mr-edd.co.uk :: horsing around with the C++ programming language

embd: a tool to embed files in applications

[24th November 2007]

Occasionally I like to make little programs where it is convenient to have a file embedded within the application itself. Perhaps a particular texture is needed in a graphics demo, or some kind of default configuration file is stored internally so that the user can ask the program copy it out to a desired location (for example, it seems doxygen does this). Sometimes embedding a handful of files is simply the most convenient option.

To this end, I decided to make a program that makes the process of embedding files in an application and accessing them in the source code easy.

I've had code to to this kicking around for a while now. You'll see that one of the jpegxx examples contains an embedded image that was made with the old version. But the code wasn't particularly good, so I decided to re-write it and release in to the wild. It's come in handy on the odd occasion. Maybe you'll find a use for it, too.

embd generates a C++ source file and a corresponding header. The source file contains the embedded data and the header provides the declarations and definitions needed to access the data easily.

Here's how you might use it:

> embd texture.png readme.txt default.cfg

This creates a source file and a corresponding header called embd.cpp and embd.hpp respectively. By compiling and linking embd.cpp in to your application, the files are embedded within.

To access the data in your software, #include the header where needed and use the file and file_name_iterator classes defined inside:

This creates a source file and a corresponding header called embd.cpp and embd.hpp respectively. By compiling and linking embd.cpp in to your application, the files are embedded within.

To access the data in your software, #include the header where needed and use the file and file_name_iterator classes defined inside:

#include "embd.hpp"

int main()
{
    typedef embd::file_name_iterator nameiter;

    for (nameiter b = nameiter::begin(), e = nameiter::end(); b != e; ++b)
    {
        std::string filename = *b; // a name of an embedded file

        embd::file f(filename); // open an embedded file
        std::istream &in = f.istream(); // access its data

        // now read from in like you would any other istream
        // ...
    }
}

By default all the stuff declared and defined by the header is placed inside the embd namespace. This is configurable, as are the names of the C++ source files generated by embd. There are a bunch of other options that I won't bother going in to here. You can find out more heading over to the embd project page.

Comments