/// <summary>
/// Handles the DoWork event of the queued background worker.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="Manina.Windows.Forms.QueuedWorkerDoWorkEventArgs"/> instance
/// containing the event data.</param>
void Bw_DoWork(object sender, QueuedWorkerDoWorkEventArgs e)
{
CacheRequest request = e.Argument as CacheRequest;
// Should we continue processing this item?
// The callback checks the following and returns false if
// the item is already cached -OR-
// the item is in the edit cache -OR-
// the item is outside the visible area (only if the CacheMode is OnDemand).
if (!OnCanContinueProcessing(request))
{
e.Cancel = true;
return;
}
Image thumb = null;
string diskCacheKey = request.Adaptor.GetUniqueIdentifier(request.VirtualItemKey, request.Size, request.UseEmbeddedThumbnails, request.AutoRotate, request.UseWIC);
// Check the disk cache
using (Stream stream = DiskCache.Read(diskCacheKey))
{
if (stream.Length > 0)
{
thumb = new Bitmap(stream);
}
}
//Trace.WriteLine("BwGetThumbnail:"+request.VirtualItemKey);
// Extract the thumbnail from the source image.
if (thumb == null)
{
thumb = request.Adaptor.GetThumbnail(request.VirtualItemKey, request.Size, request.UseEmbeddedThumbnails, request.AutoRotate, request.UseWIC);
// Save to disk cache
if (thumb != null)
{
using (MemoryStream stream = new MemoryStream())
{
thumb.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
DiskCache.Write(diskCacheKey, stream);
}
}
}
// Return the thumbnail
CacheItem result = null;
if (thumb == null && !RetryOnError)
{
result = new CacheItem(request.Guid, request.Size, null, CacheState.Error, request.UseEmbeddedThumbnails, request.AutoRotate, request.UseWIC);
}
else
{
result = new CacheItem(request.Guid, request.Size, thumb, CacheState.Cached, request.UseEmbeddedThumbnails, request.AutoRotate, request.UseWIC);
}
e.Result = result;
}
