react-native-wagmi-charts/lib/module/charts/line/Cursor.js

A sweet candlestick chart for React Native

import React from 'react';
import Animated, { runOnJS } from 'react-native-reanimated';
import { Gesture, GestureDetector } 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';
import { useEffect } from 'react';
export const CursorContext = /*#__PURE__*/ React.createContext({
  type: '',
});
LineChartCursor.displayName = 'LineChartCursor';
export function LineChartCursor({
  children,
  snapToPoint,
  type,
  at,
  shouldCancelWhenOutside = false,
  minDurationMs = 0,
  onActivated,
  onEnded,
}) {
  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 }) => {
    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 curveSegment =
      closestIndex > 0 && parsedPath.curves[closestPathCurve]
        ? parsedPath.curves[closestPathCurve]
        : null;
    const newXPosition = (curveSegment ? curveSegment.to : parsedPath.move).x;
    // Update values
    currentIndex.value = closestIndex;
    currentX.value = newXPosition;
  };
  useEffect(() => {
    if (at !== undefined) {
      const xPosition = scaleX(at);
      runOnJS(linearScalePositionAndIndex)({
        xPosition,
      });
      isActive.value = true;
    }
  }, [at, scaleX]);
  const updatePosition = (xPosition) => {
    'worklet';

    if (parsedPath) {
      // 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;
      }
    }
  };
  const longPressGesture = Gesture.LongPress()
    .minDuration(minDurationMs ?? 0)
    .maxDistance(999999)
    .shouldCancelWhenOutside(shouldCancelWhenOutside)
    .onStart((event) => {
      'worklet';

      if (parsedPath) {
        const xPosition = Math.max(0, event.x <= width ? event.x : width);
        isActive.value = true;
        updatePosition(xPosition);
        if (onActivated) {
          runOnJS(onActivated)();
        }
      }
    })
    .onTouchesMove((event) => {
      'worklet';

      if (
        parsedPath &&
        isActive.value &&
        event.allTouches.length > 0 &&
        event.allTouches[0]
      ) {
        const touchX = event.allTouches[0].x;
        const xPosition = Math.max(0, touchX <= width ? touchX : width);
        updatePosition(xPosition);
      }
    })
    .onEnd(() => {
      'worklet';

      isActive.value = false;
      currentIndex.value = -1;
      if (onEnded) {
        runOnJS(onEnded)();
      }
    });
  return /*#__PURE__*/ React.createElement(
    CursorContext.Provider,
    {
      value: {
        type,
      },
    },
    /*#__PURE__*/ React.createElement(
      GestureDetector,
      {
        gesture: longPressGesture,
      },
      /*#__PURE__*/ React.createElement(
        Animated.View,
        {
          style: StyleSheet.absoluteFill,
        },
        children
      )
    )
  );
}
//# sourceMappingURL=Cursor.js.map