@nebula.gl/layers/src/mode-handlers/translate-handler.ts

A suite of 3D-enabled data editing layers, suitable for deck.gl

import turfBearing from '@turf/bearing';
import turfDistance from '@turf/distance';
import turfTransformTranslate from '@turf/transform-translate';
import { point } from '@turf/helpers';
import { FeatureCollection, Position } from '@nebula.gl/edit-modes';
import { PointerMoveEvent, StartDraggingEvent, StopDraggingEvent } from '../event-types';
import { EditAction, ModeHandler } from './mode-handler';

// TODO edit-modes: delete handlers once EditMode fully implemented
export class TranslateHandler extends ModeHandler {
  _geometryBeforeTranslate: FeatureCollection | null | undefined;
  _isTranslatable: boolean;

  handlePointerMove(
    event: PointerMoveEvent
  ): { editAction: EditAction | null | undefined; cancelMapPan: boolean } {
    let editAction: EditAction | null | undefined = null;

    this._isTranslatable =
      Boolean(this._geometryBeforeTranslate) || this.isSelectionPicked(event.picks);

    if (!this._isTranslatable || !event.pointerDownGroundCoords) {
      // Nothing to do
      return { editAction: null, cancelMapPan: false };
    }

    if (event.isDragging && this._geometryBeforeTranslate) {
      // Translate the geometry
      editAction = this.getTranslateAction(
        event.pointerDownGroundCoords,
        event.groundCoords,
        'translating'
      );
    }

    return { editAction, cancelMapPan: true };
  }

  handleStartDragging(event: StartDraggingEvent): EditAction | null | undefined {
    if (!this._isTranslatable) {
      return null;
    }

    this._geometryBeforeTranslate = this.getSelectedFeaturesAsFeatureCollection();
    return null;
  }

  handleStopDragging(event: StopDraggingEvent): EditAction | null | undefined {
    let editAction: EditAction | null | undefined = null;

    if (this._geometryBeforeTranslate) {
      // Translate the geometry
      editAction = this.getTranslateAction(
        event.pointerDownGroundCoords,
        event.groundCoords,
        'translated'
      );
      this._geometryBeforeTranslate = null;
    }

    return editAction;
  }

  getCursor({ isDragging }: { isDragging: boolean }): string {
    if (this._isTranslatable) {
      return 'move';
    }
    return isDragging ? 'grabbing' : 'grab';
  }

  getTranslateAction(
    startDragPoint: Position,
    currentPoint: Position,
    editType: string
  ): EditAction | null | undefined {
    if (!this._geometryBeforeTranslate) {
      return null;
    }
    const p1 = point(startDragPoint);
    const p2 = point(currentPoint);

    const distanceMoved = turfDistance(p1, p2);
    const direction = turfBearing(p1, p2);

    const movedFeatures = turfTransformTranslate(
      // @ts-ignore
      this._geometryBeforeTranslate,
      distanceMoved,
      direction
    );

    let updatedData = this.getImmutableFeatureCollection();

    const selectedIndexes = this.getSelectedFeatureIndexes();
    for (let i = 0; i < selectedIndexes.length; i++) {
      const selectedIndex = selectedIndexes[i];
      const movedFeature = movedFeatures.features[i];
      updatedData = updatedData.replaceGeometry(selectedIndex, movedFeature.geometry);
    }

    return {
      updatedData: updatedData.getObject(),
      editType,
      featureIndexes: selectedIndexes,
      editContext: null,
    };
  }
}