1 files changed, 60 insertions, 0 deletions
diff --git a/Sources/NorgUI/Math/SwiftMathRenderer.swift b/Sources/NorgUI/Math/SwiftMathRenderer.swift
new file mode 100644
index 0000000..6012a44
--- /dev/null
+++ b/Sources/NorgUI/Math/SwiftMathRenderer.swift
@@ -0,0 +1,60 @@
+#if SwiftMathSupport
+  import SwiftMath
+  import SwiftUI
+
+  /// ``NorgMathRenderer`` backed by SwiftMath. Enabled by the
+  /// `SwiftMathSupport` package trait.
+  struct SwiftMathRenderer: NorgMathRenderer {
+    @MainActor
+    func render(
+      latex: String, mode: NorgMathMode, fontSize: CGFloat, color: Color?
+    ) async -> NorgMathImage? {
+      let label = MTMathUILabel()
+      label.latex = latex
+      label.labelMode = mode == .block ? .display : .text
+      label.fontSize = mode == .block ? fontSize * 1.4 : fontSize
+      if let color {
+        #if canImport(UIKit)
+          label.textColor = UIColor(color)
+        #elseif canImport(AppKit)
+          label.textColor = NSColor(color)
+        #endif
+      }
+
+      let size = label.intrinsicContentSize
+      guard size.width > 0, size.height > 0, !latex.isEmpty else { return nil }
+      guard let image = rasterize(label, size: size) else { return nil }
+
+      // SwiftMath does not expose the layout descent publicly, so approximate
+      // it by centring the formula on the text line. Tune if inline math sits
+      // too high or low against surrounding text.
+      let descent = max(0, (size.height - fontSize) / 2)
+      return NorgMathImage(image: image, size: size, descent: descent)
+    }
+
+    @MainActor
+    private func rasterize(_ label: MTMathUILabel, size: CGSize) -> PlatformImage? {
+      label.frame = CGRect(origin: .zero, size: size)
+      #if canImport(UIKit)
+        label.layoutIfNeeded()
+        let format = UIGraphicsImageRendererFormat()
+        format.scale = UIScreen.main.scale
+        format.opaque = false
+        let renderer = UIGraphicsImageRenderer(size: size, format: format)
+        return renderer.image { context in
+          let cg = context.cgContext
+          cg.translateBy(x: 0, y: size.height)
+          cg.scaleBy(x: 1, y: -1)
+          label.layer.render(in: cg)
+        }
+      #elseif canImport(AppKit)
+        label.layoutSubtreeIfNeeded()
+        guard let rep = label.bitmapImageRepForCachingDisplay(in: label.bounds) else { return nil }
+        label.cacheDisplay(in: label.bounds, to: rep)
+        let image = NSImage(size: size)
+        image.addRepresentation(rep)
+        return image
+      #endif
+    }
+  }
+#endif