Headings on markdown preset use different sizes (#59)

* Headings increase in size

* Fixes insertion point graphical glitches

* Updates markdown preset snapshots for large headings

* Updates markdown preset snapshots for large headings in AppKit

Sources/HighlightedTextEditor/HighlightedTextEditor.AppKit.swift

@@ -54,6 +54,7 @@ public struct HighlightedTextEditor: NSViewRepresentable, HighlightingTextEditor
 
  public func updateNSView(_ view: ScrollableTextView, context: Context) {
  context.coordinator.updatingNSView = true
+ let typingAttributes = view.textView.typingAttributes
 
  let highlightedText = HighlightedTextEditor.getHighlightedText(
  text: text,
@@ -63,6 +64,7 @@ public struct HighlightedTextEditor: NSViewRepresentable, HighlightingTextEditor
  view.attributedText = highlightedText
  runIntrospect(view)
  view.selectedRanges = context.coordinator.selectedRanges
+ view.textView.typingAttributes = typingAttributes
  context.coordinator.updatingNSView = false
  }
 

Sources/HighlightedTextEditor/Presets/Markdown.swift

@@ -53,14 +53,22 @@ let lighterColor = UIColor.lightGray
 let textColor = UIColor.label
 #endif
 
+private let maxHeadingLevel = 6
+
 public extension Sequence where Iterator.Element == HighlightRule {
  static var markdown: [HighlightRule] {
  [
  HighlightRule(pattern: inlineCodeRegex, formattingRule: TextFormattingRule(key: .font, value: codeFont)),
  HighlightRule(pattern: codeBlockRegex, formattingRule: TextFormattingRule(key: .font, value: codeFont)),
  HighlightRule(pattern: headingRegex, formattingRules: [
  TextFormattingRule(fontTraits: headingTraits),
- TextFormattingRule(key: .kern, value: 0.5)
+ TextFormattingRule(key: .kern, value: 0.5),
+ TextFormattingRule(key: .font, calculateValue: { content, _ in
+ let uncappedLevel = content.prefix(while: { char in char == "#" }).count
+ let level = Swift.min(maxHeadingLevel, uncappedLevel)
+ let fontSize = CGFloat(maxHeadingLevel - level) * 2.5 + defaultEditorFont.pointSize
+ return SystemFontAlias(descriptor: defaultEditorFont.fontDescriptor, size: fontSize) as Any
+ })
  ]),
  HighlightRule(
  pattern: linkOrImageRegex,