Undo just the last edit on featurelayer graphic?

[NjålEkern]

Hi,

I am looking for a way to undo edit on a graphic.
I am trying UndoEdits (Graphic) described here: UndoEdits.html but this undoes all unsaved graphics changes on the graphic, and not just the last one.
As an example:
1. I draw a new polygon A of 4 vertices
2. I draw a new polygon B of 4 vertices
3. I change polygon A to have 5 vertices

Now, if I click a button that I have coded to perform 'myfeaturelayer.UndoEdits(polygonA)', what happens is polygon A disappears.
(Polygon B is still there).
What happened is that UndoEdits(polygonA) reverted all changes on polygonA, including it's creation. As the documentation of the API said it would.
What I would like, is to get polygon A back to its previous condition, of having 4 vertices.

Is it possible to do that?

We are using Silverlight API 2.4

Njål

[JustinCornell · Accepted solution]

We do just what you are talking about, however, we had to write our own.  You can listen to the EditGeomety event and check when the Action == EditCompleted and just keep track of your own graphics.  Below is a rough example of what we ended up doing.  There is a class and two extension methods we us to clone graphics.  We just push and pop the graphics sets off the stack for undo/redo.

public static ESRI.ArcGIS.Client.Graphic CloneGraphic(this ESRI.ArcGIS.Client.Graphic g) {     ESRI.ArcGIS.Client.Graphic newGraphic = new ESRI.ArcGIS.Client.Graphic()     {         MapTip = g.MapTip,         Symbol = g.Symbol,         TimeExtent = g.TimeExtent,         Selected = g.Selected,         Geometry = g.Geometry.CloneGeometry()     };      g.Attributes.CopyTo(newGraphic.Attributes);      return newGraphic; }  public static Geometry CloneGeometry(this Geometry g) {     Geometry newGeometry = null;      if (g is ESRI.ArcGIS.Client.Geometry.Envelope)     {         var env = g as Envelope;         newGeometry = new Envelope()         {             SpatialReference = env.SpatialReference,             XMax = env.XMax,             YMax = env.YMax,             XMin = env.XMin,             YMin = env.YMin,         };     }     else if (g is ESRI.ArcGIS.Client.Geometry.MapPoint)     {         var point = g as MapPoint;         newGeometry = new MapPoint(point.X, point.Y, point.SpatialReference);     }     else if (g is ESRI.ArcGIS.Client.Geometry.MultiPoint)     {         var mpoint = g as MultiPoint;         var pc = new PointCollection();         foreach (var p in mpoint.Points)             pc.Add(new MapPoint(p.X, p.Y, p.SpatialReference));          newGeometry = new MultiPoint(pc, mpoint.SpatialReference);     }     else if (g is ESRI.ArcGIS.Client.Geometry.Polygon)     {         var poly = g as Polygon;         var newPoly = new Polygon() { SpatialReference = poly.SpatialReference };         foreach (var ring in poly.Rings)         {             var pc = new PointCollection();             foreach (var p in ring)                 pc.Add(new MapPoint(p.X, p.Y, p.SpatialReference));              newPoly.Rings.Add(pc);         }          newGeometry = newPoly;     }     else if (g is ESRI.ArcGIS.Client.Geometry.Polyline)     {         var line = g as Polyline;         var newline = new Polyline() { SpatialReference = line.SpatialReference };          foreach (var path in line.Paths)         {             var pc = new PointCollection();             foreach (var p in path)                 pc.Add(new MapPoint(p.X, p.Y, p.SpatialReference));              newline.Paths.Add(pc);         }          newGeometry = newline;     }      return newGeometry; }  public class EditSnapshot {     public EditSnapshot()     {         Graphics = new List<Graphic>();     }     public EditSnapshot(Graphic g)         : this()     {         Graphics.Add(g);     }      public EditSnapshot(IEnumerable<Graphic> graphics)         : this()     {         Graphics.AddRange(graphics);     }     public List<Graphic> Graphics { get; set; } }    //Here is the actual code that we use.  Pretty simple. internal protected Stack<EditSnapshot> Snapshots { get; set; }  private void EditGeometry_GeometryEdit(object sender, EditGeometry.GeometryEditEventArgs e) {     if (e.Action == EditGeometry.Action.EditCompleted)             Snapshots.Push(new EditSnapshot(_editLayer.Graphics.Select(x => x.CloneGraphic()))); }

[NjålEkern]

Thank you very much for your answer Justin.
I will try it out, and come back to this.
Marking it as answer, it seems it will do as I want.
Regards, Njål