[Rd] invalid graphics state using dev.print (fwd)
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Feb 20 08:56:57 CET 2006
On Mon, 20 Feb 2006, Paul Murrell wrote:
>> >> x11()
>> >> plot(rnorm(10))
>> >> dev.print(png)
>> Paul> Error in dev.copy(device = function (filename = "Rplot%03d.png", width =
>> Paul> 480, :
>> Paul> invalid graphics state
> I think the problem is that the width and height of the PNG device is
> being taken (without regard for units) from the X11 device. So
> approximately 7 inches square screen window gets drawn into
> approximately 7 *pixel* square PNG file and (understandably) R complains
> that there is not enough room for the plot.
Yes, that it how it is documented to work.
> Another workaround is something like ...
> dev.print(png, width=480, height=480)
(Just one will do if you want to preserve the aspect ratio.)
> ... and a fix requires making dev.print() smarter so that it figures out
> that it needs to convert width/height from inches to pixels.
I don't think there is a way to do that unambiguously (there is no
standard way to do the conversion), and in any case dev.print() was passed
a function, not the name of a function, and so does not in general know
how it behaves (and your 'png' need not be R's png()).
All we can do is to re-emphasize this on the help page, and add a warning
if a known bitmap device is detected (possibly inaccurately) by name.
BTW, I think it was perverse to call dev.print() except to do printing.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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