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Re: [css-writing-modes] Computed values of obsolete writing-mode values

From: Gérard Talbot <www-style@gtalbot.org>
Date: Wed, 30 Sep 2015 21:05:07 -0400
To: fantasai <fantasai.lists@inkedblade.net>
Cc: Koji Ishii <kojiishi@gmail.com>, Jonathan Kew <jfkthame@gmail.com>, www-style@w3.org, www-svg <www-svg@w3.org>
Message-ID: <2e59e2500f1ddab5c23427e21175eb46@gtalbot.org>
Le 2015-09-30 18:42, fantasai a écrit :
> On 09/23/2015 09:18 AM, Koji Ishii wrote:
>> 
>> So this should go to SVG spec rather than CSS spec I guess?
> 
> The computation behavior needs to go into the CSS spec,
> but the SVGWG needs to resolve on what they want and to
> clarify their spec accordingly. (There's currently a
> lot of text in the SVG spec about how the 'rl' and 'lr'
> values should behave differently.)
> 
> p.s. Gérard, we should probably turn this SVG into a test.
> 
> ~fantasai

The 6 obsolete writing-modes values are: lr, lr-tb, rl, rl-tb, tb, and 
tb-rl
   SVG 1.1, section 10.7.2 Setting the inline-progression-direction
   http://www.w3.org/TR/SVG11/text.html#SettingInlineProgressionDirection

The 'writing-mode' property in SVG specifies exclusively the 
inline-progression-direction for a 'text' element; so block flow 
direction should *not* be affected ...

lr and lr-tb are equivalent to CSS 'direction: ltr' and 'writing-mode: 
horizontal-tb'.

rl and rl-tb are equivalent to CSS 'direction: rtl' and 'writing-mode: 
horizontal-tb'.

tb, and tb-rl are the equivalent of CSS 'writing-mode: vertical-rl' but 
for only the inline-progression-direction.

- - - - -

As far as checking computed values of the 6 obsolete writing-mode values 
are involved, aren't the 2 following tests from Koji sufficient? Just 
asking ...

http://test.csswg.org/source/css-writing-modes-3/writing-mode-parsing-svg1-001.html

http://test.csswg.org/source/css-writing-modes-3/writing-mode-parsing-svg1-002.html

computed values of all/each of the 6 obsolete writing-mode values are 
tested in those 2 tests.

- - - - -

I looked at your attached SVG...

1-
If the 3 <text>s have the same x and y values, then aren't they going to 
overlap each other? Shouldn't they overlap?

2-
What's the expected result of

<g style="direction: rtl">
   <text x="300" y="100" style="writing-mode: lr; fill: blue;">1 2 
3</text>
</g>

3-
What's the expected result of

<g style="direction: rtl">
   <text x="500" y="100" style="writing-mode: rl; fill: orange;">1 2 
3</text>
</g>

4-
What's the difference of meaning between "shift the text string" and 
"reverse the order of all glyphs in the text."? I ask because I sincerly 
do not know, do not understand the difference of meaning in terms of 
rendering.

These expressions are coming from this sentence:
"
There are varying interpretations on whether this process causes 
"writing-mode: rl" to merely shift the text string or reverse the order 
of all glyphs in the text.
"
3.1.1. Obsolete SVG1.1 writing-mode Values
https://drafts.csswg.org/css-writing-modes-3/#svg-writing-mode

Gérard
Received on Thursday, 1 October 2015 01:05:40 UTC

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