ArcObjects OnChangeFeature event not firing unless you move feature

Question

I am displaying points, lines and polygons on ArcMap as features with an addin. I want my end users to be able to change features (move geometries, add vertex, delete vertex etc) and get the updated feature's geometry.

For this purpose, I subscribe to OnChangeFeauture event with the following piece of code:

IEditEvents_Event editEvent = (IEditEvents_Event)ArcMap.Editor;
editEvent.OnChangeFeature += OnChangeFeature;

OnChangeFeauture event is fired only if a feature is moved. For points, this is fine, but for lines and polygon an edit doesn't necessarily mean the geometry needs to move (dragged somewhere else).

I subscribed to OnVertexMoved hoping to receive events if a vertex of line or polygon is moved.

((IEditEvents2_Event)Map.Editor).OnVertexMoved += OnVertexMoved;

UPDATE OnVertexMoved event DID work. It has a reference to the vertex as an IPoint object, which is fine. But when I checked ShapeCopy property of the selected feature (when that event is fired), it was not updated at all. So when should I expect to get ShapeCopy updated in an edit session unless it is moved explicitly?

Otherwise, I had to ask users to drag geometry as a whole a little bit even if they move just a vertex (to get their updated geometry). That doesn't make sense at all.

Answer 1

You need to cast obj to IRowChanges and loop to find what changed.

IRowChanges prowchange = obj as IRowChanges; 
for (int i = 0; i < obj.Fields.FieldCount; i++) {
  if (prowchange.get_ValueChanged(i) == true) {
    //Custom code here, this is the row that changed
  }
}