Copying existing graphic to another graphic layer - out of range exeception.

Ravichandran_M_Kaushika

dear Readers,

good afternoon.  I have successfully loaded graphics from SQL Server geometry objects using certain query conditions and associated them with certain colors based on their attribute values.

When user selects them from the grid (not esri feature grid - this app was begun at esri API 1.x), the selected row is associated with the graphic in the collection using an ID and it is flashed for a few seconds using utils.flash.  to make it convenient on the user, the 1st vertex is highlighted with a pushphin.  all these work great.

PROBLEM:
the users want to highlight the selected graphic in a different color - since cyan is not used in the coloring scheme for displaying attribute information, and since majority of the users come from an ArcMap background, i thought it might be appropriate to assign it to cyan.

so i copied the selected graphic into another graphic object and tried to add it to ANOTHER LAYER and the application is complaining that:
Specified argument was out of the range of valid values. Parameter name: Graphic is already associated with another layer.

@ esri.arcgis.client.graphicslayer.addgraphic(graphic g).

i have attached a pdf of the error message screen capture.  i did a exc.ToString() and got all the info I could.

i do not wnat to complicate the app by adding the Nth dictionary to keep track of the existing color and the ID - clearing it etc.  if it comes to that, i will do it.  i was wondering whether there was another simpler way of doing it.

thanks for your help.

regards
Ravi.

AddingExistingGrphErr.pdf

JssicaDalCol_0-1642800807945.png

ChristopherHill

Hi Ravi,

When copying the graphic you need to use the Clone() method or you will have two references to the same graphic, when you try to add the second graphic reference to another GraphicsLayer our API will throw an exception because it knows that the graphic belongs to a different GraphicsLayer already. If you want to copy to a new GraphicsLayer you can make a new instance like below.

Graphic myGraphic = new Graphic();
myGraphic.Geometry = selectedGraphic.Geometry.Clone();

My question to you is why are you going to this length in the first place. If you are using FeatureLayer with graphics comming from a FeatureServer then a selection color is built into the FeatureLayer and all you have to do is set myGraphic.Selected = true and the renderer associated with the FeatureLayer will change the selection color for you. then when you set MyGraphic.Selected = false the color will change back.

If you are using a GraphicsLayer you will need to add selection state to your symbols using this SDK Sample
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#SelectGraphics