19. Aug 2001

## SDL rwops

Example to make an SDL_rwops interface.

some MSVC help in README.MSVC6 and README.SDL

### Source

The example sources of the zziplib library are usually put under the ZLIB license so that you can reuse the code freely in your own projects. Here we talk about the example that might be most useful for SDL based programs. Just copy the two files SDL_rwops_zzip.h and SDL_rwops_zzip.c to the directory with your other project sources, and make sure to link it somehow to your programs. I did not make the effort to create a separate library out of it - it would just export one single function `SDL_RWFromZZIP` that has the same call-synopsis like `SDL_RWFromFile` (but it can not (yet) write a zip-file).

The source file SDL_rwops_zzip.c is quite short - it just stores a ZZIP_FILE handle in the userdata field of the `SDL_rwops` structure. The SDL'rwop calls will then fetch that pointer and call the corresponding functions from the zziplib library. Most of the glue code is in the `SDL_RWFromZZIP` function that allocates an `SDL_rwops` structure and fills the handler-functions into the callback fields.

### Usage

If you link this file to your project, remember that your executables do now have additional dependencies - not only -lzzip to link with the zziplib library - do not forget to link with zlib library via -lz. Of course, there is a lib-config script that you can use: `zzip-config --libs` will return these linker-infos (unless you have a native-windows system - it is shell-script).

As an example, replace that `SDL_RWFromFile` that accesses your game-graphic files - these files are stored in shared/myapp of course where they belong. When you've done that then go to X/share/myapp and
``(cd graphics/ && zip -9r ../graphics.zip .)``
and rename the graphics/ subfolder - and still all your files are found: a filepath like X/shared/graphics/game/greetings.bmp will open X/shared/graphics.zip and return the zipped file game/greetings.bmp in the zip-archive (for reading that is).

### Test

The zziplib configure script does not look for SDL. If you know that you have SDL installed then you can check this `SDL_rwops` example by using ``make testsdl``. This will compile the two source files SDL_rwops_zzip.c and SDL_rwops_zzcat.c to be linked together into an executable called `zzcatsdl`. The test will continue with a ``zzcatsdl test/README`` - just like it is done for ``make test3``.

The corresponding section in the Makefile.am is also an example how to use lib-config scripts to build files. Here there is no build-processing that had been tweaked much by automake/autoconf. Just use sdl-config and zzip-config to add the needed flags.