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.bine(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ComboBoxfor (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();}}
