Rework graphical train HUD code

- A basic texture manipulation API is added; currently this is only a
  (selected) subset of texture modifiers provided by MT; the goal is to
  avoid writing (potentially incorrect) texture strings by hand;
- The graphical HUD code is cleaned up; in particular, most code used
  for generating texture patterns are moved to texture.lua so that the
  code can be used outside of the HUD;
- Inactive elements are given the darkslategray background.

A basic unittest is added; however, it needs to be expanded for better
coverage.

Reported-by: Lars Müller <appgurulars@gmx.de>

1 files changed, 228 insertions, 0 deletions

diff --git a/advtrains/texture.lua b/advtrains/texture.lua
new file mode 100644
index 0000000..1ecc91b
--- /dev/null
+++ b/advtrains/texture.lua
@@ -0,0 +1,228 @@
+local tx = {}
+setmetatable(tx, {__call = function(_, ...) return tx.base(...) end})
+
+function tx.escape(str)
+	return (string.gsub(tostring(str), [[([%^:\])]], [[\%1]]))
+end
+
+local function getargs(...)
+	return select("#", ...), {...}
+end
+
+local function curry(f, x)
+	return function(...)
+		return f(x, ...)
+	end
+end
+
+local function xmkmodifier(func)
+	return function(self, ...)
+		table.insert(self, (func(...)))
+		return self
+	end
+end
+
+local function mkmodifier(fmt, spec)
+	return xmkmodifier(function(...)
+		local count = select("#", ...)
+		local args = {...}
+		for k, f in pairs(spec) do
+			args[k] = f(args[k])
+		end
+		return string.format(fmt, unpack(args, 1, count))
+	end)
+end
+
+-- Texture object
+local tx_lib = {}
+local tx_mt = {
+	__index = tx_lib,
+	__tostring = function(self)
+		return table.concat(self, "^")
+	end,
+	__concat = function(a, b)
+		return tx.raw(("%s^%s"):format(tostring(a), tostring(b)))
+	end,
+}
+
+function tx.raw(str)
+	return setmetatable({str}, tx_mt)
+end
+function tx.base(str)
+	return tx.raw(tx.escape(str))
+end
+-- TODO: use [fill when 5.8.0 becomes widely used client-side
+function tx.fill(w, h, color)
+	return tx"advtrains_hud_bg.png":resize(w, h):colorize(color)
+end
+
+-- Most texture modifiers
+tx_lib.colorize = xmkmodifier(function(c, a)
+	local str = ("[colorize:%s"):format(tx.escape(c))
+	if a then
+		str = str .. ":" .. a
+	end
+	return str
+end)
+tx_lib.multiply = mkmodifier("[multiply:%s", {tx.escape})
+tx_lib.resize = mkmodifier("[resize:%dx%d", {})
+tx_lib.transform = mkmodifier("[transform%s", {tx.escape})
+
+-- [combine
+
+local combine = {}
+
+function combine:add(x, y, ent)
+	table.insert(self.st, ([[%d,%d=%s]]):format(x, y, tx.escape(tostring(ent))))
+	return self
+end
+
+local combine_mt = {
+	__index = combine,
+	__tostring = function(self)
+		return table.concat(self.st, ":")
+	end,
+}
+
+function tx.combine(w, h, bg)
+	local base = ("[combine:%dx%d"):format(w, h)
+	local obj = setmetatable({width = w, height = h, st = {base}}, combine_mt)
+	if bg then
+		obj:add_fill(0, 0, w, h, bg)
+	end
+	return obj
+end
+
+function combine:add_fill(x, y, ...)
+	return self:add(x, y, tx.fill(...))
+end
+
+local function add_multicolor_fill(n, self, x, y, w, h, ...)
+	local argc, argv = getargs(...)
+	local t = 0
+	for k = 1, argc, 2 do
+		t = t + argv[k]
+	end
+	local newargs = {x, y, w, h}
+	local sk, wk = n, n+2
+	local s = newargs[wk]/t
+	for k = 1, argc, 2 do
+		local v = argv[k] * s
+		newargs[wk] = v
+		newargs[5] = argv[k+1]
+		self:add_fill(unpack(newargs))
+		newargs[sk] = newargs[sk] + v
+	end
+	return self
+end
+combine.add_multicolor_fill_topdown = curry(add_multicolor_fill, 2)
+combine.add_multicolor_fill_leftright = curry(add_multicolor_fill, 1)
+
+local function add_segmentbar(n, self, x, y, w, h, m, c, ...)
+	local argc, argv = getargs(...)
+	local baseargs = {x, y, w, h}
+	local ss = (baseargs[n+2]+m)/c
+	local bs = ss - m
+	for k = 1, argc, 3 do
+		local lower, upper, fill = argv[k], argv[k+1], argv[k+2]
+		lower = math.max(0, math.floor(lower)+1)
+		upper = math.min(c, math.floor(upper))
+		if lower < upper then
+			local args = {x, y, w, h, fill}
+			args[n+2] = bs
+			args[n] = args[n] + ss*lower
+			for i = lower, upper do
+				self:add_fill(unpack(args))
+				args[n] = args[n] + ss
+			end
+		end
+	end
+	return self
+end
+combine.add_segmentbar_topdown = curry(add_segmentbar, 2)
+combine.add_segmentbar_leftright = curry(add_segmentbar, 1)
+
+local function add_lever(n, self, x, y, w, h, hs, ss, val, hf, sf)
+	local baseargs = {x, y, w, h}
+	local sargs = {x, y, w, h, sf}
+	sargs[5-n] = ss
+	sargs[n+2] = baseargs[n+2] + ss - hs
+	for k = 1, 2 do
+		sargs[k] = baseargs[k] + (baseargs[k+2] - sargs[k+2])/2
+	end
+	self:add_fill(unpack(sargs))
+	local hargs = {x, y, w, h, hf}
+	hargs[n+2] = hs
+	hargs[n] = baseargs[n] + (baseargs[n+2]-hs)*val
+	self:add_fill(unpack(hargs))
+	return self
+end
+combine.add_lever_topdown = curry(add_lever, 2)
+combine.add_lever_leftright = curry(add_lever, 1)
+
+--[[ Seven-segment display
+ -1-
+6   2
+ -7-
+5   3
+ -4-
+--]]
+local sevenseg_digits = {
+	["0"] = {1, 2, 3, 4, 5, 6},
+	["1"] = {2, 3},
+	["2"] = {1, 2, 4, 5, 7},
+	["3"] = {1, 2, 3, 4, 7},
+	["4"] = {2, 3, 6, 7},
+	["5"] = {1, 3, 4, 6, 7},
+	["6"] = {1, 3, 4, 5, 6, 7},
+	["7"] = {1, 2, 3},
+	["8"] = {1, 2, 3, 4, 5, 6, 7},
+	["9"] = {1, 2, 3, 4, 6, 7},
+}
+
+function combine:add_str7seg(x0, y0, tw, th, str, fill)
+	--[[ w and h (as width/height of individual (horizontal) segments) have the following properties:
+	tw = n(w+3h)-h
+	th = 2w+3h
+	--]]
+	local len = #str
+	local h = (2*tw-len*th)/(3*len-2)
+	local w = (th-3*h)/2
+	local ws = w+3*h
+	local segs = {
+		{h, 0, w, h},
+		{w+h, h, h, w},
+		{w+h, w+2*h, h, w},
+		{h, 2*(w+h), w, h},
+		{0, w+2*h, h, w},
+		{0, h, h, w},
+		{h, w+h, w, h},
+	}
+	for i = 1, len do
+		for _, k in pairs(sevenseg_digits[string.sub(str, i, i)] or {}) do
+			local s = segs[k]
+			self:add_fill(s[1]+x0, s[2]+y0, s[3], s[4], fill)
+		end
+		x0 = x0 + ws
+	end
+	return self
+end
+
+function combine:add_n7seg(x, y, w, h, n, prec, ...)
+	if not (type(n) == "number" and type(prec) == "number") then
+		error("passed non-numeric value or precision to numeric display")
+	elseif prec < 0 then
+		error("negative length")
+	end
+	local pfx = ""
+	if n >= 0 then
+		n = math.min(10^prec-1, n)
+	else
+		n = math.min(10^(prec-1)-1, -n)
+		pfx = "-"
+	end
+	local str = ("%d"):format(n)
+	return self:add_str7seg(x, y, w, h, pfx .. ("0"):rep(prec-#str-#pfx) .. str, ...)
+end
+
+return tx