MathFont and MathTable added, both do not rely on existing SwifthMath code.

Sources/SwiftMath/MathBundle/MathFont.swift

@@ -0,0 +1,145 @@
+//
+//  File.swift
+//  
+//
+//  Created by Peter Tang on 10/9/2023.
+//
+
+import Foundation
+import CoreText
+
+public enum MathFont: String, CaseIterable {
+    
+    case latinModernFont = "latinmodern-math"
+    case kpMathLightFont = "KpMath-Light"
+    case kpMathSansFont  = "KpMath-Sans"
+    case xitsFont        = "xits-math"
+    case termesFont      = "texgyretermes-math"
+    
+    public func cgFont() -> CGFont? {
+        BundleManager.manager.obtainCGFont(font: self)
+    }
+    public func ctFont(withSize size: CGFloat) -> CTFont? {
+        BundleManager.manager.obtainCTFont(font: self, withSize: size)
+    }
+    internal func mathTable() -> NSDictionary? {
+        BundleManager.manager.obtainMathTable(font: self)
+    }
+    internal func get(nameForGlyph glyph: CGGlyph) -> String {
+        let name = cgFont()?.name(for: glyph) as? String
+        return name ?? ""
+    }
+    internal func get(glyphWithName name: String) -> CGGlyph? {
+        cgFont()?.getGlyphWithGlyphName(name: name as CFString)
+    }
+}
+internal extension CTFont {
+    /** The size of this font in points. */
+    var fontSize: CGFloat {
+        CTFontGetSize(self)
+    }
+    var unitsPerEm: UInt {
+        return UInt(CTFontGetUnitsPerEm(self))
+    }
+}
+private class BundleManager {
+    static fileprivate(set) var manager: BundleManager = {
+        return BundleManager()
+    }()
+
+    private var cgFonts = [MathFont: CGFont]()
+    private var ctFonts = [CTFontPair: CTFont]()
+    private var mathTables = [MathFont: NSDictionary]()
+
+    private var initializedOnceAlready: Bool = false
+    
+    private func registerCGFont(mathFont: MathFont) throws {
+        guard let frameworkBundleURL = Bundle.module.url(forResource: "mathFonts", withExtension: "bundle"),
+              let resourceBundleURL = Bundle(url: frameworkBundleURL)?.path(forResource: mathFont.rawValue, ofType: "otf") else {
+            throw FontError.fontPathNotFound
+        }
+        guard let fontData = NSData(contentsOfFile: resourceBundleURL), let dataProvider = CGDataProvider(data: fontData) else {
+            throw FontError.invalidFontFile
+        }
+        guard let defaultCGFont = CGFont(dataProvider) else {
+            throw FontError.initFontError
+        }
+        
+        cgFonts[mathFont] = defaultCGFont
+        
+        var errorRef: Unmanaged<CFError>? = nil
+        guard CTFontManagerRegisterGraphicsFont(defaultCGFont, &errorRef) else {
+            throw FontError.registerFailed
+        }
+        print("mathFonts bundle: \(mathFont.rawValue) registered.")
+    }
+    
+    private func registerMathTable(mathFont: MathFont) throws {
+        guard let frameworkBundleURL = Bundle.module.url(forResource: "mathFonts", withExtension: "bundle"),
+              let mathTablePlist = Bundle(url: frameworkBundleURL)?.url(forResource: mathFont.rawValue, withExtension:"plist") else {
+            throw FontError.fontPathNotFound
+        }
+        guard let rawMathTable = NSDictionary(contentsOf: mathTablePlist),
+                let version = rawMathTable["version"] as? String,
+                version == "1.3" else {
+            throw FontError.invalidMathTable
+        }
+        //FIXME: mathTable = MTFontMathTable(withFont:self, mathTable:rawMathTable)
+        mathTables[mathFont] = rawMathTable
+    }
+    
+    private func registerAllBundleResources() {
+        guard !initializedOnceAlready else { return }
+        MathFont.allCases.forEach { font in
+            do {
+                try BundleManager.manager.registerCGFont(mathFont: font)
+                try BundleManager.manager.registerMathTable(mathFont: font)
+            } catch {
+                fatalError("MTMathFonts:\(#function) Couldn't load math fonts \(font.rawValue), reason \(error)")
+            }
+        }
+        initializedOnceAlready.toggle()
+    }
+    
+    fileprivate func obtainCGFont(font: MathFont) -> CGFont? {
+        if !initializedOnceAlready { registerAllBundleResources() }
+        return cgFonts[font]
+    }
+    
+    fileprivate func obtainCTFont(font: MathFont, withSize size: CGFloat) -> CTFont? {
+        if !initializedOnceAlready { registerAllBundleResources() }
+        let fontPair = CTFontPair(font: font, size: size)
+        guard let ctFont = ctFonts[fontPair] else {
+            if let cgFont = cgFonts[font] {
+                let ctFont = CTFontCreateWithGraphicsFont(cgFont, size, nil, nil)
+                ctFonts[fontPair] = ctFont
+                return ctFont
+            }
+            return nil
+        }
+        return ctFont
+    }
+    fileprivate func obtainMathTable(font: MathFont) -> NSDictionary? {
+        if !initializedOnceAlready { registerAllBundleResources() }
+        return mathTables[font]
+    }
+    deinit {
+        ctFonts.removeAll()
+        var errorRef: Unmanaged<CFError>? = nil
+        cgFonts.values.forEach { cgFont in
+            CTFontManagerUnregisterGraphicsFont(cgFont, &errorRef)
+        }
+    }
+    public enum FontError: Error {
+        case invalidFontFile
+        case fontPathNotFound
+        case initFontError
+        case registerFailed
+        case invalidMathTable
+    }
+    
+    private struct CTFontPair: Hashable {
+        let font: MathFont
+        let size: CGFloat
+    }
+}