refactor: packages/

1 files changed, 568 insertions, 0 deletions

diff --git a/packages/excalidraw/element/textWrapping.ts b/packages/excalidraw/element/textWrapping.ts
new file mode 100644
index 0000000..1913f6e
--- /dev/null
+++ b/packages/excalidraw/element/textWrapping.ts
@@ -0,0 +1,568 @@
+import { ENV } from "../constants";
+import { charWidth, getLineWidth } from "./textMeasurements";
+import type { FontString } from "./types";
+
+let cachedCjkRegex: RegExp | undefined;
+let cachedLineBreakRegex: RegExp | undefined;
+let cachedEmojiRegex: RegExp | undefined;
+
+/**
+ * Test if a given text contains any CJK characters (including symbols, punctuation, etc,).
+ */
+export const containsCJK = (text: string) => {
+  if (!cachedCjkRegex) {
+    cachedCjkRegex = Regex.class(...Object.values(CJK));
+  }
+
+  return cachedCjkRegex.test(text);
+};
+
+const getLineBreakRegex = () => {
+  if (!cachedLineBreakRegex) {
+    try {
+      cachedLineBreakRegex = getLineBreakRegexAdvanced();
+    } catch {
+      cachedLineBreakRegex = getLineBreakRegexSimple();
+    }
+  }
+
+  return cachedLineBreakRegex;
+};
+
+const getEmojiRegex = () => {
+  if (!cachedEmojiRegex) {
+    cachedEmojiRegex = getEmojiRegexUnicode();
+  }
+
+  return cachedEmojiRegex;
+};
+
+/**
+ * Common symbols used across different languages.
+ */
+const COMMON = {
+  /**
+   * Natural breaking points for any grammars.
+   *
+   * Hello world
+   *      ↑ BREAK ALWAYS " " → ["Hello", " ", "world"]
+   * Hello-world
+   *       ↑ BREAK AFTER "-" → ["Hello-", "world"]
+   */
+  WHITESPACE: /\s/u,
+  HYPHEN: /-/u,
+  /**
+   * Generally do not break, unless closed symbol is followed by an opening symbol.
+   *
+   * Also, western punctation is often used in modern Korean and expects to be treated
+   * similarly to the CJK opening and closing symbols.
+   *
+   * Hello(한글)→ ["Hello", "(한", "글)"]
+   *      ↑ BREAK BEFORE "("
+   *          ↑ BREAK AFTER ")"
+   */
+  OPENING: /<\(\[\{/u,
+  CLOSING: />\)\]\}.,:;!\?…\//u,
+};
+
+/**
+ * Characters and symbols used in Chinese, Japanese and Korean.
+ */
+const CJK = {
+  /**
+   * Every CJK breaks before and after, unless it's paired with an opening or closing symbol.
+   *
+   * Does not include every possible char used in CJK texts, such as currency, parentheses or punctuation.
+   */
+  CHAR: /\p{Script=Han}\p{Script=Hiragana}\p{Script=Katakana}\p{Script=Hangul}｀＇＾〃〰〆＃＆＊＋－ー／＼＝｜￤〒￢￣/u,
+  /**
+   * Opening and closing CJK punctuation breaks before and after all such characters (in case of many),
+   * and creates pairs with neighboring characters.
+   *
+   * Hello た。→ ["Hello", "た。"]
+   *        ↑ DON'T BREAK "た。"
+   * * Hello「た」 World → ["Hello", "「た」", "World"]
+   *       ↑ DON'T BREAK "「た"
+   *        ↑ DON'T BREAK "た"
+   *      ↑ BREAK BEFORE "「"
+   *         ↑ BREAK AFTER "」"
+   */
+  // eslint-disable-next-line prettier/prettier
+  OPENING:/（［｛〈《｟｢「『【〖〔〘〚＜〝/u,
+  CLOSING: /）］｝〉》｠｣」』】〗〕〙〛＞。．，、〟‥？！：；・〜〞/u,
+  /**
+   * Currency symbols break before, not after
+   *
+   * Price￥100 → ["Price", "￥100"]
+   *      ↑ BREAK BEFORE "￥"
+   */
+  CURRENCY: /￥￦￡￠＄/u,
+};
+
+const EMOJI = {
+  FLAG: /\p{RI}\p{RI}/u,
+  JOINER:
+    /(?:\p{Emoji_Modifier}|\uFE0F\u20E3?|[\u{E0020}-\u{E007E}]+\u{E007F})?/u,
+  ZWJ: /\u200D/u,
+  ANY: /[\p{Emoji}]/u,
+  MOST: /[\p{Extended_Pictographic}\p{Emoji_Presentation}]/u,
+};
+
+/**
+ * Simple fallback for browsers (mainly Safari < 16.4) that don't support "Lookbehind assertion".
+ *
+ * Browser support as of 10/2024:
+ * - 91% Lookbehind assertion https://caniuse.com/mdn-javascript_regular_expressions_lookbehind_assertion
+ * - 94% Unicode character class escape https://caniuse.com/mdn-javascript_regular_expressions_unicode_character_class_escape
+ *
+ * Does not include advanced CJK breaking rules, but covers most of the core cases, especially for latin.
+ */
+const getLineBreakRegexSimple = () =>
+  Regex.or(
+    getEmojiRegex(),
+    Break.On(COMMON.HYPHEN, COMMON.WHITESPACE, CJK.CHAR),
+  );
+
+/**
+ * Specifies the line breaking rules based for alphabetic-based languages,
+ * Chinese, Japanese, Korean and Emojis.
+ *
+ * "Hello-world" → ["Hello-", "world"]
+ * "Hello 「世界。」🌎🗺" → ["Hello", " ", "「世", "界。」", "🌎", "🗺"]
+ */
+const getLineBreakRegexAdvanced = () =>
+  Regex.or(
+    // Unicode-defined regex for (multi-codepoint) Emojis
+    getEmojiRegex(),
+    // Rules for whitespace and hyphen
+    Break.Before(COMMON.WHITESPACE).Build(),
+    Break.After(COMMON.WHITESPACE, COMMON.HYPHEN).Build(),
+    // Rules for CJK (chars, symbols, currency)
+    Break.Before(CJK.CHAR, CJK.CURRENCY)
+      .NotPrecededBy(COMMON.OPENING, CJK.OPENING)
+      .Build(),
+    Break.After(CJK.CHAR)
+      .NotFollowedBy(COMMON.HYPHEN, COMMON.CLOSING, CJK.CLOSING)
+      .Build(),
+    // Rules for opening and closing punctuation
+    Break.BeforeMany(CJK.OPENING).NotPrecededBy(COMMON.OPENING).Build(),
+    Break.AfterMany(CJK.CLOSING).NotFollowedBy(COMMON.CLOSING).Build(),
+    Break.AfterMany(COMMON.CLOSING).FollowedBy(COMMON.OPENING).Build(),
+  );
+
+/**
+ * Matches various emoji types.
+ *
+ * 1. basic emojis (😀, 🌍)
+ * 2. flags (🇨🇿)
+ * 3. multi-codepoint emojis:
+ *    - skin tones (👍🏽)
+ *    - variation selectors (☂️)
+ *    - keycaps (1️⃣)
+ *    - tag sequences (🏴󠁧󠁢󠁥󠁮󠁧󠁿)
+ *    - emoji sequences (👨‍👩‍👧‍👦, 👩‍🚀, 🏳️‍🌈)
+ *
+ * Unicode points:
+ * - \uFE0F: presentation selector
+ * - \u20E3: enclosing keycap
+ * - \u200D: zero width joiner
+ * - \u{E0020}-\u{E007E}: tags
+ * - \u{E007F}: cancel tag
+ *
+ * @see https://unicode.org/reports/tr51/#EBNF_and_Regex, with changes:
+ * - replaced \p{Emoji} with [\p{Extended_Pictographic}\p{Emoji_Presentation}], see more in `should tokenize emojis mixed with mixed text` test
+ * - replaced \p{Emod} with \p{Emoji_Modifier} as some engines do not understand the abbreviation (i.e. https://devina.io/redos-checker)
+ */
+const getEmojiRegexUnicode = () =>
+  Regex.group(
+    Regex.or(
+      EMOJI.FLAG,
+      Regex.and(
+        EMOJI.MOST,
+        EMOJI.JOINER,
+        Regex.build(
+          `(?:${EMOJI.ZWJ.source}(?:${EMOJI.FLAG.source}|${EMOJI.ANY.source}${EMOJI.JOINER.source}))*`,
+        ),
+      ),
+    ),
+  );
+
+/**
+ * Regex utilities for unicode character classes.
+ */
+const Regex = {
+  /**
+   * Builds a regex from a string.
+   */
+  build: (regex: string): RegExp => new RegExp(regex, "u"),
+  /**
+   * Joins regexes into a single string.
+   */
+  join: (...regexes: RegExp[]): string => regexes.map((x) => x.source).join(""),
+  /**
+   * Joins regexes into a single regex as with "and" operator.
+   */
+  and: (...regexes: RegExp[]): RegExp => Regex.build(Regex.join(...regexes)),
+  /**
+   * Joins regexes into a single regex with "or" operator.
+   */
+  or: (...regexes: RegExp[]): RegExp =>
+    Regex.build(regexes.map((x) => x.source).join("|")),
+  /**
+   * Puts regexes into a matching group.
+   */
+  group: (...regexes: RegExp[]): RegExp =>
+    Regex.build(`(${Regex.join(...regexes)})`),
+  /**
+   * Puts regexes into a character class.
+   */
+  class: (...regexes: RegExp[]): RegExp =>
+    Regex.build(`[${Regex.join(...regexes)}]`),
+};
+
+/**
+ * Human-readable lookahead and lookbehind utilities for defining line break
+ * opportunities between pairs of character classes.
+ */
+const Break = {
+  /**
+   * Break on the given class of characters.
+   */
+  On: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    return Regex.build(`([${joined}])`);
+  },
+  /**
+   * Break before the given class of characters.
+   */
+  Before: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?=[${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "FollowedBy"
+    >;
+  },
+  /**
+   * Break after the given class of characters.
+   */
+  After: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?<=[${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "PreceededBy"
+    >;
+  },
+  /**
+   * Break before one or multiple characters of the same class.
+   */
+  BeforeMany: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?<![${joined}])(?=[${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "FollowedBy"
+    >;
+  },
+  /**
+   * Break after one or multiple character from the same class.
+   */
+  AfterMany: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?<=[${joined}])(?![${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "PreceededBy"
+    >;
+  },
+  /**
+   * Do not break before the given class of characters.
+   */
+  NotBefore: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?![${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "NotFollowedBy"
+    >;
+  },
+  /**
+   * Do not break after the given class of characters.
+   */
+  NotAfter: (...regexes: RegExp[]) => {
+    const joined = Regex.join(...regexes);
+    const builder = () => Regex.build(`(?<![${joined}])`);
+    return Break.Chain(builder) as Omit<
+      ReturnType<typeof Break.Chain>,
+      "NotPrecededBy"
+    >;
+  },
+  Chain: (rootBuilder: () => RegExp) => ({
+    /**
+     * Build the root regex.
+     */
+    Build: rootBuilder,
+    /**
+     * Specify additional class of characters that should precede the root regex.
+     */
+    PreceededBy: (...regexes: RegExp[]) => {
+      const root = rootBuilder();
+      const preceeded = Break.After(...regexes).Build();
+      const builder = () => Regex.and(preceeded, root);
+      return Break.Chain(builder) as Omit<
+        ReturnType<typeof Break.Chain>,
+        "PreceededBy"
+      >;
+    },
+    /**
+     * Specify additional class of characters that should follow the root regex.
+     */
+    FollowedBy: (...regexes: RegExp[]) => {
+      const root = rootBuilder();
+      const followed = Break.Before(...regexes).Build();
+      const builder = () => Regex.and(root, followed);
+      return Break.Chain(builder) as Omit<
+        ReturnType<typeof Break.Chain>,
+        "FollowedBy"
+      >;
+    },
+    /**
+     * Specify additional class of characters that should not precede the root regex.
+     */
+    NotPrecededBy: (...regexes: RegExp[]) => {
+      const root = rootBuilder();
+      const notPreceeded = Break.NotAfter(...regexes).Build();
+      const builder = () => Regex.and(notPreceeded, root);
+      return Break.Chain(builder) as Omit<
+        ReturnType<typeof Break.Chain>,
+        "NotPrecededBy"
+      >;
+    },
+    /**
+     * Specify additional class of characters that should not follow the root regex.
+     */
+    NotFollowedBy: (...regexes: RegExp[]) => {
+      const root = rootBuilder();
+      const notFollowed = Break.NotBefore(...regexes).Build();
+      const builder = () => Regex.and(root, notFollowed);
+      return Break.Chain(builder) as Omit<
+        ReturnType<typeof Break.Chain>,
+        "NotFollowedBy"
+      >;
+    },
+  }),
+};
+
+/**
+ * Breaks the line into the tokens based on the found line break opporutnities.
+ */
+export const parseTokens = (line: string) => {
+  const breakLineRegex = getLineBreakRegex();
+
+  // normalizing to single-codepoint composed chars due to canonical equivalence
+  // of multi-codepoint versions for chars like č, で (~ so that we don't break a line in between c and ˇ)
+  // filtering due to multi-codepoint chars like 👨‍👩‍👧‍👦, 👩🏽‍🦰
+  return line.normalize("NFC").split(breakLineRegex).filter(Boolean);
+};
+
+/**
+ * Wraps the original text into the lines based on the given width.
+ */
+export const wrapText = (
+  text: string,
+  font: FontString,
+  maxWidth: number,
+): string => {
+  // if maxWidth is not finite or NaN which can happen in case of bugs in
+  // computation, we need to make sure we don't continue as we'll end up
+  // in an infinite loop
+  if (!Number.isFinite(maxWidth) || maxWidth < 0) {
+    return text;
+  }
+
+  const lines: Array<string> = [];
+  const originalLines = text.split("\n");
+
+  for (const originalLine of originalLines) {
+    const currentLineWidth = getLineWidth(originalLine, font);
+
+    if (currentLineWidth <= maxWidth) {
+      lines.push(originalLine);
+      continue;
+    }
+
+    const wrappedLine = wrapLine(originalLine, font, maxWidth);
+    lines.push(...wrappedLine);
+  }
+
+  return lines.join("\n");
+};
+
+/**
+ * Wraps the original line into the lines based on the given width.
+ */
+const wrapLine = (
+  line: string,
+  font: FontString,
+  maxWidth: number,
+): string[] => {
+  const lines: Array<string> = [];
+  const tokens = parseTokens(line);
+  const tokenIterator = tokens[Symbol.iterator]();
+
+  let currentLine = "";
+  let currentLineWidth = 0;
+
+  let iterator = tokenIterator.next();
+
+  while (!iterator.done) {
+    const token = iterator.value;
+    const testLine = currentLine + token;
+
+    // cache single codepoint whitespace, CJK or emoji width calc. as kerning should not apply here
+    const testLineWidth = isSingleCharacter(token)
+      ? currentLineWidth + charWidth.calculate(token, font)
+      : getLineWidth(testLine, font);
+
+    // build up the current line, skipping length check for possibly trailing whitespaces
+    if (/\s/.test(token) || testLineWidth <= maxWidth) {
+      currentLine = testLine;
+      currentLineWidth = testLineWidth;
+      iterator = tokenIterator.next();
+      continue;
+    }
+
+    // current line is empty => just the token (word) is longer than `maxWidth` and needs to be wrapped
+    if (!currentLine) {
+      const wrappedWord = wrapWord(token, font, maxWidth);
+      const trailingLine = wrappedWord[wrappedWord.length - 1] ?? "";
+      const precedingLines = wrappedWord.slice(0, -1);
+
+      lines.push(...precedingLines);
+
+      // trailing line of the wrapped word might still be joined with next token/s
+      currentLine = trailingLine;
+      currentLineWidth = getLineWidth(trailingLine, font);
+      iterator = tokenIterator.next();
+    } else {
+      // push & reset, but don't iterate on the next token, as we didn't use it yet!
+      lines.push(currentLine.trimEnd());
+
+      // purposefully not iterating and not setting `currentLine` to `token`, so that we could use a simple !currentLine check above
+      currentLine = "";
+      currentLineWidth = 0;
+    }
+  }
+
+  // iterator done, push the trailing line if exists
+  if (currentLine) {
+    const trailingLine = trimLine(currentLine, font, maxWidth);
+    lines.push(trailingLine);
+  }
+
+  return lines;
+};
+
+/**
+ * Wraps the word into the lines based on the given width.
+ */
+const wrapWord = (
+  word: string,
+  font: FontString,
+  maxWidth: number,
+): Array<string> => {
+  // multi-codepoint emojis are already broken apart and shouldn't be broken further
+  if (getEmojiRegex().test(word)) {
+    return [word];
+  }
+
+  satisfiesWordInvariant(word);
+
+  const lines: Array<string> = [];
+  const chars = Array.from(word);
+
+  let currentLine = "";
+  let currentLineWidth = 0;
+
+  for (const char of chars) {
+    const _charWidth = charWidth.calculate(char, font);
+    const testLineWidth = currentLineWidth + _charWidth;
+
+    if (testLineWidth <= maxWidth) {
+      currentLine = currentLine + char;
+      currentLineWidth = testLineWidth;
+      continue;
+    }
+
+    if (currentLine) {
+      lines.push(currentLine);
+    }
+
+    currentLine = char;
+    currentLineWidth = _charWidth;
+  }
+
+  if (currentLine) {
+    lines.push(currentLine);
+  }
+
+  return lines;
+};
+
+/**
+ * Similarly to browsers, does not trim all trailing whitespaces, but only those exceeding the `maxWidth`.
+ */
+const trimLine = (line: string, font: FontString, maxWidth: number) => {
+  const shouldTrimWhitespaces = getLineWidth(line, font) > maxWidth;
+
+  if (!shouldTrimWhitespaces) {
+    return line;
+  }
+
+  // defensively default to `trimeEnd` in case the regex does not match
+  let [, trimmedLine, whitespaces] = line.match(/^(.+?)(\s+)$/) ?? [
+    line,
+    line.trimEnd(),
+    "",
+  ];
+
+  let trimmedLineWidth = getLineWidth(trimmedLine, font);
+
+  for (const whitespace of Array.from(whitespaces)) {
+    const _charWidth = charWidth.calculate(whitespace, font);
+    const testLineWidth = trimmedLineWidth + _charWidth;
+
+    if (testLineWidth > maxWidth) {
+      break;
+    }
+
+    trimmedLine = trimmedLine + whitespace;
+    trimmedLineWidth = testLineWidth;
+  }
+
+  return trimmedLine;
+};
+
+/**
+ * Check if the given string is a single character.
+ *
+ * Handles multi-byte chars (é, 中) and purposefully does not handle multi-codepoint char (👨‍👩‍👧‍👦, 👩🏽‍🦰).
+ */
+const isSingleCharacter = (maybeSingleCharacter: string) => {
+  return (
+    maybeSingleCharacter.codePointAt(0) !== undefined &&
+    maybeSingleCharacter.codePointAt(1) === undefined
+  );
+};
+
+/**
+ * Invariant for the word wrapping algorithm.
+ */
+const satisfiesWordInvariant = (word: string) => {
+  if (import.meta.env.MODE === ENV.TEST || import.meta.env.DEV) {
+    if (/\s/.test(word)) {
+      throw new Error("Word should not contain any whitespaces!");
+    }
+  }
+};