@@ -30,8 +30,13 @@ protocol LayoutManagerDelegate: AnyObject {
3030 var textContainerInset : UIEdgeInsets { get }
3131
3232 var listLineFormatting : LineFormatting { get }
33+
34+ var isLineNumbersEnabled : Bool { get }
35+ var lineNumberFormatting : LineNumberFormatting { get }
36+ var lineNumberWrappingMarker : String ? { get }
3337
3438 func listMarkerForItem( at index: Int , level: Int , previousLevel: Int , attributeValue: Any ? ) -> ListLineMarker
39+ func lineNumberString( for index: Int ) -> String ?
3540}
3641
3742class LayoutManager : NSLayoutManager {
@@ -270,11 +275,33 @@ class LayoutManager: NSLayoutManager {
270275 return stringRect
271276 }
272277
278+ private func rectForLineNumbers( markerSize: CGSize , rect: CGRect , width: CGFloat ) -> CGRect {
279+ let topInset = layoutManagerDelegate? . textContainerInset. top ?? 0
280+ let spacerRect = CGRect ( origin: CGPoint ( x: 0 , y: topInset) , size: CGSize ( width: width, height: rect. height) )
281+
282+ let scaleFactor = markerSize. height / spacerRect. height
283+ var markerSizeToUse = markerSize
284+ // Resize maintaining aspect ratio if bullet height is more than available line height
285+ if scaleFactor > 1 {
286+ markerSizeToUse = CGSize ( width: markerSize. width/ scaleFactor, height: markerSize. height/ scaleFactor)
287+ }
288+
289+ let trailingPadding : CGFloat = 2
290+ let yPos = topInset + rect. minY
291+ let stringRect = CGRect ( origin: CGPoint ( x: spacerRect. maxX - markerSizeToUse. width - trailingPadding, y: yPos) , size: markerSizeToUse)
292+
293+ // debugRect(rect: spacerRect, color: .blue)
294+ // debugRect(rect: stringRect, color: .red)
295+
296+ return stringRect
297+ }
298+
273299 override func drawBackground( forGlyphRange glyphsToShow: NSRange , at origin: CGPoint ) {
274300 super. drawBackground ( forGlyphRange: glyphsToShow, at: origin)
275301 guard let textStorage = textStorage,
276302 let currentCGContext = UIGraphicsGetCurrentContext ( )
277303 else { return }
304+ currentCGContext. saveGState ( )
278305
279306 let characterRange = self . characterRange ( forGlyphRange: glyphsToShow, actualGlyphRange: nil )
280307 textStorage. enumerateAttribute ( . backgroundStyle, in: characterRange) { attr, bgStyleRange, _ in
@@ -321,6 +348,54 @@ class LayoutManager: NSLayoutManager {
321348 drawBackground ( backgroundStyle: backgroundStyle, rects: rects, currentCGContext: currentCGContext)
322349 }
323350 }
351+ drawLineNumbers ( textStorage: textStorage, currentCGContext: currentCGContext)
352+ currentCGContext. restoreGState ( )
353+ }
354+
355+ private func drawLineNumbers( textStorage: NSTextStorage , currentCGContext: CGContext ) {
356+ var lineNumber = 1
357+ guard layoutManagerDelegate? . isLineNumbersEnabled == true ,
358+ let lineNumberFormatting = layoutManagerDelegate? . lineNumberFormatting else { return }
359+
360+ let lineNumberWrappingMarker = layoutManagerDelegate? . lineNumberWrappingMarker
361+ enumerateLineFragments ( forGlyphRange: textStorage. fullRange) { [ weak self] rect, usedRect, _, range, _ in
362+ guard let self else { return }
363+ let paraRange = self . textStorage? . mutableString. paragraphRange ( for: range) . firstCharacterRange
364+ let lineNumberToDisplay = layoutManagerDelegate? . lineNumberString ( for: lineNumber) ?? " \( lineNumber) "
365+
366+ if range. location == paraRange? . location {
367+ self . drawLineNumber ( lineNumber: lineNumberToDisplay, rect: rect. integral, lineNumberFormatting: lineNumberFormatting, currentCGContext: currentCGContext)
368+ lineNumber += 1
369+ } else if let lineNumberWrappingMarker {
370+ self . drawLineNumber ( lineNumber: lineNumberWrappingMarker, rect: rect. integral, lineNumberFormatting: lineNumberFormatting, currentCGContext: currentCGContext)
371+ }
372+ }
373+
374+ // Draw line number for additional new line with \n, if exists
375+ drawLineNumber ( lineNumber: " \( lineNumber) " , rect: extraLineFragmentRect. integral, lineNumberFormatting: lineNumberFormatting, currentCGContext: currentCGContext)
376+ }
377+
378+ func drawLineNumber( lineNumber: String , rect: CGRect , lineNumberFormatting: LineNumberFormatting , currentCGContext: CGContext ) {
379+ let gutterWidth = lineNumberFormatting. gutter. width
380+ let attributes = lineNumberAttributes ( lineNumberFormatting: lineNumberFormatting)
381+ let text = NSAttributedString ( string: " \( lineNumber) " , attributes: attributes)
382+ let markerSize = text. boundingRect ( with: . zero, options: [ ] , context: nil ) . integral. size
383+ var markerRect = self . rectForLineNumbers ( markerSize: markerSize, rect: rect, width: gutterWidth)
384+ let listMarkerImage = self . generateBitmap ( string: text, rect: markerRect)
385+ listMarkerImage. draw ( at: markerRect. origin)
386+ }
387+
388+ private func lineNumberAttributes( lineNumberFormatting: LineNumberFormatting ) -> [ NSAttributedString . Key : Any ] {
389+ let font = lineNumberFormatting. font
390+ let textColor = lineNumberFormatting. textColor
391+ let paraStyle = NSMutableParagraphStyle ( )
392+ paraStyle. alignment = . right
393+
394+ return [
395+ NSAttributedString . Key. font: font,
396+ NSAttributedString . Key. foregroundColor: textColor,
397+ NSAttributedString . Key. paragraphStyle: paraStyle
398+ ]
324399 }
325400
326401 private func drawBackground( backgroundStyle: BackgroundStyle , rects: [ CGRect ] , currentCGContext: CGContext ) {
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