getting back bounding box coords of found indices?

[leeoniya]

hey @mourner

i'm currently reading back bounding box coords to render a hover rect over the matched index, it looks something like below bound to mousemove. this works well enough for my-sized datasets. i assume there isn't anything more efficient than let offs = index._indices.indexOf(idx) * 4; besides wasting mem/cpu to store some kind of additional mapping between returned index and coords externally?

function searchFlat(xMin, yMin, xMax, yMax) {
  let flatIdxs = index.search(xMin, yMin, xMax ?? xMin + 1, yMax ?? yMin + 1);

  if (flatIdxs.length > 0) {
    for (let j = 0; j < flatIdxs.length; j++) {
      let idx = flatIdxs[j];

      let offs = index._indices.indexOf(idx) * 4;
      let minX = index._boxes[offs++];
      let minY = index._boxes[offs++];
      let maxX = index._boxes[offs++];
      let maxY = index._boxes[offs++];

      if (hoveredIdx !== idx) {
        hoverStyle.display = "block";

        hoverStyle.top = `${Math.round(minY / pxRatio)}px`;
        hoverStyle.left = `${Math.round(minX / pxRatio)}px`;
        hoverStyle.width = `${Math.round((maxX - minX) / pxRatio)}px`;
        hoverStyle.height = `${Math.round((maxY - minY) / pxRatio)}px`;

        hoveredIdx = idx;
      }

      break;
    }
  }
  else {
    hoverStyle.display = "none";
    hoveredIdx = null;
  }
}

[mourner]

Yeah, there's no fast way to get original coords from the index. indexOf is gross — as a workaround, I'd rather generate a Uint16/32Array that maps an id to its position in _indices/_boxes array. Linear to generate (just a loop over ids once after indexing), doesn't take much space, and allows for constant time lookups.