Updated for Vault 2012: New image types are now supported for thumbnails. In Vault 2011 and earlier, Metafile was the only image type. In Vault 2012, anything that can be streamed into System.Drawing.Image is supported.
This post contains the updated code. The old code can be found here.
Basically there are two possible algorithms, and you don't know which one to use upfront. So the code tries one algorithm. If it fails, the second algorithm is run.
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private System.Drawing.Image GetImage(PropInst prop, int width, int height)
{
byte[] thumbnailRaw = (byte[])prop.Val;
System.Drawing.Image retVal = null;
using (System.IO.MemoryStream ms = new System.IO.MemoryStream(thumbnailRaw))
{
// we don't know what format the image is in, so we try a couple of formats
try
{
// try the meta file format
ms.Seek(12, System.IO.SeekOrigin.Begin);
System.Drawing.Imaging.Metafile metafile =
new System.Drawing.Imaging.Metafile(ms);
retVal = metafile.GetThumbnailImage(width, height,
new System.Drawing.Image.GetThumbnailImageAbort(GetThumbnailImageAbort),
System.IntPtr.Zero);
}
catch
{
// I guess it's not a met
afile
retVal = null;
}
if (retVal == null)
{
try
{
// try to stream to System.Drawing.Image
ms.Seek(0, System.IO.SeekOrigin.Begin);
System.Drawing.Image rawImage = System.Drawing.Image.FromStream(ms, true);
retVal = rawImage.GetThumbnailImage(width, height,
new System.Drawing.Image.GetThumbnailImageAbort(GetThumbnailImageAbort),
System.IntPtr.Zero);
}
catch
{
// not compatible Image object
retVal = null;
}
}
}
return retVal;
}
private static bool GetThumbnailImageAbort()
{
return false;
} |
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Private Function GetImage(ByVal prop As PropInst, ByVal width As Integer, _
ByVal height As Integer) _
As System.Drawing.Image
Dim thumbnailRaw As Byte() = DirectCast(prop.Val, Byte())
Dim retVal As System.Drawing.Image = Nothing
Using ms As New System.IO.MemoryStream(thumbnailRaw)
' we don't know what format the image is in, so we try a couple of formats
Try
' try the meta file format
ms.Seek(12, System.IO.SeekOrigin.Begin)
Dim metafile As New System.Drawing.Imaging.Metafile(ms)
retVal = metafile.GetThumbnailImage(width, height, _
New System.Drawing.Image.GetThumbnailImageAbort( _
AddressOf GetThumbnailImageAbort), _
System.IntPtr.Zero)
Catch

0; ' I guess it's not a metafile
retVal = Nothing
End Try
If retVal Is Nothing Then
Try
' try a serialized System.Drawing.Image
ms.Seek(0, System.IO.SeekOrigin.Begin)
Dim rawImage As System.Drawing.Image = System.Drawing.Image.FromStream(ms, True)
retVal = rawImage.GetThumbnailImage(width, height, _
New System.Drawing.Image.GetThumbnailImageAbort( _
AddressOf GetThumbnailImageAbort), _
System.IntPtr.Zero)
Catch
' not a serialized Image object
retVal = Nothing
End Try
End If
End Using
Return retVal
End Function
Private Shared Function GetThumbnailImageAbort() As Boolean
Return False
End Function
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