Help with ​System.​Drawing.​Bitmap

I have code that kind of looks like this:

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bmp.Save(mem, ImageFormat.Bmp);

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Where:

bmp is a Bitmap object (not null)
mem is a memory stream (also not null)

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I get the following exception:

System.ArgumentException
  Message="Parameter is not valid."
  Source="System.Drawing"

I fixed the issue (apperently bmp.Dispose() was being called from somewhere else in the application .. sigh). But I have a new issue, nothing seems to be going into the memory stream.

Care to post the code where you obtain, save to, and consume the memory stream?

Bass said:

I fixed the issue (apperently bmp.Dispose() was being called from somewhere else in the application .. sigh). But I have a new issue, nothing seems to be going into the memory stream.

MemoryStream mem = new MemoryStream();

bmp.Save(mem, ImageFormat.Bmp);

Secrat.Sause.ProperitaryPixelFormat pixbuf = new Secrat.Sause.Bmp.Loader(mem);

Secrat.Sause.Bmp.Loader is returning "Invalid bitmap, no header".

Basically what I am trying to do is convert a Bitmap into another, unmanaged representation "Secrat.Sause.ProperitaryPixelFormat".

Bass said:

Bass said:

*snip*

MemoryStream mem = new MemoryStream();

bmp.Save(mem, ImageFormat.Bmp);

Secrat.Sause.ProperitaryPixelFormat pixbuf = new Secrat.Sause.Bmp.Loader(mem);

Secrat.Sause.Bmp.Loader is returning "Invalid bitmap, no header".

 

Basically what I am trying to do is convert a Bitmap into another, unmanaged representation "Secrat.Sause.ProperitaryPixelFormat".

Per chance, does anyone here know if a call to LockBits() prohibits the bitmap object from being garbage collected?

I am thinking of perhaps a much more efficent way to do this, passing the pointer bmp.LockBits().Scan0

Bass said:

Bass said:

*snip*

Per chance, does anyone here know if a call to LockBits() prohibits the bitmap object from being garbage collected?

I am thinking of perhaps a much more efficent way to do this, passing the pointer bmp.LockBits().Scan0

If you’re just wanting to access the bitmap data then that’s probably the best way to do it in C#.

Bass said:

Bass said:

*snip*

Per chance, does anyone here know if a call to LockBits() prohibits the bitmap object from being garbage collected?

I am thinking of perhaps a much more efficent way to do this, passing the pointer bmp.LockBits().Scan0

Why does it matter if LockBits prevents the bitmap from being collected? If you want it to be collected then Dispose it. If you don't want to be collected then keep a reference to it. In any case, if you call LockBits you should also call UnlockBits:

BitmapData bmpData = bmp.LockBits(...);

Secrat.Sause.ProperitaryPixelFormat pixbuf = new Secrat.Sause.Bmp.Loader(bmpData.Scan0);

bmp.UnlockBits(bmpData);

Of course, if the Loader doesn't make a copy of the pixels you'll have to make one yourself.

PS:

The MemoryStream code sample: you may want to set the stream position to 0 after you save the bitmap. If the "loader" doesn't do it then it's no wonder you get "Invalid bitmap, no header".

Dexter said:

Bass said:

*snip*

Why does it matter if LockBits prevents the bitmap from being collected? If you want it to be collected then Dispose it. If you don't want to be collected then keep a reference to it. In any case, if you call LockBits you should also call UnlockBits:

BitmapData bmpData = bmp.LockBits(...);

Secrat.Sause.ProperitaryPixelFormat pixbuf = new Secrat.Sause.Bmp.Loader(bmpData.Scan0);

bmp.UnlockBits(bmpData);

Of course, if the Loader doesn't make a copy of the pixels you'll have to make one yourself.

PS:

The MemoryStream code sample: you may want to set the stream position to 0 after you save the bitmap. If the "loader" doesn't do it then it's no wonder you get "Invalid bitmap, no header".

You win the thread.