Convert a struct array to a byte array with GCHandle

convert-struct.cs

[StructLayout(LayoutKind.Sequential)]
public struct Pixel32
{
    public byte r;
    public byte g;
    public byte b;
    public byte a;
}

// -----------------------

Pixel32[] pixels = new Pixel32[width * height];

// do something to the pixel array.

GCHandle handle = GCHandle.Alloc(pixels, GCHandleType.Pinned);

try
{
    IntPtr pointer = handle.AddrOfPinnedObject();
    byte[] destination = new byte[width * height * 4];
    Marshal.Copy(pointer, destination, 0, destination.Length);
}
finally
{
    if (handle.IsAllocated)
    {
        handle.Free();
    }
}