Flash more than one feature in ArcMap using ArcObjects and C#?

Question

How to flash many features at same time in ArcMap using C# coding?

Currently I call this function in a loop,

private void FlashFeature(IActiveView _activeView, IFeature _feature)
{
 IActiveView activeView = _activeView;
 IFeatureIdentifyObj featIdentify = new FeatureIdentifyObject();
 featIdentify.Feature = _feature;
 IIdentifyObj identify = featIdentify as IIdentifyObj;
 identify.Flash(activeView.ScreenDisplay);
}

but unfortunately it flashes one feature at a time, and while flashing is happening it holds the process. As a result of that it flashes around 2 features in a second, instead of them all at once. I also want to flash thous features without changing my curent feature selection in map, if posable. The default ArcMap Find tool(form or whatever it is) can do it, and i'm trying to find a way to implement that in my tool.

• JC5577: I removed my answer--so many stupid things in that class that I decided to drop it. One of the issues that I had was when I was flashing coincident geometries, their symbols would cancel each other out (due to the esriROPNotXOrPen raster operation). So it looked like it was doing nothing (had me stumped for quite a while). Also, I found this: help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/… which I think I used when I built my class. It might be better to start with it and tweak it to handle multiple geoms.

Answer 1

Please see my customized flash routine in the answer to this question: ESRI Flash Command in custom code

I think this will work for you as it accepts GeometryBags along with Polygon, Polyline, Point and Multipoint geometries. It does not union the geometries but draws each one individually.

Alternatively you might try adding the geometries to an array and using IHookActions.DoActionOnMultiple as in this sample.

• Sunder: Tried your first solution, and it works great. In a matter of fact "Jay Cummins" answer(which he removed) was actually working as well, but I forgot to zoom out to check if its drawing somewhere else(whick is currently happening in this case as well). I'm probably missing some SpatialReference somewhere. About flashing - its done, works like a charm!
• blah238: Good to hear. If it's not on the screen obviously it won't flash, but the built-in Identify tool does a nifty crosshairs effect so you can see "something" happen even if it's off-screen. I haven't yet figured out how to replicate that.

Answer 2

The method I used in one of my add-ins was to put all the features into a GeometryBag and use ITopologicalOperator::ConstructUnion to merge it into a single geometry. I passed this geometry into the FlashGeometry snippet.

Here's how I did it (in VB.NET). In my case, I was using an IQueryFilter to make the selection of features (either polygons or polylines) to flash

 Dim pFCursor As ESRI.ArcGIS.Geodatabase.IFeatureCursor
 Dim pFeature As ESRI.ArcGIS.Geodatabase.IFeature
 Dim pGeometry As ESRI.ArcGIS.Geometry.IGeometry
 Dim pGeometryBag As ESRI.ArcGIS.Geometry.IGeometryCollection = New ESRI.ArcGIS.Geometry.GeometryBag
 Dim pPolygon As ESRI.ArcGIS.Geometry.IPolygon
 Dim pPolyline As ESRI.ArcGIS.Geometry.IPolyline
 Dim pQFilter As New ESRI.ArcGIS.Geodatabase.QueryFilter
 Dim pRgbColor As New ESRI.ArcGIS.Display.RgbColor
 Dim pTopoOp As ESRI.ArcGIS.Geometry.ITopologicalOperator4
 Using releaser As New ESRI.ArcGIS.ADF.ComReleaser
 releaser.ManageLifetime(pFCursor)
 pQFilter.WhereClause = [String].Format("{0} in ({1})", pFClass.OIDFieldName, sender.Rows(e.RowIndex).Cells("colAdjacentOIDs").value)
 pFCursor = pFClass.Search(pQFilter, True)
 pFeature = pFCursor.NextFeature
 Do Until pFeature Is Nothing
 pGeometryBag.AddGeometry(pFeature.ShapeCopy)
 pFeature = pFCursor.NextFeature
 Loop
 Select Case pFClass.ShapeType
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolygon
 pTopoOp = New ESRI.ArcGIS.Geometry.Polygon
 pTopoOp.ConstructUnion(pGeometryBag)
 pPolygon = pTopoOp
 pGeometry = pPolygon
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolyline
 pTopoOp = New ESRI.ArcGIS.Geometry.Polyline
 pTopoOp.ConstructUnion(pGeometryBag)
 pPolyline = pTopoOp
 pGeometry = pPolyline
 End Select
 pRgbColor.Red = 255
 FlashGeometry(pGeometry, pRgbColor, My.ArcMap.Document.ActiveView.ScreenDisplay, 500)
 End Using
Public Sub FlashGeometry(ByVal geometry As ESRI.ArcGIS.Geometry.IGeometry, ByVal color As ESRI.ArcGIS.Display.IRgbColor, ByVal display As ESRI.ArcGIS.Display.IDisplay, ByVal delay As System.Int32)
 If geometry Is Nothing OrElse color Is Nothing OrElse display Is Nothing Then
 Return
 End If
 display.StartDrawing(display.hDC, CShort(ESRI.ArcGIS.Display.esriScreenCache.esriNoScreenCache))
 Select Case geometry.GeometryType
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolygon
 'Set the flash geometry's symbol.
 Dim simpleFillSymbol As ESRI.ArcGIS.Display.ISimpleFillSymbol = New ESRI.ArcGIS.Display.SimpleFillSymbolClass
 simpleFillSymbol.Color = color
 Dim symbol As ESRI.ArcGIS.Display.ISymbol = TryCast(simpleFillSymbol, ESRI.ArcGIS.Display.ISymbol) ' Dynamic Cast
 symbol.ROP2 = ESRI.ArcGIS.Display.esriRasterOpCode.esriROPNotXOrPen
 'Flash the input polygon geometry.
 display.SetSymbol(symbol)
 display.DrawPolygon(geometry)
 System.Threading.Thread.Sleep(delay)
 display.DrawPolygon(geometry)
 Exit Select
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolyline
 'Set the flash geometry's symbol.
 Dim simpleLineSymbol As ESRI.ArcGIS.Display.ISimpleLineSymbol = New ESRI.ArcGIS.Display.SimpleLineSymbolClass
 simpleLineSymbol.Width = 4
 simpleLineSymbol.Color = color
 Dim symbol As ESRI.ArcGIS.Display.ISymbol = TryCast(simpleLineSymbol, ESRI.ArcGIS.Display.ISymbol) ' Dynamic Cast
 symbol.ROP2 = ESRI.ArcGIS.Display.esriRasterOpCode.esriROPNotXOrPen
 'Flash the input polyline geometry.
 display.SetSymbol(symbol)
 display.DrawPolyline(geometry)
 System.Threading.Thread.Sleep(delay)
 display.DrawPolyline(geometry)
 Exit Select
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPoint
 'Set the flash geometry's symbol.
 Dim simpleMarkerSymbol As ESRI.ArcGIS.Display.ISimpleMarkerSymbol = New ESRI.ArcGIS.Display.SimpleMarkerSymbolClass
 simpleMarkerSymbol.Style = ESRI.ArcGIS.Display.esriSimpleMarkerStyle.esriSMSCircle
 simpleMarkerSymbol.Size = 12
 simpleMarkerSymbol.Color = color
 Dim symbol As ESRI.ArcGIS.Display.ISymbol = TryCast(simpleMarkerSymbol, ESRI.ArcGIS.Display.ISymbol) ' Dynamic Cast
 symbol.ROP2 = ESRI.ArcGIS.Display.esriRasterOpCode.esriROPNotXOrPen
 'Flash the input point geometry.
 display.SetSymbol(symbol)
 display.DrawPoint(geometry)
 System.Threading.Thread.Sleep(delay)
 display.DrawPoint(geometry)
 Exit Select
 Case ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryMultipoint
 'Set the flash geometry's symbol.
 Dim simpleMarkerSymbol As ESRI.ArcGIS.Display.ISimpleMarkerSymbol = New ESRI.ArcGIS.Display.SimpleMarkerSymbolClass
 simpleMarkerSymbol.Style = ESRI.ArcGIS.Display.esriSimpleMarkerStyle.esriSMSCircle
 simpleMarkerSymbol.Size = 12
 simpleMarkerSymbol.Color = color
 Dim symbol As ESRI.ArcGIS.Display.ISymbol = TryCast(simpleMarkerSymbol, ESRI.ArcGIS.Display.ISymbol) ' Dynamic Cast
 symbol.ROP2 = ESRI.ArcGIS.Display.esriRasterOpCode.esriROPNotXOrPen
 'Flash the input multipoint geometry.
 display.SetSymbol(symbol)
 display.DrawMultipoint(geometry)
 System.Threading.Thread.Sleep(delay)
 display.DrawMultipoint(geometry)
 Exit Select
 End Select
 display.FinishDrawing()
End Sub

• Sunder: I were already considering this, and your suggestion seems like a valid solution if you'r dealing with one type of geometries. The drawback is that it can't functionate with different kind of geometries because you cant merge points, polylines and polygons in single geometry... or can it? In worst case I can flash them in order - first points, then polylines, etc. I'll replay my results on this matter tomorrow.
• Sunder: In the end I sticked with blah238 answer. As it is more viable in my case.
• user98848: What is FlashGeometry(....) in above code?
• kenbuja: Added that function to the code