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Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073)

From: Anthony Grasso <anthony.grasso@cisra.canon.com.au>
Date: Mon, 13 Oct 2008 10:10:42 +1000
Message-ID: <48F29202.6000800@cisra.canon.com.au>
To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
CC: www-svg@w3.org

Hi Dr. Hoffmann,

Dr. Olaf Hoffmann wrote:
> Anthony Grasso:
>> Hi Dr. Hoffmann,
> Hello ;o)
>> Excellent find in the specification! 
> It is old and I already noted this previously a longer time ago, but 
> there was not much interest to care about it or to test it. At least 
> I have related tests about this issue in my own test suite for 
> more than two years ;o)
> Note, that Opera 9.5 manages both critical situations with determinant
> 0 and indefinite (due to a possible skew transformation of for example
> 90 degree) and has only minor problems in relation with vector-effect
> non-scaling-stroke (instead of a constrained transformation).
> I think, this indicates already, that Opera uses another (more clever?)
> method to get the effect of the constrained transformation anyway, 
> obviously without using the inverse matrix and avoiding the problem.
> On the other hand, the problems of Opera with vector-effect 
> non-scaling-stroke indicates that it maybe could be even more clever -
> especially because for non-scaling-stroke an inversion is not even
> mentioned ;o)
>> The SVG Working Group discussed this 
>> issue and we concluded that we should add wording that warns authors of the
>> problem.
>> As a result I was given ACTION-2284 [1] to add the wording to the
>> specification. The new wording can be found in "The TransformRef value" [2]
>> section of the specification.
> Can you point out more precisely the position of the change?
> I looked into the section twice and could not find a change from
> the working draft to the editors draft.

Sorry, my mistake. The change can be found in the master version of the 
specification [1].

Please let me know if you still have problems viewing it.

Kind Regards,

Anthony Grasso.

[1] http://dev.w3.org/SVG/profiles/1.2T/master/coords.html#transform-ref
Received on Monday, 13 October 2008 00:11:29 UTC

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