MemoryStream throws System.ObjectDisposedException - wpf

Question

I want to resize images for iOS so that I don't have to do it manually all the time. This should be done using WPF but it throws a ObjectDisposedException.
What it does is the user selects a csproj file and then an image which will be resized in 3 sizes. After resizing the file should be safed to disk but it throws an exception.
retrieving the bytes of the original BitmapImage
byte[] data = original.GetByteArray();
The used method:
public static byte[] GetByteArray(this BitmapImage bmi)
{
byte[] data;
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bmi));
using (Sys.MemoryStream ms = new Sys.MemoryStream())
{
encoder.Save(ms);
data = ms.ToArray();
}
return data;
}
the resizing:
private BitmapImage ResizeImage(byte[] imageData, double dheight, double dwidth)
{
int height = (int)dheight;
int width = (int)dwidth;
BitmapImage resizedImage = new BitmapImage();
using (Sys.MemoryStream ms = new Sys.MemoryStream(imageData))
{
resizedImage.CreateOptions = BitmapCreateOptions.IgnoreColorProfile;
resizedImage.CacheOption = BitmapCacheOption.OnLoad;
resizedImage.DecodePixelHeight = height;
resizedImage.DecodePixelWidth = width;
resizedImage.BeginInit(); // Needed only so we can call EndInit()
resizedImage.StreamSource = ms;
resizedImage.EndInit();// This does the actual loading and resizing
}
return resizedImage;
}
then the saving of the files:
public static void Save(this BitmapImage image, string filePath)
{
//PngBitmapEncoder encoder = new PngBitmapEncoder();
//encoder.Frames.Add(BitmapFrame.Create(image));
//using (var fileStream = new System.IO.FileStream(filePath, System.IO.FileMode.Create))
//{
// encoder.Save(fileStream);
//}
File.WriteAllBytes(filePath, image.GetByteArray());
}
how I used it:
var bmi512 = ResizeImage(data, 512, 512);
var bmi256 = ResizeImage(data, 256, 256);
var bmi128 = ResizeImage(data, 128, 128);
bmi512.Save(Sys.Path.Combine(imageFolderPath, String.Format("{0}512{1}", imageName, imageExt)));
bmi256.Save(Sys.Path.Combine(imageFolderPath, String.Format("{0}256{1}", imageName, imageExt)));
bmi128.Save(Sys.Path.Combine(imageFolderPath, String.Format("{0}128{1}", imageName, imageExt)));
it works for retrieving the byte[] of the original but when it try it for bmi512 I get the exception.
Thanks in advance

Answer 1

You have to call BeginInit before you set any of the BitmapImage's properties:
using (var ms = new MemoryStream(imageData))
{
resizedImage.BeginInit();
resizedImage.CreateOptions = BitmapCreateOptions.IgnoreColorProfile;
resizedImage.CacheOption = BitmapCacheOption.OnLoad;
resizedImage.DecodePixelHeight = height;
resizedImage.DecodePixelWidth = width;
resizedImage.StreamSource = ms;
resizedImage.EndInit();
}