png() ... dev.off() don't work in RInside when I use ggplot2

Question

This code works in R very well

library(ggplot2);
tbl <- data.frame( name = c ("AAA", "BBB"),  qty = c(100, 150)  );
p <- ggplot(data = tbl ) + geom_bar(stat='identity', aes(x =name, y = qty));
png(file='sample.png', bg ='transparent', width = 300, height = 300 );
p;
dev.off();

But if I evaluate this code from C++ like this:

std::string code =""
    "library(ggplot2);"
    "tbl <- data.frame( name = c ("AAA", "BBB"),  qty = c(100, 150)  );"
    "p <- ggplot(data = tbl ) + geom_bar(stat='identity', aes(x =name, y = qty));"
    "png(file='sample.png', bg ='transparent', width = 300, height = 300 );"
   "p;"
   "dev.off();"

myR.parseEval( code );

The png-file is not created.

I investigated this problem and found that problem depended with ggplot2. For example simple code:

std::string code =""
   "png(file='sample.png', bg ='transparent', width = 300, height = 300 );"
   "plot( 1:20 );"
   "dev.off();"

works well. Also file created if I use grid.circle() from "grid" packages. ggsave() function works good too.

Why ggplot can't create file through graphic device?

Old hat and known story -- `png` devices _must have_ x11 around so you need to call with `xvfb` around it. Or use one of the Cairo devices instead who work without x11. — Dirk Eddelbuettel, Jul 09 '18 at 11:37
Also, just an fyi, R code does not need a `;` at the end of each line — Conor Neilson, Jul 09 '18 at 12:16
I know, but if you send code as one long string it won't work without any separator like ";" or return symbol — Arcady Perla, Jul 09 '18 at 17:25

png() ... dev.off() don't work in RInside when I use ggplot2

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