onStop_() {
    if (this.ws_.isDisabled()) {
      return;
    }

    if (this.isGesture) {
      const startDistance = Math.sqrt(
        Math.pow(this.startTouches[0].x - this.startTouches[1].x, 2) +
        Math.pow(this.startTouches[0].y - this.startTouches[1].y, 2)
      );
      const endDistance = Math.sqrt(
        Math.pow(this.endTouches[0].x - this.endTouches[1].x, 2) +
        Math.pow(this.endTouches[0].y - this.endTouches[1].y, 2)
      );
      if (startDistance > endDistance) {
        // Pinch gesture
        this.ws_.toggleZoom();
      }
      this.isGesture = false;
    } else {
      const diffX = this.startX_ - this.endX_;
      const diffY = this.startY_ - this.endY_;

      // It's an horizontal drag
      if (Math.abs(diffX) > Math.abs(diffY)) {
        if (diffX < -this.ws_.options.slideOffset) {
          this.ws_.goPrev();
        } else if(diffX > this.ws_.options.slideOffset) {
          this.ws_.goNext();
        }
      }
    }
  }
Stop touch handler. Checks if it needs to make any actions.
@private