Basalt/source/project/lib/utils.lua

local function getTextHorizontalAlign(text, width, textAlign, replaceChar)
    text = string.sub(text, 1, width)
    local offset = width - string.len(text)
    if (textAlign == "right") then
        text = string.rep(replaceChar or " ", offset) .. text
    elseif (textAlign == "center") then
        text = string.rep(replaceChar or " ", math.floor(offset / 2)) .. text .. string.rep(replaceChar or " ", math.floor(offset / 2))
        text = text .. (string.len(text) < width and (replaceChar or " ") or "")
    else
        text = text .. string.rep(replaceChar or " ", offset)
    end
    return text
end

local function getTextVerticalAlign(h, textAlign)
    local offset = 0
    if (textAlign == "center") then
        offset = math.ceil(h / 2)
        if (offset < 1) then
            offset = 1
        end
    end
    if (textAlign == "bottom") then
        offset = h
    end
    if(offset<1)then offset=1 end
    return offset
end

local function rpairs(t)
    return function(t, i)
        i = i - 1
        if i ~= 0 then
            return i, t[i]
        end
    end, t, #t + 1
end

-- shrink system is copy pasted (and slightly changed) from blittle by Bomb Bloke: http://www.computercraft.info/forums2/index.php?/topic/25354-cc-176-blittle-api/
local function shrink(bLittleData, bgColor)
    local relations = { [0] = { 8, 4, 3, 6, 5 }, { 4, 14, 8, 7 }, { 6, 10, 8, 7 }, { 9, 11, 8, 0 }, { 1, 14, 8, 0 }, { 13, 12, 8, 0 }, { 2, 10, 8, 0 }, { 15, 8, 10, 11, 12, 14 },
                        { 0, 7, 1, 9, 2, 13 }, { 3, 11, 8, 7 }, { 2, 6, 7, 15 }, { 9, 3, 7, 15 }, { 13, 5, 7, 15 }, { 5, 12, 8, 7 }, { 1, 4, 7, 15 }, { 7, 10, 11, 12, 14 } }

    local colourNum, exponents, colourChar = {}, {}, {}
    for i = 0, 15 do
        exponents[2 ^ i] = i
    end
    do
        local hex = "0123456789abcdef"
        for i = 1, 16 do
            colourNum[hex:sub(i, i)] = i - 1
            colourNum[i - 1] = hex:sub(i, i)
            colourChar[hex:sub(i, i)] = 2 ^ (i - 1)
            colourChar[2 ^ (i - 1)] = hex:sub(i, i)

            local thisRel = relations[i - 1]
            for i = 1, #thisRel do
                thisRel[i] = 2 ^ thisRel[i]
            end
        end
    end

    local function getBestColourMatch(usage)
        local lastCol = relations[exponents[usage[#usage][1]]]
        if(lastCol~=nil)then
            for j = 1, #lastCol do
                local thisRelation = lastCol[j]
                for i = 1, #usage - 1 do
                    if usage[i][1] == thisRelation then
                        return i
                    end
                end
            end
        end
        return 1
    end

    local function colsToChar(pattern, totals)
        if not totals then
            local newPattern = {}
            totals = {}
            for i = 1, 6 do
                local thisVal = pattern[i]
                local thisTot = totals[thisVal]
                totals[thisVal], newPattern[i] = thisTot and (thisTot + 1) or 1, thisVal
            end
            pattern = newPattern
        end

        local usage = {}
        for key, value in pairs(totals) do
            usage[#usage + 1] = { key, value }
        end

        if #usage > 1 then
            -- Reduce the chunk to two colours:
            while #usage > 2 do
                table.sort(usage, function(a, b)
                    return a[2] > b[2]
                end)
                local matchToInd, usageLen = getBestColourMatch(usage), #usage
                local matchFrom, matchTo = usage[usageLen][1], usage[matchToInd][1]
                for i = 1, 6 do
                    if pattern[i] == matchFrom then
                        pattern[i] = matchTo
                        usage[matchToInd][2] = usage[matchToInd][2] + 1
                    end
                end
                usage[usageLen] = nil
            end

            -- Convert to character. Adapted from oli414's function:
            -- http://www.computercraft.info/forums2/index.php?/topic/25340-cc-176-easy-drawing-characters/
            local data = 128
            for i = 1, #pattern - 1 do
                if pattern[i] ~= pattern[6] then
                    data = data + 2 ^ (i - 1)
                end
            end
            return string.char(data), colourChar[usage[1][1] == pattern[6] and usage[2][1] or usage[1][1]], colourChar[pattern[6]]
        else
            -- Solid colour character:
            return "\128", colourChar[pattern[1]], colourChar[pattern[1]]
        end
    end

    local results, width, height, bgCol = { {}, {}, {} }, 0, #bLittleData + #bLittleData % 3, bgColor or colors.black
    for i = 1, #bLittleData do
        if #bLittleData[i] > width then
            width = #bLittleData[i]
        end
    end

    for y = 0, height - 1, 3 do
        local cRow, tRow, bRow, counter = {}, {}, {}, 1

        for x = 0, width - 1, 2 do
            -- Grab a 2x3 chunk:
            local pattern, totals = {}, {}

            for yy = 1, 3 do
                for xx = 1, 2 do
                    pattern[#pattern + 1] = (bLittleData[y + yy] and bLittleData[y + yy][x + xx]) and (bLittleData[y + yy][x + xx] == 0 and bgCol or bLittleData[y + yy][x + xx]) or bgCol
                    totals[pattern[#pattern]] = totals[pattern[#pattern]] and (totals[pattern[#pattern]] + 1) or 1
                end
            end

            cRow[counter], tRow[counter], bRow[counter] = colsToChar(pattern, totals)
            counter = counter + 1
        end

        results[1][#results[1] + 1], results[2][#results[2] + 1], results[3][#results[3] + 1] = table.concat(cRow), table.concat(tRow), table.concat(bRow)
    end

    results.width, results.height = #results[1][1], #results[1]

    return results
end