@applicaster/zapp-react-native-ui-components/Components/Viewport/utils.js

Applicaster Zapp React Native ui components for the Quick Brick App

import * as React from "react";

export function callOnChildren(children, method, ...args) {
  const childMethod = React.Children.only(children).props[method];
  typeof childMethod === "function" && childMethod?.(...args);
}

export function isInViewport(
  viewportOffset,
  viewportSize,
  elementOffset,
  elementSize,
  preTriggerRatio
) {
  let isInViewPort = true;

  const preTriggerAreaSize = preTriggerRatio
    ? preTriggerRatio * viewportSize
    : 0;

  const elementEnd = elementOffset + elementSize;
  const viewportEnd = viewportOffset + viewportSize;
  const isViewportOffsetBeforeElement = viewportOffset <= elementOffset;

  if (isViewportOffsetBeforeElement) {
    isInViewPort = elementOffset - preTriggerAreaSize <= viewportEnd;
  } else {
    isInViewPort = elementEnd + preTriggerAreaSize >= viewportOffset;
  }

  return isInViewPort;
}