Instantiate a Grob

Functions used to instantiate grob descriptions appearing in the gTree produced by loonGrob().

l_updateGrob(grobDesc, grobFun, ...)

l_instantiateGrob(loonGrob, gPath, grobFun, ...)

l_setGrobPlotView(loonGrob, margins)

Arguments

grobDesc	A grob description. Generally, it is created by the function grob().
grobFun	A new grob function. If missing, a best guess (based on gPath) will be tried.
...	arguments used to set in the new grob function
loonGrob	A loonGrob (a gTree object)
gPath	A grob path object specifing a descendant of the specified gTree
margins	plot view margins. If missing, a loon default margin will be used.

Details

• l_updateGrob: query arguments from a grob description and assign these arguments to a new grob function.

• l_instantiateGrob: query a descendant from a loonGrob, update it via a new grob function, then return the new editted loonGrob

See also

loonGrob

Examples

library(grid)
grobDesc <- grob(label = "loon",
                 gp = gpar(col = "red"))
grid.newpage()
# Nothing is displayed
grid.draw(grobDesc)
textDesc <- l_updateGrob(grobDesc, grid::textGrob)
grid.newpage()
# label "loon" is shown
grid.draw(textDesc)

if(interactive()) {
# a loon plot with hidden labels
p <- l_plot(iris, showLabels = FALSE)
lg <- loonGrob(p)
# x label and y label are invisible
grid.newpage()
grid.draw(lg)

# show x label
lg <- l_instantiateGrob(lg, "x label: textGrob arguments")
# show y label
lg <- l_instantiateGrob(lg, "y label: textGrob arguments")
# reset margins
lg <- l_setGrobPlotView(lg)
grid.newpage()
grid.draw(lg)

# show axes
if(packageVersion("loon") < '1.3.8') {
  lg <- l_instantiateGrob(lg, "x axis: .xaxisGrob arguments")
  lg <- l_instantiateGrob(lg, "y axis: .yaxisGrob arguments")
} else {
  lg <- l_instantiateGrob(lg, "x axis: xaxisGrob arguments")
  lg <- l_instantiateGrob(lg, "y axis: yaxisGrob arguments")
}

lg <- l_setGrobPlotView(lg)
grid.newpage()
# the labels are too close to the plot
grid.draw(lg)

# reset the labels' positions
lg <- l_instantiateGrob(lg, "x label: textGrob arguments",
                        y = unit(-3.5, "lines"))
lg <- l_instantiateGrob(lg, "y label: textGrob arguments",
                        x = unit(-6.5, "lines"))
grid.newpage()
grid.draw(lg)
}