Internal function. Takes a raster .spadesGrob, and converts zoomExtent into a zoom, and legendRange into a legend. Then calculates the maxpixels to plot for speed.
.prepareRaster(grobToPlot, zoomExtent, legendRange, takeFromPlotObj, arr,
speedup, newArr)
.spadesGrob
an extent object
a numeric vector of length >=2 indicating the desired legend range.
logical. Should the object be found in the Plot call or .GlobalEnv
an .arrangement
object
numeric, greater than 1 will usually speed up plotting at the expense of resolution
logical, whether this is a new arrangement or just adding to a previous one