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);
}
|
.NET
C#, office, PowerPoint, thumbnail
