@tamagui/react-native-web-lite/dist/esm/vendor/react-native/VirtualizeUtils/index.mjs

React Native for Web

function elementsThatOverlapOffsets(offsets, props, getFrameMetrics, zoomScale = 1) {
  const itemCount = props.getItemCount(props.data);
  const result = [];
  for (let offsetIndex = 0; offsetIndex < offsets.length; offsetIndex++) {
    const currentOffset = offsets[offsetIndex];
    let left = 0;
    let right = itemCount - 1;
    while (left <= right) {
      const mid = left + (right - left >>> 1);
      const frame = getFrameMetrics(mid, props);
      const scaledOffsetStart = frame.offset * zoomScale;
      const scaledOffsetEnd = (frame.offset + frame.length) * zoomScale;
      if (mid === 0 && currentOffset < scaledOffsetStart || mid !== 0 && currentOffset <= scaledOffsetStart) {
        right = mid - 1;
      } else if (currentOffset > scaledOffsetEnd) {
        left = mid + 1;
      } else {
        result[offsetIndex] = mid;
        break;
      }
    }
  }
  return result;
}
function newRangeCount(prev, next) {
  return next.last - next.first + 1 - Math.max(0, 1 + Math.min(next.last, prev.last) - Math.max(next.first, prev.first));
}
function computeWindowedRenderLimits(props, maxToRenderPerBatch, windowSize, prev, getFrameMetricsApprox, scrollMetrics) {
  const itemCount = props.getItemCount(props.data);
  if (itemCount === 0) {
    return {
      first: 0,
      last: -1
    };
  }
  const {
    offset,
    velocity,
    visibleLength,
    zoomScale = 1
  } = scrollMetrics;
  const visibleBegin = Math.max(0, offset);
  const visibleEnd = visibleBegin + visibleLength;
  const overscanLength = (windowSize - 1) * visibleLength;
  const leadFactor = 0.5;
  const fillPreference = velocity > 1 ? "after" : velocity < -1 ? "before" : "none";
  const overscanBegin = Math.max(0, visibleBegin - (1 - leadFactor) * overscanLength);
  const overscanEnd = Math.max(0, visibleEnd + leadFactor * overscanLength);
  const lastItemOffset = getFrameMetricsApprox(itemCount - 1, props).offset * zoomScale;
  if (lastItemOffset < overscanBegin) {
    return {
      first: Math.max(0, itemCount - 1 - maxToRenderPerBatch),
      last: itemCount - 1
    };
  }
  let [overscanFirst, first, last, overscanLast] = elementsThatOverlapOffsets([overscanBegin, visibleBegin, visibleEnd, overscanEnd], props, getFrameMetricsApprox, zoomScale);
  overscanFirst = overscanFirst == null ? 0 : overscanFirst;
  first = first == null ? Math.max(0, overscanFirst) : first;
  overscanLast = overscanLast == null ? itemCount - 1 : overscanLast;
  last = last == null ? Math.min(overscanLast, first + maxToRenderPerBatch - 1) : last;
  const visible = {
    first,
    last
  };
  let newCellCount = newRangeCount(prev, visible);
  while (true) {
    if (first <= overscanFirst && last >= overscanLast) {
      break;
    }
    const maxNewCells = newCellCount >= maxToRenderPerBatch;
    const firstWillAddMore = first <= prev.first || first > prev.last;
    const firstShouldIncrement = first > overscanFirst && (!maxNewCells || !firstWillAddMore);
    const lastWillAddMore = last >= prev.last || last < prev.first;
    const lastShouldIncrement = last < overscanLast && (!maxNewCells || !lastWillAddMore);
    if (maxNewCells && !firstShouldIncrement && !lastShouldIncrement) {
      break;
    }
    if (firstShouldIncrement && !(fillPreference === "after" && lastShouldIncrement && lastWillAddMore)) {
      if (firstWillAddMore) {
        newCellCount++;
      }
      first--;
    }
    if (lastShouldIncrement && !(fillPreference === "before" && firstShouldIncrement && firstWillAddMore)) {
      if (lastWillAddMore) {
        newCellCount++;
      }
      last++;
    }
  }
  if (!(last >= first && first >= 0 && last < itemCount && first >= overscanFirst && last <= overscanLast && first <= visible.first && last >= visible.last)) {
    throw new Error("Bad window calculation " + JSON.stringify({
      first,
      last,
      itemCount,
      overscanFirst,
      overscanLast,
      visible
    }));
  }
  return {
    first,
    last
  };
}
function keyExtractor(item, index) {
  if (typeof item === "object" && item?.key != null) {
    return item.key;
  }
  if (typeof item === "object" && item?.id != null) {
    return item.id;
  }
  return String(index);
}
export { computeWindowedRenderLimits, elementsThatOverlapOffsets, keyExtractor, newRangeCount };
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