[ByteCodeViewer] IDEA-375353 Synchronize the class file being shown with the source file open in the main editor

This is optional, the user can toggle/untoggle this behavior.

GitOrigin-RevId: 6e7b8420db67b6b2fd6b36426e6f2a1478fee5bd

plugins/ByteCodeViewer/resources/messages/BytecodeViewerBundle.properties

@@ -1,5 +1,6 @@
 action.BytecodeViewer.text=Show Bytecode
 action.show.debug.action.name=Show Debug Info
+action.sync.with.editor.name=Sync With Editor
 deserialization.error=Could not read class file
 bytecode.not.found.title=Could not find bytecode
 please.build.project=Please build the project and try again.

plugins/ByteCodeViewer/src/com/intellij/byteCodeViewer/BytecodeEditorSynchronizer.kt

@@ -0,0 +1,56 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.byteCodeViewer
+
+import com.intellij.openapi.components.Service
+import com.intellij.openapi.fileEditor.FileEditorManagerEvent
+import com.intellij.openapi.fileEditor.FileEditorManagerListener
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.openapi.wm.ToolWindowManager
+import com.intellij.psi.PsiJavaFile
+import com.intellij.psi.PsiManager
+import com.intellij.ui.content.Content
+
+/**
+ * Synchronizes the bytecode viewer with the currently active editor.
+ * When the user switches between files in the editor, this service will
+ * automatically switch to the corresponding bytecode in the bytecode viewer.
+ */
+@Service(Service.Level.PROJECT)
+class BytecodeEditorSynchronizer(private val project: Project) : FileEditorManagerListener {
+
+  /**
+   * Called when the selected editor changes.
+   * If sync with editor is enabled, this will switch to the corresponding bytecode.
+   */
+  override fun selectionChanged(event: FileEditorManagerEvent) {
+    if (!BytecodeViewerSettings.getInstance().state.syncWithEditor) return
+
+    val virtualFile = event.newFile ?: return
+    val toolWindow = ToolWindowManager.getInstance(project).getToolWindow(BytecodeToolWindowPanel.TOOL_WINDOW_ID) ?: return
+    if (!toolWindow.isVisible) return
+    val content = findContentForSourceFile(toolWindow.contentManager.contents, virtualFile) ?: return
+    toolWindow.contentManager.setSelectedContent(content)
+  }
+
+  /**
+   * Finds the content pane (tab) in the bytecode viewer tool window that corresponds to the given `sourceFile`.
+   */
+  private fun findContentForSourceFile(contents: Array<Content>, sourceFile: VirtualFile): Content? {
+    val psiFile = PsiManager.getInstance(project).findFile(sourceFile) ?: return null
+    if (psiFile !is PsiJavaFile) return null
+    for (psiClass in psiFile.classes) {
+      val classFile = ByteCodeViewerManager.findClassFile(psiClass) ?: continue
+      val content = contents.firstOrNull { it.getUserData(JAVA_CLASS_FILE) == classFile } ?: continue
+      return content
+    }
+
+    return null
+  }
+
+  companion object {
+    fun getInstance(project: Project): BytecodeEditorSynchronizer {
+      return project.getService(BytecodeEditorSynchronizer::class.java)
+    }
+  }
+}

plugins/ByteCodeViewer/src/com/intellij/byteCodeViewer/BytecodeViewerSettings.kt

@@ -6,7 +6,10 @@ import com.intellij.openapi.components.*
 @Service(Service.Level.APP)
 @State(name = "BytecodeViewerSettings", storages = [Storage(StoragePathMacros.NON_ROAMABLE_FILE)])
 internal class BytecodeViewerSettings : PersistentStateComponent<BytecodeViewerSettings.State> {
-  data class State(var showDebugInfo: Boolean = true)
+  data class State(
+    var showDebugInfo: Boolean = true,
+    var syncWithEditor: Boolean = true,
+  )
 
   private var myState = State()
 

plugins/ByteCodeViewer/src/com/intellij/byteCodeViewer/ShowBytecodeAction.kt

@@ -5,6 +5,7 @@ import com.intellij.icons.AllIcons
 import com.intellij.notification.Notification
 import com.intellij.notification.NotificationType
 import com.intellij.openapi.actionSystem.*
+import com.intellij.openapi.fileEditor.FileEditorManagerListener
 import com.intellij.openapi.util.Key
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.wm.IdeFocusManager
@@ -34,6 +35,12 @@ internal class ShowBytecodeAction : AnAction() {
                      }
     BytecodeToolWindowService.getInstance(project).ensureContentManagerListenerRegistered(toolWindow)
 
+    // Register the editor synchronizer if not already registered
+    project.messageBus.connect(toolWindow.disposable).subscribe(
+      topic = FileEditorManagerListener.FILE_EDITOR_MANAGER,
+      handler = BytecodeEditorSynchronizer.getInstance(project),
+    )
+
     val editor = event.getData(CommonDataKeys.EDITOR) ?: return
     val psiFile = event.getData(CommonDataKeys.PSI_FILE) ?: return
     val psiElement = psiFile.findElementAt(editor.caretModel.offset) ?: return
@@ -85,7 +92,7 @@ internal class ShowBytecodeAction : AnAction() {
   }
 
   private fun createActionGroup(): ActionGroup {
-    val action = object : ToggleAction(BytecodeViewerBundle.messagePointer("action.show.debug.action.name")) {
+    val showDebugAction = object : ToggleAction(BytecodeViewerBundle.messagePointer("action.show.debug.action.name")) {
       override fun getActionUpdateThread(): ActionUpdateThread = ActionUpdateThread.EDT
 
       override fun isSelected(e: AnActionEvent): Boolean {
@@ -102,6 +109,19 @@ internal class ShowBytecodeAction : AnAction() {
         }
       }
     }
-    return DefaultActionGroup(action)
+    
+    val syncWithEditorAction = object : ToggleAction(BytecodeViewerBundle.messagePointer("action.sync.with.editor.name")) {
+      override fun getActionUpdateThread(): ActionUpdateThread = ActionUpdateThread.EDT
+
+      override fun isSelected(e: AnActionEvent): Boolean {
+        return BytecodeViewerSettings.getInstance().state.syncWithEditor
+      }
+
+      override fun setSelected(e: AnActionEvent, state: Boolean) {
+        BytecodeViewerSettings.getInstance().state.syncWithEditor = state
+      }
+    }
+    
+    return DefaultActionGroup(showDebugAction, syncWithEditorAction)
   }
 }