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Re: [mediaqueries] undefined behavior for the resolution media query

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 17 Jun 2015 16:33:22 -0700
Message-ID: <CAAWBYDAwm5Usfu_VsWOz14u_kN7Z2yJDhef0cuPQk+UDWLkfTg@mail.gmail.com>
To: Florian Rivoal <florian@rivoal.net>
Cc: www-style list <www-style@w3.org>
On Wed, Jun 17, 2015 at 2:51 AM, Florian Rivoal <florian@rivoal.net> wrote:
>> I'd prefer Suggestion 4: same as 1, but we adopt a rasterize media
>> feature with the same syntax, which gives the rasterization threshold
>> resolution.  Add a "none" value to both 'resolution' and 'rasterize'
>> which indicate there's no threshold/the resolution is infinity; you
>> can then use them in a boolean context to indicate whether the output
>> format is vector (`(resolution)` is false) and whether there's a
>> rasterization threshold (`(rasterize)` is true).
>
> I am not 100% sure what you mean by "the rasterization threshold". If you mean the resolution at which vector things are rasterized, that's what 'resolution' does already (expect we haven't defined what it does when vector things don't rasterize).
>
> If you mean the threshold to which high res rasters are down sampled to, it should be called something else. Maybe downsampling-threshold?

Yes, that one.

> Either way, since you have 2 numeric queries, your system is somewhat more expressive, since you can express "vectors get rasterized to 600dpi, and high res images get downsampled to 450 dpi" or other variations of the situation where vectors are rasterized to a resolution that is different from the one rasters are downsampled to. However, I am not convinced that this is actually useful to expose, and it makes the whole thing a lot less intuitive.

I think the exact opposite!  (rasterize)+(resolution) means
(resolution) gets two different meanings, depending on the whether
(rasterize) is true or false: if true, it represents the output
medium's resolution (the meaning as currently defined); if false, it
represents the downsampling threshold.  This means you have to use
(rasterize) and (resolution) together in a number of non-obvious
cases; exactly what queries distinguish between "printing" and "PDF
with down-sampled raster images" isn't obvious.

Having (resolution) continue to mean the output format's resolution
(with a value added for infinity), and then having (raster-resolution)
or (downsample-resolution) or (image-resolution) or something with the
same grammar (and a value for infinity) makes the situations directly
analogous.  (image-resolution) will always be less than or equal to
(resolution) (by definition; the output medium can't represent an
image at a higher resolution than itself), and it's clearer what jobs
each is meant for.

~TJ
Received on Wednesday, 17 June 2015 23:34:10 UTC

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