react-native-reanimated/src/platformFunctions/measure.ts

More powerful alternative to Animated library for React Native.

'use strict';
import type { Component } from 'react';

import type { MeasuredDimensions, ShadowNodeWrapper } from '../commonTypes';
import type {
  AnimatedRef,
  AnimatedRefOnJS,
  AnimatedRefOnUI,
} from '../hook/commonTypes';
import { logger } from '../logger';
import {
  isChromeDebugger,
  isFabric,
  isJest,
  shouldBeUseWeb,
} from '../PlatformChecker';

type Measure = <T extends Component>(
  animatedRef: AnimatedRef<T>
) => MeasuredDimensions | null;

/**
 * Lets you synchronously get the dimensions and position of a view on the
 * screen.
 *
 * @param animatedRef - An [animated
 *   ref](https://docs.swmansion.com/react-native-reanimated/docs/core/useAnimatedRef#returns)
 *   connected to the component you'd want to get the measurements from.
 * @returns An object containing component measurements or null when the
 *   measurement couldn't be performed- {@link MeasuredDimensions}.
 * @see https://docs.swmansion.com/react-native-reanimated/docs/advanced/measure/
 */
export let measure: Measure;

function measureFabric(animatedRef: AnimatedRefOnJS | AnimatedRefOnUI) {
  'worklet';
  if (!_WORKLET) {
    return null;
  }

  const viewTag = animatedRef();
  if (viewTag === -1) {
    logger.warn(
      `The view with tag ${viewTag} is not a valid argument for measure(). This may be because the view is not currently rendered, which may not be a bug (e.g. an off-screen FlatList item).`
    );
    return null;
  }

  const measured = global._measureFabric!(viewTag as ShadowNodeWrapper);
  if (measured === null) {
    logger.warn(
      `The view has some undefined, not-yet-computed or meaningless value of \`LayoutMetrics\` type. This may be because the view is not currently rendered, which may not be a bug (e.g. an off-screen FlatList item).`
    );
    return null;
  } else if (measured.x === -1234567) {
    logger.warn(
      `The view returned an invalid measurement response. Please make sure the view is currently rendered.`
    );
    return null;
  } else if (isNaN(measured.x)) {
    logger.warn(
      `The view gets view-flattened on Android. To disable view-flattening, set \`collapsable={false}\` on this component.`
    );
    return null;
  } else {
    return measured;
  }
}

function measurePaper(animatedRef: AnimatedRefOnJS | AnimatedRefOnUI) {
  'worklet';
  if (!_WORKLET) {
    return null;
  }

  const viewTag = animatedRef();
  if (viewTag === -1) {
    logger.warn(
      `The view with tag ${viewTag} is not a valid argument for measure(). This may be because the view is not currently rendered, which may not be a bug (e.g. an off-screen FlatList item).`
    );
    return null;
  }

  const measured = global._measurePaper!(viewTag as number);
  if (measured === null) {
    logger.warn(
      `The view with tag ${
        viewTag as number
      } has some undefined, not-yet-computed or meaningless value of \`LayoutMetrics\` type. This may be because the view is not currently rendered, which may not be a bug (e.g. an off-screen FlatList item).`
    );
    return null;
  } else if (measured.x === -1234567) {
    logger.warn(
      `The view with tag ${
        viewTag as number
      } returned an invalid measurement response. Please make sure the view is currently rendered.`
    );
    return null;
  } else if (isNaN(measured.x)) {
    logger.warn(
      `The view with tag ${
        viewTag as number
      } gets view-flattened on Android. To disable view-flattening, set \`collapsable={false}\` on this component.`
    );
    return null;
  } else {
    return measured;
  }
}

function measureJest() {
  logger.warn('measure() cannot be used with Jest.');
  return null;
}

function measureChromeDebugger() {
  logger.warn('measure() cannot be used with Chrome Debugger.');
  return null;
}

function measureDefault() {
  logger.warn('measure() is not supported on this configuration.');
  return null;
}

if (!shouldBeUseWeb()) {
  // Those assertions are actually correct since on Native platforms `AnimatedRef` is
  // mapped as a different function in `shareableMappingCache` and
  // TypeScript is not able to infer that.
  if (isFabric()) {
    measure = measureFabric as unknown as Measure;
  } else {
    measure = measurePaper as unknown as Measure;
  }
} else if (isJest()) {
  measure = measureJest;
} else if (isChromeDebugger()) {
  measure = measureChromeDebugger;
} else {
  measure = measureDefault;
}