Mixin Visualizer

Mixin Visualizer is an IntelliJ IDEA plugin that allows you to preview the effects of SpongePowered Mixins on target classes directly within the IDE.

License | CONTRIBUTING | Changelog

---

Supported features:

Currently, the plugin implements a custom ASM transformer supporting:

• Merging:
  • Fields (shadows handled partially)
  • Unique methods
• @Overwrite: Full method replacement
• @Redirect:
  • Method invocations (INVOKE)
  • Field access (GETFIELD/PUTFIELD)
• @Inject:
  • HEAD: Injection at the start.
  • TAIL / RETURN: Injection before return statements.
  • INVOKE: Injection before/after specific method calls (supports shift).
  • Basic local variable remapping is implemented.

More to see: Mixin Documentation

TODOs (todo: use Projects in GH):

The project is a Work In Progress, with the following planned features:

• Core transformation logic (ASM-based)
• UI features (Editor tabs, Diff view, Toolbar)
• Bytecode/Decompiler toggle
• Handle Shadow members (skip/validate them properly)
• Handle super calls
• More @At targets (support FIELD, NEW, etc.)
• Static inits (<clinit> merging)
• Exception handling (try-catch blocks in injections)
• Support 3rd party extensions:
  • MixinExtras (WrapOperation, etc.)
  • MixinSquared (button to see class transformed with MixinSquared)
• Improve code structure and error handling (refactor transformer code, please)
• Auto compile and refresh on file save (maybe settings to control this behavior)
• Syntax highlighting for bytecode/decompiler view
• Handle @Accessor and @Invoker
• Fix variable names
• Add mixin builder

Tested on:

• IntelliJ IDEA 2025.1.4.1+ (Community & Ultimate)
• Java 17+ && Java 21+
• Forge 1.20.1
• NeoForge 1.21.1
• Fabric 1.21.7
• Mixin 0.8.7+

Usage:

1. Install the plugin from the JetBrains Marketplace
2. Open a project with Mixin usage.
3. Open a class that is a Mixin target.
4. Click the "Mixin Preview" button in the toolbar or use the shortcut ALT-SHIFT-RIGHT to open the Mixin Visualizer tab.
5. Explore the transformed class in the new tab, using the Diff View to see changes.

---

Note: This plugin is not affiliated with SpongePowered.