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Re: [css3-images] linear-gradient keywords and angles are opposite

From: Alan Gresley <alan@css-class.com>
Date: Wed, 08 Jun 2011 18:47:14 +1000
Message-ID: <4DEF3712.6040404@css-class.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Brad Kemper <brad.kemper@gmail.com>, Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
On 8/06/2011 5:35 PM, Tab Atkins Jr. wrote:
> On Wed, Jun 8, 2011 at 4:27 AM, Brad Kemper<brad.kemper@gmail.com>  wrote:
>> On Jun 7, 2011, at 11:34 AM, Brian Manthos<brianman@microsoft.com>  wrote:
>>> Paraphrasing [1]:
>>> When specified via angle, the angle can be understood as both the direction
>>> ("toward the<angle>") and the ending point ("ends at<angle>").
>>> Paraphrasing [2] and [3]:
>>> When specified via keyword, the keyword can be understood as both opposite
>>> direction ("away from the<keyword(s)>") and the starting point ("starts at
>>>   <keyword>").
>>> Is it intentional that these two ways of specifying gradient-line are
>>> opposite?
>> I don't think they are. In [1], the angle determines the starting AND ending
>> points. In [2] and [3], the ending point (and thus the direction) is
>> determined by the starting point. I see no inconsistency.
> This was brought up during the ftf, and I think it's a valid point.
> In my head (and I expect in others'), when I think of what angle to
> use for a gradient I do so by imagining a compass rose, with 0deg at
> the top, 90deg to the right, etc.  I then set the gradient angle by
> choosing which angle I want the gradient to point toward.

Yes, indeed the Compass Rose which has been used for thousands of years 
by the people of the Mediterranean. Just imagine saying to a RTL author 
that 0 degrees is West on a compass since that works with geometry (Who 
invented decimals?). In the East, the natural inclination would be that 
0 degrees is on the East when relating to geometry. I would like to see 
the Yin and Yang of CSS for true balance. Up, north, zero or 12 o.clock, 
seems to have some universal meaning.

> Similarly, if I imagine keywords, I do so with 'top' at the top,
> 'right' at the right, etc.  Now, though, I have to reverse how I deal
> with my mental image - if I want the gradient to point up, I don't
> choose 'top', I choose 'bottom'.

Tab, can you please elaborate...., I just can't imagine that in my 
mental model.

> I'm not sure if this is an important enough disconnect to justify
> changing the keywords, but we brainstormed it a bit at the ftf.  I
> don't think we came up with any set of directional keywords that was
> sufficiently decent to work as replacements, though.  If anyone has
> any suggestions, please speak up!  The current front-runner is
> 'upward'/'rightward'/etc, which isn't very good.
> ~TJ

Before, after, start and end. Works regardless of base direction or 
block progression.

Alan Gresley
Received on Wednesday, 8 June 2011 08:47:44 UTC

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