From ripley@stats.ox.ac.uk  Wed Aug  7 17:14:22 2002
From: ripley@stats.ox.ac.uk (ripley@stats.ox.ac.uk)
Date: Wed, 7 Aug 2002 17:14:22 +0100 (BST)
Subject: (PR#1881) polygon() draws non-transparent border, erase.screen
 draws non-transparent border (PR#1881)
In-Reply-To: <13936.1028735362@www33.gmx.net>
Message-ID: <Pine.LNX.4.31.0208071710530.22725-100000@gannet.stats>

On Wed, 7 Aug 2002 oehl_list@gmx.de wrote:

>
> Dear Brian,
>
> thank you for your answer.
>
> > There's a bug in GA_Polyline (not Polygon) stemming from the changes to
> > graphics device internals at 1.4.0, it seems.  It is transparent polylines
> > one cannot draw, and only on the windows() device.
> >
> > You don't give an example for erase.screen: does this need a separate fix?
>
> The original call to polygon in erase.screen() did use border=NA. I did not
> find documentation saying what an NA color means !? Testing a bit, I find
> rect(border=NA) to interpret it as "tranparent" resp. lty=0. To my understanding
> erase.screen() rather should also erase the borders in background color AS
> THE PROTOTYPE DOES (WinS+2000), look at example code below. Thus I vote for
> changing erase.screen() to use border=0 (zero). If polygon() get's fixed, there
> is no need to use rect() instead of polygon().

NA is a colour that is the same as "transparent".  Unfortunately, border=0
for polygon() is documented to mean `do not draw', but that is not what
happens.  Looks like this needs sorting out.

Thanks for drawing it to our attention.

>
> Best
>
>
> Jens
>
>
> oldpar <- par(no.readonly=TRUE)
> par(mar=c(0,0,0,0), oma=c(0,0,0,0))
> figs <- rbind(
> c( 0.0, 0.5, 0.0, 1.0)  # left
> , c( 0.5, 1.0, 0.0, 1.0)  # right
> )
> dimnames(figs) <- list(
> c("left","right" )
> , c("xlow","xhigh","ylow","yhigh")
> )
> screens <- split.screen(figs)
>
> par(usr=c(0, 1, 0, 1))
>
> #plot a box on border of left screen in some color
> box(col=5)
>
> # now switching to right screen ERASES border of right screen in Prototype
> (S+2000)
> # thus the right border of the left box gets deleted
> screen(2)
>
> close.screen(all.screens=TRUE)
> par(oldpar)
>
>
> --
> GMX - Die Kommunikationsplattform im Internet.
> http://www.gmx.net
>
>

-- 
Brian D. Ripley,                  ripley@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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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(PR#1881) polygon() draws non-transparent border, erase.screen draws non-transparent border (PR#1881)
ripley@stats.ox.ac.uk