Making CGlyph of an extended grapheme cluster.

making_glyph_with_ctfont.swift

// CTFontGetGlyphsForCharacters(_:_:_:_:)
// [UniChar] → [CGGlyph]

import Foundation

func makeUnichars(from str: NSString) -> [UInt16] {
    let range = NSRange(location:0, length: str.length)

    let encoding = String.Encoding.utf16.rawValue
    let maxLength = str.maximumLengthOfBytes(using: encoding)
    let rawPointer = UnsafeMutableRawPointer.allocate(byteCount: maxLength, alignment: 0)
    var usedLength: Int = 0

    str.getBytes(rawPointer, 
        maxLength: maxLength, 
        usedLength: &usedLength,
        encoding: encoding, 
        range: range,
        remaining: nil)

    let rawBufferPointer = UnsafeRawBufferPointer(start: rawPointer, count: usedLength)
    let bufferPointer = rawBufferPointer.bindMemory(to: UInt16.self)

    return Array(bufferPointer)
}

// EXAMPLE

let str: NSString = "\u{0001F469}\u{200D}\u{0001F469}\u{200D}\u{0001F467}\u{200D}\u{0001F466}"
print("Inputed: \(str)")
let unichars = makeUnichars(from: str)

var font = CTFontCreateWithName("AppleColorEmoji" as CFString, 17.0, nil)
font = CTFontCreateForString(font, str, CFRange(location: 0, length: str.length))

let fontName = CTFontCopyDisplayName(font)
print("font = \(fontName)")

var glyphs: [CGGlyph] = Array(repeating: 0, count: str.length)

if (CTFontGetGlyphsForCharacters(font, unichars, &glyphs, str.length)) {
    print("succeed in generating glyph")
    print("glyphs = \(glyphs)")
} else {
    print("failed in generating glyph")
}

/* output
Inputed: 👩‍👩‍👧‍👦
font = Apple Color Emoji
succeed in generating glyph
glyphs = [1164, 0, 43, 1164, 0, 43, 1056, 0, 43, 1050, 0]     
*/

making_glyph_with_ctrun.swift

// CTFrameSetter → CTFrame → [CTLine] → [CTRun] → [CGGlyph]

import Foundation

func makeRuns(from str: String) -> [CTRun] {
    let attStr = NSAttributedString(string: str)
    let range = CFRange(location: 0, length: attStr.length)
    let size = CGSize(width: 100, height: 100)
    let path = CGPath(rect: CGRect(origin: .zero, size: size), transform: nil)

    let framesetter = CTFramesetterCreateWithAttributedString(attStr)
    let frame = CTFramesetterCreateFrame(framesetter, range, path, nil)
    let lines = CTFrameGetLines(frame) as! [CTLine]
    return lines.flatMap { 
        return CTLineGetGlyphRuns($0) as! [CTRun]
    }
}

func makeGlyphs(from run: CTRun) -> [CGGlyph] {
    let glyphsCount = CTRunGetGlyphCount(run)
    let range = CFRange(location: 0, length: glyphsCount)
    var glyphs: [CGGlyph] = Array(repeating: 0, count: glyphsCount)
    CTRunGetGlyphs(run, range, &glyphs)
    return glyphs
}


// EXAMPLE

// 👩‍👩‍👧‍👦
let str = "\u{0001F469}\u{200D}\u{0001F469}\u{200D}\u{0001F467}\u{200D}\u{0001F466}"
print("Inputed: \(str)")

let run = makeRuns(from: str)[0]

let attributes = CTRunGetAttributes(run) as! [String :Any]
let font = attributes["NSFont"] as! CTFont
let fontName = CTFontCopyDisplayName(font)
print("font = \(fontName)")

let glyphs = makeGlyphs(from: run)
print(glyphs) // [1289]