I am trying to use the freeimage library in my project..causes error

Question

The following code snippet causes error....the logcat has been attached...I am tring to pass the image path from teh java code to the NDK code and from there I am trying to open the bitmap using FreeImage library....

JNIEXPORT void JNICALL Java_com_example_ImageActivity_brightness(JNIEnv* env, jobject  obj, jstring bitmappath, jfloat brightnessValue)
{
    AndroidBitmapInfo  info;

    int ret;
    void* pixels;

    if ( !bitmappath ) LString();

       const jsize len      = env->GetStringUTFLength(bitmappath);
       const char* strChars = env->GetStringUTFChars(bitmappath, (jboolean *)0);

       std::string Result(strChars, len);

       env->ReleaseStringUTFChars(bitmappath, strChars);

     FIBITMAP *bitmap = FreeImage_Load(FIF_BMP,Result.c_str(), BMP_DEFAULT);
     if (bitmap) {
    // bitmap successfully loaded!
        FreeImage_Unload(bitmap);
    }

Error log

flock@QS57:~/Desktop/android-imagefilter-ndk$ /home/flock/ANDROID/android-ndk-r8/ndk-build
Compile thumb  : imageprocessing <= imageprocessing.c
jni/imageprocessing.c: In function 'Java_com_example_ImageActivity_brightness':
jni/imageprocessing.c:77: error: request for member 'GetStringUTFLength' in something not a structure or union
jni/imageprocessing.c:78: error: request for member 'GetStringUTFChars' in something not a structure or union
jni/imageprocessing.c:80: error: expected expression before ':' token
jni/imageprocessing.c:82: error: request for member 'ReleaseStringUTFChars' in something not a structure or union
jni/imageprocessing.c:84: error: 'FIBITMAP' undeclared (first use in this function)
jni/imageprocessing.c:84: error: (Each undeclared identifier is reported only once
jni/imageprocessing.c:84: error: for each function it appears in.)
jni/imageprocessing.c:84: error: 'bitmap' undeclared (first use in this function)
jni/imageprocessing.c:84: error: 'FIF_BMP' undeclared (first use in this function)
jni/imageprocessing.c:84: error: 'Result' undeclared (first use in this function)
jni/imageprocessing.c:84: error: 'BMP_DEFAULT' undeclared (first use in this function)
make: *** [obj/local/armeabi/objs/imageprocessing/imageprocessing.o] Error 1

Answer 1

The way you are calling JNI functions is possible only if you compile code as C++ code.

If you need or want to compile code as C then you must write JNI calls in following way:

const jsize len      = (*env)->GetStringUTFLength(env, bitmappath);
const char* strChars = (*env)->GetStringUTFChars(env, bitmappath, (jboolean *)0);