- From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
- Date: Tue, 29 Jun 2010 13:57:22 +0200
- To: www-svg@w3.org
Erik Dahlstrom: .... >What other operations? Where in the spec? >Are you suggesting adding all the porter-duff equations for 'over', 'xor' >etc to the feComposite section? .... Yes, for operator = "over | in | out | atop | xor" of feComposite. This should be not very difficult, because at least for them the usual implementations seem to agree on a result. Interestingly, for the arithmetic operator, where a formula is provided, I have seen different interpretations, for example Batik/Squiggle differs sometimes from Opera ;o) But I think, this is no indication, that providing formuals is a disadvantage. Informative additions would be enough, if it is not intended to risk some relevant change (what is not really likely). To find out, what the operators mean (including opacity), I had to search, read an article at wikipedia, finding a reference to the online version of the article from Porter and Duff, reading and understanding this, deviating the meaning for SVG filters. I think, this cascade of actions for the reader can be shortened dramatically by simply providing the formulas. If we assume, that the online version of the article is not accessible forever, the necessary action can be even more time consuming - traveling to a specialised library, booking the magazine, maybe including interlending, waiting, finally reading, captured by Star Wars reminiscences... ;o) Olaf
Received on Tuesday, 29 June 2010 11:59:32 UTC