- From: Peter Speck <speck@vitality.dk>
- Date: Thu, 07 Jun 2007 18:53:38 +0000
- To: Nicholas Shanks <contact@nickshanks.com>
- Cc: ietf-http-wg@w3.org, Web-Kit Dev <webkit-dev@opendarwin.org>
Hi,
More systematic description of idea with using ranges:
The Accept-Resolution header has the same overall syntax as the other
accept headers to simplify parsing (and reduce bugs in web-servers).
Each item-value is a range of non-negative integer dpi values. The
range includes both values and the two values are separated by a
dash. A range with the first number larger than the second is empty/
invalid and is ignored.
If multiple medias match a range, the media closest to the range's
midpoint is selected.
If the header is not specified, it is equvalent to:
Accept-Resolution: 70-80;q=3, 50-150;q=2, *;q=1
so the server defaults to send media fitted for most computer displays.
If the header is specified, no default value/asterix is assumed. If
no range match the available media, a 406 error is returned.
To get normal usage for a desktop browser:
Accept-Resolution: 70-80;q=3, 50-150;q=2, *;q=1
A high-resolution for printing would use e.g.:
Accept-Resolution: 250-400;q=3, 150-600;q=2, *;q=1
A phone could use:
Accept-Resolution: 70-80;q=3, 10-120;q=2
as the phone doesn't specify the asterix, no media of dpi=200 is
allowed to be sent to it. The phone UA might ask the user if it
should retry and allow higher-resolution.
If the server response does not include a "Content-Resolution"
header, it is assumed that only one version of the media is
available. So only for reponses including the header should the
browser try to obtain high-resolution media for printouts.
----
- Peter Speck
Received on Thursday, 7 June 2007 20:05:31 UTC