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Re: Gradient syntax proposal -- Problems

From: James Elmore <James.Elmore@cox.net>
Date: Thu, 27 Aug 2009 16:57:06 -0700
Message-Id: <6CCAA6A3-51B3-493E-97B2-22EC3C9E04D9@cox.net>
Cc: CSS <www-style@w3.org>
To: Tab Atkins Jr. <jackalmage@gmail.com>

> Edits have been made to the master proposal, located at
> http://www.xanthir.com/:4bhipd.  I also added a line with the syntax
> to the first example.
>
> I'm not happy with how I phrased the comma thing, or with the fact
> that I had to say it at all.  I think it's confusing.  I suspect that
> it would be better to handle that in the grammar, but I'm not sure of
> how to write it.  Ideas?
>
> ~TJ
>

Thanks for the updated proposal. I am working my way through it and  
hope to find few problems -- many have already been pointed out in  
the discussion. However, in the following paragraph, I believe the  
corners are misstated.

<<If the <bg-position> is omitted in the first argument, the starting- 
point is in one of the box's corners, based on the <angle>. If the  
angle is between [0deg,90deg], the starting point is the bottom-left  
corner. If the angle is between [90deg,180deg], the starting point is  
the bottom-right corner. If the angle is between [180deg,270deg], the  
starting point is the top-left corner. If the angle is between  
[270deg,360deg], the starting point is the top-right corner. The  
ending-point is determined in the manner described by the previous  
paragraph.>>

Odeg to 90deg is the lower left corner. [correct]
90 to 180 is the lower right corner. [correct]
180 to 270 should be the upper right corner. [states top-right]
and 270deg to 360deg then has to be the top left corner.

Also -- what about overlaps? Can we safely ignore 0/360, 90, 180, and  
270 degrees simply because they align with one side of the box? Would  
the gradient not still be visible, but be drawn in opposite  
directions, depending on which direction the gradient line is drawn?

For example, suppose the user specifies 90 degrees. The gradient line  
would be parallel to the bottom of the box. If there are no offsets  
from the bg-position, it will be on top (underneath?) the bottom of  
the box. However, if the UA selects 90 degrees to start at the bottom  
left corner, the gradient line would be oriented left-to-right. Or,  
if the UA selects 90 degrees as the bottom right corner, the gradient  
line would be oriented right-to-left. The specification needs to make  
clear which behavior is correct, or allow some way for users /  
designers to specify the direction of the gradient line. Clearly, the  
users can reverse the order of their color-stops, PROVIDED they know  
in advance which direction the UA will pick. Otherwise, the gradient  
might be reversed and the users will not be able to know the correct  
direction.

</James>
Received on Thursday, 27 August 2009 23:57:49 GMT

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