[Zope-PTK] Retro-GUI Widgets

[Spicklemire, Jerry]

Hi PTK Fans,

After going over the posts from yesterday it looks like a few 
points got glossed over:

Chris was asking about "transparent" images, which I didn't 
quite catch, at first. Chris points out that one benefit of 
tranparency is that, since the background color of the cell 
should show through, so a single file can be "recycled" as a 
spacer in any cell, regardles of color. 

Another good point is that when a link is anchored to an image, 
the entire image is "clickable". This gives a usability advantage 
to a link on a single pixel transparent image that gets re-sized 
to fill an entire table cell, usability is improved, over a cell 
with just clickable text. The appearance of the text 
(alt='alt_text') should be controllable by class='style' in the 
<td> tag, but I need to test this to see whether text in alt='' 
acts similarly to table cell content, in terms of postioning, 
formatting, etc., when it's "under" a transparent image. 

So, now we're talking about using a transparent image to overlay 
the links, rather than as a spacer for all the cells that make 
up the shading. Also, by assigning a name='link_name' within the 
<img> tag, one image can be recycled to carry out any number of 
actions, via JavaScript.

Beyond transparent images, the notion of generating images brings 
up some interesting possibilities to reduce clutter. For example, 
there are lot's of cases in the example where the hi-lighted edge 
of one tab is adjacent to the "low-lighted" edge of another. In 
these cases a single two pixel image could do the job. Then the 
advantages of caching, and reusing one image apply here as well. 
Since we know the final cell size ahead of time, the images will 
render faster than with dynamic re-sizing. By adopting a naming 
convention a "library" of shading images could be built up on by 
generating non-existent images, on demand, but only when the named 
image doesn't yet exist.

Also, Paul asked if it would be possible to apply the example to 
"pages", but using layers, each tab linking to a JavaScript action 
to bring the corresponding layer "to the top". I started an example 
page, but that led to the conclusion that it would almost be 
simpler to build the Zope pieces to compose this solution, than 
hand coding a sample page.

So, that's what I'll do.

Later,
Jerry S.