[whatwg] Canonical Image and Color
anewpage.media at gmail.com
Mon Feb 11 16:17:25 PST 2013
Sure thing. Let me go through the use cases that I see as applicable
today, derived from instances where an existing vendor or service currently
utilizes a non-standard implementation.
* Social network sharing
Facebook currently scrapes "OpenGraph tags" from shared pages to create a
content snippet. One such tag is og:image, which specifies the image to
display in that snippet. Twitter and Google+ use these same tags in
addition to their own implementations for developers. For the title and
description of the snippet, scrapers will fall back to <title> and the meta
description. A canonical image would serve the same purpose, but for
* News aggregation
Flipboard, a highly visual, magazine-style news and article reader,
displays a hero image from the target page. It does this by parsing and
analyzing the <img> elements in a page, sometimes displaying a non-optimal
or even vacant result. A canonical image would allow developers to control
this kind of representation with more specificity, and provide the 3rd
party app with another presentation option.
* OS Integration
Apple currently parses their own "apple-touch-icon" element that specifies
which image will serve as a web application's icon after the user has added
to the homescreen. Android's browser uses this same element, while
Microsoft uses a similar "msapplication-TileImage". When these element is
not specified, a screenshot of the website is used instead or, in
Microsoft's case, the favicon. Firefox OS has still another means of
implementation for this. A canonical image could either replace or provide
an additional fallback for this functionality.
In all these cases, a canonical color allows external parsers to provide
further branding or additional flourish in their representation of apps and
pages. Microsoft's "msapplication-TileColor" and
"msapplication-navbutton-color" elements aim to fulfill this purpose in IE
by coloring the app's tile on the Windows 8 homescreen and IE's own
navigation UI, respectively.
On Mon, Feb 11, 2013 at 5:41 PM, Tab Atkins Jr. <jackalmage at gmail.com>wrote:
> On Mon, Feb 11, 2013 at 2:33 PM, Brian Blakely <anewpage.media at gmail.com>
> > * Proposal
> > Meta elements for defining a canonical image and color to be associated
> > with the page(s) in which they are included. This is intended for use by
> > user agents and third-party applications (such as social networks),
> > referred to collectively as "parsers" in this document. It is inspired
> > Microsoft's recent work in site pinning and Apple's "standalone" webapp
> > implementation in iOS Safari.
> Can you elaborate? I have no idea what UAs and third-party apps would
> do with a "canonical image" or "canonical color".
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