[Rd] Graphics driver test script?

Paul Murrell p.murrell at auckland.ac.nz
Mon Feb 12 21:55:17 CET 2007


Byron Ellis wrote:
> On 2/11/07, Geoff Russell <geoffrey.russell at gmail.com> wrote:
>> Hi,
>> 1. I started work on a metapost graphics driver a week or so ago and it is
>> gradually taking shape. I'm building up my own test cases into a
>> script as I go, but
>> figured you may have a "canonical testing script" of cases a driver must handle?
> I typically use demo(graphics) for initial development and then things
> like example(plotmath) to make sure I'm getting font encoding working
> properly.
>> 2. The clipping function looks like being a tricky problem. It seems
>> to me that the
>> callers of the driver assume that clipping affects all following calls
>> until the next
>> clipping call resets the clipping box.   With metapost, the clipping
>> function clips the
>> current graphics region and has no effect on following drawing functions.  I'm
>> not sure how to handle this --- the 2 models are very different.
> Sounds like you get to make a lot of clipping calls in metapost.

Yes, it may not be the most efficient approach, but one method would be
to keep track of the R's latest clipping region within your device
structure (just update it whenever R asks your device to set the clip
region, i.e., in MetaPost_Clip()) and enforce the current clip region
for each drawing call.


>> Cheers,
>> Geoff Russell
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel

Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz

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