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Re: Projection media type in fullscreen browser mode

From: Bert Bos <bert@w3.org>
Date: Tue, 18 Aug 2009 20:27:01 +0200
To: www-style@w3.org
Message-Id: <200908182027.01870.bert@w3.org>
On Tuesday 18 August 2009, Aryeh Gregor wrote:
> On Mon, Aug 17, 2009 at 7:00 PM, 
fantasai<fantasai.lists@inkedblade.net> wrote:
> > Opera's fullscreen mode is different from the others in that it is
> > a paged medium and is intended for use with a hookup to projectors.
> > Opera doesn't automatically paginate to the screen size, but if you
> > force a page break this paginates the document and can be used to
> > create slide shows. (See the OperaShow documentation.)
> >
> > It's a very useful mode; it would be nice if other browsers also
> > supported it. It would make things like S5 a lot less of a JS/CSS
> > mess.
> The mode sounds useful, but I don't think treating all use of
> full-screen as media type projection is a good solution here.  If you
> want a plain old screen stylesheet, and aren't providing a separate
> projection stylesheet -- i.e., you're 99.97% of websites out there --
> you would want full-screen mode to render exactly like screen.
> Therefore screen stylesheets need to apply in full-screen mode, in
> the overwhelming majority of cases.  Having projection apply to
> full-screen mode just means that "screen" alone is useless for almost
> all authors, and everyone needs to specify "screen,projection".  It's
> the tiny minority who want to support projections who should have to
> opt-in somehow, not everyone else who has to opt out to not have
> their site break.

There is a difference between maximizing the window and running in 
full-screen mode. The former is just a normal 'screen' mode with a 
larger viewport, the latter is what you use for projecting with a video 
projector. I rarely maximize my browser, but I use projection mode for 
all my presentations. It removes the visible browser interface so it 
isn't very useful for anything *else* than presentations. It is a paged 
mode, so you can put multiple slides in one file. (Very handy, 
especially if you're *not* projecting, but editing, or printing, or 
reading the slides by yourself.) And full-screen mode turns the screen 
saver off: ideal if you're giving a presentation, but it would be a 
nuisance if maximizing the window did that, too.

As there is no browser "chrome" in projection mode, nobody in the 
audience knows that you aren't using Powerpoint. Which is as it should 
be, of course, but it is a bit unfair to Opera, who are doing the right 
thing here and don't often get credit for it.

Maybe what is confusing is that Opera chose to call it "Full Screen" in 
the menu, while it is called "projection" in HTML. It is in fact doing 
the same as "Print Preview," "Small Screen" and "User Mode": switch to 
a different mode of interacting with the document and perhaps to a 
different style sheet as well. ("Small Screen" corresponds to 
the 'handheld' mode.)

Opera has the widest choice of modes nowadays, but it wasn't the first 
to provide a mode switch: that was MacIE. (But Opera wins with its "Fit 
to Width" mode: this mode is enough to make many fixed-width pages 
flexible again, without having to go as far as "User Mode." When I use 
Opera, it is often because of this feature.)

> This feature really seems orthogonal to media queries to me.  It
> should be triggered by the author, not the user.  Only the author
> knows if he wants to use his web page as a slideshow.  The user
> shouldn't trigger it by using a mode that at least I (and apparently
> the majority of browser developers) would expect to do nothing but
> give more space to the page's content.

No, quite the opposite. Only the user knows if he wants to read the page 
on his phone, on paper, on a computer screen, or projected. The author 
can suggest different styles that are adapted for the different media, 
but it is the user who chooses. It would he bad if upon loading a page 
I get a message "Sorry, this page can only be projected" or worse: it 
automatically turns my projector on...

> Why couldn't the spec allow authors to explicitly make continuous
> media paged somehow?  (At least handheld/screen/tv.  Obviously it
> makes no sense to page, e.g., speech.)  For instance, UAs could be
> required to make the media paged if @page rules are found.  Or a new
> rule could be invented to trigger this.  Then if you want to create a
> slideshow, you can do that in an interoperable way.  If you just want
> to create a normal web page, you should be able to provide screen
> stylesheets and expect them to apply to all users using a normal
> display.

The WG discussed many years ago whether it was useful to have 
machine-readable hints in the document or style sheet by means of which 
an author could indicate that a particular page was primarily meant to 
be printed, or to be projected, or even more detailed: projected in 
color at 640x480 pixels, etc. We decided there was no need. No user 
would let his browser follow those hints automatically anyway. The 
author could just as well express his intention in English, if the 
intention wasn't already clear from the context (such as HTML's LINK 

Something else is the use of paged rendering *inside* a continuous 
(scrolled) layout. The WG has discussed that, too, and not rejected, 
although it certainly isn't easy to define and doesn't have a high 
priority right now. It could be an alternative way to handle overflow.

A large element could be rendered in a small area as a stack 
(conceptually) of mini-pages, rather than as a box with scrollbars. You 
don't scroll to see its contents, but flip the pages. (We have in fact 
an old request from the mobile phone industry to provide such a 
rendering, i.e., flipping pages instead of scrolling. There was a first 
proposal in a previous version of the Template Layout module, but we 
removed it.)

  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Tuesday, 18 August 2009 18:27:41 UTC

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