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Re: [cssom-view] ISSUE-4: Coordinate space of the return value of getBoxQuads()

From: Edward O'Connor <eoconnor@apple.com>
Date: Fri, 20 Jun 2014 11:33:18 -0700
To: www-style@w3.org
Message-id: <m2zjh7ph1t.fsf@eoconnor.apple.com>
Hi,

I wrote:

>> What is the coordinate space of the DOMQuads returned from
>> getBoxQuads()?

Tab replied:

> That depends on the options passed in. The function doesn't yet
> specify what the default relativeTo argument is, but once it does,
> that'll be the default; if you pass in an explicit value, it's
> relative to what you passed in.

Suppose I call getBoxQuads() like so:

var quads = document.querySelector("some element").getBoxQuads({
  relativeTo:document
});

Given your reply, I would expect each DOMQuad to be in the document's
coordinate space. But the MDN post heralding the introduction of this
API to Firefox says the following[1]:

| For documents, the origin of the document?s viewport is used.

This doesn't match what Tab assumed.

I prefer Tab's assumed behavior for the relativeTo:document case, that
it should be in document coordinates. If we really also want a way to
get viewport coordinates, we should have a special relativeTo:"viewport"
value or some such.

And, of course, we need to decide what the default is if you don't pass
in relativeTo. document is probably best there.


Ted

1. https://hacks.mozilla.org/2014/03/introducing-the-getboxquads-api/
Received on Friday, 20 June 2014 18:33:48 UTC

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