ArcGIS Engine9.3的分级着色法制作专题图

分级着色法制作专题地图，一般首先从两个极值颜色生成一个颜色带，并按数值高低，赋予图元相应的颜色。ArcEngine9.3中无法使用IColorPallete、IColorSelector、IColorBrower等颜色板接口，一个可行的办法是使用.net的颜色对话框选择颜色，然后将选中颜色转换为ESRI的颜色。专题图显示后，需要带颜色带的图例才能观察，方法是，用panel控件的背景色进行设置。

程序如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using ESRI.ArcGIS.Controls;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.Display;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.esriSystem;
namespace WorldMap
{
    public partial class ThematicMapForm : Form
    {
        public ThematicMapForm()
        {
            InitializeComponent();
        }
        public ThematicMapForm(IMapControl3 pMapC)
        {
            InitializeComponent();
            this.pMapControl = pMapC;//获得MapControl的引用
        }
        private IMapControl3 pMapControl;
        private IEnumColors pEnumColors;//颜色带
        private double[] classes;//断点值，两端分别是渲染字段的最小值和最大值
        private Color startColor;//低值颜色
        private Color endColor;//高值颜色

        //在地图中添加label，参数为字段
        private void AddLabel2Map(string strField)
        {
            IGeoFeatureLayer pGeoFeatureLayer;
            ILineLabelPosition pLineLabelPosition;
            ILabelEngineLayerProperties pLabelEngineLayerProperties;
            IAnnotateLayerProperties pAnnotateLayerProperties;
            pGeoFeatureLayer = (IGeoFeatureLayer)this.pMapControl.get_Layer(4);
            pGeoFeatureLayer.AnnotationProperties.Clear();
            pLineLabelPosition = new LineLabelPositionClass();
            pLineLabelPosition.Above = false;
            pLineLabelPosition.AtEnd = false;
            pLineLabelPosition.Below = false;
            pLineLabelPosition.Horizontal = false;
            pLineLabelPosition.InLine = true;
            pLineLabelPosition.OnTop = true;
            pLineLabelPosition.Parallel = true;
            pLineLabelPosition.ProduceCurvedLabels = true;
            pLabelEngineLayerProperties = new LabelEngineLayerPropertiesClass();
            pLabelEngineLayerProperties.Symbol = new TextSymbolClass();
            pLabelEngineLayerProperties.IsExpressionSimple = true;
            pLabelEngineLayerProperties.Expression = "[" + strField + "]";//需要中括号
            pLabelEngineLayerProperties.BasicOverposterLayerProperties.LineLabelPosition = pLineLabelPosition;
            pAnnotateLayerProperties = (IAnnotateLayerProperties)pLabelEngineLayerProperties;
            pAnnotateLayerProperties.DisplayAnnotation = true;
            pAnnotateLayerProperties.FeatureLayer = pGeoFeatureLayer;
            pAnnotateLayerProperties.LabelWhichFeatures = esriLabelWhichFeatures.esriVisibleFeatures;
            pAnnotateLayerProperties.WhereClause = "";
            pGeoFeatureLayer.AnnotationProperties.Add(pAnnotateLayerProperties);
            pGeoFeatureLayer.DisplayAnnotation = true;
            this.pMapControl.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null);
        }
        //产生图例（色带+数值区间）
        private void ProduceLegend(IEnumColors pEnumColors,double[] classes)
        {
            this.panel1.Controls.Clear();
            pEnumColors.Reset();//必须重设
            IColor pC = pEnumColors.Next();//获取ESRI色带的下一个颜色
            int j = 0;
            while (pC != null)
            {
                Panel p = new Panel();//色带用p的背景颜色表示
                Label l = new Label();//数值区间用l的tex表示
                p.BackColor = ColorTranslator.FromOle(pC.RGB);//ESRI颜色转换为.net颜色
                p.BorderStyle = BorderStyle.FixedSingle;
                p.Size = new System.Drawing.Size(88, 25);
                p.Location = new System.Drawing.Point(5, 5 + j * 25);
                l.Size = new System.Drawing.Size(120, 25);
                l.Location = new System.Drawing.Point(102, 13 + j * 25);
                l.Text = this.classes[j].ToString("#0.00") + "—" + this.classes[j + 1].ToString("#0.00");//保留两位小数
                this.panel1.Controls.Add(p);//添加到一个panel中
                this.panel1.Controls.Add(l);//添加到一个panel中
                j++;
                pC = pEnumColors.Next();
            }
        }
        
        //将.net颜色转变为ESRI的颜色
        public IColor ConvertColorToIColor(Color color)
        {
            IColor pColor = new RgbColorClass();
            pColor.RGB = color.B * 65536 + color.G * 256 + color.R;
            return pColor;
        }

        //专题图渲染（多级颜色）。参数为需要渲染的字段（数值类型）,分级数目
        private void ClassBreaksMap(string strField, int numDesiredClasses)
        {
            IGeoFeatureLayer pGeoFeatureLayer;
            ITable pTable;
            IClassifyGEN pClassify;
            ITableHistogram pTableHistogram;
            IBasicHistogram pBasicHistogram;
            object dataFrequency;
            object dataValues;
            int classesCount;
            IClassBreaksRenderer pClassBreaksRenderer;
            IColor pColor;
            ISimpleFillSymbol pSimpleFillSymbol;
            int breakIndex;
            pGeoFeatureLayer = (IGeoFeatureLayer)this.pMapControl.get_Layer(4);
            pTable = (ITable)pGeoFeatureLayer.FeatureClass;
            pTableHistogram = new BasicTableHistogramClass();
            pBasicHistogram = (IBasicHistogram)pTableHistogram;
            pTableHistogram.Field = strField;
            pTableHistogram.Table = pTable;
            pBasicHistogram.GetHistogram(out dataValues, out dataFrequency);
            pClassify = new EqualIntervalClass();
            try
            {
                pClassify.Classify(dataValues, dataFrequency, ref numDesiredClasses);
            }
            catch (Exception ee)
            {
                MessageBox.Show(ee.Message);
            }
            classes = (double[])pClassify.ClassBreaks;
            classesCount = classes.GetUpperBound(0);
            pClassBreaksRenderer = new ClassBreaksRendererClass();
            pClassBreaksRenderer.Field = strField;
            pClassBreaksRenderer.BreakCount = classesCount;
            pClassBreaksRenderer.SortClassesAscending = true;
            pEnumColors = this.ProduceEnumColors(this.startColor, this.endColor, classesCount);//产生色带
            for (breakIndex = 0; breakIndex < classesCount; breakIndex++)
            {
                pColor = pEnumColors.Next();
                pSimpleFillSymbol = new SimpleFillSymbolClass();
                pSimpleFillSymbol.Color = pColor;
                pSimpleFillSymbol.Style = esriSimpleFillStyle.esriSFSSolid;
                pClassBreaksRenderer.set_Symbol(breakIndex, pSimpleFillSymbol as ISymbol);
                pClassBreaksRenderer.set_Break(breakIndex, classes[breakIndex + 1]);
            }
            pGeoFeatureLayer.Renderer = (IFeatureRenderer)pClassBreaksRenderer;
            this.pMapControl.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
        }

        //根据起点颜色、终点颜色和级别数目，产生色带
        private IEnumColors ProduceEnumColors(Color start, Color end, int gradecount)
        {
            //创建一个新AlgorithmicColorRampClass对象
            IAlgorithmicColorRamp algColorRamp = new AlgorithmicColorRampClass();
            algColorRamp.ToColor = this.ConvertColorToIColor(end);//从.net的颜色转换
            algColorRamp.FromColor = this.ConvertColorToIColor(start);
            //设置梯度类型
            algColorRamp.Algorithm = esriColorRampAlgorithm.esriCIELabAlgorithm;
            //设置颜色带颜色数量
            algColorRamp.Size = gradecount;
            //创建颜色带
            bool bture = true;
            algColorRamp.CreateRamp(out bture);
            //使用IEnumColors获取颜色带
            return algColorRamp.Colors;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            try
            {
                this.ClassBreaksMap("数据", 7);//按值分级渲染地图
                this.ProduceLegend(this.pEnumColors, this.classes);//绘制图例
            }
            catch(Exception thematicE)
            {
                MessageBox.Show(thematicE.Message+Environment.NewLine+"渲染地图错误，请重新设置！");
            }
            try
            {
                this.AddLabel2Map("数据");
            }
            catch (Exception addLabelE)
            {
                MessageBox.Show(addLabelE.Message + Environment.NewLine + "添加地图Label错误，请重新设置！");
            }
        }

       
        private void button4_Click(object sender, EventArgs e)
        {
            DialogResult dr = this.colorDialog1.ShowDialog();
            if (dr == DialogResult.OK)
            {
                this.startColor = this.colorDialog1.Color;
                this.button4.BackColor = this.startColor;
            }
        }
        private void button5_Click(object sender, EventArgs e)
        {
            DialogResult dr = this.colorDialog1.ShowDialog();
            if (dr == DialogResult.OK)
            {
                this.endColor = this.colorDialog1.Color;
                this.button5.BackColor = this.endColor;
            }
        }
    }
}

效果图：

由于该图只有6个地区，效果不是很明显。当地区较多时，效果会比较好。

另外，分级着色法，必须保证级别数目大于等于2，当小于2时，无法正确绘制。