Documentation

Mixins and Access Wideners

Add-ons are Fabric mods, so they can change Minecraft's code, and LiquidBounce's, with Mixins, and open up private members with an access widener.

Mixins

Mixins are Java classes listed in a Mixin config, which fabric.mod.json names under mixins:

{
  "required": true,
  "minVersion": "0.8",
  "package": "com.example.addon.mixin",
  "compatibilityLevel": "JAVA_25",
  "client": [
    "MixinExampleTitleScreen"
  ],
  "injectors": {
    "defaultRequire": 1
  }
}

A Mixin into a Minecraft class targets Mojang's names, as everything else in the add-on does:

@Mixin(TitleScreen.class)
public class MixinExampleTitleScreen {

    @Inject(method = "init", at = @At("RETURN"))
    private void onInit(CallbackInfo info) {
        System.out.println("[ExampleAddon] Title screen initialised");
    }

}

Mixins are always Java, also in a Kotlin add-on.

Into LiquidBounce

LiquidBounce's classes are targeted like any other. They have no mappings, so these Mixins set remap = false:

@Mixin(value = CommandManager.class, remap = false)
public class MixinCommandManager {

    @Inject(method = "execute", at = @At("HEAD"))
    private void onExecute(String command, CallbackInfo ci) {
        System.out.println("[ExampleAddon] ." + command);
    }

}

A Kotlin object like CommandManager compiles to a class with the same name and its functions as instance methods. The Script API add-on mixes into ModuleManager and Value this way.

Code reached only through a Mixin is not part of the stable API and can change in any build.

Priority

Mixins into the same class are applied in order of their priority, lowest first, and a higher priority wins where two Mixins conflict. LiquidBounce's Mixin config uses priority 1337 for its own Mixins into Minecraft, the default is 1000. A Mixin that has to be applied after LiquidBounce's, for example to see or override what LiquidBounce changed in the same class, needs a priority above 1337:

@Mixin(value = LocalPlayer.class, priority = 1500)
public class MixinLocalPlayer {

    @Inject(method = "tick", at = @At("HEAD"))
    private void onTick(CallbackInfo ci) {
    }

}

"mixinPriority" in the Mixin config sets the default for all of the add-on's Mixins.

Access wideners

An access widener makes private or final members of Minecraft accessible. fabric.mod.json names it under accessWidener, and build.gradle.kts points Loom at it so the add-on compiles against the widened classes:

loom {
    accessWidenerPath = file("src/main/resources/example-addon.accesswidener")
}

accessWidener	v1	official

accessible field net/minecraft/client/gui/screens/inventory/AbstractSignEditScreen sign Lnet/minecraft/world/level/block/entity/SignBlockEntity;

The header is separated by tabs and uses the official namespace, Mojang's names. ./gradlew build checks every entry against Minecraft and fails on members that do not exist.

LiquidBounce's own access widener does not carry over. Its entries are plain accessible and mutable, not transitive-, so Loom does not apply them when the add-on compiles. Widen everything the add-on uses in its own file, even members LiquidBounce has widened already.