Draw Grid API (ComputerCraft)

local ro = function(input, max)
    return math.floor(input % max)
end
local stringShift = function(str,amt)
    return str:sub(ro(amt-1,#str)+1)..str:sub(1,ro(amt-1,#str))
end
--[[
Example on how to use:

local grid = {   ---That's how the grid is formatted.
    "+---",
    "|   ",
    "|   ",
}

local x,y = term.getSize()

--If you want to fill the whole screen with that grid, then:

drawGrid(1, 1, x, y, 0, 0)

--and if you want a specific coloration, you can add bg color and txt color as two more arguments.

--]]

function drawGrid(_x1,_y1,_x2,_y2,grid,_xscroll,_yscroll,_bgcol,_txtcol)
    local scr_x, scr_y = term.getSize()
    local _txt, _bg = term.getTextColor(), term.getBackgroundColor()
    local _x, _y = term.getCursorPos()
    local xscroll, yscroll = _xscroll or 0, _yscroll or 0
    local x1,x2,y1,y2 = _x1,_x2,_y1,_y2
    if _x2 < _x1 then
        x1,x2=_x2,_x1
    end
    if _y2 < _y1 then
        y1,y2=_y2,_y1
    end
    local lenx, leny = (x2-x1)+1, y2-y1
    if _bgcol then
        term.setBackgroundColor(_bgcol)
    end
    if _txtcol then
        term.setTextColor(_txtcol)
    end
    for y = y1, y2 do
        term.setCursorPos(x1,y)
        term.write(stringShift(grid[ro(y+(yscroll+2),#grid)+1],xscroll+1):rep(math.ceil(lenx/#grid[ro(y+(yscroll+2),#grid)+1])):sub(1,lenx))
    end
    term.setCursorPos(_x,_y)
    term.setBackgroundColor(_bg)
    term.setTextColor(_txt)
end