comicgen/src/interpolate.js

Add comics to your website or app with an API. Choose a character, angle, emotion and pose. Embed on your page.

// https://github.com/d3/d3-interpolate/blob/main/src/number.js
function number(a, b) {
  return (
    (a = +a),
    (b = +b),
    function (t) {
      return a * (1 - t) + b * t;
    }
  );
}

// https://github.com/d3/d3-interpolate/blob/main/src/string.js
var reA = /[-+]?(?:\d+\.?\d*|\.?\d+)(?:[eE][-+]?\d+)?/g,
  reB = new RegExp(reA.source, "g");

function zero(b) {
  return function () {
    return b;
  };
}

function one(b) {
  return function (t) {
    return b(t) + "";
  };
}

function string(a, b) {
  var bi = (reA.lastIndex = reB.lastIndex = 0), // scan index for next number in b
    am, // current match in a
    bm, // current match in b
    bs, // string preceding current number in b, if any
    i = -1, // index in s
    s = [], // string constants and placeholders
    q = []; // number interpolators

  // Coerce inputs to strings.
  (a = a + ""), (b = b + "");

  // Interpolate pairs of numbers in a & b.
  while ((am = reA.exec(a)) && (bm = reB.exec(b))) {
    if ((bs = bm.index) > bi) {
      // a string precedes the next number in b
      bs = b.slice(bi, bs);
      if (s[i])
        s[i] += bs; // coalesce with previous string
      else s[++i] = bs;
    }
    if ((am = am[0]) === (bm = bm[0])) {
      // numbers in a & b match
      if (s[i])
        s[i] += bm; // coalesce with previous string
      else s[++i] = bm;
    } else {
      // interpolate non-matching numbers
      s[++i] = null;
      q.push({ i: i, x: number(am, bm) });
    }
    bi = reB.lastIndex;
  }

  // Add remains of b.
  if (bi < b.length) {
    bs = b.slice(bi);
    if (s[i])
      s[i] += bs; // coalesce with previous string
    else s[++i] = bs;
  }

  // Special optimization for only a single match.
  // Otherwise, interpolate each of the numbers and rejoin the string.
  return s.length < 2
    ? q[0]
      ? one(q[0].x)
      : zero(b)
    : ((b = q.length),
      function (t) {
        for (var i = 0, o; i < b; ++i) s[(o = q[i]).i] = o.x(t);
        return s.join("");
      });
}

module.exports = {
  number,
  string,
};