(PR#1881) polygon() draws non-transparent border, erase.screen draws non-transparent border (PR#1881)

oehl_list@gmx.de oehl_list@gmx.de
Wed, 7 Aug 2002 17:49:22 +0200 (MEST)

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().



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

# now switching to right screen ERASES border of right screen in Prototype
# thus the right border of the left box gets deleted



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