Re: [css3-background] box-shadow syntax

On May 13, 2008, at 5:56 AM, Henrik Hansen wrote:

> I've made, yet another, diagram explaining my idea down to the  
> aboslute basics. (All shadows in the diagram is set to 50% opacity  
> unless the point is it is changed.)
> http://img180.imageshack.us/my.php?image=shadowtrancemaskyq0.png
>
> Two columns one with the 'shadow-mask' and and one without.
> There are also four rows, each with a different value from 'shadow- 
> transmittance'.
> Any comments on it now? Suggestions? Changes? Just write it.

My feeling is that once you need to start dealing with non-rectangular  
shapes other than text, and with variable shadow strengths on a single  
element (masks) and color gel effects (transmittance), that you are  
going way beyond what most HTML authors would need. Perhaps it would  
be more appropriate for SVG, where there is more of a focus on the  
ability to do more complex renderings.

I do think that being able to thicken or thin the shadow size without  
hacking the border (spread) would be more commonly used in HTML, as  
would being able to cast a shadow with a box as though the box was cut  
out of the surrounding area (inner/outer casting). As an author, I  
could easily see myself using those features (especially spread) very  
often. But they would still be a light weight effect to add a little  
dimensionality, not to try to recreate a photorealistic effect.

> ---
>
> Eli wrote:
> Which reminds me. It isn't clear whether border and padding (and  
> margin?) get included in the calculation for how big the shadow is.  
> Are UAs supposed to use 'width' and 'height'? (I expect so, but it  
> needs to be asked.)
>
> That's a good question! I'd say padding should effect the shadow.  
> But margin? hmm, I could see reasons why,

Not me. Outer shadows should start at the outer edge of the border box  
and cast outward, and inner shadows should start at inner edge the  
border and cast inward. Here is another version of my mock-up, this  
time with borders, and with the shadows at 50% opacity:

http://bradclicks.com/cssplay/Shadows2.html


> but also conditions where it's a problem. Borders should definitely  
> be projected in the shadow, it would be weird if they didn't,  
> because borders affect the surrounding elements it should also  
> affect the shadow.
> But margins do that to! Hmm, anyone got some ideas?
>
>
> -Henrik