png(), then
func(), then dev.off(). So func must
be a function that will generate a plot when used this
way.plotPNG(func, filename = tempfile(fileext = ".png"),
width = 400, height = 400, res = 72, ...).png.png. Note that this affects the
resolution of PNG rendering in R; it won't change the
actual ppi of the browser.png. These can be used to set
the width, height, background color, etc.png),
then CairoPNG, and finally
png. This is in order of quality
of output. Notably, plain png output on Linux and
Windows may not antialias some point shapes, resulting in
poor quality output. In some cases, Cairo() provides output that looks
worse than png(). To disable Cairo output for an
app, use options(shiny.usecairo=FALSE).