A lightweight REXPaint .xp file reader for LOVE2D.

rexpaint.lua

--
-- A lightweight REXPaint .xp reader for LOVE2D.
-- By Vriska Serket / @arachonteur
-- Adapted by drhayes to not use self, make constants uppercase,
-- and updated to work with love 11.2.
-- From https://gist.github.com/vriska-serket/334bfcfa7dfe7265ddbe089e4a51e522
--
-- Output table looks like this.
--[[
	{
		version = 0,
		layerCount = 0,
		layers = {
			[1] = {
				width = 20,
				height = 20,
				index = 1,
				cells = {
					[1] = {
						x = 0,
						y = 0,
						char = 0,
						fg = {255, 255, 255},
						bg = {0, 0, 0}
					},
					[...]
				}
			},
			[...]
		}
	}
]]
--
--

local VERSION_BYTES = 4
local LAYER_COUNT_BYTES = 4
local LAYER_WIDTH_BYTES = 4
local LAYER_HEIGHT_BYTES = 4
local LAYER_KEYCODE_BYTES = 4
local LAYER_FOREGROUND_RGB_BYTES = 3
local LAYER_BACKGROUND_RGB_BYTES = 3

local function read(file)
	local fileString = love.data.decompress('string', 'gzip', file)

	local xp = {
		version = 0,
		layerCount = 0,

		layers = {}
	}

	local offset = 0
	local version = { fileString:byte(offset, VERSION_BYTES) }
	offset = offset + VERSION_BYTES + 1

	local layer_count = { fileString:byte(offset, offset + LAYER_COUNT_BYTES) }
	offset = offset + LAYER_COUNT_BYTES

	xp.version = version
	xp.layerCount = layer_count[1]

	for i = 1, layer_count[1] do
		local layerWidth = fileString:byte(offset, offset + LAYER_WIDTH_BYTES)
		offset = offset + LAYER_WIDTH_BYTES

		local layerHeight = fileString:byte(offset, offset + LAYER_HEIGHT_BYTES)
		offset = offset + LAYER_HEIGHT_BYTES

		local layer = {
			index = i,
			width = layerWidth,
			height = layerHeight,
			cells = {}
		}

		for j = 0, (layerWidth * layerHeight - 1) do
			local cell = {
				x = 0,
				y = 0,
				char = 0,
				fg = {
					r = 255,
					g = 255,
					b = 255
				},
				bg = {
					r = 255,
					g = 255,
					b = 255
				}
			}

			cell.y = j % layer.height
			cell.x = (j - cell.y) / layer.height

			local tempOffset = offset
			local keycode = { fileString:byte(tempOffset, tempOffset + LAYER_KEYCODE_BYTES - 1) }
			cell.char = string.char(keycode[1])
			tempOffset = tempOffset + LAYER_KEYCODE_BYTES
			local fg = { fileString:byte(tempOffset, tempOffset + LAYER_FOREGROUND_RGB_BYTES - 1) }
			cell.fg = fg
			tempOffset = tempOffset + LAYER_FOREGROUND_RGB_BYTES
			local bg = { fileString:byte(tempOffset, tempOffset + LAYER_BACKGROUND_RGB_BYTES - 1) }
			cell.bg = bg
			tempOffset = tempOffset + LAYER_BACKGROUND_RGB_BYTES

			offset = tempOffset

			table.insert(layer.cells, cell)
		end

		table.insert(xp.layers, layer)
	end

	return xp
end

return read