Thank you Paul Murrel for answering and thank you Brian Ripley for
correcting this behaviour in R-patched.
I am sorry, but I think there is just another 'misfeature' with
transparent figures since R-2.4.0 and it seems not to be corrected in
todays R-2.4.0 Patched (2006-11-24 r39989).
In earlier versions when producing a transparent figure without any
border (=NA), nothing was drawn. In newer versions there is something
like a white border line. You can see it in particular when drawing a
new dotted line above this border of the underlying figure. I should
demonstrate it with a small example:
--------------------------------------------------------------------
pdf("test_alpha.pdf", version="1.4")
plot(1:8, 1:8, type="n", xlab="", ylab="")
lines(c(1,8), c(1,8), type="l", col="lightblue", lwd=15)
# rectangle with alphachannel=255 (no transparency)
goldenrod1 <- rgb(255,193,37,255, names=c("goldenrod1"), max=255)
rect(4,4,7,7, col=goldenrod1, border=NA)
lines(c(4,4,7,7,4), c(4,7,7,4,4), col="red", lty=2)
text(5,7, "no transparency")
# polygon with alphachannel=64 (transparency near 40%)
polygon(c(5,2,2,5,5), c(2,2,5,5,2), col=rgb(255,192,203,64, max = 255),
border=NA)
lines(c(5,2,2,5,5), c(2,2,5,5,2), col="red", lty=2)
text(4,2, "transparency 40%")
dev.off()
--------------------------------------------------------------------
It is probably just a mistake. What do you think?
Rainer Hurling
Paul Murrell schrieb:
Hi
This appears to have been fixed in r-patched (by Brian Ripley)
Paul
Rainer Hurling wrote:
Dear R users,
since R-2.4.0 I am not able any more to draw figures without
transparency after drawing one figure with alphachannel set lower than 100%.
For better unterstanding here a small example of my problem:
-----------------------------------------------
pdf(paste("test_alpha_rgb.pdf",sep=""), version="1.4")
plot(1:8, 1:8, type="n", xlab="", ylab="")
lines(c(1,8), c(1,8), type="l", col="lightblue", lwd=15)
# polygon with alphachannel=64 (transparency 40%)
polygon(c(5,2,2,5,5), c(2,2,5,5,2), col=rgb(255,192,203,64, max = 255),
border=NA)
text(4,2, "transparency 40%")
# rectangle with alphachannel=255 (no transparency)
goldenrod1 <- rgb(255,193,37,255, names=c("goldenrod1"), max=255)
rect(4,4,7,7, col=goldenrod1, border=goldenrod1)
text(5,7, "no transparency")
dev.off()
-----------------------------------------------
In this example (see pdf in attachment) after plotting a line without
any transparency a polygon is drawn with alphachannel set to 40%. All
following figures and even text is shown with transparency.
The described behaviour seems to be the same on FreeBSD 7.0-CURRENT and
on WindowsXP.
Am I doing something wrong?
Many thanks for any help,
Rainer Hurling
pdf("test_alpha.pdf", version="1.4")
plot(1:8, 1:8, type="n", xlab="", ylab="")
lines(c(1,8), c(1,8), type="l", col="lightblue", lwd=15)
# rectangle with alphachannel=255 (no transparency)
goldenrod1 <- rgb(255,193,37,255, names=c("goldenrod1"), max=255)
rect(4,4,7,7, col=goldenrod1, border=NA)
lines(c(4,4,7,7,4), c(4,7,7,4,4), col="red", lty=2)
text(5,7, "no transparency")
# polygon with alphachannel=64 (transparency near 40%)
polygon(c(5,2,2,5,5), c(2,2,5,5,2), col=rgb(255,192,203,64, max = 255),
border=NA)
lines(c(5,2,2,5,5), c(2,2,5,5,2), col="red", lty=2)
text(4,2, "transparency 40%")
#for (x in 1:8)
# for (y in 1:8)
# rect(x-0.5,y-0.5, x+0.5, y+0.5, col=rgb(255,193,37, 255/(x*y), max=255))
#rect(5,5,7,7, col=rgb(255,0,0, 255, max=255), border=NA)
dev.off()
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