public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
if (!LabelOperator.isObjectExistingFile(value))
{
return(null);
}
string btwFileName = (string)value;
try
{
System.Drawing.Image btwImage =
LabelFormatThumbnail.Create(btwFileName, System.Drawing.Color.Gray, 500, 500);
using (var ms = new MemoryStream())
{
btwImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
ms.Position = 0;
var bi = new BitmapImage();
bi.BeginInit();
bi.CacheOption = BitmapCacheOption.OnLoad;
bi.StreamSource = ms;
bi.EndInit();
btwImage.Dispose(); //if bmp is not used further.
return(bi);
}
}
catch (Exception ex)
{
Log.Instance.Logger.Error($"获取缩略图错误:{ex.Message}");
return(null);
}
}
/// <summary>
/// Loads thumbnails in a background thread so the UI doesn't hang.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void thumbnailCacheWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = (BackgroundWorker)sender;
int index;
string fileName;
// Loop until the queue of items that need to be loaded is empty or the worker was cancelled.
while ((generationQueue.Count > 0) && !worker.CancellationPending && !isClosing)
{
lock (generationQueue)
{
// Get the index to use.
index = generationQueue.Dequeue();
}
// If this is way out of our view don't bother generating it.
if (Math.Abs(index - topIndex) < 30)
{
fileName = browsingFormats[index];
// Check to see if the listitem is already generated and just waiting for a thumbnail.
ListViewItem item = (ListViewItem)listItems[fileName];
if (item == null)
{
item = new ListViewItem(fileName);
item.ImageIndex = (int)ImageIndex.LoadingFormatImage;
listItems.Add(fileName, item);
}
// If the listitem doesn't already have a thumbnail, generate it.
if (item.ImageIndex == (int)ImageIndex.LoadingFormatImage)
{
try
{
Image btwImage = LabelFormatThumbnail.Create(fileName, Color.Gray, 100, 100);
object[] progressReport = new object[] { item, btwImage };
worker.ReportProgress(100, progressReport);
}
// If the file isn't an actual btw format file we will get an exception.
catch
{
object[] progressReport = new object[] { item, null };
worker.ReportProgress(0, progressReport);
}
}
}
}
}
/// <summary>
/// Finds all BarTender documents in the server's Documents directory, generates thumbnails for them,
/// and returns a list of valid files. In a real application, we recommend implementing some form of caching.
/// Thumbnail generation can be slow, so our own implementation keeps track of file modification times to
/// avoid re-generating thumbnails unnecessarily.
/// </summary>
public static List <WebLabelPrintDocument> GenerateDocumentsList()
{
List <WebLabelPrintDocument> documentsList = new List <WebLabelPrintDocument>();
string documentsFullPath = HttpContext.Current.Server.MapPath("~/Documents");
if (!Directory.Exists(documentsFullPath))
{
return(documentsList);
}
foreach (string fileName in Directory.GetFiles(documentsFullPath))
{
// Filter for BarTender documents (.btw files)
if (!fileName.ToLowerInvariant().EndsWith("btw"))
{
continue;
}
string thumbnailFileName = fileName.Substring(0, fileName.Length - 3) + "png";
// Use the BarTender .NET Print SDK to generate a thumbnail. Note that this does not go through a Print Engine like many
// of the other Print SDK functions. Communication with BarTender occurs via the Print Scheduler service.
using (Image thumbnailImage = LabelFormatThumbnail.Create(fileName, Color.Transparent, 150, 150))
{
if (thumbnailImage != null)
{
thumbnailImage.Save(thumbnailFileName);
WebLabelPrintDocument document = new WebLabelPrintDocument();
document.FullPath = fileName;
document.DisplayName = Path.GetFileName(fileName);
document.ThumbnailRelativePath = "~/Documents/" + document.DisplayName.Substring(0, document.DisplayName.Length - 3) + "png";
documentsList.Add(document);
}
}
}
return(documentsList);
}