lassoEnd with no point in selection does not publish deselect event

[insertmike]

After selecting an empty region with the lasso, the select event is always triggered, with 0 points array:

  const select = (pointIdxs, { merge = false, preventEvent = false } = {}) => {

Internally, the function clears the selectionPoints state and triggers the deselect method:

selectedPoints = pointIdxsArr;
if (currSelectedPoints.length > 0 && selectedPoints.length === 0) {
   deselect({ preventEvent });
   return;
}

In the deselect method, the lassoClearEvent checks goes through, which clears the lasso, but since the selectedPoints array have been updated in the select method to have a length of 0, the pubSub.publish('deslect') event is never triggered.

  const deselect = ({ preventEvent = false } = {}) => {
    if (lassoClearEvent === LASSO_CLEAR_ON_DESELECT) lassoClear();
    if (selectedPoints.length) {
      if (!preventEvent) pubSub.publish('deselect');
      selectedPointsConnectionSet.clear();
      setPointConnectionColorState(selectedPoints, 0);
      selectedPoints = [];
      selectedPointsSet.clear();
      draw = true;
    }
  };

Creating a PR now.

[flekschas]

After selecting an empty region with the lasso, the select event is always triggered, with 0 points array:

This is not true. Selecting an empty region does not trigger a select event because of https://github.com/flekschas/regl-scatterplot/blob/master/src/index.js#L704-L707.

But I think I know what mean. After having select some number of points and then lassoing to select no points will clear the selection but does not trigger a deselect event.

[flekschas]

Closing this as #133 is merged