将ColorCamp对象添加到ComboBox中

主要包括下面几个步骤：

1.自定义一个PictureComboBox类，可以Image作为Item添加的ComboBox；

//构造函数

      public PictureComboBox()
        {
            //以下两句是关键的；
            DrawMode = DrawMode.OwnerDrawFixed;
            DropDownStyle. = ComboBoxStyle.DropDownList;   
        }

        //重写函数

        protected override void OnDrawItem(DrawItemEventArgs e)
        {
            e.DrawBackground();
            e.DrawFocusRectangle();
            try
            {
                //显示图片
                if(e.Index!=-1)//反正初始化失败
                {
                Image image = (Image)Items[e.Index];
                System.Drawing.Rectangle rect = e.Bounds;
                e.Graphics.DrawImage(image, rect);
                }           
           }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                base.OnDrawItem(e);
            }
        }

2.将自定义的PictureComboBox添加到窗体上；

        先添加一个普通的ComboBox，然后在定义的地方修改：

           private PictureComboBox cmbColorRamp;

           this.cmbColorRamp = new CreateGDB.ThemeMap.PictureComboBox();

3.读取ESRI.ServerStyle文件中esriStyleClassColorRamps下的ColorRamp；

           这里是借助AxSymbologyControl来实现读取的。

4.将各个ColorRamp对象转换为Image；

5.将Image添加到PictureComboBox中。

     static AxSymbologyControl m_SymbologyControl = new  AxSymbologyControl();
     private ISymbologyStyleClass symbologyStyleClass = null;
     //需要将AxSymbologyControl 添加到窗体中
     this.Controls.Add(m_SymbologyControl);

     m_SymbologyControl.LoadStyleFile(Application.StartupPath + "\\ESRI.ServerStyle");

                m_SymbologyControl.StyleClass = esriSymbologyStyleClass.esriStyleClassColorRamps;

                symbologyStyleClass = m_SymbologyControl.GetStyleClass(esriSymbologyStyleClass.esriStyleClassColorRamps)

 for (int i = 0; i < symbologyStyleClass.get_ItemCount(symbologyStyleClass.StyleCategory); i++)
                {
                    IStyleGalleryItem pStyleGalleryItem = symbologyStyleClass.GetItem(i);
                    string aa = pStyleGalleryItem.Category;
                    int bb = pStyleGalleryItem.ID;
                    string cc = pStyleGalleryItem.Name;
                    stdole.IPictureDisp picture = symbologyStyleClass.PreviewItem(pStyleGalleryItem, pComboBox.Width, pComboBox.Height - 1);
                    System.Drawing.Image image = System.Drawing.Image.FromHbitmap(new System.IntPtr(picture.Handle));
                    pComboBox.Items.Add(image);

                }