DiffClamp.js

export const diffClamp = function(
  a: Animated.Value<number>,
  min: number,
  max: number,
): AnimatedDiffClamp {
  return new AnimatedDiffClamp(a, min, max);
};

class AnimatedDiffClamp {
  constructor(a: Animated.Value<number>, min: number, max: number) {
    this.a = a;
    this.emitValue = this.lastInputVal = this.a.__getValue();
    this.min = min;
    this.max = max;
  }

  getValue(): number {
    const currentInputVal = this.a.__getValue();
    const diff = currentInputVal - this.lastInputVal;
    this.lastInputVal = currentInputVal;
    this.emitValue = Math.min(Math.max(this.emitValue + diff, this.min), this.max);
    return this.emitValue;
  }
}