When using officer and rvg, can you remove or prevent the background white square behind the image inserted into PowerPoint from the code?

Question

When using officer and the rvg graphics I want my images to not have the background white square. The reason for this is that some functions leave a lot of empty space up at the top and often this will overlap with the header. I can go in and delete each one but when making 20 or more plots this gets tedious fast.

Specifically I want to use this with the forest function in metafor used here in the example.

Before deleting the background.

**

After deleting the background.

**

library(officer)
doc <- read_pptx()
doc <- add_slide(doc, "Title and Content", "Office Theme")
doc <- ph_with_vg_at(doc, code = barplot(1:5, col = 2:6),
                     left = 1, top = 2, width = 6, height = 4)


library(metafor)
library(gemtc)
network <-mtc.network(smoking$data.ab)
data(dat.bcg)
plot(network)
res <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, data=dat.bcg, measure="RR",
           slab=paste(author, year, sep=", "), method="REML")
forest(res)
doc <- add_slide(doc, "Title and Content", "Office Theme")
doc <-  ph_with_vg(doc, code = plot(network), type = "body", width = 8, height = 6)
doc <- add_slide(doc, "Title and Content", "Office Theme")
doc <-  ph_with_vg(doc, code = forest(res), type = "body", width = 8, height = 6)

print(doc, target = "vg.pptx")

Answer 1

This is now possible using the latest rvg update and setting the background to "NA".

anyplot = dml(code = barplot(1:5, col = 2:6), bg = "NA")

    doc <- read_pptx()
    doc <- add_slide(doc)
    doc <- ph_with(doc, anyplot, location = ph_location_fullsize())

    print(doc, target = "bg.pptx")