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interest in a "getFractionalVisibleRange" method: #217
Description
In my local fork of react list I wrote a helper method based on getVisibleRange. It is useful for me because I'm making a minimap of the whole list that needs to show exactly what is being shown in the list. This is contrived and fake data, but I think you can see the general idea:
The blue highlight layer is tracking the scroll percentage and to get the fraction of the scroll, I use getFractionalVisibleRange:
Here it is:
getFractionalVisibleRange() {
const { from, size } = this.state;
const { start, end } = this.getStartAndEnd(0);
const cache = {};
let first, last;
for (let i = from; i < from + size; ++i) {
const itemStart = this.getSpaceBefore(i, cache);
const itemEnd = itemStart + this.getSizeOf(i);
if (first == null && itemEnd > start)
first = i + 1 - (itemEnd - start) / (itemEnd - itemStart);
if (first != null && itemStart < end)
last = i - (itemEnd - end) / (itemEnd - itemStart);
}
return [first, last];
}Anyways, I thought it might be useful to someone else or could maybe even be added to the library.
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