[boost] [iostreams] binary memory stream

Subject: [boost] [iostreams] binary memory stream
From: Kenny Riddile (kfriddile_at_[hidden])
Date: 2009-03-29 20:41:24

I'm still pretty inexperienced with the iostreams library, so this may 
be a simple question.  I'm trying to use GIL to write a PNG to a memory 
stream instead of a file stream.  The write_view() function in the new 
version of GIL's io extension expects an ostream opened in binary mode 
as it's first parameter, such as:

using namespace std;
using namespace boost::gil;

ofstream outputStream( "foo.png", ios::out | ios::binary );
write_view( outputStream, const_view(image), png_tag() );

I'm attempting to write to memory instead of a file, by doing this:

using namespace boost::gil;
using namespace boost::iostreams;

typedef stream< back_insert_device< std::vector<char> > > BufferStream;

std::vector<char> buffer;
BufferStream bufferStream( buffer );

write_view( bufferStream, const_view(image), png_tag() );

The data that ends up in buffer is identical to the data that ends up in 
foo.png from the first example if I don't open outputStream in binary 
mode.  So how can I make a binary memory stream with the iostreams 
library?  Do I need to write my own filter?