Arcgis Engine 实现单波段栅格图层色带渲染(包括色带反转)

    最近有同事问我ArcMap中的色带反转怎么实现，刚好我在整理以前的项目，找到了一些源码备忘。

            

    先说下思路，简单来说就是得到栅格图层的IRasterRenderer,转换为IRasterStretchColorRampRenderer,在将这个接口转换为IRasterStretch,IRasterStretch中有个Invert的方法可以控制色带是否反转。下面详细说下实现过程。

    1、重写一个可以添加图片的ComboBox

    public partial class ComboboxSymbol : ComboBox
    {
        public ComboboxSymbol()
        {
            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
                Image image = (Image)Items[e.Index];
                System.Drawing.Rectangle rect = e.Bounds;
                e.Graphics.DrawImage(image, rect);
            }
            catch
            {
            }
            finally
            {
                base.OnDrawItem(e);
            }
        }
    }

2、设计一个窗体，就下图中的几个按钮，另外添加一个隐藏显示的AxSymbologyControl，用来调用显示系统色带

3、窗体下的代码如下

        private IRasterLayer _pRasyerLayer = null;
        
        public ColorRamp(IRasterLayer pRasterLayer,int X,int Y)
        {
            InitializeComponent();
            _pRasyerLayer = pRasterLayer;
            this.Location = new System.Drawing.Point(X, Y); //得到当前鼠标位置，用来确定窗体显示的位置
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void LoadSymbolProperty(IRasterLayer mRasterLayer)
        {
            IRasterStretchColorRampRenderer pStretchRen;
            try
            {
                pStretchRen = (IRasterStretchColorRampRenderer)mRasterLayer.Renderer;
                IRasterStretch pRasterStretch = pStretchRen as IRasterStretch;
                if (pRasterStretch.Invert)
                {
                    ckInvert.Checked = true;
                }
            }
            catch (Exception ex)
            {
                WriteLog.LogWritter.WriteLogToFile(ex.Message);
                return;
            }
            try
            {
                //加载系统样式
                string sInstall = ESRI.ArcGIS.RuntimeManager.ActiveRuntime.Path;
                string defaultStyle = System.IO.Path.Combine(sInstall, "Styles\\ESRI.ServerStyle");

                axSymbologyControl1.LoadStyleFile(defaultStyle);
                axSymbologyControl1.StyleClass = esriSymbologyStyleClass.esriStyleClassColorRamps;
                ISymbologyStyleClass symbologyStyleClass = axSymbologyControl1.GetStyleClass(esriSymbologyStyleClass.esriStyleClassColorRamps);

                IStyleGalleryItem styleGalleryItem = new ServerStyleGalleryItem();
                styleGalleryItem.Item = pStretchRen.ColorRamp;
                styleGalleryItem.Name = "mySymbol";
                symbologyStyleClass.AddItem(styleGalleryItem, 0);
                symbologyStyleClass.SelectItem(0);

                //将样式转为图片并添加入ComboBox
                for (int i = 0; i < symbologyStyleClass.get_ItemCount(symbologyStyleClass.StyleCategory); i++)
                {
                    stdole.IPictureDisp picture = symbologyStyleClass.PreviewItem(symbologyStyleClass.GetItem(i), cbSymbol.Width, cbSymbol.Height);
                    System.Drawing.Image image = System.Drawing.Image.FromHbitmap(new System.IntPtr(picture.Handle));
                    cbSymbol.Items.Add(image);
                }
                if (cbSymbol.Items.Count > 0)
                    cbSymbol.SelectedIndex = 0;
            }
            catch (Exception ex)
            {
                WriteLog.LogWritter.WriteLogToFile(ex.Message);
            }
        }
        private void SetRasterSymbol(IRasterLayer mRasterLayer)
        {

            try
            {
                //获取选择的序号
                int symbol_index = cbSymbol.SelectedIndex;
                ISymbologyStyleClass symbologyStyleClass = axSymbologyControl1.GetStyleClass(esriSymbologyStyleClass.esriStyleClassColorRamps);
                IStyleGalleryItem mStyleGalleryItem = symbologyStyleClass.GetItem(symbol_index);
                //获取选择的符号
                IColorRamp colorramp_select = (IColorRamp)mStyleGalleryItem.Item;
                IRasterStretchColorRampRenderer pStretchRen = (IRasterStretchColorRampRenderer)mRasterLayer.Renderer;
                pStretchRen.ColorRamp = colorramp_select;
                IRasterStretch pRasterStretch = pStretchRen as IRasterStretch;
                //控制色带是否反转
                if (ckInvert.Checked)
                {
                    pRasterStretch.Invert = true;
                }
                else
                {
                    pRasterStretch.Invert = false;
                }
            }
            catch (Exception ex)
            {
                WriteLog.LogWritter.WriteLogToFile(ex.Message);
                this.Close();
            }

        }
        private void ColorRamp_Load(object sender, EventArgs e)
        {
            LoadSymbolProperty(_pRasyerLayer);
        }

        private void btnOk_Click(object sender, EventArgs e)
        {
            SetRasterSymbol(_pRasyerLayer);
            this.DialogResult = DialogResult.OK;
            this.Close();
        }
    }