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[whatwg] [WebApps] canvas transform()/setTransform()

From: Ian Hickson <ian@hixie.ch>
Date: Wed, 17 Jan 2007 00:37:45 +0000 (UTC)
Message-ID: <Pine.LNX.4.62.0701170025210.4611@dhalsim.dreamhost.com>
On Thu, 28 Dec 2006, ????????(KUROSAWA, Takeshi) wrote:
> 
> Web Application 1.0 adds the transform() and the setTransform() to the 
> canvas 2d context. The conversion of the arguments of these methods to 
> the matrices is described in the section 3.14.6.1.2.
> 
> > The transform(m11, m12, m21, m22, dx, dy) method must multiply the current
> > transformation matrix with the matrix described by:
> > m11  m12  dx
> > m21  m22  dy
> > 0     0     1
> > 
> > The setTransform(m11, m12, m21, m22, dx, dy) method...
> - http://www.whatwg.org/specs/web-apps/current-work/#transform
> 
> However, this is repugnant. And it isn't compatible with many graphics 
> systems. So the matrix should be
> 
> m11  m21  dx
> m12  m22  dy ... (b)
> 0     0     1
> 
> In addtion, the rhino-canvas implements both methods. It uses the matrix (b).
> http://rhino-canvas.sourceforge.net/

I have fixed the spec as you request. Sorry for the delay in responding.


On Thu, 28 Dec 2006, Charles McCathieNevile wrote:
>
> In particular, this would make for easy compatibility with SVG 
> transformations, helping authors to copy them from one to hte other 
> format and back.

Indeed.


On Mon, 15 Jan 2007, Stefan Haustein wrote:
> 
> could somebody please clarify whether the unusual parameter order is 
> intended -- or simply a bug in the specification?

It was a bug in the specification.

Cheers,
-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 16 January 2007 16:37:45 UTC

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