grid Graphics
from Top to Bottom

library(grid)

grid.text("CPI data")

grid.text(c("CPI data", "code", "???"),
          x=c(2/4, 1/4, 3/4), y=c(2/3, 1/3, 1/3))

grid.circle(x=c(2/4, 1/4, 3/4), y=c(2/3, 1/3, 1/3),
            r=.1)

ellipse <- function(a, b) {
    angle <- seq(0, 2*pi, length=101)
    grid.polygon(.5 + a*cos(angle),
                 .5 + b*sin(angle))
}

grid.text("CPI data")
ellipse(.3, .1)

ellipse <- function(a, b) {
    pushViewport(viewport(width=2*a, height=2*b,
                          name="vp"))
    angle <- seq(0, 2*pi, length=101)
    grid.polygon(.5 + .5*cos(angle),
                 .5 + .5*sin(angle))
    upViewport()
}

grid.text("CPI data")
ellipse(.3, .1)

grid.text("CPI data")
ellipse(unit(.3, "npc"), unit(.1, "npc"))

grid.text("CPI data")
ellipse(unit(2, "in"), unit(1, "in"))

grid.text("CPI data")
ellipse(stringWidth("CPI data"), unit(1, "in"))

ellipse <- function(x, y, a, b) {
    pushViewport(viewport(x, y,
                          width=2*a, height=2*b))
    angle <- seq(0, 2*pi, length=101)
    grid.polygon(.5 + .5*cos(angle),
                 .5 + .5*sin(angle))
    popViewport()
}

node <- function(x, y, label) {
    grid.text(label, x, y)
    ellipse(x, y, stringWidth(label),
            unit(1, "lines"))
}

node(2/4, 2/3, "CPI data")
node(1/4, 1/3, "code")
node(3/4, 1/3, "???")

library(png)
img <- readPNG("pk.png")

grid.raster(img)

grid.raster(img, .1, .1, width=.5,
            just=c("left", "bottom"))
pushViewport(viewport(.75, .75, .25, .25,
                      angle=45))
grid.raster(img)
popViewport()

grid.segments(.2, .2, .8, .2)
grid.lines(c(.2, .5, .8), c(.4, .5, .4))
grid.xspline(c(.2, .5, .8), c(.6, .9, .6),
             shape=1)

grid.segments(.2, .2, .8, .2)
grid.lines(c(.2, .5, .8), c(.4, .5, .4),
           gp=gpar(lty="dotted"))
grid.xspline(c(.2, .5, .8), c(.6, .9, .6),
             shape=1,
             gp=gpar(lty="dotted", col="grey"))

arrow <- arrow(angle=20, length=unit(.1, "in"),
               type="closed")

grid.segments(.2, .2, .8, .2, arrow=arrow)
grid.lines(c(.2, .5, .8), c(.4, .5, .4),
           arrow=arrow)
grid.xspline(c(.2, .5, .8), c(.6, .9, .6),
             shape=1, arrow=arrow)

ellipseGrob <- function(x=.5, y=.5, a, b) {
    vp <- viewport(x, y, width=2*a, height=2*b)
    angle <- seq(0, 2*pi, length=101)
    polygonGrob(.5 + .5*cos(angle), .5 + .5*sin(angle),
                vp=vp)
}

eg <- ellipseGrob(a=.3, b=.1)

grid.draw(eg)

for (i in seq(0, 360, length.out=9)) {
    grid.circle(x=grobX(eg, i), y=grobY(eg, i),
                r=unit(1, "mm"),
                gp=gpar(fill=bg))
}

ellipseGrob <- function(x=.5, y=.5, a, b, name) {
    vp <- viewport(x, y, width=2*a, height=2*b)
    angle <- seq(0, 2*pi, length=101)
    polygonGrob(.5 + .5*cos(angle), .5 + .5*sin(angle),
                vp=vp, name=name)
}

eg <- ellipseGrob(a=.3, b=.1, name="el")

grid.draw(eg)

for (i in seq(0, 360, length.out=9)) {
    grid.circle(x=grobX("el", i), y=grobY("el", i),
                r=unit(1, "mm"),
                gp=gpar(fill=bg))
}

library(graph)

gnel <- new("graphNEL",
            nodes=c("CPI", "code", "data"),
            edgeL=list(CPI=list(
                         edges=c("code", "data")),
                       code=list(),
                       data=list()),
            edgemode="directed")

library(Rgraphviz)

plot(gnel)

library(gridGraphviz)

rag <- agopenTrue(gnel, "",
                  attrs=list(node=
                    list(shape="ellipse")))

grid.graph(rag)

grid.ls(rag)

grid.ls(grobs=FALSE, viewports=TRUE)

showViewport()

downViewport("graphScaleVP")
grid.raster(img, 1, 1, width=.4, just="bottom",
            name="img")
grid.segments(grobX("img", "west"),
              grobY("img", "west"),
              grobX(grid.get("box-CPI"), 45),
              grobY(grid.get("box-CPI"), 45),
              gp=gpar(lty="dotted"))

eg <- ellipseGrob(a=.3, b=.1, name="el")

grid.draw(eg)

svg("ellipse-svg.svg")
grid.draw(eg)
dev.off()

library(gridSVG)

gridsvg("ellipse-gridsvg.svg")
grid.draw(eg)
dev.off()

blurAlpha <- feGaussianBlur(input="SourceAlpha",
                            sd=3, result="blur")
offset <- feOffset(input="blur",
                   unit(3, "mm"), unit(-3, "mm"),
                   result="drop")
composite <- feComposite(input1="SourceGraphic",
                         input2="drop")
drop <- filterEffect(list(blurAlpha,
                          offset,
                          composite))

gridsvg("ellipse-drop.svg")
grid.draw(eg)
grid.filter("el", drop)
dev.off()

grid.graph(rag)

grid.ls(rag)

grid.get("box", grep=TRUE, global=TRUE)

grid.edit("box", grep=TRUE, global=TRUE,
          gp=gpar(fill="white"))

grid.filter("box", grep=TRUE, global=TRUE,
            drop)