feat: add DrawLineStringByDraggingMode

Author: ben-xD

docs/api-reference/modes/overview.md

@@ -113,6 +113,10 @@ User can draw a new `Polygon` feature with 90 degree corners (right angle) by cl
 
 User can draw a new `Polygon` feature by dragging (similar to the lasso tool commonly found in photo editing software).
 
+## [DrawLineStringByDraggingMode](https://github.com/uber/nebula.gl/blob/master/modules/edit-modes/src/lib/draw-line-string-by-dragging-mode.ts)
+
+User can draw a new `LineString` feature by dragging (similar to the pencil tool commonly found in sketching software).
+
 ### ModeConfig
 
 The following options can be provided in the `modeConfig` object:

examples/advanced/src/example.tsx

@@ -34,6 +34,7 @@ import {
   DrawRectangleUsingThreePointsMode,
   Draw90DegreePolygonMode,
   DrawPolygonByDraggingMode,
+  DrawLineStringByDraggingMode,
   MeasureDistanceMode,
   MeasureAreaMode,
   MeasureAngleMode,
@@ -105,6 +106,7 @@ const ALL_MODES: any = [
       { label: 'Draw Polygon', mode: DrawPolygonMode },
       { label: 'Draw 90° Polygon', mode: Draw90DegreePolygonMode },
       { label: 'Draw Polygon By Dragging', mode: DrawPolygonByDraggingMode },
+      { label: 'Draw LineString By Dragging', mode: DrawLineStringByDraggingMode },
       { label: 'Draw Rectangle', mode: DrawRectangleMode },
       { label: 'Draw Rectangle From Center', mode: DrawRectangleFromCenterMode },
       { label: 'Draw Rectangle Using 3 Points', mode: DrawRectangleUsingThreePointsMode },
@@ -966,6 +968,11 @@ export default class Example extends React.Component<
         ...modeConfig,
         throttleMs: 100,
       };
+    } else if (mode === DrawLineStringByDraggingMode) {
+      modeConfig = {
+        ...modeConfig,
+        throttleMs: 100,
+      };
     }
 
     // Demonstrate how to override sub layer properties

modules/edit-modes/src/index.ts

@@ -36,6 +36,7 @@ export { DrawEllipseUsingThreePointsMode } from './lib/draw-ellipse-using-three-
 export { DrawRectangleUsingThreePointsMode } from './lib/draw-rectangle-using-three-points-mode';
 export { Draw90DegreePolygonMode } from './lib/draw-90degree-polygon-mode';
 export { DrawPolygonByDraggingMode } from './lib/draw-polygon-by-dragging-mode';
+export { DrawLineStringByDraggingMode } from './lib/draw-line-string-by-dragging-mode';
 export { ImmutableFeatureCollection } from './lib/immutable-feature-collection';
 
 // Other modes

modules/edit-modes/src/lib/draw-line-string-by-dragging-mode.ts

@@ -0,0 +1,72 @@
+import throttle from 'lodash.throttle';
+import { DebouncedFunc } from 'lodash';
+import {
+  ClickEvent,
+  StartDraggingEvent,
+  StopDraggingEvent,
+  DraggingEvent,
+  ModeProps,
+} from '../types';
+import { LineString, FeatureCollection } from '../geojson-types';
+import { getPickedEditHandle } from '../utils';
+import { DrawLineStringMode } from './draw-line-string-mode';
+
+type DragHandler = (event: DraggingEvent, props: ModeProps<FeatureCollection>) => void;
+
+type ThrottledDragHandler = DebouncedFunc<DragHandler>;
+
+export class DrawLineStringByDraggingMode extends DrawLineStringMode {
+  handleDraggingThrottled: ThrottledDragHandler | DragHandler | null | undefined = null;
+
+  // Override the default behavior of DrawLineStringMode to not add a point when the user clicks on the map
+  handleClick(event: ClickEvent, props: ModeProps<FeatureCollection>) {
+    return;
+  }
+
+  handleStartDragging(event: StartDraggingEvent, props: ModeProps<FeatureCollection>) {
+    event.cancelPan();
+    if (props.modeConfig && props.modeConfig.throttleMs) {
+      this.handleDraggingThrottled = throttle(this.handleDraggingAux, props.modeConfig.throttleMs);
+    } else {
+      this.handleDraggingThrottled = this.handleDraggingAux;
+    }
+  }
+
+  handleStopDragging(event: StopDraggingEvent, props: ModeProps<FeatureCollection>) {
+    this.addClickSequence(event);
+    const clickSequence = this.getClickSequence();
+    if (this.handleDraggingThrottled && 'cancel' in this.handleDraggingThrottled) {
+      this.handleDraggingThrottled.cancel();
+    }
+
+    if (clickSequence.length > 2) {
+      const lineStringToAdd: LineString = {
+        type: 'LineString',
+        coordinates: clickSequence,
+      };
+
+      this.resetClickSequence();
+
+      const editAction = this.getAddFeatureAction(lineStringToAdd, props.data);
+      if (editAction) {
+        props.onEdit(editAction);
+      }
+    }
+  }
+
+  handleDraggingAux(event: DraggingEvent, props: ModeProps<FeatureCollection>) {
+    const { picks } = event;
+    const clickedEditHandle = getPickedEditHandle(picks);
+
+    if (!clickedEditHandle) {
+      // Don't add another point right next to an existing one.
+      this.addClickSequence(event);
+    }
+  }
+
+  handleDragging(event: DraggingEvent, props: ModeProps<FeatureCollection>) {
+    if (this.handleDraggingThrottled) {
+      this.handleDraggingThrottled(event, props);
+    }
+  }
+}

modules/layers/src/layers/editable-geojson-layer.ts

@@ -26,6 +26,7 @@ import {
   DrawEllipseUsingThreePointsMode,
   Draw90DegreePolygonMode,
   DrawPolygonByDraggingMode,
+  DrawLineStringByDraggingMode,
   SnappableMode,
   TransformMode,
   EditAction,
@@ -260,6 +261,7 @@ const modeNameMapping = {
   drawEllipseUsing3Points: DrawEllipseUsingThreePointsMode,
   draw90DegreePolygon: Draw90DegreePolygonMode,
   drawPolygonByDragging: DrawPolygonByDraggingMode,
+  drawLineStringByDragging: DrawLineStringByDraggingMode,
 };
 
 // type State = {

modules/main/src/index.ts

@@ -57,6 +57,7 @@ export { DrawEllipseUsingThreePointsMode } from '@nebula.gl/edit-modes';
 export { DrawRectangleUsingThreePointsMode } from '@nebula.gl/edit-modes';
 export { Draw90DegreePolygonMode } from '@nebula.gl/edit-modes';
 export { DrawPolygonByDraggingMode } from '@nebula.gl/edit-modes';
+export { DrawLineStringByDraggingMode } from '@nebula.gl/edit-modes';
 export { ImmutableFeatureCollection } from '@nebula.gl/edit-modes';
 
 // Other modes

modules/react-map-gl-draw/src/index.ts

@@ -14,6 +14,7 @@ export {
   DrawPolygonMode,
   DrawRectangleMode,
   DrawPolygonByDraggingMode,
+  DrawLineStringByDraggingMode,
   MeasureDistanceMode,
   MeasureAreaMode,
   MeasureAngleMode,