Stanley Yao's Blog

It's sometimes useful to generate JPEG thumbnails of office documents programmatically.  With Office object library, it's very convenient to do this in C#.NET.  If it's for a quick and dirty task, an easy way is to convert the office document into a webpage and then use a WebBrowser control to generate the thumbnail.  For a more performance oriented task, customized controls subclassed from the Office classes could be written to dump the bitmaps directly into images.  The following is a sample implementation of the first approach.  Don't forget to add the reference to COM object library "Microsoft PointPoint 12.0 Object Library".

Creating Thumbnails for PowerPoint Presentations

using PowerPoint = Microsoft.Office.Interop.PowerPoint; private void pptThumbnail(string sourceFile, string targetFile, int thumbW, int thumbH) {     // Open the document and convert into HTML pages     PowerPoint.ApplicationClass oApp = new PowerPoint.ApplicationClass();     PowerPoint.Presentation oDoc = oApp.Presentations.Open(         sourceFile,         Microsoft.Office.Core.MsoTriState.msoTrue, // read only         Microsoft.Office.Core.MsoTriState.msoTrue, // untitled         Microsoft.Office.Core.MsoTriState.msoFalse); // with window     string tmpHtmlFile = System.IO.Path.GetTempFileName() + ".html";     oApp.Presentations[1].SaveCopyAs(         tmpHtmlFile,         PowerPoint.PpSaveAsFileType.ppSaveAsHTML, // format         Microsoft.Office.Core.MsoTriState.msoTrue); // embed true type font     // Create the thumbnail from the HTML pages     Size browserSize = new Size(800, 800);     WebBrowser browser = new WebBrowser();     browser.Size = browserSize;     browser.Navigate(tmpHtmlFile);     while (WebBrowserReadyState.Complete != browser.ReadyState)     {         Application.DoEvents();     }     Bitmap bm = new Bitmap(browserSize.Width, browserSize.Height);     browser.DrawToBitmap(bm,         new Rectangle(0, 0, browserSize.Width, browserSize.Height));     Bitmap thumbnail = new Bitmap(thumbW, thumbH);     Graphics g = Graphics.FromImage(thumbnail);     g.DrawImage(         bm,         new Rectangle(0, 0, thumbnail.Width, thumbnail.Height),         new Rectangle(0, 0, browserSize.Width, browserSize.Height),         GraphicsUnit.Pixel);     thumbnail.Save(targetFile); }