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Re: [css3-text] <spacing-limit> incompatible with calc due to different treatment of lengths and %s

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 5 Jan 2012 12:33:18 -0800
Message-ID: <CAAWBYDCs-QVeDvRboZ9=QKK3_yj+8M21XhLEANbLDtB3_8=PPQ@mail.gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org
On Thu, Jan 5, 2012 at 12:19 PM, fantasai <fantasai.lists@inkedblade.net> wrote:
> On 01/05/2012 02:28 PM, Tab Atkins Jr. wrote:
>> The<spacing-limit>  type defined for 'word-spacing' in Text 3
>> <http://dev.w3.org/csswg/css3-text/#spacing-limit>  assigns
>> substantially different meanings to percentages and lengths - the
>> former sets the word spacing to the given value, while the latter
>> *increments* the word spacing by the given value.
>>
>> If calc() is used here and mixes %s and lengths, like "calc(50% +
>> 1ch)", what does this mean?  If I'm reading correctly, I think this
>> would result in a<length>  equal to 1ch + half the default word
>> spacing, making the total word spacing equal to 1ch + 150% the
>> default.  Is this intended?
>
>
> I expected it to mean "half the word spacing plus 1ch". But you're saying
> that doesn't make sense...

Yes, it resolves to a *length* equal to half the word spacing plus
1ch.  That gives a total word spacing of 1.5 times the default word
spacing plus 1ch, since lengths are added to the default word-spacing.


>> If so, this seems suboptimal, as it's then impossible to, say, use
>> calc() to set the word-spacing to a particular length.  (I had
>> expected "calc(0% + 1ch)" to kinda work like that.)  Perhaps we can
>> alter word-spacing to accept both a percentage and a length, and
>> combine their effects?
>
> word-spacing takes up to three values, so that wouldn't be parseable.

Oh, darn, I missed that.  Is it possible to change <spacing-limit> at
this point, perhaps to a grammar like:

<spacing-piece> = normal | [ <length> || <percentage> ]
<spacing-limit> = <spacing-piece> [ [min <spacing-piece>] || [max
<spacing-piece>] ]?

The first piece is the optimal size.  If min or max clauses are
omitted, they're the same as the optimal size.

~TJ
Received on Thursday, 5 January 2012 20:34:06 GMT

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