How do I handle such a replacement macro using for default values of some parameters?

[lancewoo]

Hi @saudet , I am doing a translation of mp4v2 on Android.
Right now I am stuck in the macro definition
# define DEFAULT(x) =x.
This macro is used everywhere in the interfaces of this library, for default values of some parameters, like this one:

MP4V2_EXPORT
MP4FileHandle MP4CreateEx(
    const char* fileName,
    uint32_t    flags DEFAULT(0),
    int         add_ftyp DEFAULT(1),
    int         add_iods DEFAULT(1),
    char*       majorBrand DEFAULT(0),
    uint32_t    minorVersion DEFAULT(0),
    char**      compatibleBrands DEFAULT(0),
    uint32_t    compatibleBrandsCount DEFAULT(0) );

I just used

            infoMap.put(new Info("DEFAULT").cppTypes().annotations().cppText(""))

to skip it. Is that correct?

My whole map function goes like this:

public void map(InfoMap infoMap) {
    infoMap
            .put(new Info("MP4_INVALID_FILE_HANDLE").cppTypes("MP4FileHandle"))
            .put(new Info("MP4V2_EXPORT").cppTypes().annotations().cppText(""))
            .put(new Info("DEFAULT").cppTypes().annotations().cppText(""))
            .put(new Info("defined( _WIN32 )").define(false))
            .put(new Info("defined( __MINGW32__ )").define(false))
            .put(new Info("defined( _WIN32 ) || defined( __MINGW32__ )").define(false))
            // https://github.com/bytedeco/javacpp-presets/blob/4c446f1e5016a3906551fc8ccf523c8dddd4ece4/libffi/src/main/java/org/bytedeco/libffi/presets/ffi.java#L80
            .put(new Info("__attribute__((deprecated))").annotations("@Deprecated"))
            // Of course we have __cplusplus for Android NDK bundle
            .put(new Info("__cplusplus").define(true))
            .put(new Info("defined( __cplusplus )").define(true))
            .put(new Info("!defined( __cplusplus )").define(false))
            // _MSC_VER should not be valid on Android
            .put(new Info("_MSC_VER").define(false));
}

It seems the Parser and Compiler Gradle tasks work well now. I simply don't know if it works for this translation.
Thanks!

Lance

[saudet]

We shouldn't need to do anything special for default arguments, they get mostly ignored by default, but if you want to redefine a macro, what we need to do is shown on this page: https://github.com/bytedeco/javacpp/wiki/Mapping-Recipes#redefining-the-code-of-a-macro

Specifically in this case:

infoMap.put(new Info("DEFAULT").cppText("#define DEFAULT(x)"));

[lancewoo]

It works now, thanks!

I also removed this macro translation:

#   define MP4V2_EXPORT __attribute__((visibility("default")))

and removed the include of mp4v2.h.

[lancewoo]

I just found if I don't skip the macro
# define MP4V2_EXPORT __attribute__((visibility("default")))
with
infoMap.put(new Info("MP4V2_EXPORT").cppText("#define MP4V2_EXPORT"))
, return types of interfaces would not be translated correctly since all of them are prefixed with MP4V2_EXPORT.

Is this a bug of the JavaCPP Gradle plugin or is this the duty for us developers to ensure its correct behavior?

@saudet

[lancewoo]

Oh, this has been explained on this page:
Ignoring attributes and macros
Sorry I missed it.
Thanks!

[lancewoo]

I tried your approach. I seemed that didn't work.
Like this code:

/* 3GP specific utilities */

MP4V2_EXPORT
bool MP4Make3GPCompliant(
    const char* fileName,
    char*       majorBrand DEFAULT(0),
    uint32_t    minorVersion DEFAULT(0),
    char**      supportedBrands DEFAULT(NULL),
    uint32_t    supportedBrandsCount DEFAULT(0),
    bool        deleteIodsAtom DEFAULT(true) );

got translated as:

/* 3GP specific utilities */

public static native @Cast("bool") boolean MP4Make3GPCompliant(
    @Cast("const char*") BytePointer fileName,
    @Cast("char*") BytePointer majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") PointerPointer supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    @Cast("const char*") BytePointer fileName,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    @Cast("const char*") BytePointer fileName,
    @Cast("char*") BytePointer majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr BytePointer supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    String fileName,
    @Cast("char*") ByteBuffer majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr ByteBuffer supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    String fileName,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    @Cast("const char*") BytePointer fileName,
    @Cast("char*") byte[] majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr byte[] supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    String fileName,
    @Cast("char*") BytePointer majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr BytePointer supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    @Cast("const char*") BytePointer fileName,
    @Cast("char*") ByteBuffer majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr ByteBuffer supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );
public static native @Cast("bool") boolean MP4Make3GPCompliant(
    String fileName,
    @Cast("char*") byte[] majorBrand/*0*/,
    @Cast("uint32_t") int minorVersion/*0*/,
    @Cast("char**") @ByPtrPtr byte[] supportedBrands/*NULL*/,
    @Cast("uint32_t") int supportedBrandsCount/*0*/,
    @Cast("bool") boolean true );

Anything wrong?

[saudet]

Sorry, just remove the x like this:

infoMap.put(new Info("DEFAULT").cppText("#define DEFAULT(x)"));

I've updated the answer.