ant-design-vue/components/style/color/bezierEasing.less

/* stylelint-disable declaration-bang-space-before,no-duplicate-selectors */
.bezierEasingMixin() {
  @functions: ~`(function() {
    var NEWTON_ITERATIONS = 4;
    var NEWTON_MIN_SLOPE = 0.001;
    var SUBDIVISION_PRECISION = 0.0000001;
    var SUBDIVISION_MAX_ITERATIONS = 10;
  
    var kSplineTableSize = 11;
    var kSampleStepSize = 1.0 / (kSplineTableSize - 1.0);
  
    var float32ArraySupported = typeof Float32Array === 'function';
  
    function A (aA1, aA2) { return 1.0 - 3.0 * aA2 + 3.0 * aA1; }
    function B (aA1, aA2) { return 3.0 * aA2 - 6.0 * aA1; }
    function C (aA1)      { return 3.0 * aA1; }
  
    // Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
    function calcBezier (aT, aA1, aA2) { return ((A(aA1, aA2) * aT + B(aA1, aA2)) * aT + C(aA1)) * aT; }
  
    // Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
    function getSlope (aT, aA1, aA2) { return 3.0 * A(aA1, aA2) * aT * aT + 2.0 * B(aA1, aA2) * aT + C(aA1); }
  
    function binarySubdivide (aX, aA, aB, mX1, mX2) {
      var currentX, currentT, i = 0;
      do {
        currentT = aA + (aB - aA) / 2.0;
        currentX = calcBezier(currentT, mX1, mX2) - aX;
        if (currentX > 0.0) {
          aB = currentT;
        } else {
          aA = currentT;
        }
      } while (Math.abs(currentX) > SUBDIVISION_PRECISION && ++i < SUBDIVISION_MAX_ITERATIONS);
      return currentT;
    }
  
    function newtonRaphsonIterate (aX, aGuessT, mX1, mX2) {
     for (var i = 0; i < NEWTON_ITERATIONS; ++i) {
       var currentSlope = getSlope(aGuessT, mX1, mX2);
       if (currentSlope === 0.0) {
         return aGuessT;
       }
       var currentX = calcBezier(aGuessT, mX1, mX2) - aX;
       aGuessT -= currentX / currentSlope;
     }
     return aGuessT;
    }
  
    var BezierEasing = function (mX1, mY1, mX2, mY2) {
      if (!(0 <= mX1 && mX1 <= 1 && 0 <= mX2 && mX2 <= 1)) {
        throw new Error('bezier x values must be in [0, 1] range');
      }
  
      // Precompute samples table
      var sampleValues = float32ArraySupported ? new Float32Array(kSplineTableSize) : new Array(kSplineTableSize);
      if (mX1 !== mY1 || mX2 !== mY2) {
        for (var i = 0; i < kSplineTableSize; ++i) {
          sampleValues[i] = calcBezier(i * kSampleStepSize, mX1, mX2);
        }
      }
  
      function getTForX (aX) {
        var intervalStart = 0.0;
        var currentSample = 1;
        var lastSample = kSplineTableSize - 1;
  
        for (; currentSample !== lastSample && sampleValues[currentSample] <= aX; ++currentSample) {
          intervalStart += kSampleStepSize;
        }
        --currentSample;
  
        // Interpolate to provide an initial guess for t
        var dist = (aX - sampleValues[currentSample]) / (sampleValues[currentSample + 1] - sampleValues[currentSample]);
        var guessForT = intervalStart + dist * kSampleStepSize;
  
        var initialSlope = getSlope(guessForT, mX1, mX2);
        if (initialSlope >= NEWTON_MIN_SLOPE) {
          return newtonRaphsonIterate(aX, guessForT, mX1, mX2);
        } else if (initialSlope === 0.0) {
          return guessForT;
        } else {
          return binarySubdivide(aX, intervalStart, intervalStart + kSampleStepSize, mX1, mX2);
        }
      }
  
      return function BezierEasing (x) {
        if (mX1 === mY1 && mX2 === mY2) {
          return x; // linear
        }
        // Because JavaScript number are imprecise, we should guarantee the extremes are right.
        if (x === 0) {
          return 0;
        }
        if (x === 1) {
          return 1;
        }
        return calcBezier(getTForX(x), mY1, mY2);
      };
    };
  
    this.colorEasing = BezierEasing(0.26, 0.09, 0.37, 0.18);
    // less 3 requires a return
    return '';
  })()`;
  }
  // It is hacky way to make this function will be compiled preferentially by less
  // resolve error: `ReferenceError: colorPalette is not defined`
  // https://github.com/ant-design/ant-motion/issues/44
  .bezierEasingMixin();