_changeSlide(event) {
    const changePosition = event.screenX;
    const diffPosition = changePosition - this.firstPosition;
    let touchPx = this.firstLeft + diffPosition;
    touchPx = touchPx > this.rangeWidth ? this.rangeWidth : touchPx;
    touchPx = touchPx < 0 ? 0 : touchPx;

    this.pointer.style.left = `${touchPx}px`;
    this.subbar.style.right = `${this.rangeWidth - touchPx}px`;

    const ratio = touchPx / this.rangeWidth;
    const resultValue = this._absMax * ratio + this._min;
    const value = this._useDecimal ? resultValue : toInteger(resultValue);
    const isValueChanged = this.value !== value;

    if (isValueChanged) {
      this.value = value;
      if (this.realTimeEvent) {
        this.fire('change', this._value, false);
      }
    }
  }
change angle event
@param {object} event - change event
@private