android - 如何通过 JNI 将图像从 Java 传递到 Cocos2d-x？

Question

我需要通过 JNI 将图像数据(如 drawable)从 java 端传递到 cocos2d-x。我该如何实现？ JNI函数的参数应该是什么，在cocos2d-x端如何转换？

Answer 1

1. 为 JNI 创建一个 Java 接口(interface)，例如:

   public static native void setBG(int[] raw, int width, int height);
   

2. 在 C++ 代码中做:

   //Use static variable here for simplicity
   
   int *imagedata;
   int staticwidth;
   int staticheight;
   Texture2D *userBackgroundImage;
   
   
   
   void Java_com_my_company_JniHelper_setBG(JNIEnv*  env, jobject thiz, jintArray raw, jint width, jint height)
   {
       jint *carr;
       carr = env->GetIntArrayElements(raw, 0);
       if(carr == NULL) {
           return; /* exception occurred */
       }
       ssize_t dataLen = (int)width * (int)height;
       int *data = new int[dataLen];
       for (long i = 0; i < dataLen; i++)
       {
           data[i] = carr[i];
       }
       imagedata = data;//Make a copy because it need to be done in GLThread
       staticwidth = (int)width;
       staticheight = (int)height;
       env->ReleaseIntArrayElements(raw, carr, 0);
       LOGD("set image: %d * %d", width, height);
   }
   

然后在 duration layer init 或其他 cocos2d-x 代码中调用以下方法:

    void createImage(const void *data, ssize_t dataLen, int width, int height)
    {
        Texture2D *image = new Texture2D();
        if (!image->initWithData(data, dataLen, Texture2D::PixelFormat::BGRA8888, width,      height, Size(width, height)))
        {
            delete image;
            delete imagedata;
            image = NULL;
            imagedata = NULL;
            userBackgroundImage = NULL;
            return;
        }
        delete imagedata;
        imagedata = NULL;
        userBackgroundImage = image;
    }

然后您可以使用 Texture2D 对象创建 Sprite 或做任何您想做的事情

1. 要从 java 调用此代码:

   public static int[] BitmapToRaw(Bitmap bitmap) {
       Bitmap image = bitmap.copy(Bitmap.Config.ARGB_8888, false);
       int width = image.getWidth();
       int height = image.getHeight();
       int[] raw = new int[width * height];
       image.getPixels(raw, 0, width, 0, 0, width, height);
       return raw;
   }
   
   Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.bg);
   JniHelper.setBG(BitmapToRaw(image), image.getWidth(), image.getHeight());