stream save_png to cout

[carlinski]

I'm using the following code, which saves a CImg as png to disk, opens it, and streams it to console (fcgi).

It's working perfectly, but wondered if there was a way of doing this without saving it to disk?

img.save_png("test.png", 0);
std::ifstream image("test.png", std::ifstream::binary);

if (image)
{
    image.seekg (0, image.end);
    int length = image.tellg();
    image.seekg (0, image.beg);

    char * buffer = new char [length];
    image.read (buffer,length);
    image.close();

    for(int iPos = 0; iPos < length; iPos++)
    {
        std::cout << buffer[iPos];
    }

    delete[] buffer;
}

[dtschump]

You could try img.save_png("-.png"); to output the file on stdout.

[carlinski]

Thanks, but it doesn't seem to to work. This is the code in CImg.h just to jog your memory. I also tried it with just a dash, and a dash dot.

const bool is_stdout = *filename=='-' && (!filename[1] || filename[1]=='.');

[dtschump]

Are you compiling with the support of libpng ?
Like : g++ -o out souces.cpp -lX11 -lpthread -Dcimg_use_png -lpng

If libpng is not used, CImg tries to use ImageMagick's convert as a fallback, to read png files.
Using libpng makes iI work for me.

[carlinski]

OK, getting somewhere now. Yes, you were correct it needed libpng support.

Within my fcgi program, because the buffer has been captured to used std::cout whenever I write to it, it gets sent to the browser. Output from img.save_png("-.png"); is getting sent to the console. Is it using a different method of writing to the console?