726919 - Treat broken images according to HTML5 spec

Status: RESOLVED WORKSFORME

(Core :: Layout: Images, Video, and HTML Frames, defect)

Description

[Dan Jacobson]

User Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0a2) Gecko/20120210 Firefox/12.0a2 Iceweasel/12.0a2
Build ID: 20120210042013

Steps to reproduce:

The default behavior of Firefox with unavailable images is just
outrageous.

The user thinks:

"Every page looks great any you'll never encounter any image problems
when one uses Firefox.

Yup, Firefox works great. That **** Google Chrome often has image
problems. All those stupid cracked picture logos, etc.

It can't even find some of the images I put one my own web pages. Ha!"

Until one day he realizes which browser is his real friend, and which
browser just says we have money in the bank when we really don't.

Save this into file.html and browse it in both Firefox (-safe-mode of
course) and Chrome to see the difference.

 <h2>７公里內視野 7 km
 viewshed</h2>

 <p><img width="446" height="396" alt=
 "Many points are visible within 7 km." src=
 "images/gone.png"></p>

 <p><img alt="Others aren't." src="images/also_gone.png"></p>

 <p>
 這裡（ｘ）所能見的（白），鄉鎮界（黑）Points
 visible from here (x) marked in white. Grid=230,235km W; 2670,2675</P>

Of course for the second image Chrome can't deal with the alt= whereas
Firefox indeed does... Maybe someone should tell them.

Anyway with the default FF settings there will be a whole next generation of users who come to school
wondering why the other students were aware of the problems in the homework page and got the hardcopy from the teaching assistant, whereas they remained blissfully unaware the entire weekend, etc.

Comment 1

[Dan Jacobson]

OK I told them about the second image's ALT string.
http://code.google.com/p/chromium/issues/detail?id=114145

Comment 2

[Dan Jacobson]

Attachment: Example of danger

Comment 3

[Matthias Versen [:Matti]]

Attachment: Testcase from the reporter

Comment 4

[Matthias Versen [:Matti]]

Please limit your comments to technical details.
i see a placeholder for the broken image with the testcase and the alt text is displayed as it should be.

Mozilla/5.0 (Windows NT 6.1; rv:13.0a1) Gecko/20120213 Firefox/13.0a1 SeaMonkey/2.10a1

Comment 5

[Matthias Versen [:Matti]]

oh, my testcase is incomplete as your bug description.
You want to see a broken image icon if you have an image without dimensions and without alt text. showing nothing is however intended if i read bug41924

I guess that this is a wontfix

Comment 6

[Dan Jacobson]

Well one browser is right and one browser is wrong, right?

Comment 7

[Matthias Versen [:Matti]]

No, it's a design decision which can be different if the behavior isn't specified in a standard.
You want a broken image icon (as google) and I don't want it (as Mozilla). 
A standard icon with a standard size can destroy the page layout if the original image (that is now broken) is smaller than the standard icon.

Comment 8

[Masatoshi Kimura [:emk]]

HTML5 now encourages for User-Agents to display something if the image is broken and alt attribute is absent.
http://dev.w3.org/html5/spec/Overview.html#img-good
Is the decision still appropriate?
> A standard icon with a standard size can destroy the page layout if the original image (that is now broken) is smaller than the standard icon.
The page layout will be broken anyway if nothing is displayed.

Comment 9

[Masatoshi Kimura [:emk]]

Attachment: Testcase of an image with dimension without alt

Nothing displayed even if the dimension is present. It will break the page layout.

Comment 10

[Masatoshi Kimura [:emk]]

Confirming to reconsider the bug 41924 decision in HTML5 era.

Comment 11

[Masatoshi Kimura [:emk]]

Attachment: patch

Comment 12

[Dan Jacobson]

The spec says

   If the src attribute is set and the alt attribute is set to a value that isn't empty ... 
   If the image is available ... 
    Otherwise, the element represents the text given by the alt attribute. User agents may
    provide the user with a notification that an image is present but has been omitted from
    the rendering.

So it says MAY... so are you fellows going to give inconsistent behavior just because there is something in alt="..."?

Comment 13

[Masatoshi Kimura [:emk]]

Comment on attachment 596980 [details] [diff] [review]
patch

Hm, this patch "regressed" bug 468263. However, the image should not be hidden for images with empty src attribute per spec.

Comment 14

[Boris Zbarsky [:bzbarsky]]

Hold.  Back up.

There's a difference between "show an icon" and "show a sized box".  This patch is conflating the two.

I'd like to see a clear description of which behavior you're after and why before you start messing with any of this code, because I don't think we should change it more than once, if at all.

Note that there are existing (open) bugs on showing a placeholder icon next to the alt text when images fall back, by the way.

Comment 15

[Masatoshi Kimura [:emk]]

The spec says "the user agent should display some sort of indicator that there is an image that is not being rendered", but it doesn't define what "some sort of indicator" is.

Comment 16

[Masatoshi Kimura [:emk]]

> Note that there are existing (open) bugs on showing a placeholder icon next to the alt text when images fall back, by the way.
If alt text is present, it is a different bug. Spec says "the element represents the text given by the alt attribute." when non-empty alt attribute is present.

Comment 17

[Boris Zbarsky [:bzbarsky]]

Yes, I know what the spec says.  What I'm asking is what behavior you're actually trying to produce and why.  Specifically in this testcase:

  <img src="bogus" width="100" height="100">

what rendering do you want?  Depending on the desired rendering, simply showing an icon next to the (possibly empty, as in this case) alt text may do what you want.

In particular, how do you want the rendering of the above to compare to:

  <img src="bogus" width="100" height="100" alt="">

?

Comment 18

[Masatoshi Kimura [:emk]]

I have no strong opinion what should be rendered for images without unless it disappears completely.
However, I'm not sure it is right to render an icon if alt is not empty.

Comment 19

[Masatoshi Kimura [:emk]]

> for images without
 for images without alt

Comment 20

[Boris Zbarsky [:bzbarsky]]

OK.  That's fine.  We can do any mix of behaviors here, but we need to decide what behavior we actually want.

Comment 21

[Dan Jacobson]

Simple: if (both height and width) dimensions present, always draw a box.
(Else one messes up the "structure of the page", right?)
If the image is available, put it in the (now invisible) box.
Else if there is an ALT, put that in the (top) of the box, even if 0
characters long.

There, full disclosure achieved. (Let users turn bits of it off by
about:config if they prefer.)

Isn't that what Google Chrome does?

Comment 22

[Boris Zbarsky [:bzbarsky]]

> Simple: if (both height and width) dimensions present, always draw a box.

That makes the alt text unreadable, which is broken.

> (Else one messes up the "structure of the page", right?)

Not for a properly coded page.

> Isn't that what Google Chrome does?

Yes, and its rendering of this testcase:

  <img src="bogus" height="100" width="100" alt="This is an image of a flower">

is completely broken: it doesn't show the alt text.

Since you insist on changing the summary to something other than what this bug is about, marking worksforme; our behavior is completely spec compliant.

Comment 23

[Boris Zbarsky [:bzbarsky]]

Matashosi-san, please move any work you actually want to do to a bug that won't get spammed, ok?

Comment 24

[Masatoshi Kimura [:emk]]

Ok.