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1.dlopen
failed:"lib_xyz.so"is64-bit
instead of 32-bit
这个表示你编译出来的是64bit，但是你应用的地方是32bit，
这时你应该修改一下APP_ABI，
from arm64-v8a to armeabi-v7a
#APP_ABI
:= arm64-v8a
APP_ABI := armeabi-v7a
2.dlsym
failed: undefined symbol: sobel_filter
这表示你可能用C++编译器编译的，需要再编译引用的函数名前extern
"C" like this
extern "C" int sobel_filter(uchar* pInImg,uchar*
pOutImg,int width,int height);
3. 学会使用dlerror打印错误原因， dl 动态库详解http://blog.csdn.net/jernymy/article/details/6903683
4. 学会使用extern “C"http://www.jianshu.com/p/5d2eeeb93590
5.armeabi-v7a（32位ARM设备），arm64-v8a（64位ARM设备）
6.
applicate.mk 详解http://blog.sina.com.cn/s/blog_602f877001014ptu.html
一个简单的opencv 例子使用NDK 编译
Android.mk
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
OPENCV_LIB_TYPE=STATIC
#include $(OPENCV_ANDROID_ROOT)/sdk/native/jni/OpenCV.mk
include C:/workspace/OpenCV-3.0.0-android-sdk-1/OpenCV-android-sdk/sdk/native/jni/OpenCV.mk
LOCAL_MODULE := libplat_recog
LOCAL_CFLAGS := -Werror
LOCAL_SRC_FILES := plat_recog.cpp
#LOCAL_LDLIBS += -llog -landroid -lEGL -lGLESv1_CM
LOCAL_LDLIBS += -llog
#build dynamic library
include $(BUILD_SHARED_LIBRARY)
Application.mkLOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
OPENCV_LIB_TYPE=STATIC
#include $(OPENCV_ANDROID_ROOT)/sdk/native/jni/OpenCV.mk
include C:/workspace/OpenCV-3.0.0-android-sdk-1/OpenCV-android-sdk/sdk/native/jni/OpenCV.mk
LOCAL_MODULE := libplat_recog
LOCAL_CFLAGS := -Werror
LOCAL_SRC_FILES := plat_recog.cpp
#LOCAL_LDLIBS += -llog -landroid -lEGL -lGLESv1_CM
LOCAL_LDLIBS += -llog
#build dynamic library
include $(BUILD_SHARED_LIBRARY)
plat_recog.cpp
#include <opencv2/opencv.hpp>
#include <android/log.h>
#define LOG_TAG "plate_recognition"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
using namespace cv;
extern "C" int sobel_filter(uchar* pInImg,uchar* pOutImg,int width,int height);
int sobel_filter(uchar* pInImg,uchar* pOutImg,int width,int height)
{
if(pInImg == NULL){
LOGE("input is null!");
return -1;
}
/*
CV_8UC1: single channel
CV_8UC2: two channels
CV_8UC3: three channels
*/
Mat srcImg(height,width,CV_8UC1,pInImg);
Mat outImg(height,width,CV_8UC1,pOutImg);
Sobel(srcImg, outImg, outImg.depth(), 1, 0, 3);
imwrite("test.jpg",outImg);
memcpy(pInImg,pOutImg,width*height);
LOGE("sobel filter is done");
return 0;
}
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