[Webkit-unassigned] [Bug 5566] ALT attribute value not displayed when image is missing

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=5566





--- Comment #24 from Gérard Talbot <browserbugs at gtalbot.org>  2010-07-02 15:41:44 PST ---
(In reply to comment #6)

> a decision on how to render missing images with alt text
> (a) when their dimensions are specified (...) and when the text and the error image won't fit together, what do you do?

This has been answered in UAAG 1 and UAAG 2. 

"
allow the user to configure how the conditional content should be rendered. For example, within the [author-]specified [placeholder] geometry, or by ignoring the specified geometry altogether.
"
Techniques for User Agent Accessibility Guidelines 1.0
2.3  Render conditional content
Example techniques, item 4
http://www.w3.org/TR/UAAG10-TECHS/guidelines.html#gl-feature-on-off

So, within the [author-]specified [placeholder] geometry would mean truncate (if exceeding) while ignoring [author-]specified [placeholder] geometry would imply to expand as needed, necessary by text replacement.

"
In cases where the alternative content has different dimensions than the original content, the user has the option to specify how the layout/reflow of the document should be handled. (Level A). 
"
User Agent Accessibility Guidelines 2.0 (*DRAFT*)
W3C Working Draft 17 June 2010
Guideline 3.1 Provide access to alternative content.
http://www.w3.org/TR/UAAG20/#principle-perceivable

In other words, the user chooses again via user prefs/settings: truncate if exceeding author-specified placeholder dimensions or expand if needed to render all alt text.


Firefox 2+ renders alt text inline without truncation of alt text when in standards compliant rendering mode and this can be verified with the 2 testcases I provided. Firefox follows Ian "Hixie" Hickson recommendation here (which I propose and recommend too). The 

(in about:config)
browser.display.force_inline_alttext      

http://kb.mozillazine.org/About:config_entries#Browser.

explains what happens in backward-compliant "quirks" rendering mode when  
no alt text is provided and when author-specified placeholder dimensions are provided.

(In reply to comment #19)
> to treat it like an anonymous text node, i.e. not stylable
Anonymous (text, block box) node inherit inheritable properties (like color, font-size) from their container.

> and indistinguishable from replacing the whole element with its @alt text.
Replaced content should be styled according to inherited properties from containers, otherwise it can/will become very distinguishable from their container.

<h1>Welcome to <img src="brand-logo.gif" alt="Brand Name"></h1>

Let's say brand-logo.gif is unretrievable here.
Why the replaced textual content "Brand Name" should not be using a default font-size 2em? Why should it be using a 16px font-size? 
Firefox 2+, Opera, Safari 3.1+, Konqueror 4+, IE8, Amaya all have an user-agent default stylesheet setting for <h1> heading set to a font-size of 2em (32px). Unstyled body text is set to 16px by all browsers (user-agent default stylesheet).
Recent releases of all mainstream browsers are following appendix D of CSS 2.1.

regards, Gérard

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