Persist LineChart.CursorCrosshair

[ErionTp]

Hello, it would be great if there will be a property to allow persisting LineChart.CursorCrosshair

something like this:

import * as React from 'react';

import Animated, {
  runOnJS,
  useAnimatedGestureHandler,
} from 'react-native-reanimated';
import {
  GestureEvent,
  LongPressGestureHandler,
  LongPressGestureHandlerEventPayload,
  LongPressGestureHandlerProps,
} from 'react-native-gesture-handler';

import { LineChartDimensionsContext } from './Chart';
import { StyleSheet } from 'react-native';
import { bisectCenter } from 'd3-array';
import { scaleLinear } from 'd3-scale';
import { useLineChart } from './useLineChart';

export type LineChartCursorProps = LongPressGestureHandlerProps & {
  children: React.ReactNode;
  type: 'line' | 'crosshair';
  persistCursorCrosshair?:boolean
  // Does not work on web due to how the Cursor operates on web
  snapToPoint?: boolean;
};

export const CursorContext = React.createContext({ type: '' });

LineChartCursor.displayName = 'LineChartCursor';

export function LineChartCursor({
  children,
  snapToPoint,
  type,
  persistCursorCrosshair,
  ...props
}: LineChartCursorProps) {
  const { pathWidth: width, parsedPath } = React.useContext(
    LineChartDimensionsContext
  );
  const { currentX, currentIndex, isActive, data, xDomain } = useLineChart();
  const xValues = React.useMemo(
    () => (data ?? []).map(({ timestamp }, i) => (xDomain ? timestamp : i)),
    [data, xDomain]
  );

  // Same scale as in /src/charts/line/utils/getPath.ts
  const scaleX = React.useMemo(() => {
    const domainArray = xDomain ?? [0, xValues.length];
    return scaleLinear().domain(domainArray).range([0, width]);
  }, [width, xDomain, xValues.length]);

  const linearScalePositionAndIndex = ({
    xPosition,
  }: {
    xPosition: number;
  }) => {
    if (!parsedPath) {
      return;
    }

    // Calculate a scaled timestamp for the current touch position
    const xRelative = scaleX.invert(xPosition);

    const closestIndex = bisectCenter(xValues, xRelative);
    const pathDataDelta = Math.abs(parsedPath.curves.length - xValues.length); // sometimes there is a difference between data length and number of path curves.
    const closestPathCurve = Math.max(
      Math.min(closestIndex, parsedPath.curves.length + 1) - pathDataDelta,
      0
    );

    const newXPosition = (
      closestIndex > 0
        ? parsedPath.curves[closestPathCurve]!.to
        : parsedPath.move
    ).x;
    // Update values
    currentIndex.value = closestIndex;
    currentX.value = newXPosition;
  };

  const onGestureEvent = useAnimatedGestureHandler<
    GestureEvent<LongPressGestureHandlerEventPayload>
  >({
    onActive: ({ x }) => {
      if (parsedPath) {
        const xPosition = Math.max(0, x <= width ? x : width);
        isActive.value = true;

        // on Web, we could drag the cursor to be negative, breaking it
        // so we clamp the index at 0 to fix it
        // https://github.com/coinjar/react-native-wagmi-charts/issues/24
        const minIndex = 0;
        const boundedIndex = Math.max(
          minIndex,
          Math.round(xPosition / width / (1 / (data ? data.length - 1 : 1)))
        );

        if (snapToPoint) {
          // We have to run this on the JS thread unfortunately as the scaleLinear functions won't work on UI thread
          runOnJS(linearScalePositionAndIndex)({ xPosition });
        } else if (!snapToPoint) {
          currentX.value = xPosition;
          currentIndex.value = boundedIndex;
        }
      }
    },
    onEnd: () => {
      if(!persistCursorCrosshair)
      {
        isActive.value = false
      }
      currentIndex.value = -1;
    },
  });

  return (
    <CursorContext.Provider value={{ type }}>
      <LongPressGestureHandler
        minDurationMs={0}
        maxDist={999999}
        onGestureEvent={onGestureEvent}
        shouldCancelWhenOutside={false}
        {...props}
      >
        <Animated.View style={StyleSheet.absoluteFill}>
          {children}
        </Animated.View>
      </LongPressGestureHandler>
    </CursorContext.Provider>
  );
}

In the above component I've added persistCursorCrosshair