Applying aribtrary transformations to a View's CTM

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2 total messages Started by David Rochberg Fri, 07 Aug 1992 03:34

#479

Author: David Rochberg
Date: Fri, 07 Aug 1992 03:34

29 lines
1552 bytes

I would like to exchange the coordinate axes of a view.  To do this
before drawing is simple.  I just call a pswrap that does

  [0 1 1 0 0 0] concat

and the drawing is done in a transposed coordinate system.  However, I
want to exchange the coordinates in the *View's* CTM.  This way,
coordinates for drawSelf:: and mouse coordinates would be
automatically transposed and I could use the exact same code in both
the transposed and untransposed states.  

This transform cannot be constructed from a sequence of -rotate: and
-translate::'s, and setFlipped does not treat the coordinate system
kindly when it's called late in the scheme of things, so I must use an
arbitrary transform.  How can I do this?

I've tried cheating in two ways:
1)  Putting coordinate transforms in an initGState method.
2)  Putting them into a 
	PSgrestore()
	transform coords
	PSgsave()
Both cases failed miserably (as was to be expected).  

Thanks in advance for any leads you might have!  My fast-approaching
deadline thanks you too. 

				-david

Re: Applying aribtrary transformations to a View's CTM

#480

Author: David Rochberg
Date: Fri, 07 Aug 1992 05:30

16 lines
1083 bytes

While I was explaining to myself why it was impossible to generate an
odd isometry with scale and rotate, I realized that [self scale:1:-1]
is a reflection, and so one can get odd isometries, like reflection
about the diagonal.  
[self rotate:45];
[self scale:1:-1];
[self rotate:-45];
exchanges the view coordinate axes.  

However, I'd still like to know if it's possible to do this more
directly.

			emabarrased at having overlooked the obvious
			but still curious,
			david

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