xmin, xmax: x location (in data coordinates) giving horizontal location of raster
ymin, ymax: y location (in data coordinates) giving vertical location of raster
Details
Most useful for adding tables, inset plots, and other grid-based decorations
Note
annotation_custom() expects the grob to fill the entire viewport defined by xmin, xmax, ymin, ymax. Grobs with a different (absolute) size will be center-justified in that region. Inf values can be used to fill the full plot panel