Add functions for parsing and drawing nft (#458)
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--- Provides utilities for working with "nft" images.
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--
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-- nft ("Nitrogen Fingers Text") is a file format for drawing basic images.
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-- Unlike the images that @{paintutils.parseImage} uses, nft supports coloured
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-- text.
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--
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-- @module cc.image.nft
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-- @usage Load an image from `example.nft` and draw it.
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--
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-- local nft = require "cc.image.nft"
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-- local image = assert(nft.load("example.nft"))
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-- nft.draw(image)
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local expect = require "cc.expect".expect
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--- Parse an nft image from a string.
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--
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-- @tparam string image The image contents.
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-- @return table The parsed image.
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local function parse(image)
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expect(1, image, "string")
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local result = {}
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local line = 1
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local foreground = "0"
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local background = "f"
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local i, len = 1, #image
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while i <= len do
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local c = image:sub(i, i)
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if c == "\31" and i < len then
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i = i + 1
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foreground = image:sub(i, i)
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elseif c == "\30" and i < len then
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i = i + 1
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background = image:sub(i, i)
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elseif c == "\n" then
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if result[line] == nil then
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result[line] = { text = "", foreground = "", background = "" }
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end
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line = line + 1
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else
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local next = image:find("[\n\30\31]", i) or #image + 1
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local seg_len = next - i
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local this_line = result[line]
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if this_line == nil then
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this_line = { foreground = "", background = "", text = "" }
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result[line] = this_line
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end
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this_line.text = this_line.text .. image:sub(i, next - 1)
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this_line.foreground = this_line.foreground .. foreground:rep(seg_len)
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this_line.background = this_line.background .. background:rep(seg_len)
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i = next - 1
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end
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i = i + 1
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end
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return result
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end
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--- Load an nft image from a file.
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--
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-- @tparam string path The file to load.
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-- @treturn[1] table The parsed image.
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-- @treturn[2] nil If the file does not exist or could not be loaded.
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-- @treturn[2] string An error message explaining why the file could not be
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-- loaded.
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local function load(path)
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expect(1, path, "string")
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local file, err = io.open(path, "r")
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if not file then return nil, err end
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local result = file:read("*a")
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file:close()
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return parse(result)
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end
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--- Draw an nft image to the screen.
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--
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-- @tparam table image An image, as returned from @{load} or @{draw}.
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-- @tparam number xPos The x position to start drawing at.
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-- @tparam number xPos The y position to start drawing at.
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-- @tparam[opt] term.Redirect target The terminal redirect to draw to. Defaults to the
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-- current terminal.
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local function draw(image, xPos, yPos, target)
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expect(1, image, "table")
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expect(2, xPos, "number")
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expect(3, yPos, "number")
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expect(4, target, "table", "nil")
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if not target then target = term end
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for y, line in ipairs(image) do
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target.setCursorPos(xPos, yPos + y - 1)
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target.blit(line.text, line.foreground, line.background)
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end
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end
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return {
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parse = parse,
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load = load,
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draw = draw,
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}
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@ -0,0 +1,91 @@
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local helpers = require "test_helpers"
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describe("cc.image.nft", function()
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local nft = require("cc.image.nft")
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describe("parse", function()
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it("validates arguments", function()
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nft.parse("")
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expect.error(nft.parse, nil):eq("bad argument #1 (expected string, got nil)")
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end)
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it("parses an empty string", function()
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expect(nft.parse("")):same {}
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end)
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it("parses a string with no colours", function()
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expect(nft.parse("Hello")):same { { text = "Hello", foreground = "00000", background = "fffff" } }
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end)
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it("handles background and foreground colours", function()
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expect(nft.parse("\30a\31bHello"))
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:same { { text = "Hello", foreground = "bbbbb", background = "aaaaa" } }
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end)
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it("parses multi-line files", function()
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expect(nft.parse("Hello\nWorld")):same {
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{ text = "Hello", foreground = "00000", background = "fffff" },
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{ text = "World", foreground = "00000", background = "fffff" },
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}
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end)
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it("handles empty lines", function()
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expect(nft.parse("\n\n")):same {
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{ text = "", foreground = "", background = "" },
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{ text = "", foreground = "", background = "" },
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}
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end)
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end)
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describe("load", function()
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it("validates arguments", function()
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nft.load("")
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expect.error(nft.load, nil):eq("bad argument #1 (expected string, got nil)")
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end)
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it("loads from a file", function()
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local image = fs.open("/test-files/example.nft", "w")
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image.write("\30aHello, world!")
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image.close()
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expect(nft.load("/test-files/example.nft")):same {
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{ background = "aaaaaaaaaaaaa", foreground = "0000000000000", text = "Hello, world!" },
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}
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end)
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it("fails on missing files", function()
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expect({ nft.load("/test-files/not_a_file.nft") })
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:same { nil, "/test-files/not_a_file.nft: No such file" }
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end)
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end)
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describe("draw", function()
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it("validates arguments", function()
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expect.error(nft.draw, nil):eq("bad argument #1 (expected table, got nil)")
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expect.error(nft.draw, {}, nil):eq("bad argument #2 (expected number, got nil)")
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expect.error(nft.draw, {}, 1, nil):eq("bad argument #3 (expected number, got nil)")
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expect.error(nft.draw, {}, 1, 1, false):eq("bad argument #4 (expected table, got boolean)")
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end)
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it("draws an image", function()
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local win = helpers.with_window(7, 3, function()
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nft.draw({
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{ background = "aaaaa", foreground = "f000f", text = "Hello" },
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}, 2, 2)
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end)
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expect(win.getLine(1)):eq(" ")
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expect({ win.getLine(2) }):same { " Hello ", "0f000f0", "faaaaaf" }
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expect(win.getLine(3)):eq(" ")
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end)
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it("draws an image to a custom redirect", function()
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local win = window.create(term.current(), 1, 1, 5, 1, false)
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nft.draw({
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{ background = "aaaaa", foreground = "f000f", text = "Hello" },
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}, 1, 1, win)
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expect({ win.getLine(1) }):same { "Hello", "f000f", "aaaaa" }
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end)
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end)
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end)
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