OpenComputers pattern API

-- import stuff

comp = require "component"

gpu = comp.gpu


-- pattern {{"##00##", "#0#0#0"}, {{"#", 0xffffff}, {"0", 0x00ff00}}}
pattern = {}


--[[due to the fact, opencomputers doesnt support drawing individual pixel, this program uses a workaround to draw space characters instead of pixels
    on a certain position. The problem is that the space character's shape doesnt match a square pixel. to avoid this you can set this value to 2. 1 will work
    aswell, but it will look a little bit squeezed]]
pattern.pixel_width = 2

-- reads the given pattern table and replaces the chars with the given colors
function pattern.draw(x, y, pat)

  local old_color = gpu.getBackground()
  for index,line in ipairs(pat[1]) do
    for i = 1, #line do
      local char = string.sub(line, i, i)
      pattern.setColor(char, pat)

      local filling_string = " "
      filling_string = string.rep(filling_string, pattern.pixel_width)
      gpu.set(x+((i-1)*pattern.pixel_width), y+index-1, filling_string)
    end
  end

  gpu.setBackground(old_color)

end

-- set the background color depending on the char's color definition in the table
function pattern.setColor(char, pat)
  success = false
  for _,v in pairs(pat[2]) do
    if v[1] == char then
      if v[2] == nil then v[2] = 0xffffff end
      gpu.setBackground(v[2])
      success = true
    end
  end
  if not success then gpu.setBackground(0xffffff) end
end

return pattern