addToDrawing_(coordinate) {
    const geometry = this.sketchFeature_.getGeometry();
    const projection = this.getMap().getView().getProjection();
    let done;
    let coordinates;
    const mode = this.mode_;
    if (mode === 'LineString' || mode === 'Circle') {
      this.finishCoordinate_ = coordinate.slice();
      coordinates = /** @type {LineCoordType} */ (this.sketchCoords_);
      if (coordinates.length >= this.maxPoints_) {
        if (this.freehand_) {
          coordinates.pop();
        } else {
          done = true;
        }
      }
      coordinates.push(coordinate.slice());
      this.geometryFunction_(coordinates, geometry, projection);
    } else if (mode === 'Polygon') {
      coordinates = /** @type {PolyCoordType} */ (this.sketchCoords_)[0];
      if (coordinates.length >= this.maxPoints_) {
        if (this.freehand_) {
          coordinates.pop();
        } else {
          done = true;
        }
      }
      coordinates.push(coordinate.slice());
      if (done) {
        this.finishCoordinate_ = coordinates[0];
      }
      this.geometryFunction_(this.sketchCoords_, geometry, projection);
    }
    this.createOrUpdateSketchPoint_(coordinate.slice());
    this.updateSketchFeatures_();
    if (done) {
      return this.finishDrawing();
    }
    return this.sketchFeature_;
  }
Add a new coordinate to the drawing.
@param {!PointCoordType} coordinate Coordinate
@return {Feature<import("../geom/SimpleGeometry.js").default>} The sketch feature.
@private