800
To: Alex Mogilevsky <alexmog@microsoft.com>
Cc: "robert@ocallahan.org" <robert@ocallahan.org>, www-style <www-style@w3.org>
Message-ID: <20100111022629.GA3510@pickering.dbaron.org>
On Tuesday 2010-01-05 17:45 +0000, Alex Mogilevsky wrote:
> For the record, IE treats “pt” the way you propose for a number of
> versions already. At this time there is no physical units in IE
> (that is there is no unit that doesn’t grow or shrink with zoom) .

This discussion isn't about whether the units grow or shrink with
zoom, though.  I think we all accept that zoom is something that
happens after we've processed the meanings of length units, so that
it zooms all lengths.

> New units have been proposed that would be defined as strictly
> physical (I believe somebody has proposed “dpx” for “display
> pixel”).

Even the proposed physical units (e.g., all but pt and pc, if we go
with that proposal) would respond to zoom, as I think should any
unit for display pixels.


The issue here is what the meaning of a 'pt' is at a zoom of 1, and
whether the number of display pixels in a 'pt' should depend on the
physical size of the display (in cases other than where the size of
the display causes the number of CSS pixels per device pixel to
change) or whether it should have a hard-coded relationship to CSS
pixels.

(So the relevant question for IE behavior is whether it honors the
settings in Windows preferences that set the dpi to be used for
font sizes.)

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Monday, 11 January 2010 03:47:14 GMT

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