Plugin for toggling syntax highlighting in the current file (same as built-in "Highlighting level" slider in the inspector popup)

plugin.kts

import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer
import com.intellij.codeInsight.daemon.impl.analysis.FileHighlightingSetting.FORCE_HIGHLIGHTING
import com.intellij.codeInsight.daemon.impl.analysis.FileHighlightingSetting.SKIP_HIGHLIGHTING
import com.intellij.codeInsight.daemon.impl.analysis.HighlightLevelUtil
import com.intellij.codeInsight.daemon.impl.analysis.HighlightingLevelManager
import com.intellij.lang.injection.InjectedLanguageManager
import com.intellij.openapi.project.Project
import liveplugin.PluginUtil
import liveplugin.currentFile
import liveplugin.registerAction
import liveplugin.show

// See https://gist.github.com/dkandalov/da7f58c4b0cfbed4e3ee1cade3cc5174

registerAction("Toggle Highlighting", "ctrl shift H") { event ->
    toggleCurrentEditorHighlighting(event.project)
}

if (!isIdeStartup) show("Reloaded 'Toggle Highlighting'")

fun toggleCurrentEditorHighlighting(project: Project?) {
    if (project == null) return
    val virtualFile = project.currentFile ?: return
    val psiFile = PluginUtil.psiFile(virtualFile, project) ?: return
    val manager = HighlightingLevelManager.getInstance(project)
    val isSyntaxHighlightingEnabled = manager.shouldHighlight(psiFile)
    val isInspectionsHighlightingEnabled = manager.shouldInspect(psiFile)

    if (isSyntaxHighlightingEnabled && isInspectionsHighlightingEnabled) {
        HighlightLevelUtil.forceRootHighlighting(psiFile, SKIP_HIGHLIGHTING)
    } else {
        HighlightLevelUtil.forceRootHighlighting(psiFile, FORCE_HIGHLIGHTING)
    }
    InjectedLanguageManager.getInstance(project).dropFileCaches(psiFile)
    DaemonCodeAnalyzer.getInstance(project).restart()
}