@tamagui/react-native-web-lite
Version:
React Native for Web
73 lines (72 loc) • 3.91 kB
JavaScript
function elementsThatOverlapOffsets(offsets, props, getFrameMetrics) {
for (var zoomScale = arguments.length > 3 && arguments[3] !== void 0 ? arguments[3] : 1, itemCount = props.getItemCount(props.data), result = [], offsetIndex = 0; offsetIndex < offsets.length; offsetIndex++) for (var currentOffset = offsets[offsetIndex], left = 0, right = itemCount - 1; left <= right;) {
var mid = left + (right - left >>> 1),
frame = getFrameMetrics(mid, props),
scaledOffsetStart = frame.offset * zoomScale,
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) {
var itemCount = props.getItemCount(props.data);
if (itemCount === 0) return {
first: 0,
last: -1
};
var {
offset,
velocity,
visibleLength,
zoomScale = 1
} = scrollMetrics,
visibleBegin = Math.max(0, offset),
visibleEnd = visibleBegin + visibleLength,
overscanLength = (windowSize - 1) * visibleLength,
leadFactor = 0.5,
fillPreference = velocity > 1 ? "after" : velocity < -1 ? "before" : "none",
overscanBegin = Math.max(0, visibleBegin - (1 - leadFactor) * overscanLength),
overscanEnd = Math.max(0, visibleEnd + leadFactor * overscanLength),
lastItemOffset = getFrameMetricsApprox(itemCount - 1, props).offset * zoomScale;
if (lastItemOffset < overscanBegin) return {
first: Math.max(0, itemCount - 1 - maxToRenderPerBatch),
last: itemCount - 1
};
var [overscanFirst, first, last, overscanLast] = elementsThatOverlapOffsets([overscanBegin, visibleBegin, visibleEnd, overscanEnd], props, getFrameMetricsApprox, zoomScale);
overscanFirst = overscanFirst ?? 0, first = first ?? Math.max(0, overscanFirst), overscanLast = overscanLast ?? itemCount - 1, last = last ?? Math.min(overscanLast, first + maxToRenderPerBatch - 1);
for (var visible = {
first,
last
}, newCellCount = newRangeCount(prev, visible); !(first <= overscanFirst && last >= overscanLast);) {
var maxNewCells = newCellCount >= maxToRenderPerBatch,
firstWillAddMore = first <= prev.first || first > prev.last,
firstShouldIncrement = first > overscanFirst && (!maxNewCells || !firstWillAddMore),
lastWillAddMore = last >= prev.last || last < prev.first,
lastShouldIncrement = last < overscanLast && (!maxNewCells || !lastWillAddMore);
if (maxNewCells && !firstShouldIncrement && !lastShouldIncrement) break;
firstShouldIncrement && !(fillPreference === "after" && lastShouldIncrement && lastWillAddMore) && (firstWillAddMore && newCellCount++, first--), lastShouldIncrement && !(fillPreference === "before" && firstShouldIncrement && firstWillAddMore) && (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) {
return typeof item == "object" && item?.key != null ? item.key : typeof item == "object" && item?.id != null ? item.id : String(index);
}
export { computeWindowedRenderLimits, elementsThatOverlapOffsets, keyExtractor, newRangeCount };
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