src/buttons/AbstractZoomButton.js
/**
   * @summary Continues zooming as long as the user presses the button
   * @private
   */
@summary Continues zooming as long as the user presses the button
@private
@summary Continues zooming as long as the user presses the button @private
__startLongPressInterval() {
    if (!this.prop.buttondown) {
      return;
    }
    const end = this.prop.value < 0 ? 0 : 100;
    this.prop.longPressAnimation = new Animation({
      properties: {
        zoom: { start: this.psv.prop.zoomLvl, end: end },
      },
      duration  : 1500 * Math.abs(this.psv.prop.zoomLvl - end) / 100,
      easing    : 'linear',
      onTick    : (properties) => {
        this.psv.zoom(properties.zoom);
      },
    })
      .catch(() => {}); 
  }
__startLongPressInterval ( ) { if ( ! this . prop . buttondown ) { return ; } const end = this . prop . value < 0 ? 0 : 100 ; this . prop . longPressAnimation = new Animation ( { properties : { zoom : { start : this . psv . prop . zoomLvl , end : end } , } , duration : 1500 * Math . abs ( this . psv . prop . zoomLvl - end ) / 100 , easing : 'linear' , onTick : ( properties ) => { this . psv . zoom ( properties . zoom ) ; } , } ) . catch ( ( ) => { } ) ; }
@summary Continues zooming as long as the user presses the button
 @private
@summary Continues zooming as long as the user presses the button @private
// ignore cancellation