grafana-jool/public/app/features/explore/TraceView/useViewRange.ts

import { useCallback, useState } from 'react';
import { ViewRangeTimeUpdate, ViewRange } from '@jaegertracing/jaeger-ui-components';

/**
 * Controls state of the zoom function that can be used through minimap in header or on the timeline. ViewRange contains
 * state not only for current range that is showing but range that is currently being selected by the user.
 */
export function useViewRange() {
  const [viewRange, setViewRange] = useState<ViewRange>({
    time: {
      current: [0, 1],
    },
  });

  const updateNextViewRangeTime = useCallback(function updateNextViewRangeTime(update: ViewRangeTimeUpdate) {
    setViewRange(
      (prevRange): ViewRange => {
        const time = { ...prevRange.time, ...update };
        return { ...prevRange, time };
      }
    );
  }, []);

  const updateViewRangeTime = useCallback(function updateViewRangeTime(start: number, end: number) {
    const current: [number, number] = [start, end];
    const time = { current };
    setViewRange(
      (prevRange): ViewRange => {
        return { ...prevRange, time };
      }
    );
  }, []);

  return { viewRange, updateViewRangeTime, updateNextViewRangeTime };
}