c#唯一值渲染实例代码

该着色方法一句着色图层中要素类的某个数值字段的属性值，按这个属性值为每种不同值得要素单独分配一种显示符号样式。关键在于获取该字段所有要素的唯一值（即将所有在该字段中属性值相同的要素归为一种），利用UniqueValueRenderer的AddValue方法即可进行渲染

需要添加的类库

代码如下:

using System.Collections;
using System.Windows.Forms;
using ESRI.ArcGIS.Display;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Geodatabase;

具体代码（本例为单值渲染）

代码如下:

private ISymbol GetSymbol(IColor pColor)
        {
            ISymbol pSymbol;
            ISimpleFillSymbol pSymbolFillSymbol = new SimpleFillSymbolClass();
            pSymbolFillSymbol.Color = pColor;
            pSymbolFillSymbol.Outline.Width = 0.4;
            pSymbol = pSymbolFillSymbol as ISymbol;
            return pSymbol;
        }
 private void uniqueValueRendererToolStripMenuItem_Click(object sender, EventArgs e)
        {
            IMap pMap = this.axMapControl1.ActiveView.FocusMap;
            if (pMap.LayerCount== 0)
            {
                MessageBox.Show("地图为空，请加载地图！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }
            IGeoFeatureLayer pGeoLayer = this.axMapControl1.get_Layer(0) as IGeoFeatureLayer ;
            ITable pTable = pGeoLayer.FeatureClass as ITable;
            ICursor pCursor;
            IQueryFilter pQueryFilter = new QueryFilter();
            pQueryFilter.AddField("PERIMETER");
            pCursor = pTable.Search(pQueryFilter, true);//获取字段
            IEnumerator pEnumreator;

//获取字段中各要素属性唯一值
            IDataStatistics pDataStatistics = new DataStatisticsClass();
            pDataStatistics.Field = "PERIMETER";//获取统计字段
            pDataStatistics.Cursor = pCursor;
            pEnumreator = pDataStatistics.UniqueValues;
            int fieldcount = pDataStatistics.UniqueValueCount;//唯一值个数，以此确定颜色带范围

IUniqueValueRenderer pUniqueValueR = new UniqueValueRendererClass();
            pUniqueValueR.FieldCount = 1;//单值渲染
            pUniqueValueR.set_Field(0, "PERIMETER");//渲染字段
            IEnumColors pEnumColor = GetColorRamp(fieldcount).Colors;
            pEnumColor.Reset();

while (pEnumreator.MoveNext())
            {
                string value = pEnumreator.Current.ToString();
                if (value != null)
                {
                    IColor pColor = pEnumColor.Next();
                    ISymbol pSymbol = GetSymbol(pColor);
                    pUniqueValueR.AddValue(value, "PERIMETER", pSymbol);
                    //pUniqueValueR.set_Symbol(value, pSymbol);

}

}
            pGeoLayer.Renderer = pUniqueValueR as IFeatureRenderer;
            this.axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
            this.axTOCControl1.Update();

}
        private IRandomColorRamp GetColorRamp(int size)
        {
            IRandomColorRamp pRandomColorRamp = new RandomColorRampClass();
            pRandomColorRamp.StartHue = 10;
            pRandomColorRamp.EndHue = 300;
            pRandomColorRamp.MaxSaturation =100;
            pRandomColorRamp.MinSaturation = 0;
            pRandomColorRamp.MaxValue = 100;
            pRandomColorRamp.MinValue = 0;
            pRandomColorRamp.Size = size;
            bool ok = true;
            pRandomColorRamp.CreateRamp(out ok);
            return pRandomColorRamp;
        }

其中datastatistic和uniqueValueRenderer的field必须要明确，且为相同值