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

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Fri Jul 2 15:41:45 PDT 2010


--- 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

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.

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)


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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