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[css3-ui][css-images] cursor x and y coordinate system and <image>

From: Florian Rivoal <florian@rivoal.net>
Date: Fri, 10 Apr 2015 17:33:00 +0200
Message-Id: <D2119FF9-C42C-4E62-8EFD-BEFE01641C5C@rivoal.net>
Cc: Tantek Çelik <tantek@cs.stanford.edu>
To: www-style list <www-style@w3.org>
In the cursor property definition (http://dev.w3.org/csswg/css-ui/#propdef-cursor)
we find this statement:

  The x-coordinate and y-coordinate of the position in the
  cursor’s coordinate system (left/top relative)

I think this needs to be clarified. That the origin is at the
top left is clear. This also probably means that:
* that for a bitmap image the unit is in image pixels
* that for an svg image, the unit is the unitless length integer

However, it isn't clear what this means for a gradient or
an image-set, which has images at multiple resolutions.

The full list of possible <image> values is:

<image> = 
<url> | <image()> | <image-set()> | <element()> | <cross-fade()> | <gradient>

We need to define this, and I think it would actually be better
and more maintainable for this to be defined in css-images,
and referenced from css-ui, so that things just work when new
<image> values are added.


As for the actual definitions, I propose:
bitmaps
  -> the unit is the image pixel for bitmap images

svg
  -> the svg unit

gradients
  -> 0 to 100 on both axis

<image()>
  -> the coordinate system of the image you end up loading
     ISSUE: what to do if we fallback to a color?

<image-set()>
  -> the coordinate system of the first image in the list

<element()>
  -> CSS pixels?

<cross-fade>
  -> the coordinate system of the <cf-mixing-image>

<gradient>
  -> each axis goes from 0 to 100

 - Florian
Received on Friday, 10 April 2015 15:33:28 UTC

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