Unique Values and Subtypes [C#]

Question

I am trying to colour subtypes for an empty featureclass by unique values.

I can do this manually by doing the following, this is a Point Layer.
Layer Properties > Symbology > Categories > Unique values > Value Field = SUBTYPE > click on Add All Values > 8 Subtypes will appear with random colours. Then I would manually change each Subtype marker symbol to a square with a colour that I want.

Once again, this is an empty featureclass.

I would like to perform the above actions using C# ArcObjects.

I have already tried SimpleMarkerSymbol code that would attempt to assign colours using a custom colour ramp, but this did not work because the code required the layer to have data in it. My featureclass will not data in it, but I need to assign colour to each subtype manually, and yes hardcode it in ArcObjects.

Please let me know if this is possible and how, thanks!

AlexanderBrown1 · Answer

Akhil,

I know this response is really late--did not find this board until yesterday.  However, for any up and coming developers (such as myself) it is great to have some type of solution posted on these boards.

You need to utilize the IQueryFilterDefinition interface.  This allows you to set a post fix clause to order by a field value.  In your case, this would be SUBTYPE.  Forgive me if my C# is rusty, as I mostly deal in VB.NETIQueryFilter pQueryFilter = default(IQueryFilter);
pQueryFilter = new QueryFilter();
pQueryFilter.SubFields = "SUBTYPE";
//Here is the field you want to sort by
pQueryFilter.WhereClause = null;

IQueryFilterDefinition2 pQueryDefFilter = default(IQueryFilterDefinition2);
pQueryDefFilter = pQueryFilter;
 //Here you call the subfield in the query filter
pQueryDefFilter.PostfixClause = "ORDER BY SUBTYPE";

IFeatureCursor pFCursor = default(IFeatureCursor);
pFCursor = pFeatureClass.Search(pQueryFilter, true);

Apply this before you render using unique values.

AkhilParujanwala · Answer

I am now trying to find the object that can perform "Reverse Sorting" in the symbology.
If you go to a layer's properties > Symbology > Unique Values > right click under the heading Value > the Reverse Sorting function appears.

I would like to have that method using ArcObjects, if it is possible.

I am using a featureclass that already has unique values applied to it, the next step is for me to do is perform the Reverse Sort method.

Can anyone shed some light on how to get that method?

Thanks in advance.

AkhilParujanwala · Answer

Great news everyone, I have gotten very close to what I wanted.

1) I have removed the default <all other value> by using the following code:
[PHP]
pUniqueValueRenderer.UseDefaultSymbol = false;
[/PHP]

2) I was getting a problem where all my classes were becoming the same color, for example blue. But I solved this problem by moving the declaration of the SimpleMarkerSymbol inside the loop, rather than being outside the loop.

3) Below is the near perfect solution to creating custom colors for a fixed number of classes using UniqueValueRenderer. The cases were changed for this post.

[PHP]
public static void TestSymbol(IGeoFeatureLayer pGeoFeatureLayer)
        {
            IUniqueValueRenderer pUniqueValueRenderer = pGeoFeatureLayer.Renderer as IUniqueValueRenderer;
            pUniqueValueRenderer.UseDefaultSymbol = false;

for (int i = 0; i <= pUniqueValueRenderer.ValueCount - 1; i++)
            {
                ISimpleMarkerSymbol pSimpleMarkerSymbol = new SimpleMarkerSymbol();
                pSimpleMarkerSymbol.Size = 4;
                pSimpleMarkerSymbol.Style = esriSimpleMarkerStyle.esriSMSSquare;
                pSimpleMarkerSymbol.Outline = false;

string value = pUniqueValueRenderer.get_Value(i);
                string description = pUniqueValueRenderer.get_Label(value);

switch (description)
                {
                    case "T1":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(204, 204, 204);                         
                        break;
                    case "T2":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(115, 76, 0);                        
                        break;
                    case "T3":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(0, 0, 0);                        
                        break;
                    case "T4":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(0, 112, 225);                        
                        break;
                    case "T5":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(132, 0, 168);                        
                        break;
                    case "T6":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(255, 0, 0);                        
                        break;
                    case "T7":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(255, 170, 0);                        
                        break;
                    case "T8":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(255, 255, 0);                        
                        break;
                    case "T9":
                        pSimpleMarkerSymbol.Color = Utilities.CreateRGBColor(38, 115, 0);                     
                        break;
                }

pUniqueValueRenderer.set_Symbol(value, pSimpleMarkerSymbol as ISymbol);                
            }

pGeoFeatureLayer.Renderer = pUniqueValueRenderer as IFeatureRenderer;
        }
[/PHP]

4) My next issue is the order in which the classes appear in the table of contents.
I want them to appear in a specific order.
When I add the layer to the map, the classes appear in alphabetical order or seamingly random.
Existing List (Order of classes in TOC):T2T5T6T9T1T4T3T7T8
This example shows how I would like the list of classes to appear in the table of contents (TOC).
Desired List (Order of classes in TOC):T1T2T3T4T5T6T7T8T9
Any suggestions on how to re-arrange the classes?
Should I remove all values, and then add them manually one by one in the correct order instead?

Kindly advise, thanks!