Add display model

2026-01-03 07:45:34 +01:00
parent e9657c186e
commit 8e4db3cf0e
11 changed files with 365 additions and 0 deletions
--- a/Sources/SwiftUIMath/Internal/Display/DisplayLargeOperator.swift
+++ b/Sources/SwiftUIMath/Internal/Display/DisplayLargeOperator.swift
@@ -0,0 +1,79 @@
+import CoreGraphics
+import Foundation
+
+extension Math {
+  final class DisplayLargeOperator: DisplayNode {
+    var upperLimit: DisplayList?
+    var lowerLimit: DisplayList?
+    var nucleus: DisplayNode?
+
+    var limitShift: CGFloat = 0
+    var upperLimitGap: CGFloat = 0 { didSet { updateUpperLimitPosition() } }
+    var lowerLimitGap: CGFloat = 0 { didSet { updateLowerLimitPosition() } }
+    var extraPadding: CGFloat = 0
+
+    init(nucleus: DisplayNode?, upperLimit: DisplayList?, lowerLimit: DisplayList?, limitShift: CGFloat, extraPadding: CGFloat) {
+      self.upperLimit = upperLimit
+      self.lowerLimit = lowerLimit
+      self.nucleus = nucleus
+      self.limitShift = limitShift
+      self.extraPadding = extraPadding
+      super.init()
+
+      var maxWidth = max(nucleus?.width ?? 0, upperLimit?.width ?? 0)
+      maxWidth = max(maxWidth, lowerLimit?.width ?? 0)
+      width = maxWidth
+    }
+
+    override var ascent: CGFloat {
+      get {
+        guard let nucleus else { return 0 }
+        if let upperLimit {
+          return nucleus.ascent + extraPadding + upperLimit.ascent + upperLimitGap + upperLimit.descent
+        }
+        return nucleus.ascent
+      }
+      set { super.ascent = newValue }
+    }
+
+    override var descent: CGFloat {
+      get {
+        guard let nucleus else { return 0 }
+        if let lowerLimit {
+          return nucleus.descent + extraPadding + lowerLimitGap + lowerLimit.descent + lowerLimit.ascent
+        }
+        return nucleus.descent
+      }
+      set { super.descent = newValue }
+    }
+
+    override var position: CGPoint {
+      didSet {
+        updateLowerLimitPosition()
+        updateUpperLimitPosition()
+        updateNucleusPosition()
+      }
+    }
+
+    private func updateLowerLimitPosition() {
+      guard let lowerLimit, let nucleus else { return }
+      lowerLimit.position = CGPoint(
+        x: position.x - limitShift + (width - lowerLimit.width) / 2,
+        y: position.y - nucleus.descent - lowerLimitGap - lowerLimit.ascent
+      )
+    }
+
+    private func updateUpperLimitPosition() {
+      guard let upperLimit, let nucleus else { return }
+      upperLimit.position = CGPoint(
+        x: position.x + limitShift + (width - upperLimit.width) / 2,
+        y: position.y + nucleus.ascent + upperLimitGap + upperLimit.descent
+      )
+    }
+
+    private func updateNucleusPosition() {
+      guard let nucleus else { return }
+      nucleus.position = CGPoint(x: position.x + (width - nucleus.width) / 2, y: position.y)
+    }
+  }
+}