Nrthugu

i have a problem with Marshal.UnsafeAddrOfPinnedArrayElement() method.

What i want to do, is return Bitmap object from byte array. But first, some code below with explenation what i do.

1. 
   

   First, i load my Bitmap to method that i return byte array from it:

   
   
   

    //return tuple with pointer to array and bytearray   
   
   public static (byte, IntPtr) GetByteArray(Bitmap bitmap)
   
   {
   
   
   
       //lockbits 
   
       BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
   
                                               ImageLockMode.ReadWrite,
   
                                               bitmap.PixelFormat
   
                                               );
   
   
   
       int pixels = bitmapData.Stride * bitmap.Height;
   
       byte resultArray = new byte[pixels];
   
   
   
       //copying bytes to array
   
       Marshal.Copy(bitmapData.Scan0, resultArray, 0, pixels);
   
   
   
       bitmap.UnlockBits(bitmapData);
   
   
   
       //returns array and pointer to it
   
       return (resultArray, bitmapData.Scan0);
   
   }
   
   

   
   


2. 
   

   Second, i want to edit that byte array:

   
   
   

   public static Bitmap Execute(Bitmap bitmap, int filter)
   
   {
   
       //get byte array from method that i mentioned before with pointer to it
   
       (byte pixelsFromBitmap, IntPtr pointer) = PictureUtilities.GetByteArray(bitmap);
   
   
   
       byte newPixels = pixelsFromBitmap;
   
   
   
       int stride = bitmap.Width;
   
   
   
       int height = bitmap.Height;
   
       int width  = bitmap.Width;
   
   
   
       Parallel.For(0, height - 1, y =>
   
       {
   
           int offset = y * stride;
   
           for(int x = 0; x < width - 1; x++)
   
           {
   
               //some stuff i doing with array, not neceserry what im doing here
   
               int positionOfPixel = x + offset;
   
               newPixels[positionOfPixel] = (byte)122;
   
           }
   
   
   
       });
   
   
   
       //copying values from newPixels to pixelsFromBitmap that i get from method GetByteArray() that i mentioned it before
   
       newPixels.CopyTo(pixelsFromBitmap, 0);
   
   
   
       //copying bytes again
   
       Marshal.Copy(pixelsFromBitmap, 0, pointer, pixelsFromBitmap.Length);
   
   
   
       //generete new bitmap from byte array
   
       Bitmap result = new Bitmap(bitmap.Width, bitmap.Height, stride,
   
                                  bitmap.PixelFormat,
   
                                  pointer);
   
       return result;
   
   
   
   
   
   }
   
   

   
   

After all that process i get an Exception in Execute() method: System.ArgumentException in line, when i getting new Bitmap result.

Could you tell me, what i doing wrong? i want to get a byte array from my bitmap from method (for readability), edit it and return new bitmap depends on my new byte array.

I bet, that i not clearly get, how Marshall.Copy works and i get wrong pointer to returning byte array from GetByteArray() method.

Thanks for help