[OC] Paintutils for opencomputers

local com = require"component"
local e = require"event"
local term = require"term"
local sbc = com.gpu.setBackground
local stc = com.gpu.setForeground
local scp = term.setCursor
local write = term.write

local ui = {}

function ui.gwrite(t)
    local x,y = term.getCursor()
    com.gpu.set(x,y,t)
end

function ui.drawPixel(x,y)
   scp(x,y)
   ui.gwrite(" ") -- add ui. when you call your own functions!
end

function ui.drawLine( startX, startY, endX, endY, nColour )
    startX = math.floor(startX)
    startY = math.floor(startY)
    endX = math.floor(endX)
    endY = math.floor(endY)
    sbc(nColour)
    if startX == endX and startY == endY then
       ui.drawPixel( startX, startY )
        return
    end

    local minX = math.min( startX, endX )
    if minX == startX then
        minY = startY
        maxX = endX
        maxY = endY
    else
        minY = endY
        maxX = startX
        maxY = startY
    end

    -- TODO: clip to screen rectangle?

    local xDiff = maxX - minX
    local yDiff = maxY - minY

    if xDiff > math.abs(yDiff) then
        local y = minY
        local dy = yDiff / xDiff
        for x=minX,maxX do
            ui.drawPixel( x, math.floor( y + 0.5 ) )
            y = y + dy
        end
    else
        local x = minX
        local dx = xDiff / yDiff
        if maxY >= minY then
            for y=minY,maxY do
                ui.drawPixel( math.floor( x + 0.5 ), y )
                x = x + dx
            end
        else
            for y=minY,maxY,-1 do
                ui.drawPixel( math.floor( x + 0.5 ), y )
                x = x - dx
            end
        end
    end
  sbc(0x000000)
end

function ui.drawBox(sx,sy,ex,ey,col)
   sbc(col)
   scp(sx,sy)
   ui.gwrite(string.rep(" ",(ex-sx)+1))
   for i = 0, ey-sy do
       scp(sx,sy+i)
       ui.gwrite(" ")
       scp(ex,sy+i)
       ui.gwrite(" ")
   end
   scp(sx,ey)
   ui.gwrite(string.rep(" ",ex-sx))
  --sbc(0x000000)
end

function ui.drawFilledBox(sx,sy,ex,ey,col)
   sbc(col)
   for i = 0, ey-sy do
      scp(sx,sy+i)
      ui.gwrite(string.rep(" ",(ex-sx)+1))
   end
  --sbc(0x000000)
end

return ui
--drawBox(1,1,10,10,0x00FF00)
--drawFilledBox(11,11,21,21,0x0000FF)
--drawLine(10,10,40,20,0xFFFFFF)