[R-gui] tkrplot and background colour

[Wayne.W.Jones at shell.com]

Hi Everyone, 

I have been using rpanel to produce a GUI for R. I came upon some formatting problems when using rp.tkrplot. 
Basically when I set the background of the tkrplot from "transparent" to "white" using the par functionality the dimensions of the plot change. 

The problem (if it really is one!) is not related to rpanel but to tkrplot. 

A reproducible example can be found below. 

Can anyone explain why this behaviour occurs?
Can anyone explain what settings are changing in the plots when the background colour is changed so 
that I can alter my code to accommodate this?

Regards

Wayne




library(tcltk)
library(tkrplot)
###### plot 1 with no background 

tt <- tktoplevel()
bb<-1
img <-tkrplot(tt, function() plot(1:20,(1:20)^bb))
f<-function(...) {
    b <- as.numeric(tclvalue("bb"))
    if (b != bb) {
        bb <<- b
        tkrreplot(img)
    }
}
s <- tkscale(tt, command=f, from=0.05, to=2.00, variable="bb",
             showvalue=FALSE, resolution=0.05, orient="horiz")
tkpack(img,s)


###### plot 2 with White background 

tt <- tktoplevel()
img <-tkrplot(tt, function() {par(bg="white"); plot(1:20,(1:20)^bb)})
s <- tkscale(tt, command=f, from=0.05, to=2.00, variable="bb",
             showvalue=FALSE, resolution=0.05, orient="horiz")
tkpack(img,s)






----------------------------------------------------------------------------------------
Wayne Jones
Statistical Consultant
Shell Global Solutions (UK)
Shell Technology Centre Thornton, P.O. Box 1, Chester CH1 3SH, United Kingdom

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Email: Wayne.W.Jones at shell.com
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