A drawing operator that generates the shape from a glyphs array,
rendered according to the current font face, font size
(font matrix), and font options.
Inputs
glyphs
glyphs array to show
offset
optional: offset into the array that specifies the starting glyph
(defaults to 0 which means first glyph)
num_glyphs
optional: number of glyphs to show (defaults to -1 which means
all glyphs)