Fix emoji display in text (#771)

* Fix emoji display in text

* Fix emoji text color

src/kaboom.ts

@@ -74,6 +74,7 @@ import {
 	// eslint-disable-next-line
 	comparePerf,
 	BinaryHeap,
+	runes,
 } from "./utils"
 
 import type {
@@ -2110,7 +2111,7 @@ export default (gopt: KaboomOpt = {}): KaboomCtx => {
 		if (tr.pos) fchar.pos = fchar.pos.add(tr.pos)
 		if (tr.scale) fchar.scale = fchar.scale.scale(vec2(tr.scale))
 		if (tr.angle) fchar.angle += tr.angle
-		if (tr.color) fchar.color = fchar.color.mult(tr.color)
+		if (tr.color) fchar.color = runes(fchar.ch).length !== fchar.ch.length ? Color.WHITE : fchar.color.mult(tr.color)
 		if (tr.opacity) fchar.opacity *= tr.opacity
 	}
 
@@ -2175,7 +2176,7 @@ export default (gopt: KaboomOpt = {}): KaboomCtx => {
 		}
 
 		const { charStyleMap, text } = compileStyledText(opt.text + "")
-		const chars = text.split("")
+		const chars = runes(text)
 
 		// if it's not bitmap font, we draw it with 2d canvas or use cached image
 		if (font instanceof FontData || typeof font === "string") {

src/utils.ts

@@ -297,3 +297,203 @@ export class BinaryHeap<T> {
 		return this._items.length
 	}
 }
+
+export const enum EnumRunesCode {
+	HIGH_SURROGATE_START = 0xd800,
+	HIGH_SURROGATE_END = 0xdbff,
+
+	LOW_SURROGATE_START = 0xdc00,
+
+	REGIONAL_INDICATOR_START = 0x1f1e6,
+	REGIONAL_INDICATOR_END = 0x1f1ff,
+
+	FITZPATRICK_MODIFIER_START = 0x1f3fb,
+	FITZPATRICK_MODIFIER_END = 0x1f3ff,
+
+	VARIATION_MODIFIER_START = 0xfe00,
+	VARIATION_MODIFIER_END = 0xfe0f,
+
+	DIACRITICAL_MARKS_START = 0x20d0,
+	DIACRITICAL_MARKS_END = 0x20ff,
+
+	SUBDIVISION_INDICATOR_START = 0x1f3f4,
+	TAGS_START = 0xe0000,
+	TAGS_END = 0xe007f,
+
+	ZWJ = 0x200d,
+}
+
+export const GRAPHEMES = Object.freeze([
+	0x0308, // ( ◌̈ ) COMBINING DIAERESIS
+	0x0937, // ( ष ) DEVANAGARI LETTER SSA
+	0x093F, // ( ि ) DEVANAGARI VOWEL SIGN I
+	0x0BA8, // ( ந ) TAMIL LETTER NA
+	0x0BBF, // ( ி ) TAMIL VOWEL SIGN I
+	0x0BCD, // ( ◌்) TAMIL SIGN VIRAMA
+	0x0E31, // ( ◌ั ) THAI CHARACTER MAI HAN-AKAT
+	0x0E33, // ( ำ ) THAI CHARACTER SARA AM
+	0x0E40, // ( เ ) THAI CHARACTER SARA E
+	0x0E49, // ( เ ) THAI CHARACTER MAI THO
+	0x1100, // ( ᄀ ) HANGUL CHOSEONG KIYEOK
+	0x1161, // ( ᅡ ) HANGUL JUNGSEONG A
+	0x11A8, // ( ᆨ ) HANGUL JONGSEONG KIYEOK
+]);
+
+export const enum EnumCodeUnits {
+	unit_1 = 1,
+	unit_2 = 2,
+	unit_4 = 4,
+}
+
+export function runes(string: string): string[] {
+	if (typeof string !== 'string')
+	{
+		throw new TypeError('string cannot be undefined or null')
+	}
+	const result: string[] = []
+	let i = 0
+	let increment = 0
+	while (i < string.length)
+	{
+		increment += nextUnits(i + increment, string)
+		if (isGrapheme(string[i + increment]))
+		{
+			increment++
+		}
+		if (isVariationSelector(string[i + increment]))
+		{
+			increment++
+		}
+		if (isDiacriticalMark(string[i + increment]))
+		{
+			increment++
+		}
+		if (isZeroWidthJoiner(string[i + increment]))
+		{
+			increment++
+			continue
+		}
+		result.push(string.substring(i, i + increment))
+		i += increment
+		increment = 0
+	}
+	return result
+}
+
+// Decide how many code units make up the current character.
+// BMP characters: 1 code unit
+// Non-BMP characters (represented by surrogate pairs): 2 code units
+// Emoji with skin-tone modifiers: 4 code units (2 code points)
+// Country flags: 4 code units (2 code points)
+// Variations: 2 code units
+// Subdivision flags: 14 code units (7 code points)
+export function nextUnits(i: number, string: string) {
+	const current = string[i]
+	// If we don't have a value that is part of a surrogate pair, or we're at
+	// the end, only take the value at i
+	if (!isFirstOfSurrogatePair(current) || i === string.length - 1)
+	{
+		return EnumCodeUnits.unit_1
+	}
+
+	const currentPair = current + string[i + 1]
+	let nextPair = string.substring(i + 2, i + 5)
+
+	// Country flags are comprised of two regional indicator symbols,
+	// each represented by a surrogate pair.
+	// See http://emojipedia.org/flags/
+	// If both pairs are regional indicator symbols, take 4
+	if (isRegionalIndicator(currentPair) && isRegionalIndicator(nextPair))
+	{
+		return EnumCodeUnits.unit_4
+	}
+
+	// https://unicode.org/emoji/charts/full-emoji-list.html#subdivision-flag
+	// See https://emojipedia.org/emoji-tag-sequence/
+	// If nextPair is in Tags(https://en.wikipedia.org/wiki/Tags_(Unicode_block)),
+	// then find next closest U+E007F(CANCEL TAG)
+	if (isSubdivisionFlag(currentPair) &&	isSupplementarySpecialpurposePlane(nextPair))
+	{
+		return string.slice(i).indexOf(String.fromCodePoint(EnumRunesCode.TAGS_END)) + 2
+	}
+
+	// If the next pair make a Fitzpatrick skin tone
+	// modifier, take 4
+	// See http://emojipedia.org/modifiers/
+	// Technically, only some code points are meant to be
+	// combined with the skin tone modifiers. This function
+	// does not check the current pair to see if it is
+	// one of them.
+	if (isFitzpatrickModifier(nextPair))
+	{
+		return EnumCodeUnits.unit_4
+	}
+	return EnumCodeUnits.unit_2
+}
+
+export function isFirstOfSurrogatePair(string: string) {
+	return string && betweenInclusive(string[0].charCodeAt(0), EnumRunesCode.HIGH_SURROGATE_START, EnumRunesCode.HIGH_SURROGATE_END)
+}
+
+export function isRegionalIndicator(string: string) {
+	return betweenInclusive(codePointFromSurrogatePair(string), EnumRunesCode.REGIONAL_INDICATOR_START, EnumRunesCode.REGIONAL_INDICATOR_END)
+}
+
+export function isSubdivisionFlag(string: string) {
+	return betweenInclusive(codePointFromSurrogatePair(string),	EnumRunesCode.SUBDIVISION_INDICATOR_START, EnumRunesCode.SUBDIVISION_INDICATOR_START)
+}
+
+export function isFitzpatrickModifier(string: string) {
+	return betweenInclusive(codePointFromSurrogatePair(string), EnumRunesCode.FITZPATRICK_MODIFIER_START, EnumRunesCode.FITZPATRICK_MODIFIER_END)
+}
+
+export function isVariationSelector(string: string) {
+	return typeof string === 'string' && betweenInclusive(string.charCodeAt(0), EnumRunesCode.VARIATION_MODIFIER_START, EnumRunesCode.VARIATION_MODIFIER_END)
+}
+
+export function isDiacriticalMark(string: string) {
+	return typeof string === 'string' && betweenInclusive(string.charCodeAt(0), EnumRunesCode.DIACRITICAL_MARKS_START, EnumRunesCode.DIACRITICAL_MARKS_END)
+}
+
+export function isSupplementarySpecialpurposePlane(string: string) {
+	const codePoint = string.codePointAt(0)
+	return (typeof string === 'string' &&	typeof codePoint === 'number' && betweenInclusive(codePoint, EnumRunesCode.TAGS_START, EnumRunesCode.TAGS_END))
+}
+
+export function isGrapheme(string: string) {
+	return typeof string === 'string' && GRAPHEMES.includes(string.charCodeAt(0))
+}
+
+export function isZeroWidthJoiner(string: string) {
+	return typeof string === 'string' && string.charCodeAt(0) === EnumRunesCode.ZWJ
+}
+
+export function codePointFromSurrogatePair(pair: string) {
+	const highOffset = pair.charCodeAt(0) - EnumRunesCode.HIGH_SURROGATE_START
+	const lowOffset = pair.charCodeAt(1) - EnumRunesCode.LOW_SURROGATE_START
+	return (highOffset << 10) + lowOffset + 0x10000
+}
+
+export function betweenInclusive(value: number, lower: number, upper: number) {
+	return value >= lower && value <= upper
+}
+
+export function substring(string: string, start?: number, width?: number) {
+	const chars = runes(string)
+	if (start === undefined)
+	{
+		return string
+	}
+	if (start >= chars.length)
+	{
+		return ''
+	}
+	const rest = chars.length - start
+	const stringWidth = width === undefined ? rest : width
+	let endIndex = start + stringWidth
+	if (endIndex > (start + rest))
+	{
+		endIndex = undefined
+	}
+	return chars.slice(start, endIndex).join('')
+}