制作专题图——柱状图

            //获取当前图层，并把它设置成IGeoFeatureLayer的实例

            IMap pMap = axMapControl1.Map;

            ILayer pLayer = pMap.get_Layer(0) as IFeatureLayer;

            IFeatureLayer pFeatureLayer = pLayer as IFeatureLayer;

            IGeoFeatureLayer pGeoFeatureLayer = pLayer as IGeoFeatureLayer;

            pGeoFeatureLayer.ScaleSymbols = false ;

            //获取图层上的feature

            IFeatureClass pFeatureClass = pFeatureLayer.FeatureClass;

 

            //定义柱状图渲染组建对象

            IChartRenderer pChartRenderer = new ChartRendererClass();

            //定义渲染字段对象并给字段对象实例化为pChartRenderer

            IRendererFields pRendererFields;

            pRendererFields = (IRendererFields)pChartRenderer;

           

            //向渲染字段对象中添加字段--- 待补充自定义添加

            pRendererFields.AddField("SHAPE_Area", "SHAPE_Area");

            pRendererFields.AddField("OBJECTID", "OBJECTID");

 

            // 通过查找features的所用字段的值，计算出数据字段的最大值，作为设置柱状图的比例大小的依据

            ITable pTable;

            int fieldNumber;

            pTable = pFeatureLayer as ITable;

            // 查找出geoFeatureLayer的属性表中的字段个数

            fieldNumber = pTable.FindField("SHAPE_Area");

            if (fieldNumber == -1)

            {

                MessageBox.Show("Can't find field called ", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);

 

            }

 

            const int numFields = 2;// 设置bars的个数

            int[] fieldIndecies = new int[2];

            //long fieldIndex;

            double maxValue;

            bool firstValue;

            //double[] fieldValue=new double[5];

            double fieldValue;

            fieldIndecies[0] = pTable.FindField("SHAPE_Area");

            fieldIndecies[1] = pTable.FindField("OBJECTID");

            firstValue = true;

            maxValue = 0;

            int n = pFeatureClass.FeatureCount(null);

            for (int i = 0; i < numFields; i++)

            {

                IFeatureCursor pFeatureCursor = pFeatureClass.Search(null, false);

                for (int j = 0; j < n; j++)

                {

                    IFeature pFeature = pFeatureCursor.NextFeature();

                    fieldValue = Convert.ToDouble(pFeature.get_Value(fieldIndecies[i]));

 

                    if (firstValue)

                    {

                        //给maxValue赋初值

                        maxValue = fieldValue;

                        firstValue = false;

                    }

                    else if (fieldValue > maxValue)

                    {

                        maxValue = fieldValue;

                    }

 

                }

            }

 

            if (maxValue <= 0)

            {

                MessageBox.Show("Failed to calculate the maximum value or maxvalue is 0.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);

            }

            //创建累积排列符号

            IStackedChartSymbol stackedChartSymbol = new StackedChartSymbolClass();

            stackedChartSymbol.Width = 10;

            //stackedChartSymbol.UseOutline = true;

 

            IMarkerSymbol pMarkerSymbol = stackedChartSymbol as IMarkerSymbol;

            pMarkerSymbol.Size = 50;

            IChartSymbol pChartSymbol = stackedChartSymbol as IChartSymbol;

            pChartSymbol.MaxValue = maxValue;

 

            //添加渲染符号

            ISymbolArray pSymbolArray = stackedChartSymbol as ISymbolArray;

 

            IFillSymbol pFillSymbol = new SimpleFillSymbolClass();

            pFillSymbol.Color = getRGB(255, 0, 0);

            pSymbolArray.AddSymbol(pFillSymbol as ISymbol );

 

            pFillSymbol = new SimpleFillSymbolClass();

            pFillSymbol.Color = getRGB(0, 255, 0);

            pSymbolArray.AddSymbol(pFillSymbol as ISymbol);

 

            //设置柱状图符号

            pChartRenderer.ChartSymbol = stackedChartSymbol as IChartSymbol;

            pFillSymbol = new SimpleFillSymbolClass();

            pFillSymbol.Color = getRGB(0, 0,255);

            pChartRenderer.BaseSymbol = pFillSymbol as ISymbol;

            pChartRenderer.UseOverposter = false ;

           

 

            //创建图例

            pChartRenderer.CreateLegend();

            pGeoFeatureLayer.Renderer = pChartRenderer as IFeatureRenderer;

            axMapControl1.Refresh();