Engine中如何为矢量或者栅格数据设置缩略图？

【解决办法】：
1, 需要获取stdole.IPicture对象，也就是先生成一个图片。对于栅格或矢量数据，可以使用IActiveView.Output输出图片，对于栅格数据，还可以使用IRasterLayerExport将栅格图层输出成图片。
2, 使用IGxThumbnail.Thumbnail设置缩略图，之前需要创建IGxDataset接口，然后将其转为IGxThumbnail。
注：该接口只能在Desktop许可中使用。下面代码以影像数据为例：

IDatasetName datasetName = new RasterDatasetNameClass();

IWorkspaceName workspaceName = new WorkspaceNameClass();

workspaceName.WorkspaceFactoryProgID = esriDataSourcesRaster.RasterWorkspaceFactory;

string pathName = @E:ZhuXinying测试数据;

string name = image.tif;

string picPathName = @E:tempzxy.jpg;

workspaceName.PathName = pathName ;

datasetName.WorkspaceName = workspaceName;

datasetName.Name = name;

System.Drawing.Image image =Image.FromFile(picPathName) ;

IPicture pic = IPictureConverter.ImageToIPicture(image);

IGxDataset gxDataset = new GxRasterDatasetClass();

gxDataset.DatasetName = datasetName;

IGxThumbnail gxThumbnail = gxDataset as IGxThumbnail;

gxThumbnail.Thumbnail = pic; 

实现Image到IPicture的转换，还需要加上下面代码：

public sealed class IPictureConverter : AxHost { private IPictureConverter() : base() { }

public static stdole.IPicture ImageToIPicture(Image image) {return (stdole.IPicture)GetIPictureFromPicture(image); }

public static Image IPictureToImage(stdole.IPicture picture) { return GetPictureFromIPicture(picture);} }