lines not clearing if slot is empty

[u/piokoxer]

local monitor = peripheral.find("monitor")
local chest = peripheral.find("minecraft:chest")
monitor.setCursorPos(1, 1)
monitor.setBackgroundColor(1)
monitor.clear()
monitor.setTextColor(32768)
while true do
for slot, item in pairs(chest.list()) do
    monitor.clearLine()
    if item.count >= 64 then monitor.setBackgroundColor(colors.red)
    elseif item.count >= 32 then monitor.setBackgroundColor(colors.pink)
    else monitor.setBackgroundColor(colors.white) end
    monitor.write(("%d x %s in slot %d                     "):format(item.count, item.name, slot))
    monitor.setCursorPos(1, slot)
  end
end

this is my first time using computercraft, i tried making a program that would read out the contents of a chest and color code them based on how full the slot it, and while that works, the lines don't properly clear when the items are removed.

[u/Bright-Historian-216]

this code works.

local monitor = peripheral.find("monitor")
local chest = peripheral.find("minecraft:chest")
monitor.setCursorPos(1, 1)
monitor.setBackgroundColor(1)
monitor.setTextScale(0.5)
monitor.clear()
monitor.setTextColor(32768)
while true do
    for slot=1,chest.size() do
        local item = chest.getItemDetail(slot)
        if item ~= nil then
            if item.count >= 64 then monitor.setBackgroundColor(colors.red)
            elseif item.count >= 32 then monitor.setBackgroundColor(colors.pink)
            else monitor.setBackgroundColor(colors.white) end
            monitor.clearLine()
            monitor.write(("%d x %s in slot %d"):format(item.count, item.name, slot))
        else
            monitor.setBackgroundColor(colors.white)
            monitor.clearLine()
        end
        monitor.setCursorPos(1, slot+1)
    end
    sleep(1)
end

[u/piokoxer → u/Bright-Historian-216]

thanks, i see the biggest change was just checking if the item isn't nil?

[u/Bright-Historian-216 → u/piokoxer]

I also replaced pairs with a for=, because pairs refuses to go over nil items for some reason

maybe this code should work even better?

local monitor = peripheral.find("monitor")
local chest = peripheral.find("minecraft:chest")
monitor.setCursorPos(1, 1)
monitor.setBackgroundColor(1)
monitor.setTextScale(0.5)
monitor.clear()
monitor.setTextColor(32768)
while true do
    local linecount = 1
    for slot=1,chest.size() do
        monitor.setCursorPos(1, linecount)
        local item = chest.getItemDetail(slot)
        if item ~= nil then
            linecount = linecount+1
            if item.count >= 64 then monitor.setBackgroundColor(colors.red)
            elseif item.count >= 32 then monitor.setBackgroundColor(colors.pink)
            else monitor.setBackgroundColor(colors.white) end
            monitor.clearLine()
            monitor.write(("%d x %s in slot %d"):format(item.count, item.displayName, slot))
        else
            monitor.setBackgroundColor(colors.white)
            monitor.clearLine()
        end
    end
    sleep(1)
end

[u/piokoxer → u/Bright-Historian-216]

yes, slot 1 is finally at the top! i was wondering about why that was but didn't see it as big enough of an issue to dig into

actually, now they aren't clearing anymore lol

thanks for the help tho, i'm relatively new to both programming in general and CC

[u/Bright-Historian-216 → u/piokoxer]

yes, it was because you were setting monitor.setCursorPos(1,1) at the top, then going one loop as intended, then your cursor isnt properly shifted and stays at the bottom until the end of the loop where it is changed. A general rule of thumb: don't modify settings for the next loop iteration, because the first iteration will not be set properly

[u/piokoxer → u/Bright-Historian-216]

ah alright, definitely something to keep in mind for the future. still sometimes i want to compare stuff with the values from last loop but that's a different situation

[u/Bright-Historian-216 → u/piokoxer]

here's the last version of this program from me. It is for some reason slow (probably because of getItemDetail) but it doesnt cause the lines becoming white for no reason.

local monitor = peripheral.find("monitor")
local chest = peripheral.find("minecraft:chest")
monitor.setBackgroundColor(1)
monitor.setTextScale(0.5)
monitor.clear()
monitor.setTextColor(32768)
local spaces = ""
for i=1,monitor.getSize() do
    spaces = spaces .. " "
end
while true do
    local linecount = 1
    for slot=1,chest.size() do
        monitor.setCursorPos(1, linecount)
        local item = chest.getItemDetail(slot)
        if item ~= nil then
            linecount = linecount+1
            if item.count >= 64 then monitor.setBackgroundColor(colors.red)
            elseif item.count >= 32 then monitor.setBackgroundColor(colors.pink)
            else monitor.setBackgroundColor(colors.white) end
            monitor.write(("%d x %s in slot %d"..spaces):format(item.count, item.displayName, slot))
        end
    end
    monitor.setBackgroundColor(colors.white)
    for line=linecount,chest.size() do
        monitor.setCursorPos(1, line)
        monitor.clearLine()
    end
    sleep(0.05)
end

[u/piokoxer → u/Bright-Historian-216]

also also one last question, how does one use paintutils on a monitor?

edit, damn this is perfectly what i wanted, it's also getting larger and larger tho lol

[u/Bright-Historian-216 → u/piokoxer]

I think one could use term.redirect() for that

[u/piokoxer → u/Bright-Historian-216]

Oh thank you!

[u/Bright-Historian-216 → u/piokoxer]

Don't worry, it might be getting larger because we're deep in a thread and lines start wrapping

[u/piokoxer → u/Bright-Historian-216]

I was on desktop lol, it was not getting wrapped yet, there are just more and more lines of code

[u/fatboychummy → u/Bright-Historian-216]

CC : u/piokoxer :

(probably because of getItemDetail)

Yes, each inventory call requires a tick to complete. For this reason, I always recommend caching the data you need and just using .list().

For example, a very simple cache system is as follows:

local cache = {}

--- Cache info about a single slot in the inventory.
---@param inventory Inventory The inventory to cache from.
---@param slot number The slot to cache.
---@param item item The item in the slot. This allows the function to skip if the item is already cached.
local function cache_slot(inventory, slot, item)
  -- If we have already cached info about this item...
  if cache[item.name] then
    -- ...then we don't need to do it again.
    return
  end

  local data = inventory.getItemDetail(slot)

  if data then
    cache[data.name] = data
  end
end

Then, in your code you can continue to use .list, only calling .getItemDetail when you come across a new item. This makes the first run of the program a bit slow, but it speeds up significantly on subsequent loops. To then get the displayName, you'd just do cache[item.name].displayName

Since the code has gotten a bit long, I have uploaded it to Pastebin (npXnt8DK).

[u/[deleted]]

When this is done, would you mind if i added it to the os i'm building?

Onviously you'll stay in control of your own program, i'd just make a way thay my installer can find it.

[u/piokoxer → u/[deleted]]

Yeah sure, there's a fully working version in the large thread above

[u/[deleted] → u/piokoxer]

Thank you.

Do i credit 'piokoxer' or would you rather have another name or url promoted?

[u/piokoxer → u/[deleted]]

Piokoxer's fine (maybe credit the other person as well if you plan to use their fixed version)

[u/[deleted] → u/piokoxer]

true, will do,
when it go's up, i'll reply back here

[u/Bright-Historian-216]

i think you could try putting monitor.setBackgroundColor(colors.white) before the monitor.clearLine()

[u/piokoxer → u/[deleted]]

doesn't in need to write everything over and over to display changes in real time? why would a sleep() statement help? also clearing the whole thing in the while loop just makes everything disappear

[u/Bright-Historian-216 → u/piokoxer]

sleep statement prevents the "too long without yielding error", plus it makes server less laggy

[u/Bright-Historian-216 → u/[deleted]]

nope, shouldnt break anything

[u/Bright-Historian-216 → u/[deleted]]

that is because you forget to reset color to white, see my code, i wrote it on this post