You can use most processing methods in propane, but where possible you should prefer these ruby alternatives (NB: use Vec2D and Vec3D instead of PVector). Here is a list of ruby alternatives to some ‘processing’ convenience methods; which with the exception of color, map1d, p5map, degrees and radians are just regular ruby methods.

function processing JRubyArt
camera camera(args) kamera(hash_args)
color string color(#cc6600) color('#cc6600')
date/time   t =
  hour t.hour
  minute t.minute
  second t.second
  year t.year
custom math map(x, b0, eo, b1, e1) map1d(x, (b0..e0), (b1..e1))
  map(x, b0, eo, b1, e1) p5map(x, b0, e0, b1, e1)
  min(array) array.min
  max(array) array.max
  constrain(x, lo, hi) x.clamp(lo, hi)
conversion degrees(theta) theta.degrees
conversion radians(theta) theta.radians
conversion hex(string) string.hex
conversion unhex(string) string.to_i(base=16)
conversion binary(c) c.to_s(2)
conversion unbinary(string) string.to_i(base=2)
math abs(x) x.abs
math round(x) x.round
math ceil(x) x.ceil
math random(x) rand(x)
math random(a, b) rand(a..b)
math power pow(a, b) a**b
square sq(x) x * x
print println(x) puts x
format trim(string) string.strip
format nf(float_value, 0, 2) format('%.2f', float_value)
format nf(num, digit) num.to_s.rjust(digit, '0')
format nf(nf(num, left, right) see below

num.to_s.rjust(left, '0').ljust(left + right, '0')

For examples of using time in sketches see learning JRubyArt blog, timestamp and this clock sketch. We actually use the ruby Enumerable methods max and min methods to make max(*array) and min(*methods) available in JRubyArt, so you could use the processing form providing you splat the array, but it is simpler to use the ruby method directly further you have the option with ruby of changing the comparator via a block.

For example of kamera usage see kamera. To use selectInput see link to File Chooser in page header.

NB: if you have any trouble with save or save_frame then use the option of providing an absolute path. You can easily do this using the data_path wrapper that does it for you see data_path method.