Previewon (Display Document On A Screen, With Scrolling!)

args = {...}
if #args < 2 then
  print("Usage: readOn <direction> <filename>")
  return
end

if not fs.exists(shell.resolve(args[2])) then
  print("File does not exist: ",args[2])
  return
end

if peripheral.getType(args[1])~="monitor" then
  print("No monitor in direction: ",args[1])
  return
end

local reader = coroutine.create( function()
  shell.run("preview", args[2])
end )

function sendEvent(...)
  coroutine.resume(reader, ...)
end

local mon = peripheral.wrap(args[1])
if not mon.isColor() then
  print("previewOn requires an advanced monitor.")
  return
end

mon.setTextScale(0.5)
_,height = mon.getSize()
midscreen = height / 2

print("Reading ", args[2], " on ", args[1], " monitor.")
print("Click top half to scroll up, bottom to scroll down.")
print("Press q to quit")

term.redirect(mon)

sendEvent()

while coroutine.status(reader)~="dead" do
  e = { os.pullEventRaw() }
  if e[1] == "char" and e[2] == "q" or e[1] == "monitor_resize" then
	sendEvent("key", 29)
	sendEvent("key", 28)
  elseif e[1] == "monitor_touch" then
	dir = e[4] > midscreen and 1 or -1
	for i=1,height-1 do
	  sendEvent("mouse_scroll",dir, 1,1)
	end
	sendEvent("mouse_click", 1, 1, 1)
  else
	sendEvent(unpack(e))
  end
end

term.restore()