DrawLibrary-OpenComputers

local component = require("component")
local term = require("term")
local gpu = component.gpu

local draw = {}
draw.gpu = gpu

local function sign(x)
    return (x < 0 and -1) or (x == 0 and 0) or (x > 0 and 1)
end

function draw.text(x, y, text, bgcolor, txcolor)
    local defaultBg, defaultTx = gpu.getBackground(), gpu.getForeground()

    gpu.setBackground(bgcolor)
    gpu.setForeground(txcolor)

    term.setCursor(x, y)
    term.write(tostring(text))

    gpu.setBackground(defaultBg)
    gpu.setForeground(defaultTx)
end

function draw.pixel(x, y, color)
    gpu.setBackground(color)
    gpu.set(x, y, " ")
    gpu.setBackground(0)
end

function draw.spixel(x, y, color)
    draw.rect(x, y, 2, 1, color)
end

function draw.rect(x, y, l, w, color)
    gpu.setBackground(color)
    gpu.fill(x, y, l, w, " ")
    gpu.setBackground(0)
end

function draw.line(p1, p2, color)
    local x0, x1, y0, y1 = p1.x, p2.x, p1.y, p2.y
    local xStart, xEnd, yStart, yEnd, isReversed, dx, dy = x0, x1, y0, y1, false, math.abs(x1 - x0), math.abs(y1 - y0)

    if dx < dy then
        xStart, xEnd, yStart, yEnd, isReversed, dx, dy = y0, y1, x0, x1, true, dy, dx
    end

    if yStart > yEnd then
        yStart, yEnd = yEnd, yStart
        xStart, xEnd = xEnd, xStart
    end

    local y, yc, ytI = yStart, 1, dx / dy
    local yt = ytI

    for x = xStart, xEnd, sign(xEnd - xStart) do
        if isReversed then
            draw.pixel(y, x, color)
        else
            draw.pixel(x, y, color)
        end

        yc = yc + 1

        if yc > yt then
            y, yt = y + 1, yt + ytI
        end
    end
end

function draw.poly(points, color)
    for i, point in ipairs(points) do
        if i < #points then
            draw.line(point, points[i + 1], color)
        else
            draw.line(point, points[1], color)
        end
    end
end

return draw