How can I detect a change of enchantment properties?

[Tavi007 1]

Hi!

 

So I've been scraching my head a lot on how I could solve my problem. I have a capability for itemstacks, that is called defenseData and which is supposed to be used not only by me, but also by other devs (it's part of my API). Now my mod also uses enchantments to interact with the defense capability. For example if an armor piece has the fire protection enchantment, the capability should get the mapping "fire":factor, with factor being a calculated integer value. If the item already has fire reduction (i.e. it has it as base value), then the factor of the enchantment should be added to the base value.

 

Now I want to change the data in the capability, whenever a change of the enchantment happens in any form. This includes enchanting, disenchanting and also combing enchantments on an anvil. There is probably a lot more occasion, if we include other mods, which I would like to detect aswell. So how could I detect such a thing?

 

Alternatively I thought about adding the enchantment value, whenever the capability gets attached to the itemstack. However this will result in incorrect data, because then the enchantment data will also be added, if I move the stack in the inventory. In an attempt to solve this issue I added another capability, called areEnchantmentsApplied (a boolean with default value false), which is turned to true, after adding the enchantment data for the first time (even if there weren't any). Sadly this wasn't not working as indented, because the newly enchanted itemstack uses the same capability data from it's origin (rightfully tho), which means that the enchantment data never gets added to the new itemstack, because areEnchantmentsApplied was already true. It did however solve the issue with moving items in the inventory.

 

Currently I'm cheating my own system by getting a copy of the itemstack capability and adding the enchantment data onto it. It works, but that's not how I intented my API to work. Here you can see my current code. Any help is much appreciated.

Edited October 16, 2020 by Tavi007

[ChampionAsh5357 160]

Unfortunately, I don't believe there is any such event or hook that calls when an enchantment is applied. You would probably need to add a new event that checks when an enchantment is applied to an item which would require a PR. There are other methods of achieving it that don't require a PR, but they all involve things that are not allowed on this forum.

[Tavi007 1]

PR stands for pull request, right? I don't have a problem with creating a new event hook, but I would have to learn how to do it. ^^"

 

Are there any 'rules', that should be followed? 

[ChampionAsh5357 160]

1 hour ago, Tavi007 said:

Are there any 'rules', that should be followed? 

https://mcforge.readthedocs.io/en/latest/forgedev/prguidelines/

[diesieben07 7588]

I am not sure why you need to react to enchantment changes here. You should be able to have access to the ItemStack inside the capability, so you can just access it's enchantments whenever you need to and act accordingly. There is no need to "change data" when the enchantments change, just compute whatever data you need when it is asked for based on the current ItemStack.

[Tavi007 1]

Do you mean, I should check for the enchantments of the itemstack in the attackCapabilitiesEvent? I tried that, but last time I checked, the itemstack hasn't had any enchantments added to it yet. So EnchantmentHelper.getEnchantments(itemstack) would always return an empty map.

 

If you were suggesting something different, then please elaborate a bit more, because I didn't understand, what you meant.

[diesieben07 7588]

No, in AttachCapabilitiesEvent you keep the ItemStack around, store it in the attached capability so that you can reference it later.

[Tavi007 1]

I'm not sure, if this will solve my problem. I want to get rid of the method ElementalCombatAPI#getDefenseDataWithEnchantment, because unlike ElementalCombat#getDefenseData this only returns a copy of the capability and not a reference. If it wouldn't return a copy, it would add the enchantment data to the capability over and over. It's also important, that ElementalCombat#getDefenseData returns the reference, becuase otherwise the API would be useless.

 

How can I achieve, that the data from the enchantments gets applied only once?

[diesieben07 7588]

I am not sure we are understanding each other. I am asking you to have your capability keep track of the ItemStack, then whenever it is asked for any data via it's getters it can enrich the returned data with the enchantments.

[Tavi007 1]

After sleeping a night I found a way to detect the change. It's not really necessary to keep track of the full itemstack, but rather just its enchantment mapping. So I did that in combination with a boolean, so it won't check over and over again. So yeah, no need for a new event hook.