Using RasterUniqueValueRenderer

Created:4/13/2001
Description:

This sample reads a raster from layer and renders with UniqueValue Renderer if table exits.

How to use:
  1. Add a raster layer that has a table into to ArcMap and make sure it is first layer.
  2. Run the procedure in ArcMap Visual Basic Editor.
Sub ChangeRenderToUVRenderer()

    On Error GoTo ERH
    Dim pMxDoc As IMxDocument
    Set pMxDoc = ThisDocument
    Dim pMap As IMap
    Set pMap = pMxDoc.FocusMap
  
   ' Get raster input from layer
     Dim pRLayer As IRasterLayer
    Set pRLayer = pMap.Layer(0)
    Dim pRaster As IRaster
    Set pRaster = pRLayer.Raster

   ' Get the number of rows from raster table
     Dim pTable As ITable
    Dim pBand As IRasterBand
    Dim pBandCol As IRasterBandCollection
    Set pBandCol = pRaster
    Set pBand = pBandCol.Item(0)
    Dim TableExist As Boolean
    pBand.HasTable TableExist
    If Not TableExist Then Exit Sub
    Set pTable = pBand.AttributeTable
    Dim NumOfValues As Integer
    NumOfValues = pTable.RowCount(Nothing)
  
   ' Specified a field and get the field index for the specified field to be rendered.     Dim FieldIndex As Integer
    Dim FieldName As String
    FieldName = "Value"   'Value is the default field, you can specify other field here..
    FieldIndex = pTable.FindField(FieldName)
  
   ' Create random color
     Dim pRamp As IRandomColorRamp
    Set pRamp = New RandomColorRamp
    pRamp.Size = NumOfValues
    pRamp.Seed = 100
    pRamp.CreateRamp (True)
    Dim pFSymbol As ISimpleFillSymbol
  
   ' Create UniqueValue renderer and QI RasterRenderer
     Dim pUVRen As IRasterUniqueValueRenderer
    Set pUVRen = New RasterUniqueValueRenderer
    Dim pRasRen As IRasterRenderer
    Set pRasRen = pUVRen
  
   ' Connect renderer and raster
     Set pRasRen.Raster = pRaster
    pRasRen.Update
  
   ' Set UniqueValue renerer
     pUVRen.HeadingCount = 1   ' Use one heading 
    pUVRen.Heading(0) = "All Data Values"
    pUVRen.ClassCount(0) = NumOfValues
    pUVRen.Field = FieldName
    Dim I As Long
    Dim pRow As IRow
    Dim LabelValue As Variant
    For I = 0 To NumOfValues - 1
        Set pRow = pTable.GetRow(I) 'Get a row from the table
 	  LabelValue = pRow.Value(FieldIndex)  ' Get value of the given index
        pUVRen.AddValue 0, I, LabelValue  'Set value for the renderer
        pUVRen.Label(0, I) = CStr(LabelValue)  ' Set label
        Set pFSymbol = New SimpleFillSymbol
        pFSymbol.Color = pRamp.Color(I)
        pUVRen.Symbol(0, I) = pFSymbol  'Set symbol
    Next I
  
   ' Update render and refresh layer
     pRasRen.Update
    Set pRLayer.Renderer = pUVRen
    pMxDoc.ActiveView.Refresh
    pMxDoc.UpdateContents

   ' Clean up
     Set pMxDoc = Nothing
    Set pRLayer = Nothing
    Set pUVRen = Nothing
    Set pRasRen = Nothing
    Set pRamp = Nothing
    Set pFSymbol = Nothing
    Set pRaster = Nothing
    Set pRLayer = Nothing
    Set pMap = Nothing
    Set pBand = Nothing
    Set pBandCol = Nothing
    Set pTable = Nothing
    Set pRow = Nothing
    Exit Sub
ERH:
    MsgBox Err.Description
End Sub