Defining a renderer for a layer

About defining a renderer for a layer

static void DefineUniqueValueRenderer(IGeoFeatureLayer pGeoFeatureLayer, string
    fieldName)
{

    IRandomColorRamp pRandomColorRamp=new RandomColorRampClass();
    //Create the color ramp for the symbols in the renderer.
    pRandomColorRamp.MinSaturation=20;
    pRandomColorRamp.MaxSaturation=40;
    pRandomColorRamp.MinValue=85;
    pRandomColorRamp.MaxValue=100;
    pRandomColorRamp.StartHue=76;
    pRandomColorRamp.EndHue=188;
    pRandomColorRamp.UseSeed=true;
    pRandomColorRamp.Seed=43;

    //Create the renderer.
    IUniqueValueRenderer pUniqueValueRenderer=new UniqueValueRendererClass();

    ISimpleFillSymbol pSimpleFillSymbol=new SimpleFillSymbolClass();
    pSimpleFillSymbol.Style=esriSimpleFillStyle.esriSFSSolid;
    pSimpleFillSymbol.Outline.Width=0.4;

    //These properties should be set prior to adding values.
    pUniqueValueRenderer.FieldCount=1;
    pUniqueValueRenderer.set_Field(0, fieldName);
    pUniqueValueRenderer.DefaultSymbol=pSimpleFillSymbol as ISymbol;
    pUniqueValueRenderer.UseDefaultSymbol=true;

    IDisplayTable pDisplayTable=pGeoFeatureLayer as IDisplayTable;
    IFeatureCursor pFeatureCursor=pDisplayTable.SearchDisplayTable(null, false)as
        IFeatureCursor;
    IFeature pFeature=pFeatureCursor.NextFeature();


    bool ValFound;
    int fieldIndex;

    IFields pFields=pFeatureCursor.Fields;
    fieldIndex=pFields.FindField(fieldName);
    while (pFeature != null)
    {
        ISimpleFillSymbol pClassSymbol=new SimpleFillSymbolClass();
        pClassSymbol.Style=esriSimpleFillStyle.esriSFSSolid;
        pClassSymbol.Outline.Width=0.4;

        string classValue;
        classValue=pFeature.get_Value(fieldIndex)as string;

        //Test to see if this value was added to the renderer. If not, add it.
        ValFound=false;
        for (int i=0; i <= pUniqueValueRenderer.ValueCount - 1; i++)
        {
            if (pUniqueValueRenderer.get_Value(i) == classValue)
            {
                ValFound=true;
                break; //Exit the loop if the value was found.
            }
        }
        //If the value was not found, it's new and will be added.
        if (ValFound == false)
        {
            pUniqueValueRenderer.AddValue(classValue, fieldName, pClassSymbol as
                ISymbol);
            pUniqueValueRenderer.set_Label(classValue, classValue);
            pUniqueValueRenderer.set_Symbol(classValue, pClassSymbol as ISymbol);
        }
        pFeature=pFeatureCursor.NextFeature();
    }
    //Since the number of unique values is known, the color ramp can be sized and the colors assigned.
    pRandomColorRamp.Size=pUniqueValueRenderer.ValueCount;
    bool bOK;
    pRandomColorRamp.CreateRamp(out bOK);

    IEnumColors pEnumColors=pRandomColorRamp.Colors;
    pEnumColors.Reset();
    for (int j=0; j <= pUniqueValueRenderer.ValueCount - 1; j++)
    {
        string xv;
        xv=pUniqueValueRenderer.get_Value(j);
        if (xv != "")
        {
            ISimpleFillSymbol pSimpleFillColor=pUniqueValueRenderer.get_Symbol(xv)
                as ISimpleFillSymbol;
            pSimpleFillColor.Color=pEnumColors.Next();
            pUniqueValueRenderer.set_Symbol(xv, pSimpleFillColor as ISymbol);

        }
    }

    //'** If you didn't use a predefined color ramp in a style, use "Custom" here. 
    //'** Otherwise, use the name of the color ramp you selected.
    pUniqueValueRenderer.ColorScheme="Custom";
    ITable pTable=pDisplayTable as ITable;
    bool isString=pTable.Fields.get_Field(fieldIndex).Type ==
        esriFieldType.esriFieldTypeString;
    pUniqueValueRenderer.set_FieldType(0, isString);
    pGeoFeatureLayer.Renderer=pUniqueValueRenderer as IFeatureRenderer;

    //This makes the layer properties symbology tab show the correct interface.
    IUID pUID=new UIDClass();
    pUID.Value="{683C994E-A17B-11D1-8816-080009EC732A}";
    pGeoFeatureLayer.RendererPropertyPageClassID=pUID as UIDClass;

}

Shared Sub DefineUniqueValueRenderer(ByVal pGeoFeatureLayer As IGeoFeatureLayer, ByVal fieldName As String)

Dim pRandomColorRamp As IRandomColorRamp=New RandomColorRampClass()
'Create the color ramp for the symbols in the renderer.
pRandomColorRamp.MinSaturation=20
pRandomColorRamp.MaxSaturation=40
pRandomColorRamp.MinValue=85
pRandomColorRamp.MaxValue=100
pRandomColorRamp.StartHue=76
pRandomColorRamp.EndHue=188
pRandomColorRamp.UseSeed=True
pRandomColorRamp.Seed=43

'Create the renderer.
Dim pUniqueValueRenderer As IUniqueValueRenderer=New UniqueValueRendererClass()

Dim pSimpleFillSymbol As ISimpleFillSymbol=New SimpleFillSymbolClass()
pSimpleFillSymbol.Style=esriSimpleFillStyle.esriSFSSolid
pSimpleFillSymbol.Outline.Width=0.4

'These properties should be set prior to adding values.
pUniqueValueRenderer.FieldCount=1
pUniqueValueRenderer.Field(0)=fieldName
pUniqueValueRenderer.DefaultSymbol=pSimpleFillSymbol
pUniqueValueRenderer.UseDefaultSymbol=True

Dim pDisplayTable As IDisplayTable=pGeoFeatureLayer
Dim pFeatureCursor As IFeatureCursor=pDisplayTable.SearchDisplayTable(Nothing, False)

Dim pFeature As IFeature=pFeatureCursor.NextFeature()



Dim ValFound As Boolean
Dim fieldIndex As Integer

Dim pFields As IFields=pFeatureCursor.Fields
fieldIndex=pFields.FindField(fieldName)

While Not pFeature Is Nothing
    Dim pClassSymbol As ISimpleFillSymbol=New SimpleFillSymbolClass()
    pClassSymbol.Style=esriSimpleFillStyle.esriSFSSolid
    pClassSymbol.Outline.Width=0.4
    
    Dim classValue As String
    classValue=pFeature.Value(fieldIndex)
    
    'Test to see if this value was added to the renderer. If not, add it.
    ValFound=False
    Dim i As Integer
    For i=0 To pUniqueValueRenderer.ValueCount - 1 Step i + 1
        If pUniqueValueRenderer.Value(i)=classValue Then
            ValFound=True
            Exit For 'Exit the loop if the value is found.
            As break
        End If
    Next
    'If the value was not found, it's new and will be added.
    If ValFound=False Then
        pUniqueValueRenderer.AddValue(classValue, fieldName, pClassSymbol)
        pUniqueValueRenderer.Label(classValue)=classValue
        pUniqueValueRenderer.Symbol(classValue)=pClassSymbol
    End If
    pFeature=pFeatureCursor.NextFeature()
End While

'Since the number of unique values is known, the color ramp can be sized and the colors assigned.

pRandomColorRamp.Size=pUniqueValueRenderer.ValueCount
Dim bOK As Boolean
pRandomColorRamp.CreateRamp( bOK)

Dim pEnumColors As IEnumColors=pRandomColorRamp.Colors
pEnumColors.Reset()

Dim j As Integer
For j=0 To pUniqueValueRenderer.ValueCount - 1 Step j + 1
    Dim xv As String
    xv=pUniqueValueRenderer.Value(j)
    If xv <> "" Then
        Dim pSimpleFillColor As ISimpleFillSymbol=pUniqueValueRenderer.Symbol(xv)
        pSimpleFillColor.Color=pEnumColors.Next()
        pUniqueValueRenderer.Symbol(xv)=pSimpleFillColor
        
    End If
    
Next


''** If you didn't use a predefined color ramp in a style, use "Custom" here.
''** Otherwise, use the name of the color ramp you selected.
pUniqueValueRenderer.ColorScheme="Custom"
Dim pTable As ITable=pDisplayTable
Dim isString As Boolean=pTable.Fields.Field(fieldIndex).Type=esriFieldType.esriFieldTypeString
pUniqueValueRenderer.FieldType(0)=isString
pGeoFeatureLayer.Renderer=pUniqueValueRenderer

'This makes the layer properties symbology tab show the correct interface.
Dim pUID As IUID=New UIDClass()
pUID.Value="{683C994E-A17B-11D1-8816-080009EC732A}"
pGeoFeatureLayer.RendererPropertyPageClassID=pUID


End Sub