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<trackbot> Date: 10 February 2011
<JAllan> http://www.w3.org/WAI/UA/2011/ED-IMPLEMENTING-UAAG20-20110202/#gl-control-inaccessible-content
<kford> zakim code?
<patrickhlauke> (sorry, code isn't working on the call-in system)
<sharper> member:zakim, ??P3 is member:sharper
<JAllan> patrick try http://www.w3.org/2006/tools/wiki/Zakim-SIP
<JAllan> simon is calling in using it.
<patrickhlauke> can that be done via skype?
<JAllan> no, but you can call in using skype
<JAllan> Mark is using that
<JAllan> patrick, what is your skype name or phone number, Jan will conference you in
<patrickhlauke> patrick_h_lauke
<JAllan> scribe: greg
Here's the draft Jim sent in email this morning:
AutoPlay
2.9.2 Time-Based Media Load-Only:
The user can load time-based media content such that the first frame
is displayed (if video), but the content is not played until explicit
user request. (Level A)
Intent:
Essentially, autoplay for media is off/paused, until the user
activates 'play'. Prevent media from playing without explicit request
from the user. For example, Uart, a screen reader user, opens a page
with an audio element that starts playing immediately. The user cannot
hear the screen reader because of the noise from the audio element,
and must search through the page to find the 'noisy' element to turn
it off (or pause). Once the screen reader is the sole source of audio
the user can read the page and determine if the audio is important and
choose to play it.
Examples:
1. one could use the same techniques that are used for pop-up blockers
to see if the play() request was from user interaction or a background
script. If isn't from direct user interaction, one could ask the user
to explicitly allow the media to play, perhaps remembering the choice
for the site.
2. playback of a <video> or <audio> element can only be triggered in
response to a user gesture on a touch screen device with no keyboard
(like pop-up blockers). This has caused no end of bug reports because
it is impossible to differentiate script originated "auto play" from
playback triggered by a script after a delay,
3. user global control in the UA, that calls "paused for user
interaction" for all media.
Resources:
1. HTML5 4.8.10.8 Playing the media resource
(http://dev.w3.org/html5/spec/Overview.html#playing-the-media-resource)
Opera is adding support for the HTML5 4.8.10.8 "Paused for user interaction" event.
I recommend changing the first sentence of the Intent to make it clear it can be opt-in. E.g. "autoplay for media can be off/paused..."
In example 2, taking out the sentence starting "this has caused no end".
Kim suggests adding recommendation of a visual or audible cue.
<JAllan> ACTION: JimA to rewrite IER for 2.9.2 for next week Feb 17 [recorded in http://www.w3.org/2011/02/10-ua-minutes.html#action01]
<trackbot> Sorry, couldn't find user - JimA
<JAllan> ACTION: JAllan to rewrite IER for 2.9.2 for next week Feb 17 [recorded in http://www.w3.org/2011/02/10-ua-minutes.html#action02]
<trackbot> Created ACTION-503 - Rewrite IER for 2.9.2 for next week Feb 17 [on Jim Allan - due 2011-02-17].
<JAllan> note: take example out of the intent or reword.
<JAllan> Background Image Toggle:
<JAllan> The user has the global option to hide/show background images. (Level A)
In many other SC we changed phrasing about global options to "the user can".
2.9.1 (former 4.9.1) Background Image Toggle: The user can have background images hidden or shown. (Level A)
2.9.1 (former 4.9.1) Background Image Toggle: The user can have all background images shown or hidden. (Level A)
Intent: It can be difficult for some people to read text or identify images when the background is complex or doesn't contrast well with the foreground.
Allowing users to disable the display of background images helps ensure that foreground content remains easy to read.
This can also help remove distractions, which is important for some users.
This can also help remove purely decorative distractions, which is important for some users.
Examples:
<JAllan> 1. If background images are turned off, make available to the user associated conditional content.
<JAllan> 2. In CSS, background images may be turned on/off with the background and background-image properties ([CSS2], section 14.2.1).
<kford> possible exampe:
<kford> James has a reading disability where he needs text to be clear from distractions that are not related to the text. He configures his user agent not to load background images and navigates to a web page. James then gets only the text from the web page without any images interfering with what he is reading.
Add the first example there to the Intent paragraph as: "Because background images occasionally convey important information, when their display is turned off the user agent should give users access to any alternative content associated with them."
<patrickhlauke> HTML doesn't let you define alternate content for images, but then again authors following WCAG shouldn't rely on images alone
We'll move Jim's example #2 into the Related Resources.
Question: do we expect user agents to recognize cases where CSS is used to place an image behind text, rather than using a background property?
Relevant definitions:
background images
Images that are rendered on the base background.
base background
The background of the content as a whole, such that no content may be layered behind it. In graphics applications, the base background is often referred to as the canvas.).
<patrickhlauke> i think the css positioned case would be non-trivial / difficult to detect
So our SC wording above does not apply to things arranged using CSS, only to things set with the background property.
<patrickhlauke> this will only apply to images set as a background. there are other ways - such as with css positioning - in which images may be placed behind text. these will not be covered...
<JAllan> This checkpoint does not address issues of multi-layered renderings and does not require the user agent to change background rendering for multi-layer renderings (refer, for example, to the z-index property in Cascading Style Sheets, level 2 ([CSS2], section 9.9.1)
<patrickhlauke> ability to force/override soild bg colour for text
Jan suggests that users have the option to, rather than turning off background images, have non-transparent backgrounds of a solid color of their choice drawn behind text.
That is another approach to getting text to be legible, and would address the problem of backgrounds above the canvas, rather than on the base background.
Patrick notes some browsers allow the user to specify foreground and background colors for text.
This approach would not address the problem of backgrounds providing distractions, or obscuring non-text such as lines and borders.
Discussion of whether blinking backgrounds are already covered by the SC about time-based media. (Recognized blinking only.)
<mhakkinen> Browsers should also honor user's OS a11y settings for foreground/background color of text. Does the OS setting override the UA settings?
Jan notes that backgrounds are often used in ways that are required for use of the page, so is reluctant to encourage omitting them.
Jim would prefer not to have another SC.
<JAllan> case for background image vs background color
Jan notes that text foreground and background colors are covered in 1.4.1 Configure Text.
Re Mark's comment, we note that in Windows, the colors specified by the user in Control Panel only override author-specified colors if the user explicitly requests it.
Jan will write another sentence for the Intent of 1.4.1 Configure Text to make this use clear.
I think this is what we have so far:
2.9.1 (former 4.9.1) Background Image Toggle: The user can have all background images shown or hidden. (Level A)
Intent:
It can be difficult for some people to read text or identify images when the background is complex or doesn't contrast well with the foreground. Allowing users to disable the display of background images helps ensure that foreground content remains easy to read. This can also help remove purely decorative distractions, which is important for some users.
Because background images occasionally convey important information, when their display is turned off the user agent should give users access to any alternative content associated with them.
This checkpoint does not address issues of multi-layered renderings and does not require the user agent to change background rendering for multi-layer renderings (refer, for example, to the z-index property in Cascading Style Sheets, level 2 ([CSS2], section 9.9.1)
Examples:
James has a reading disability where he needs text to be clear from distractions that are not related to the text. He configures his user agent not to load background images and navigates to a web page. James then gets only the text from the web page without any images interfering with what he is reading.
Related Resources:
In CSS, background images may be turned on/off with the background and background-image properties ([CSS2], section 14.2.1).
Because background images occasionally convey important information, when their display is turned off the user agent should give users access to any alternative content associated with them. (At the time of this writing, HTML does not support alternative content for background images, but this may be supported in other technologies or future versions.)
<JAllan> ACTION: jallan to rewrite 2.9.1 ier for next week. [recorded in http://www.w3.org/2011/02/10-ua-minutes.html#action03]
<trackbot> Created ACTION-504 - Rewrite 2.9.1 ier for next week. [on Jim Allan - due 2011-02-17].
<Zakim> Jan, you wanted to say I wonder if we might target the background of text instead...eg. ability to make the background of text a sold, non transparent colour?
2.9.3 (former 4.9.3) Execution Placeholder: The user can render a placeholder instead of executable content that would normally be contained within an on-screen area (e.g., Applet, Flash), until explicit user request to execute. (Level A)
2.9.3 (former 4.9.3) Execution Placeholder: The user can have placeholders rendered instead of executable content that would normally be contained within an on-screen area (e.g., Applet, Flash), until explicit user request to execute. (Level A)
Patrick asks would this cover native video? Jim thinks not, so Patrick suggests using word like plug-in or embedded.
2.9.3 (former 4.9.3) Execution Placeholder: The user can have placeholders rendered instead of embedded executable content until explicit user request to execute. (Level A)
2.9.3 (former 4.9.3) Execution Placeholder: The user can have placeholders rendered instead of embedded executable content (e.g. applets/plug-ins) until explicit user request to execute. (Level A)
Jan notes these apply to the authors of plug-ins as well as browsers.
Jan suggests combining 2.9.3 Execution Placeholder and 2.9.4 Execution Toggle.
They are both Level A.
No, it turns out 2.9.4 Execution Toggle applies to executable content that is NOT contained in a specific on-screen area (e.g. Javascript).
Discussion of changing the titles to more clearly differentiate between the two.
Jan asks, what would the authors of a Flash player make of 2.9.3 and 2.9.4?
<JAllan> need to clarify that the UA should have the control of what is turned on/off/paused
Jan is concerned that even though some users prefer to turn off some technologies, he prefers not to "bake in" in this document technologies that are not currently accessible.
<JAllan> JR: we have autoplay. stop/play/resume
<JAllan> ...also flash blocker. don't want to get to prescriptive. want to stay general to cover new technologies
<JAllan> PL: want flash to load and then start it playing.
<JAllan> JR: should cover all playable items (movies, plugins, etc)
<patrickhlauke> suggestion for 2.9.4 - can we just go with: "Scripting toggle: The user can turn on/off the execution of scripts (e.g. JavaScript). (Level A)"
<Jan> ACTION: JR to With JA to consider how multimedia and executable requirements in 2.9 might be improved? [recorded in http://www.w3.org/2011/02/10-ua-minutes.html#action04]
<trackbot> Created ACTION-505 - With JA to consider how multimedia and executable requirements in 2.9 might be improved? [on Jan Richards - due 2011-02-17].
<JAllan> gl: embedded object is the key to making this work
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