使用UniqueValue方法渲染地图

代码：

 IGeoFeatureLayer m_pGeoFeatureL;
            IUniqueValueRenderer pUniqueValueR;
            IFillSymbol pFillSymbol;
            IColor pNextUniqueColor;
            IEnumColors pEnumRamp;
            ITable pTable;
            int lfieldNumber;
            IRow pNextRow;
            IRowBuffer pNextRowBuffer;
            ICursor pCursor;
            IQueryFilter pQueryFilter;
            string codeValue;
            IRandomColorRamp pColorRamp;
            string strNameField = "地区";
            IActiveView pActiveView;
            IMap pMap;
            pActiveView = this.axMapControl1.ActiveView;
            pMap = this.axMapControl1.Map;
            pMap.ReferenceScale = 0;
            m_pGeoFeatureL = (IGeoFeatureLayer)pMap.get_Layer(4);
            pUniqueValueR = new UniqueValueRendererClass();
            pTable = (ITable)m_pGeoFeatureL;
            //ᡒߎSTATE_NAME೼ᄫ↉Ёⱘ㓪ো
            lfieldNumber = pTable.FindField(strNameField);
            if (lfieldNumber == -1)
            {
                MessageBox.Show("找不到字段： " + strNameField);
                return;
            }
            pUniqueValueR.FieldCount = 1;
            pUniqueValueR.set_Field(0, strNameField);
            pColorRamp = new RandomColorRampClass();
            pColorRamp.StartHue = 0;
            pColorRamp.MinValue = 99;
            pColorRamp.MinSaturation = 15;
            pColorRamp.EndHue = 360;
            pColorRamp.MaxValue = 100;
            pColorRamp.MaxSaturation = 30;
            pColorRamp.Size = 6;
            bool ok = true;
            pColorRamp.CreateRamp(out ok);
            pEnumRamp = pColorRamp.Colors;
            pNextUniqueColor = null;
            pQueryFilter = new QueryFilterClass();
            pQueryFilter.AddField(strNameField);
            pCursor = pTable.Search(pQueryFilter, true);
            pNextRow = pCursor.NextRow();
            while (pNextRow != null)
            {
                pNextRowBuffer = pNextRow;
                codeValue = (string)pNextRowBuffer.get_Value(lfieldNumber);//提高速度
                pNextUniqueColor = pEnumRamp.Next();
                if (pNextUniqueColor == null)
                {
                    pEnumRamp.Reset();
                    pNextUniqueColor = pEnumRamp.Next();
                }
                pFillSymbol = new SimpleFillSymbolClass();
                pFillSymbol.Color = pNextUniqueColor;
                pUniqueValueR.AddValue(codeValue, strNameField, (ISymbol)pFillSymbol);
                pNextRow = pCursor.NextRow();
            }
            m_pGeoFeatureL.Renderer = (IFeatureRenderer)pUniqueValueR;
            pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);

这种做法有时会出现一个问题：无法保证MapControl和TOC控件的样式一致，尤其是出现颜色不一致的情况，例如，MapControl里中国区域为红色，但TOC里可能表示为另外一个颜色，无论如何刷新都无法是TOC正确显示。尚不知道原因。