W3C home > Mailing lists > Public > www-style@w3.org > February 2008

Re: Collapsing elements

From: James Elmore <James.Elmore@cox.net>
Date: Sun, 24 Feb 2008 20:34:15 -0800
Message-Id: <6D55D93A-AB95-4A9D-938E-13239D255094@cox.net>
Cc: www-style mailing list <www-style@w3.org>
To: Brad Kemper <brkemper@comcast.net>

On Feb 22, 2008, at 10:15 AM, Brad Kemper wrote:

> On Feb 21, 2008, at 10:31 AM, Bert Bos wrote:
>>> But rather than invent a new state and pseudo-class, I would rather
>>> see "checked' repurposed for this type of list, and given a
>>> definition to mean open if checked and closed if unchecked.
>> My intuition says that overloading ':checked' is dangerous and not  
>> very
>> intuitive. In the examples I gave so far there is nothing that I  
>> would
>> associate with putting a check mark. It's collapsed, expanded,  
>> toggled,
>> set to an alternative state, set to a second state, maybe changed or
>> restored, but not checked...
> I see checking an element as meaning you are marking it in some way  
> to indicate a second state for it, but not necessarily a visual  
> mark. The "checked" attribute on an HTML checkbox or radio button  
> means that it has been given this second state, instead of the  
> default state that everything else has. It doesn't look like a  
> check mark in most OS's radio buttons, and even if I make the  
> checkbox invisible, its label can still change it to or from this  
> second state.
> So, to me, "checked" is perfect, because it allows you to have the  
> regular styling in one rule, and the styling for a second binary  
> state in another, regardless of how it got marked to achieve that  
> second state. With checkbox and radio button buttons, that state  
> can be set initially with an element attribute (checked). With a  
> collapsing UL it could presumably be thus marked as having that  
> second non-default state with JavaScript. But consider if an actual  
> functional collapsable UL was added to HTML, with something like  
> <UL type="tree">. In that case, its initial state would not  
> necessarily be open or closed, collapsed or expanded, but could be  
> set with another attribute, like checked:  <UL type="tree"  
> checked>. It seems to me that you would need an attribute like  
> checked as part of the DOM, so that it could be set via JavaScript  
> or non-scripted HTML, and so a click could change that state.

This might be the easiest way to define 'states' for collapsing and  
expanding elements, but I think I agree with Bert on this one. My  
mind is working on what the ability to have states for an object  
might mean, and how I could use CSS to control those states, and it  
seems to me that there is, almost certainly, more than one state  
needed. (Actually, more than two states, more than just 'checked' and  
'unchecked'). At the very least, there needs to be 'collapsed',  
'expanded', and 'none of the above' - which means there is nothing to  
expand or collapse.

For the most basic outlines, where there might be nested levels  
underneath, any or all of which might be collapsed or expanded, this  
is the minimum needed. Even better would be: collapsed, expanded 1  
level, expanded n levels, no expansion possible.

For things which are not outlines, such as thumbnail and full-sized  
images, where the expanded images might have expandable sections, the  
process of expansion could be even more complex. (Sorry about the  
denseness of the description, I will try an example.)

Example Use Case: Business web site with expandable images and  
collapsed information.

Start: an image of the business, with a label/title/caption stating  
the name/products. User clicks on the building.

The building shrinks, but the same area is still needed, because now  
the business address is listed next to it. User clicks on the address.

The address shrinks and a map showing the location of the business is  
shown below the address. User clicks on the title of the business.

The title moves to the side and shows a menu of options as in a  
normal web site: people, products, statement of purpose, etc. appear.  
User clicks on the building thumbnail and a new image appears which  
shows the inside of the building.

All this information might be easily placed in a single HTML file and  
displayed on a single (complex) screen, but it is better if some of  
the information / images are hidden until actually needed. I could,  
surely, produce a web site with multiple pages to do everything I  
described here, but then each HTML file would contain much duplicated  
information (building image, address, page caption, etc.). I want to  
have the information available, but kept in a single file with the  
displaying of different amounts of that information in different  
places and sizes controlled through CSS. This is one, complex example  
of expanding and collapsing elements.

<SIDE NOTE> The ability to collapse visually needs to be correlated  
with the ability to collapse logically, so non-sighted users can  
still understand and use the information. </SIDE NOTE>

Further, I might want to have a series of images which convey the  
same or similar information, and have only one shown at a time. This  
slideshow would probably need not only 'collapsed' and 'expanded',  
but 'forward' and 'backward' states, so the correct image is shown.

Yes, I can hear the screaming all the way from California. Yes, I can  
do this right now with Java or JavaScript. But all I care about is  
the control of the placement of the correct image, why can I not do  
this with CSS? As long as the basic CSS renderer allows me to show  
two images (call them expanded and collapsed for simplicity), why not  
allow me to show three images? Why not four?

If there are CSS properties which overlap cleanly, I am definitely in  
favor of using them. That is the simplest way But, in this case, I  
think that 'checked' and 'unchecked' do not overlap very well. (As  
another counterexample, a web site I visit occasionally has recently  
added check marks for links that the user has recently visited. This  
was an aid for colorblind who use the site. It was well received.  
But, this 'check' would conflict - at least in the mental model -  
with the use of 'checked' and 'unchecked' for expanded and collapsed  

Please continue the discussion. If we can propose most of the  
necessary CSS properties and DOM elements for a collapsing and  
expanding ability in CSS, we will be well ahead.

James Elmore
Received on Monday, 25 February 2008 04:34:31 UTC

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