Arcengine 中，创建色带

1,利用combobox创建色带，首先draw

private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
        {
         Rectangle rec=   e.Bounds;
         rec.Width = rec.Width /array.Length;
        string fromColor = comboBox1.Items[e.Index].ToString().Split('|')[0];
         string ToColor = comboBox1.Items[e.Index].ToString().Split('|')[1];
         _FromColor = Color.FromName(fromColor);
         _ToColor = Color.FromName(ToColor);
         IAlgorithmicColorRamp ramp = new AlgorithmicColorRampClass();//创建色带，也可以创建渐变色带用LinearGradientBrush类
         ramp.FromColor = ColorToIColor(_FromColor);
         ramp.ToColor = ColorToIColor(_ToColor);
         ramp.Size =array.Length ;
         bool ok=true;
            ramp.CreateRamp(out ok);
            IEnumColors EnumColor = ramp.Colors;
      IColor color = null;
       SolidBrush sb=null;

for (int i = 0; i < array.Length; i++)
         {
             color = EnumColor.Next();
             sb=new SolidBrush(IColorToColor(color));
             e.Graphics.FillRectangle(sb, rec)；    
             rec.Offset(rec.Width, 0);//对小矩形进行偏移
         }

}

2.在Load中

comboBox1.DrawMode = DrawMode.OwnerDrawFixed;  //使draw_Item有效
            comboBox1.DropDownStyle = ComboBoxStyle.DropDownList;
            comboBox1.Items.Clear();
            comboBox1.BeginUpdate();
            foreach (string oneColor in colorList)
            {
                comboBox1.Items.Add(oneColor);
            }

comboBox1.EndUpdate();

3、定义颜色，色带的起始与终止色彩

private static string[] colorList = { "Black|White", "White|Black", "Red|Blue","Green|Black" };

4、根据获取的字段值，对每一个值进行渲染

首先获取字段值（不重复）

private double[] array;
        private void button1_Click(object sender, EventArgs e)
        {
            string layername = comboBox2.SelectedItem.ToString();
            string fieldname = comboBox3.SelectedItem.ToString();
            SelectLayer sl = new SelectLayer(mapControl);
          IFeatureLayer layer=  sl.GetLayerByName(layername) as IFeatureLayer;

ITableHistogram histogram = new BasicTableHistogramClass();
          histogram.Field = fieldname;
          histogram.Table = layer as ITable;
          IBasicHistogram BasicH = histogram as IBasicHistogram;

object value=null;
            object frequece=null;
            BasicH.GetHistogram(out value, out frequece);
             array = value as double[];
            for (int i = 0; i < array.Length; i++)
            {
                listView1.Items.Add(array[i].ToString());
            }

}

最后进行渲染：

private void button2_Click(object sender, EventArgs e)
        {

SelectLayer sl = new SelectLayer(mapControl);
            IGeoFeatureLayer layer = sl.GetLayerByName(comboBox2.SelectedItem.ToString()) as IGeoFeatureLayer;
            string fieldname = comboBox3.SelectedItem.ToString();
            string item = comboBox1.SelectedItem.ToString();
            string beginColor = item.Split('|')[0];
            string finishColor = item.Split('|')[1];
            Color _beginColor = Color.FromName(beginColor);
            Color _finishColor = Color.FromName(finishColor);
            IAlgorithmicColorRamp ramp = new AlgorithmicColorRampClass();
            ramp.FromColor = ColorToIColor(_beginColor);
            ramp.ToColor = ColorToIColor(_finishColor);
            ramp.Size = array.Length;
            bool ok = true;
            ramp.CreateRamp(out ok);
            IEnumColors enumColor = ramp.Colors;
            IColor color = null;
            ISimpleFillSymbol fillSymbol = null;
            IUniqueValueRenderer valueRender = new UniqueValueRendererClass();
            valueRender.FieldCount = 1;
            valueRender.set_Field(0, fieldname);
            for (int i = 0; i < array.Length; i++)
            {
                color = enumColor.Next();
                fillSymbol = new SimpleFillSymbolClass();
                fillSymbol.Color = color;
                valueRender.AddValue(array[i].ToString(), fieldname, fillSymbol as ISymbol);
               
            }
           
            MessageBox.Show("成功！");
            layer.Renderer = valueRender as IFeatureRenderer;
            mapControl.Refresh();
        }

最后渲染结果如上图。可能方法比较笨拙，代码重复较多，只是限于水平有限，并是自己所想出来的结果，所以和各位Giser一起分享。