Add Typesetter

Sources/SwiftUIMath/Internal/Display/DisplayLargeOperator.swift

@@ -12,7 +12,10 @@ extension Math {
     var lowerLimitGap: CGFloat = 0 { didSet { updateLowerLimitPosition() } }
     var extraPadding: CGFloat = 0
 
-    init(nucleus: DisplayNode?, upperLimit: DisplayList?, lowerLimit: DisplayList?, limitShift: CGFloat, extraPadding: CGFloat) {
+    init(
+      nucleus: DisplayNode?, upperLimit: DisplayList?, lowerLimit: DisplayList?,
+      limitShift: CGFloat, extraPadding: CGFloat
+    ) {
       self.upperLimit = upperLimit
       self.lowerLimit = lowerLimit
       self.nucleus = nucleus
@@ -29,7 +32,8 @@ extension Math {
       get {
         guard let nucleus else { return 0 }
         if let upperLimit {
-          return nucleus.ascent + extraPadding + upperLimit.ascent + upperLimitGap + upperLimit.descent
+          return nucleus.ascent + extraPadding + upperLimit.ascent + upperLimitGap
+            + upperLimit.descent
         }
         return nucleus.ascent
       }
@@ -40,7 +44,8 @@ extension Math {
       get {
         guard let nucleus else { return 0 }
         if let lowerLimit {
-          return nucleus.descent + extraPadding + lowerLimitGap + lowerLimit.descent + lowerLimit.ascent
+          return nucleus.descent + extraPadding + lowerLimitGap + lowerLimit.descent
+            + lowerLimit.ascent
         }
         return nucleus.descent
       }

Sources/SwiftUIMath/Internal/Display/DisplayNode.swift

@@ -9,6 +9,9 @@ extension Math {
     var position: CGPoint = .zero
     var range: NSRange = NSRange(location: 0, length: 0)
     var hasScript: Bool = false
+    var textColor: PlatformColor?
+    var localTextColor: PlatformColor?
+    var localBackgroundColor: PlatformColor?
 
     func bounds() -> CGRect {
       CGRect(x: position.x, y: position.y - descent, width: width, height: ascent + descent)

Sources/SwiftUIMath/Internal/Display/DisplayRadical.swift

@@ -19,6 +19,25 @@ extension Math {
       self.range = range
     }
 
+    func setDegree(_ degree: DisplayList?, fontMetrics: Math.FontMetrics) {
+      guard let degree else { return }
+      let kernBefore = fontMetrics.radicalKernBeforeDegree
+      let kernAfter = fontMetrics.radicalKernAfterDegree
+      let raise = fontMetrics.radicalDegreeBottomRaisePercent * (ascent - descent)
+
+      self.degree = degree
+
+      var shift = kernBefore + degree.width + kernAfter
+      if shift < 0 {
+        shift = 0
+      }
+      radicalShift = shift
+
+      degree.position = CGPoint(x: position.x + kernBefore, y: position.y + raise)
+      width = shift + (radicalGlyph?.width ?? 0) + (radicand?.width ?? 0)
+      updateRadicandPosition()
+    }
+
     override var position: CGPoint {
       didSet { updateRadicandPosition() }
     }

Sources/SwiftUIMath/Internal/Display/DisplayTextRun.swift

@@ -7,7 +7,9 @@ extension Math {
     var font: Math.Font
     var atoms: [Math.Atom]
 
-    init(text: String, font: Math.Font, position: CGPoint = .zero, range: NSRange, atoms: [Math.Atom]) {
+    init(
+      text: String, font: Math.Font, position: CGPoint = .zero, range: NSRange, atoms: [Math.Atom]
+    ) {
       self.text = text
       self.font = font
       self.atoms = atoms