Re: [boost] [iostreams] binary memory stream

Subject: Re: [boost] [iostreams] binary memory stream
From: Chris Weed (chrisweed_at_[hidden])
Date: 2009-03-30 10:31:03

On Sun, Mar 29, 2009 at 9:10 PM, Kenny Riddile <kfriddile_at_[hidden]> wrote:
> Kenny Riddile wrote:
>>
>> 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?
>>
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>
> Ok, so redefining bufferStream like so works:
>
> std::stringstream bufferStream( std::ios_base::in | std::ios_base::out |
> std::ios_base::binary );
>
> but it just feels "weird".  Is there any cleaner way to do this with the
> iostreams library?
>

This doesn't look weird to me.
This is how I would do it.

You should probably post this to the boost-users list.
Chris