Support standard bullet styles (#1409)

Reopening: #1354

- Addressed each point in the above PR.
- Added alternate ordered list style support per level
---
Similar to web browsers, draw different bullets at different levels.

To test:
- Set the `listIndentStyle` to `.varied`
- Create an ordered or unordered list
- Add multiple levels to it
- Notice the bullet style for level one is different than level two and
three
- Also, execute "Big Lists" demo, works as expected

| Before | After |
| ------ | ------ |
|
![old](https://user-images.githubusercontent.com/10981/160511981-8ae4d3f2-537e-4d18-a705-5641d59f255d.png)
|
![new](https://user-images.githubusercontent.com/10981/160512005-04669be2-ea56-44df-a3af-2fdbb643027c.png)
|
| <img width="383" alt="Screenshot 2025-02-22 at 4 53 29 PM"
src="https://github.com/user-attachments/assets/c8ce0a76-5ff1-4523-a8b4-8547ba8905b6"
/> | <img width="384" alt="Screenshot 2025-02-22 at 4 52 42 PM"
src="https://github.com/user-attachments/assets/e20a54e3-682b-4f32-8425-22d8a3f0acde"
/> |
---
- [x] I have considered if this change warrants release notes and have
added them to the appropriate section in the `CHANGELOG.md` if
necessary.

Author: twstokes

Aztec/Classes/TextKit/LayoutManager.swift

@@ -27,6 +27,9 @@ class LayoutManager: NSLayoutManager {
     ///
     var blockquoteBorderWidth: CGFloat = 2
 
+    /// The list indent style
+    ///
+    var listIndentStyle: TextList.IndentStyle = .default
 
     /// Draws the background, associated to a given Text Range
     ///
@@ -213,15 +216,16 @@ private extension LayoutManager {
         }
 
         let characterRange = self.characterRange(forGlyphRange: glyphsToShow, actualGlyphRange: nil)
+        var firstLevelWidth: CGFloat?
 
         textStorage.enumerateParagraphRanges(spanning: characterRange) { (range, enclosingRange) in
-
             guard textStorage.string.isStartOfNewLine(atUTF16Offset: enclosingRange.location),
                 let paragraphStyle = textStorage.attribute(.paragraphStyle, at: enclosingRange.location, effectiveRange: nil) as? ParagraphStyle,
                 let list = paragraphStyle.lists.last
             else {
                 return
             }
+
             let attributes = textStorage.attributes(at: enclosingRange.location, effectiveRange: nil)
             let glyphRange = self.glyphRange(forCharacterRange: enclosingRange, actualCharacterRange: nil)
             let markerRect = rectForItem(range: glyphRange, origin: origin, paragraphStyle: paragraphStyle)
@@ -233,8 +237,22 @@ private extension LayoutManager {
                     start = textStorage.numberOfItems(in: list, at: enclosingRange.location)
                 }
             }
+
+            var indentLevel: Int?
+            // Determine indentation level, if needed. The indentation level is only determined for the standard list style
+            if listIndentStyle == .varied {
+                // only get the width of the first level once
+                if firstLevelWidth == nil {
+                    firstLevelWidth = paragraphStyle.indentToFirst(TextList.self)
+                }
+
+                // calculate current indent level
+                let indentWidth = paragraphStyle.indentToLast(TextList.self)
+                indentLevel = Int(indentWidth / firstLevelWidth!)
+            }
+
             markerNumber += start
-            let markerString = list.style.markerText(forItemNumber: markerNumber)
+            let markerString = list.style.markerText(forItemNumber: markerNumber, indentLevel: indentLevel)
             drawItem(markerString, in: markerRect, styled: attributes, at: enclosingRange.location)
         }
     }

Aztec/Classes/TextKit/ParagraphProperty/TextList.swift

@@ -1,6 +1,8 @@
 import Foundation
 import UIKit
 
+fileprivate let DefaultUnorderedListMarkerText = "\u{2022}"
+fileprivate let romanMarker = NSTextList(markerFormat: .lowercaseRoman, options: 0)
 
 // MARK: - Text List
 //
@@ -14,14 +16,51 @@ open class TextList: ParagraphProperty {
         case ordered
         case unordered
 
-        func markerText(forItemNumber number: Int) -> String {
+        func markerText(forItemNumber number: Int, indentLevel: Int? = nil) -> String {
             switch self {
-            case .ordered:      return "\(number)."
-            case .unordered:    return "\u{2022}"
+            case .ordered:
+                if indentLevel == nil {
+                    return "\(number)."
+                }
+                
+                switch indentLevel {
+                case 1:
+                    return "\(number)."
+                case 2:
+                    let text = getLetter(for: number)
+                    return "\(text)."
+                default:
+                    // marker for all levels > 2
+                    let text = romanMarker.marker(forItemNumber: number)
+                    return "\(text)."
+                }
+            case .unordered:
+                if indentLevel == nil {
+                    return DefaultUnorderedListMarkerText
+                }
+                
+                switch indentLevel {
+                case 1:
+                    return DefaultUnorderedListMarkerText
+                case 2:
+                    return "\u{2E30}"
+                default:
+                    // marker for all levels > 2
+                    return "\u{2B29}"
+                }
             }
         }
     }
 
+    /// List Indent Styles
+    ///
+    public enum IndentStyle: Int {
+        /// A default single bullet style for each indentation level
+        case `default`
+        /// Use a varied (distinct) bullet style for each indentation level (i.e., WYSIWYG style)
+        case varied
+    }
+
     public let reversed: Bool
 
     public let start: Int?
@@ -90,3 +129,22 @@ open class TextList: ParagraphProperty {
         return lhs.style == rhs.style && lhs.start == rhs.start && lhs.reversed == rhs.reversed
     }
 }
+
+/// Returns the letters to use as the ordered list marker text
+fileprivate func getLetter(for number: Int) -> String {
+    let listChars = "abcdefghijklmnopqrstuvwxyz"
+    let charCount = listChars.count
+    
+    // for recursion
+    func convert(_ value: Int) -> String {
+        if value <= charCount {
+            return String(listChars[listChars.index(listChars.startIndex, offsetBy: value - 1)])
+        }
+        
+        let quotient = (value - 1) / charCount
+        let remainder = (value - 1) % charCount
+        return convert(quotient) + String(listChars[listChars.index(listChars.startIndex, offsetBy: remainder)])
+    }
+        
+    return convert(abs(number))
+}

Aztec/Classes/TextKit/TextView.swift

@@ -231,7 +231,18 @@ open class TextView: UITextView {
     // MARK: - Properties: Text Lists
 
     var maximumListIndentationLevels = 7
-
+    
+    /// The list indent style
+    /// Default is `default`, single style for each level.
+    public var listIndentStyle: TextList.IndentStyle {
+        get {
+            return layout.listIndentStyle
+        }
+        set {
+            layout.listIndentStyle = newValue
+        }
+    }
+	
     // MARK: - Properties: Blockquotes
 
     /// The max levels of quote indentation allowed

CHANGELOG.md

@@ -38,7 +38,7 @@ _None._
 
 ### New Features
 
-_None._
+* Added support for alternate bullet styles per level for ordered and unordered lists [#1409]
 
 ### Bug Fixes
 

Example/Example/EditorDemoController.swift

@@ -174,6 +174,7 @@ class EditorDemoController: UIViewController {
         view.addSubview(separatorView)
 
         editorView.richTextView.textContainer.lineFragmentPadding = 0
+        editorView.richTextView.listIndentStyle = .varied
         // color setup
         if #available(iOS 13.0, *) {
             view.backgroundColor = UIColor.systemBackground
@@ -257,7 +258,7 @@ class EditorDemoController: UIViewController {
         rightMargin -= view.safeAreaInsets.right
 
         scrollInsets.right = -rightMargin
-        editorView.scrollIndicatorInsets = scrollInsets
+        editorView.horizontalScrollIndicatorInsets = scrollInsets
     }
 
     func updateTitleHeight() {