rsvg::rsvg_svg(system.file("extra", "moon-26619.svg", 
                     package="RGraphics"),
         "full-moon.svg")
moon <- grImport2::readPicture("full-moon.svg")


pdf(NULL, width=4.5, height=3)
pushViewport(viewport(gp=gpar(cex=0.7)),
             plotViewport(c(4, 5, 3, 1)),
             dataViewport(as.numeric(lowTideDate), 
                          as.numeric(mainHours)))
grid.rect(gp=gpar(fill="black"))
grImport2::grid.picture(moon, ext="gridSVG", x=.65)
grid.segments(unit(phases$date, "native"), 0,
              unit(phases$date, "native"), 1,
              gp=gpar(lty="dashed", col="white"))
for (subset in list(1:13, 14:29, 30:31)) {
  grid.lines(lowTideDate[subset], lowTideHour[subset],
             default.units="native", 
             gp=gpar(lwd=2, col="white"))
  grid.points(lowTideDate[subset], lowTideHour[subset],
              pch=16, size=unit(2, "mm"),
              gp=gpar(col="white"))
}
xTicks <- seq(min(lowTideDate), max(lowTideDate), by="week")
grid.xaxis(at=xTicks, label=format(xTicks, "%b %d"))
grid.yaxis(at=mainHours, label=format(mainHours, "%H:%M"))
grid.text("Time of Low Tide (NZDT)", 
          x=unit(-4, "lines"), rot=90)
grid.text("Auckland, New Zealand January 2010", 
          y=unit(-3, "lines"))
grid.xaxis(main=FALSE, at=phases$date, label=FALSE)
grid.export("Figures/import-moonplots3.svg", res=80)
system("chromium-browser --headless --screenshot=Figures/import-moonplots3.png --window-size=360x240 Figures/import-moonplots3.svg")
system("cp Figures/import-moonplots3.png Web/import-moonplots3.png")