C# Image via Memorystream error (but only second time through) - arrays

Question

I need to be able to convert an Image to a byte Array and then back again. I've followed the google results and it seemed to be working..except it doesn't :)
I am pretty sure it has something to do with the Memory stream (I'm getting that GDI+ error) but I'm using the "using" and I thought I was cleanup up after myself.
private void button1_Click(object sender, EventArgs e)
{
System.Drawing.Image myImage = null;
SetImage(ref myImage); //This one works
SetImage(ref myImage); // This call breaks on
//the first myImage.Save line
}
private void SetImage(ref System.Drawing.Image myImage)
{
try
{
byte[] myImageAsBytes = null;
//First time through we don't have an image already so we load from a file
if (myImage == null)
{
myImage = System.Drawing.Image.FromFile("C:\\temp\\test.jpg");
}
//Convert our Image to a Byte Array.
using (System.IO.MemoryStream myMemoryStream = new System.IO.MemoryStream())
{
myImage.Save(myMemoryStream, myImage.RawFormat);
myImageAsBytes = myMemoryStream.ToArray();
}
//Just debugging
myImage.Dispose();
myImage = null;
GC.Collect();
//And convert it back to an image.
//using (System.IO.MemoryStream myMemoryStream = new System.IO.MemoryStream(myImageAsBytes))
//{
// myImage = System.Drawing.Image.FromStream(myMemoryStream);
//}
System.IO.MemoryStream myMemoryStream2 = new System.IO.MemoryStream(myImageAsBytes);
myImage = System.Drawing.Image.FromStream(myMemoryStream2);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Answer 1

The documentation for Image.FromStream: https://msdn.microsoft.com/en-us/library/93z9ee4x(v=vs.110).aspx
Says:
You must keep the stream open for the lifetime of the Image.
When it comes to MemoryStreams there is actually no point in closing/disposing them. It's the only .NET class I can think of that is IDisposable that doesn't need disposing. It accidentally inherits IDisposable from System.IO.Stream, that's why.
So I would recommend that you just create your memory streams and let them be.
If you were to use Image.FromStream on a physical file, however, maybe you wont like to keep it open. What you could do in that case is to make a copy of the bitmap like this:
Bitmap safeBitmap;
using ( var stream = blah-blah-blah )
using ( var img = Image.FromStream(stream) )
safeBitmap = new Bitmap(img);

Answer 2

I know delphi but not C++. I think you have set myimage to null if myimage is an object, so tried to re-create. Or don't set it to null, just redraw on it or myimage.loadfromstream.
System.Drawing.Image myImage = null;
SetImage(ref myImage); //This one works
myimage :=create;
SetImage(ref myImage);

Answer 3

Its as simple as removing "ref" from everywhere
I suggest you read up what that key word is doing, you will then understand why its breaking it.
rather return the new image from the method.
i.e. change it from void to return the new image.
Update
below is a console version of your code basically unmodified at ALL
and it runs fine.... although i don't agree with the programming at ALL either.
Point is where are you getting an error if it seems to run with no errors
class Program
{
static void Main(string[] args)
{
Dosomething();
}
private static void Dosomething()
{
System.Drawing.Image myImage = null;
SetImage(ref myImage); //This one works
SetImage(ref myImage); // This call breaks on
}
private static void SetImage(ref System.Drawing.Image myImage)
{
try
{
byte[] myImageAsBytes = null;
//First time through we don't have an image already so we load from a file
if (myImage == null)
{
myImage = System.Drawing.Image.FromFile("C:\\temp\\test.jpg");
}
//Convert our Image to a Byte Array.
using (System.IO.MemoryStream myMemoryStream = new System.IO.MemoryStream())
{
myImage.Save(myMemoryStream, myImage.RawFormat);
myImageAsBytes = myMemoryStream.ToArray();
}
//Just debugging
myImage.Dispose();
myImage = null;
GC.Collect();
//And convert it back to an image.
//using (System.IO.MemoryStream myMemoryStream = new System.IO.MemoryStream(myImageAsBytes))
//{
// myImage = System.Drawing.Image.FromStream(myMemoryStream);
//}
System.IO.MemoryStream myMemoryStream2 = new System.IO.MemoryStream(myImageAsBytes);
myImage = System.Drawing.Image.FromStream(myMemoryStream2);
}
catch (Exception ex)
{
}
}
}