free-form drawing

Question

Does ESRI have the ability to allow free-form drawing (a.k.a. 'doodling') within a layer?

That is, where the user's finger movement is recorded into a path as can be done within iOS's Core Graphics: var simplePath = UIBezierPath() ... etc.?

Scenario:  I wish to doodle annotations (drawing) on an overlay and be able to store & recover such doodle.

How would/could that be arranged?

RyanOlson1 · Answer

You don't need to copy the geometry, it's immutable.

GraphicsOverlays can be re-used, and you can remove/add graphics from them.

FrederickLee1 · Answer

Reference: ESRI's Sketch Example:

Environment: iOS/Swift 3.0+

I notice that no overlays are used in the sketch, which uses the AGSSketchEditor.

However I believe I need the use of a graphics overlay object to display historical sketches.

Hence I've added the following:

private var myPolyLine:AGSPolyline?

private var graphicsOverlay = AGSGraphicsOverlay()

1) Making a copy of the sketch as a 'geometry':

@IBAction func clear() {

self.myPolyLine = self.sketchEditor.geometry!.copy() as? AGSPolyline

self.sketchEditor.clearGeometry()

}

2) Restoring the sketch after 'deleting' it:

case 3: // ...redraw

let lineSymbol = AGSSimpleLineSymbol(style: .solid, color: UIColor.red, width: 3)

self.graphicsOverlay.graphics.add(AGSGraphic(geometry: self.myPolyLine, symbol: lineSymbol, attributes: nil))

self.mapView.graphicsOverlays.add(self.graphicsOverlay)

I needed to create a graphics overlay to display the copy.

I can see the buildup of graphicOverlays.

So once I don't need this copy, I should REMOVE this particular overlay.

That is, each overlay would contain a previously-copied sketch and hence,

I should discard these overlays once not needed.   Correct?

As for persistent storage: a AGSPolyline is an NSObject so I could serialize it for storage accordingly.

Is this the correct way for creating a persistent store of a sketch and handling old sketches via removing the overlays?

RyanOlson1 · Answer

1. AGSSketchEditor has a "style" property which has a "feedbackLineSymbol" property. You can set that to whatever line symbol you want. It defaults to a dashed symbol.

2. You can save the resulting geometry, which will be a Polygon or Polyline as JSON. They support AGSJSONSerializable. From there you can store it in user defaults or however you want. And then re-hydrate the geometry from JSON later.