feSimple <- filterEffect(feGaussianBlur(sd=3))
grid.rect(name="r1", width=.8, height=.8)
grid.filter("r1", feSimple)


offset <- feOffset("SourceAlpha", result="offOut",
                   dx=unit(2, "mm"), dy=unit(-2, "mm"))
blur <- feGaussianBlur("offOut", sd=3, result="gaussOut")
blend <- feBlend("SourceGraphic", "gaussOut")
feComplex <- filterEffect(list(offset, blur, blend))
grid.rect(name="r2", width=.8, height=.8,
          gp=gpar(fill="white"))
grid.filter("r2", feComplex) 


pdf(NULL, width=12, height=3)
# grid.newpage()
pushViewport(viewport(x=1/4, width=.4, height=.8))
feSimple <- filterEffect(feGaussianBlur(sd=3))
grid.rect(name="r1", width=.8, height=.8)
grid.filter("r1", feSimple)
popViewport()
pushViewport(viewport(x=3/4, width=.4, height=.8))
offset <- feOffset("SourceAlpha", result="offOut",
                   dx=unit(2, "mm"), dy=unit(-2, "mm"))
blur <- feGaussianBlur("offOut", sd=3, result="gaussOut")
blend <- feBlend("SourceGraphic", "gaussOut")
feComplex <- filterEffect(list(offset, blur, blend))
grid.rect(name="r2", width=.8, height=.8,
          gp=gpar(fill="white"))
grid.filter("r2", feComplex) 
popViewport()
grid.export("Figures/export-filter.svg")
dev.off()
system("chromium-browser --headless --screenshot=Figures/export-filter.png --window-size=880x220 Figures/export-filter.svg")
system("cp Figures/export-filter.png Web/export-filter.png")