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Made the wrapping algorithm more closely align with Unicode Standard #1006

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Made the wrapping algorithm more closely align with Unicode Standard #1006

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0a1426f
Made non-BMP characters be treated as a single character for wrapping.
Wetterquarz Apr 12, 2023
2fd5303
Wrapping can no longer throw Errors and instead displays illegal char…
Wetterquarz Apr 13, 2023
f72d80a
Spaces now have special wrapping behaviour
Wetterquarz Apr 13, 2023
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75 changes: 57 additions & 18 deletions src/graphic/helper/parseText.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,9 @@ import * as imageHelper from '../helper/image';
import {
extend,
retrieve2,
retrieve3,
reduce
retrieve3
} from '../../core/util';
import { TextAlign, TextVerticalAlign, ImageLike, Dictionary } from '../../core/types';
import { TextAlign, TextVerticalAlign, ImageLike } from '../../core/types';
import { TextStyleProps } from '../Text';
import { getLineHeight, getWidth, parsePercent } from '../../contain/text';

Expand Down Expand Up @@ -604,21 +603,11 @@ function isAlphabeticLetter(ch: string) {
|| code >= 0x1E00 && code <= 0x206F; // Latin and Greek extended
}

const breakCharMap = reduce(',&?/;] '.split(''), function (obj, ch) {
obj[ch] = true;
return obj;
}, {} as Dictionary<boolean>);
/**
* If break by word. For latin languages.
*/
function isWordBreakChar(ch: string) {
if (isAlphabeticLetter(ch)) {
if (breakCharMap[ch]) {
return true;
}
return false;
}
return true;
function canLineBreakBeforeChar(ch: string) {
return !isAlphabeticLetter(ch);
}

function wrapText(
Expand All @@ -636,8 +625,8 @@ function wrapText(
let accumWidth = 0;

for (let i = 0; i < text.length; i++) {

const ch = text.charAt(i);
let ch;
[ch, i] = getWholeCharAndI(text, i);
if (ch === '\n') {
if (currentWord) {
line += currentWord;
Expand All @@ -654,7 +643,16 @@ function wrapText(
}

const chWidth = getWidth(ch, font);
const inWord = isBreakAll ? false : !isWordBreakChar(ch);

if (ch === ' ') {
line += currentWord + ch;
accumWidth += chWidth;
currentWord = '';
currentWordWidth = 0;
continue;
}

const inWord = isBreakAll ? false : !canLineBreakBeforeChar(ch);

if (!lines.length
? lastAccumWidth + accumWidth + chWidth > lineWidth
Expand Down Expand Up @@ -761,4 +759,45 @@ function wrapText(
lines: lines,
linesWidths
};
}

// Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt#getting_whole_characters
function getWholeCharAndI(str: string, i: number): [string, number] {
const code = str.charCodeAt(i);

if (isNaN(code)) {
return ['', i]; // Position not found
}
if (code < 0xd800 || code > 0xdfff) {
return [str.charAt(i), i]; // Normal character, keeping 'i' the same
}

// High surrogate (could change last hex to 0xDB7F to treat high private
// surrogates as single characters)
if (0xd800 <= code && code <= 0xdbff) {
if (str.length <= i + 1) {
return [str.charAt(i), i]; // Error: High surrogate without following low surrogate
}
const next = str.charCodeAt(i + 1);
if (next < 0xdc00 || next > 0xdfff) {
return [str.charAt(i), i]; // Error: High surrogate without following low surrogate
}
return [str.charAt(i) + str.charAt(i + 1), i + 1];
}

// Low surrogate (0xDC00 <= code && code <= 0xDFFF)
if (i === 0) {
return [str.charAt(i), i]; // Error: Low surrogate without preceding high surrogate
}

const prev = str.charCodeAt(i - 1);

// (could change last hex to 0xDB7F to treat high private surrogates
// as single characters)
if (prev < 0xd800 || prev > 0xdbff) {
return [str.charAt(i), i]; // Error: Low surrogate without preceding high surrogate
}

// Return the next character instead (and increment)
return [str.charAt(i + 1), i + 1];
}
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