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Re: where is (0,0)?

From: Ian Jacobs <ij@w3.org>
Date: Wed, 26 Jan 2000 08:58:43 -0500
Message-ID: <388EFD93.A6277B4D@w3.org>
To: "John A. Grant" <jagrant@gsc.nrcan.gc.ca>
CC: www-html-editor@w3.org
"John A. Grant" wrote:
>
> On this page:
>     http://www.w3.org/TR/html401/struct/objects.html#edef-AREA
> 
> It states:
>   "Coordinates are relative to the top, left corner of the object. All values are lengths. All values are separated by commas"
> However, it doesn't say if the (x,y) are 0-based or 1-based. Is the top left >corner (0,0) or (1,1)?  I'm guessing (0,0), but I'm a technical person. Others 
> might think (1,1).

I will ask the WG for clarification.

> Also it says "all values are lengths". Surely the (x,y) are not "lengths"? A 
>length doesn't have the concept of a reference point like (0,0). The (x,y) are 
>"co-ordinates", rather than "lengths".  But you don't have "co-ordinate" as a basic 
>element type - perhaps there should be such a type.  This distinction is akin to 
>the difference between a scalar (speed) and a vector (velocity) quantity.

The term "length" is linked to and it is explained that in the
context of this document, a length value may be either a %Pixel; value
or percentage of the available horizontal or vertical space. We chose
the term length (for better or worse) to group these two values under
one
term.

 - Ian

-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel/Fax:                     +1 212 684-1814 or 212 532-4767
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Received on Wednesday, 26 January 2000 08:59:22 GMT

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