[R] Graphics device size

Prof Brian Ripley ripley at stats.ox.ac.uk
Tue Apr 11 19:25:31 CEST 2006

On Tue, 11 Apr 2006, Prof Brian Ripley wrote:

> On Tue, 11 Apr 2006, Christos Hatzis wrote:
>> Dear All,
>> When working with composite plots many times I have to manually adjust the
>> graphics display window size to get the best results (in Windows XP).  I can
>> then find the size of the adjusted window in inches using par("din").
>> Now I would like to export the adjusted graphs as png's and have them look
>> as close to the original display as possible.  The problem is that the png
>> device accepts size arguments in pixels so that I need to convert inches to
>> pixels.  Is there a way to get the default pixels-per-inch that the windows
>> device uses?  RSiteSearch("ppi") did not return any helpful hints.
> Well, yes, but only by calling the Win API for your own C code.  It is
> often not very accurate.  Interestingly, it is actually in pixels per cm.
> What is harder is to do is to find out how large you have resized the
> graphics window to.  Since in fact that is stored in pixels, you don't
> need the pixels-per-inch, but I can see no way to do this without C code
> (the info is both in the private structure defined in devWindows.h and in
> the device-driver structure via right - left, bottom - top).

Doesn't savePlot(, type="png") do everything that you might want here?

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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