[whatwg] Canonical Image and Color

Tab Atkins Jr. jackalmage at gmail.com
Mon Feb 11 22:17:58 PST 2013

On Mon, Feb 11, 2013 at 4:17 PM, Brian Blakely <anewpage.media at gmail.com> wrote:
> 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 visual
> content.
> * 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.

These all seem fairly reasonable.  Are you sure that all of the
use-cases would use the same image?

> * Color
> 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.

Sure, seems reasonable.


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