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PngBitmapEncoder and Opacity problem

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JC asked on 02 Nov 2010, 05:28 PM

result.png

Hello Guys

I have a problem when I encode a image in png.
I use a OpenFileDialog and call this method after :

public static byte[] EncodeToPng(BitmapSource bitmap)
{
  byte[] retval;
  using (MemoryStream stream = new MemoryStream())
  {
    var encoder = new PngBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(bitmap));
    encoder.Save(stream);
    retval = stream.ToBytes();
  }
  return retval;
}

I need a byte[] to send it to my server with RIA services ... but that's not the problem

So when I bind my <Image> control to my byte array, I use an IValueConverter which call this method :

public static BitmapImage ToBitmapImage(this byte[] buffer)
{
  BitmapImage imageMateriel = new BitmapImage();
  imageMateriel.SetSource(new MemoryStream(buffer));
  return imageMateriel;
}

And it working :) BUT when I take a PNG file with opacity ... image rendenring is gray !
You can get my test file here : http://www.alfileo.fr/images/logo.png
And my result file in the attached file on this post

Can you try it please ?
Best regards

JC

6 Answers, 1 is accepted

answered on 05 Nov 2010, 08:50 AM

Hello JC,

Thank you for information.
We have reproduced the problem with transparent image for rendering using PNG-encoder. Unfortunately it will take significant time to research into the problem.

We have created the PITS issue to fix this problem in future releases.
You can track it using the following link:
http://www.telerik.com/support/pits.aspx#/public/silverlight/3900

Sincerely yours,
Andrey Murzov
the Telerik team

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