Hide line background highlighters in folded regions to fix documentation rendering

Closes #26

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/EditorLensFeatures.kt

@@ -2,6 +2,7 @@ package com.chylex.intellij.inspectionlens.editor
 
 import com.intellij.openapi.Disposable
 import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.editor.ex.FoldingModelEx
 import com.intellij.openapi.editor.ex.MarkupModelEx
 import com.intellij.openapi.editor.impl.DocumentMarkupModel
 import com.intellij.openapi.util.Disposer
@@ -13,6 +14,7 @@ import com.intellij.openapi.util.Key
 internal class EditorLensFeatures private constructor(
 	editor: Editor,
 	private val markupModel: MarkupModelEx,
+	foldingModel: FoldingModelEx?,
 	disposable: Disposable
 ) {
 	private val lensManager = EditorLensManager(editor)
@@ -22,6 +24,8 @@ internal class EditorLensFeatures private constructor(
 	init {
 		markupModel.addMarkupModelListener(disposable, markupModelListener)
 		markupModelListener.showAllValid(markupModel.allHighlighters)
+		
+		foldingModel?.addListener(LensFoldingModelListener(lensManager), disposable)
 	}
 	
 	private fun refresh() {
@@ -38,7 +42,8 @@ internal class EditorLensFeatures private constructor(
 			}
 			
 			val markupModel = DocumentMarkupModel.forDocument(editor.document, editor.project, false) as? MarkupModelEx ?: return
-			val features = EditorLensFeatures(editor, markupModel, disposable)
+			val foldingModel = editor.foldingModel as? FoldingModelEx
+			val features = EditorLensFeatures(editor, markupModel, foldingModel, disposable)
 			
 			editor.putUserData(EDITOR_KEY, features)
 			Disposer.register(disposable) { editor.putUserData(EDITOR_KEY, null) }

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/EditorLensManager.kt

@@ -56,6 +56,10 @@ internal class EditorLensManager(private val editor: Editor) {
 		}
 	}
 	
+	fun onFoldRegionsChanged() {
+		lenses.values.forEach(EditorLens::onFoldRegionsChanged)
+	}
+	
 	sealed interface Command {
 		fun apply(lensManager: EditorLensManager)
 		

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/LensFoldingModelListener.kt

@@ -0,0 +1,12 @@
+package com.chylex.intellij.inspectionlens.editor
+
+import com.intellij.openapi.editor.ex.FoldingListener
+
+/**
+ * Listens for code folding events and reports them to [EditorLensManager].
+ */
+internal class LensFoldingModelListener(private val lensManager: EditorLensManager) : FoldingListener {
+	override fun onFoldProcessingEnd() {
+		lensManager.onFoldRegionsChanged()
+	}
+}

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/lens/EditorLens.kt

@@ -4,15 +4,18 @@ import com.chylex.intellij.inspectionlens.settings.LensSettingsState
 import com.intellij.codeInsight.daemon.impl.HighlightInfo
 import com.intellij.openapi.editor.Editor
 
-internal class EditorLens private constructor(private var inlay: EditorLensInlay, private var lineBackground: EditorLensLineBackground) {
+internal class EditorLens private constructor(private var inlay: EditorLensInlay, private var lineBackground: EditorLensLineBackground, private var severity: LensSeverity) {
 	fun update(info: HighlightInfo, settings: LensSettingsState): Boolean {
 		val editor = inlay.editor
+		val oldSeverity = severity
+		
+		severity = LensSeverity.from(info.severity)
 		
 		if (!inlay.tryUpdate(info)) {
 			inlay = EditorLensInlay.show(editor, info, settings) ?: return false
 		}
 		
-		if (lineBackground.shouldRecreate(info)) {
+		if (lineBackground.isInvalid || oldSeverity != severity) {
 			lineBackground.hide(editor)
 			lineBackground = EditorLensLineBackground.show(editor, info)
 		}
@@ -20,18 +23,21 @@ internal class EditorLens private constructor(private var inlay: EditorLensInlay
 		return true
 	}
 	
+	fun onFoldRegionsChanged() {
+		lineBackground.onFoldRegionsChanged(inlay.editor, severity)
+	}
+	
 	fun hide() {
-		val editor = inlay.editor
-		
 		inlay.hide()
-		lineBackground.hide(editor)
+		lineBackground.hide(inlay.editor)
 	}
 	
 	companion object {
 		fun show(editor: Editor, info: HighlightInfo, settings: LensSettingsState): EditorLens? {
 			val inlay = EditorLensInlay.show(editor, info, settings) ?: return null
 			val lineBackground = EditorLensLineBackground.show(editor, info)
-			return EditorLens(inlay, lineBackground)
+			val severity = LensSeverity.from(info.severity)
+			return EditorLens(inlay, lineBackground, severity)
 		}
 	}
 }

src/main/kotlin/com/chylex/intellij/inspectionlens/editor/lens/EditorLensLineBackground.kt

@@ -2,33 +2,21 @@ package com.chylex.intellij.inspectionlens.editor.lens
 
 import com.intellij.codeInsight.daemon.impl.HighlightInfo
 import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.editor.ex.RangeHighlighterEx
 import com.intellij.openapi.editor.markup.HighlighterLayer
 import com.intellij.openapi.editor.markup.HighlighterTargetArea.LINES_IN_RANGE
 import com.intellij.openapi.editor.markup.RangeHighlighter
+import com.intellij.openapi.editor.markup.TextAttributes
 
 @JvmInline
 internal value class EditorLensLineBackground(private val highlighter: RangeHighlighter) {
-	@Suppress("RedundantIf")
-	fun shouldRecreate(info: HighlightInfo): Boolean {
-		if (!highlighter.isValid) {
-			return true
+	val isInvalid
+		get() = !highlighter.isValid
+	
+	fun onFoldRegionsChanged(editor: Editor, severity: LensSeverity) {
+		if (highlighter is RangeHighlighterEx) {
+			highlighter.textAttributes = getAttributes(editor, highlighter.startOffset, highlighter.endOffset, severity)
 		}
-		
-		val severity = LensSeverity.from(info.severity)
-		
-		val currentTextAttributes = highlighter.getTextAttributes(null)
-		val newTextAttributes = severity.lineAttributes
-		if (currentTextAttributes !== newTextAttributes) {
-			return true
-		}
-		
-		val currentLayer = highlighter.layer
-		val newLayer = getHighlightLayer(severity)
-		if (currentLayer != newLayer) {
-			return true
-		}
-		
-		return false
 	}
 	
 	fun hide(editor: Editor) {
@@ -42,12 +30,20 @@ internal value class EditorLensLineBackground(private val highlighter: RangeHigh
 			
 			val severity = LensSeverity.from(info.severity)
 			val layer = getHighlightLayer(severity)
+			val attributes = getAttributes(editor, startOffset, endOffset, severity)
 			
-			return EditorLensLineBackground(editor.markupModel.addRangeHighlighter(startOffset, endOffset, layer, severity.lineAttributes, LINES_IN_RANGE))
+			return EditorLensLineBackground(editor.markupModel.addRangeHighlighter(startOffset, endOffset, layer, attributes, LINES_IN_RANGE))
 		}
 		
 		private fun getHighlightLayer(severity: LensSeverity): Int {
 			return HighlighterLayer.CARET_ROW - 100 - severity.ordinal
 		}
+		
+		private fun getAttributes(editor: Editor, startOffset: Int, endOffset: Int, severity: LensSeverity): TextAttributes? {
+			return if (editor.foldingModel.let { it.isOffsetCollapsed(startOffset) || it.isOffsetCollapsed(endOffset) })
+				null
+			else
+				severity.lineAttributes
+		}
 	}
 }