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feat(troika-three-text): Add a property to toggle ligatures #352

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feat(troika-three-text): Add a property to toggle ligatures #352

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1 change: 1 addition & 0 deletions packages/troika-3d-text/src/facade/Text3DFacade.js
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ export const TEXT_MESH_PROPS = [
'textAlign',
'textIndent',
'whiteSpace',
'enableLigatures',
'material',
'color',
'colorRanges',
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3 changes: 3 additions & 0 deletions packages/troika-examples/text/TextExample.jsx
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Expand Up @@ -116,6 +116,7 @@ class TextExample extends React.Component {
textScale: 1,
lineHeight: 1.15,
letterSpacing: 0,
enableLigatures: true,
maxWidth: 2, //2m
textAlign: 'justify',
textIndent: 0,
Expand Down Expand Up @@ -217,6 +218,7 @@ class TextExample extends React.Component {
textIndent: state.textIndent,
lineHeight: state.lineHeight,
letterSpacing: state.letterSpacing,
enableLigatures: state.enableLigatures,
anchorX: state.anchorX,
anchorY: state.anchorY,
selectable: state.selectable,
Expand Down Expand Up @@ -342,6 +344,7 @@ class TextExample extends React.Component {
{type: 'number', path: "maxWidth", min: 1, max: 5, step: 0.01},
{type: 'number', path: "lineHeight", min: 1, max: 2, step: 0.01},
{type: 'number', path: "letterSpacing", min: -0.1, max: 0.5, step: 0.01},
{type: 'boolean', path: "enableLigatures", label: "Ligatures"},
{type: 'number', path: "fillOpacity", min: 0, max: 1, step: 0.0001},
{type: 'number', path: "curveRadius", min: -5, max: 5, step: 0.001},

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52 changes: 27 additions & 25 deletions packages/troika-three-text/src/FontParser.js
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Expand Up @@ -13,7 +13,7 @@ import { defineWorkerModule } from 'troika-worker-utils'
* @property {number} descender
* @property {number} xHeight
* @property {(number) => boolean} supportsCodePoint
* @property {(text:string, fontSize:number, letterSpacing:number, callback) => number} forEachGlyph
* @property {(text:string, fontSize:number, letterSpacing:number, enableLigatures:boolean, callback) => number} forEachGlyph
* @property {number} lineGap
* @property {number} capHeight
* @property {number} unitsPerEm
Expand Down Expand Up @@ -122,38 +122,40 @@ function parserFactory(Typr, woff2otf) {
return joiningForms
}

function stringToGlyphs (font, str) {
function stringToGlyphs (font, str, enableLigatures) {
const glyphIds = []
for (let i = 0; i < str.length; i++) {
const cc = str.codePointAt(i)
if (cc > 0xffff) i++
glyphIds.push(Typr.U.codeToGlyph(font, cc))
}

const gsub = font['GSUB']
if (gsub) {
const {lookupList, featureList} = gsub
let joiningForms
const supportedFeatures = /^(rlig|liga|mset|isol|init|fina|medi|half|pres|blws|ccmp)$/
const usedLookups = []
featureList.forEach(feature => {
if (supportedFeatures.test(feature.tag)) {
for (let ti = 0; ti < feature.tab.length; ti++) {
if (usedLookups[feature.tab[ti]]) continue
usedLookups[feature.tab[ti]] = true
const tab = lookupList[feature.tab[ti]]
const isJoiningFeature = /^(isol|init|fina|medi)$/.test(feature.tag)
if (isJoiningFeature && !joiningForms) { //lazy
joiningForms = detectJoiningForms(str)
}
for (let ci = 0; ci < glyphIds.length; ci++) {
if (!joiningForms || !isJoiningFeature || formsToFeatures[joiningForms[ci]] === feature.tag) {
Typr.U._applySubs(glyphIds, ci, tab, lookupList)
if (enableLigatures) {
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I noticed this part was responsible for ligature substitution, and I moved it behind the flag, but if it inadvertently disables something else do let me know!

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Ah, yeah I think we need to be more selective -- some substitutions are required for correctness (e.g. in Arabic scripts). We'll need to filter the supportedFeatures to remove just the stylistic ligatures. I think that's liga, but I'd have to research the others.

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Documentation for the feature tags: https://learn.microsoft.com/en-us/typography/opentype/spec/features_ko#tag-liga

const gsub = font['GSUB']
if (gsub) {
const {lookupList, featureList} = gsub
let joiningForms
const supportedFeatures = /^(rlig|liga|mset|isol|init|fina|medi|half|pres|blws|ccmp)$/
const usedLookups = []
featureList.forEach(feature => {
if (supportedFeatures.test(feature.tag)) {
for (let ti = 0; ti < feature.tab.length; ti++) {
if (usedLookups[feature.tab[ti]]) continue
usedLookups[feature.tab[ti]] = true
const tab = lookupList[feature.tab[ti]]
const isJoiningFeature = /^(isol|init|fina|medi)$/.test(feature.tag)
if (isJoiningFeature && !joiningForms) { //lazy
joiningForms = detectJoiningForms(str)
}
for (let ci = 0; ci < glyphIds.length; ci++) {
if (!joiningForms || !isJoiningFeature || formsToFeatures[joiningForms[ci]] === feature.tag) {
Typr.U._applySubs(glyphIds, ci, tab, lookupList)
}
}
}
}
}
})
})
}
}

return glyphIds
Expand Down Expand Up @@ -321,11 +323,11 @@ function parserFactory(Typr, woff2otf) {
supportsCodePoint(code) {
return Typr.U.codeToGlyph(typrFont, code) > 0
},
forEachGlyph(text, fontSize, letterSpacing, callback) {
forEachGlyph(text, fontSize, letterSpacing, enableLigatures, callback) {
let penX = 0
const fontScale = 1 / fontObj.unitsPerEm * fontSize

const glyphIds = stringToGlyphs(typrFont, text)
const glyphIds = stringToGlyphs(typrFont, text, enableLigatures && letterSpacing === 0)
let charIndex = 0
const positions = calcGlyphPositions(typrFont, glyphIds)

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9 changes: 9 additions & 0 deletions packages/troika-three-text/src/Text.js
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Expand Up @@ -66,6 +66,7 @@ const SYNCABLE_PROPS = [
'textAlign',
'textIndent',
'whiteSpace',
'enableLigatures',
'anchorX',
'anchorY',
'colorRanges',
Expand Down Expand Up @@ -222,6 +223,13 @@ class Text extends Mesh {
*/
this.whiteSpace = 'normal'

/**
* @member {boolean} enableLigatures
* Toggles ligature substitution.
* Defaults to true.
*/
this.enableLigatures = true


// === Presentation properties: === //

Expand Down Expand Up @@ -432,6 +440,7 @@ class Text extends Mesh {
textAlign: this.textAlign,
textIndent: this.textIndent,
whiteSpace: this.whiteSpace,
enableLigatures: this.enableLigatures,
overflowWrap: this.overflowWrap,
anchorX: this.anchorX,
anchorY: this.anchorY,
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6 changes: 4 additions & 2 deletions packages/troika-three-text/src/Typesetter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
* @property {string} [textAlign='left']
* @property {number} [textIndent=0]
* @property {'normal'|'nowrap'} [whiteSpace='normal']
* @property {boolean} [enableLigatures=true]
* @property {'normal'|'break-word'} [overflowWrap='normal']
* @property {AnchorXValue} [anchorX=0]
* @property {AnchorYValue} [anchorY=0]
Expand Down Expand Up @@ -156,6 +157,7 @@ export function createTypesetter(resolveFonts, bidi) {
textAlign='left',
textIndent=0,
whiteSpace='normal',
enableLigatures=true,
overflowWrap='normal',
anchorX = 0,
anchorY = 0,
Expand Down Expand Up @@ -256,7 +258,7 @@ export function createTypesetter(resolveFonts, bidi) {

const runText = text.slice(run.start, run.end + 1)
let prevGlyphX, prevGlyphObj
fontObj.forEachGlyph(runText, fontSize, letterSpacing, (glyphObj, glyphX, glyphY, charIndex) => {
fontObj.forEachGlyph(runText, fontSize, letterSpacing, enableLigatures, (glyphObj, glyphX, glyphY, charIndex) => {
glyphX += prevRunEndX
charIndex += run.start
prevGlyphX = glyphX
Expand Down Expand Up @@ -503,7 +505,7 @@ export function createTypesetter(resolveFonts, bidi) {
if (rtl) {
const mirrored = bidi.getMirroredCharacter(text[glyphInfo.charIndex])
if (mirrored) {
glyphInfo.fontData.fontObj.forEachGlyph(mirrored, 0, 0, setGlyphObj)
glyphInfo.fontData.fontObj.forEachGlyph(mirrored, 0, 0, enableLigatures, setGlyphObj)
}
}

Expand Down