Re: [boost] GIL io_new review

Subject: Re: [boost] GIL io_new review
From: Christian Henning (chhenning_at_[hidden])
Date: 2010-12-13 11:41:58

Hi Phil,

>
> void read_jpeg_image_from_mem(const char* begin, const char* end, gil::image
> dest)
> {
>  .....
>  jpeg_mem_src(...., begin, end-begin);
>  .....
> }
>
> So there is basically no overhead.  Wrapping a block of memory up in a
> stream, and then unwrapping it again to pass it to the image library's C
> API, and pulling in another Boost library like Boost.IOStreams to do so,
> looks like overkill.
>

As far as I understand jpeg_mem_src code only initializes the
jpeg_source_mgr with the in-memory data source callbacks. These
callbacks are used during the reading process to fill up buffers and
to skip data. io_new is having its own set of these callbacks, which
admittedly are a very close resemblance to libjpeg's ones.

Though, jpeg_mem_src doesn't read anything.

And yes, you're right it looks a bit like overkill. But it's not a
huge one, I believe.

Regards,
Christian