目录
集成步骤
下载OpenCv的so库
OpenCV官网
这里我下载的是3.4版本
拷贝文件到项目
解压下载后的文件，opencv-3.4.13-android-sdk\OpenCV-android-sdk\sdk\native\libs这个目录下的便是OpenCv编译好的动态链接库，将整个libs文件夹拷贝到Android项目的cpp目录，由于为了减少apk大小，我这里只拷贝了"armeabi-v7a"和"arm64-v8a"目录下的库，然后找到opencv-3.4.2-android-sdk\OpenCV-android-sdk\sdk\native\jni\include目录，将include文件夹也拷贝到cpp目录，如下图所示：
配置CMake
对CMakeLists.txt进行如下配置。
cmake_minimum_required(VERSION 3.4.1)
# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.
#配置加载头文件
include_directories(include)
#动态方式加载
add_library(opencv SHARED IMPORTED)
#引入第三方.so库
set_target_properties(opencv PROPERTIES IMPORTED_LOCATION ${CMAKE_SOURCE_DIR}/libs/${ANDROID_ABI}/libopencv_java3.so)
add_library( # Sets the name of the library.
native-lib
# Sets the library as a shared library.
SHARED
# Provides a relative path to your source file(s).
native-lib.cpp
#utils.cpp 这里不需要引入utils.cpp因为在native-lib.cpp已经导入了
)
# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.
find_library( # Sets the name of the path variable.
log-lib
# Specifies the name of the NDK library that
# you want CMake to locate.
log)
# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.
target_link_libraries( # Specifies the target library.
native-lib
opencv
jnigraphics
# Links the target library to the log library
# included in the NDK.
${log-lib})
配置gradle文件
这一步也很重要，目的是为了将so库打包到apk中，如果不配置这个会导致无法找到对应的库。
android {
...
sourceSets {
main {
jniLibs.srcDirs = ['src/main/cpp/libs']
}
}
...
}
简单使用
这里简单的做一个将图片转换为灰度图的案例
创建转换工具
首先创建一个可以将Mat和Bitmap互相转换的工具，这里我参考了OpenCv给的案例（案例地址）,自己简化了一下，代码如下：
#include "opencv2/core.hpp"
#include "opencv2/imgproc.hpp"
#ifdef __ANDROID__
#include <android/bitmap.h>
#include "android/log.h"
#define TAG "org.opencv.android.Utils"
#define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE, TAG, __VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN, TAG, __VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)
using namespace cv;
void BitmapToMat(JNIEnv *env, jobject bitmap, Mat &dst, jboolean needUnPremultiplyAlpha) {
AndroidBitmapInfo info;
void *pixels = 0;
try {
CV_Assert(AndroidBitmap_getInfo(env, bitmap, &info) >= 0);
CV_Assert(info.format == ANDROID_BITMAP_FORMAT_RGBA_8888 ||
info.format == ANDROID_BITMAP_FORMAT_RGB_565);
CV_Assert(AndroidBitmap_lockPixels(env, bitmap, &pixels) >= 0);
CV_Assert(pixels);
dst.create(info.height, info.width, CV_8UC4);
if (info.format == ANDROID_BITMAP_FORMAT_RGBA_8888) {
LOGD("nBitmapToMat: RGBA_8888 -> CV_8UC4");
Mat tmp(info.height, info.width, CV_8UC4, pixels);
if (needUnPremultiplyAlpha) cvtColor(tmp, dst, COLOR_mRGBA2RGBA);
else tmp.copyTo(dst);
} else {
// info.format == ANDROID_BITMAP_FORMAT_RGB_565
LOGD("nBitmapToMat: RGB_565 -> CV_8UC4");
Mat tmp(info.height, info.width, CV_8UC2, pixels);
cvtColor(tmp, dst, COLOR_BGR5652RGBA);
}
AndroidBitmap_unlockPixels(env, bitmap);
return;
} catch (const cv::Exception &e) {
AndroidBitmap_unlockPixels(env, bitmap);
LOGE("nBitmapToMat caught cv::Exception: %s", e.what());
jclass je = env->FindClass("org/opencv/core/CvException");
if (!je) je = env->FindClass("java/lang/Exception");
env->ThrowNew(je, e.what());
return;
} catch (...) {
AndroidBitmap_unlockPixels(env, bitmap);
LOGE("nBitmapToMat caught unknown exception (...)");
jclass je = env->FindClass("java/lang/Exception");
env->ThrowNew(je, "Unknown exception in JNI code {nBitmapToMat}");
return;
}
}
void MatToBitmap(JNIEnv *env, Mat &src, jobject bitmap, jboolean needPremultiplyAlpha) {
AndroidBitmapInfo info;
void *pixels = 0;
try {
LOGD("nMatToBitmap");
CV_Assert(AndroidBitmap_getInfo(env, bitmap, &info) >= 0);
CV_Assert(info.format == ANDROID_BITMAP_FORMAT_RGBA_8888 ||
info.format == ANDROID_BITMAP_FORMAT_RGB_565);
CV_Assert(src.dims == 2 && info.height == (uint32_t) src.rows &&
info.width == (uint32_t) src.cols);
CV_Assert(src.type() == CV_8UC1 || src.type() == CV_8UC3 || src.type() == CV_8UC4);
CV_Assert(AndroidBitmap_lockPixels(env, bitmap, &pixels) >= 0);
CV_Assert(pixels);
if (info.format == ANDROID_BITMAP_FORMAT_RGBA_8888) {
Mat tmp(info.height, info.width, CV_8UC4, pixels);
if (src.type() == CV_8UC1) {
LOGD("nMatToBitmap: CV_8UC1 -> RGBA_8888");
cvtColor(src, tmp, COLOR_GRAY2RGBA);
} else if (src.type() == CV_8UC3) {
LOGD("nMatToBitmap: CV_8UC3 -> RGBA_8888");
cvtColor(src, tmp, COLOR_RGB2RGBA);
} else if (src.type() == CV_8UC4) {
LOGD("nMatToBitmap: CV_8UC4 -> RGBA_8888");
if (needPremultiplyAlpha) cvtColor(src, tmp, COLOR_RGBA2mRGBA);
else src.copyTo(tmp);
}
} else {
// info.format == ANDROID_BITMAP_FORMAT_RGB_565
Mat tmp(info.height, info.width, CV_8UC2, pixels);
if (src.type() == CV_8UC1) {
LOGD("nMatToBitmap: CV_8UC1 -> RGB_565");
cvtColor(src, tmp, COLOR_GRAY2BGR565);
} else if (src.type() == CV_8UC3) {
LOGD("nMatToBitmap: CV_8UC3 -> RGB_565");
cvtColor(src, tmp, COLOR_RGB2BGR565);
} else if (src.type() == CV_8UC4) {
LOGD("nMatToBitmap: CV_8UC4 -> RGB_565");
cvtColor(src, tmp, COLOR_RGBA2BGR565);
}
}
AndroidBitmap_unlockPixels(env, bitmap);
return;
} catch (const cv::Exception &e) {
AndroidBitmap_unlockPixels(env, bitmap);
LOGE("nMatToBitmap caught cv::Exception: %s", e.what());
jclass je = env->FindClass("org/opencv/core/CvException");
if (!je) je = env->FindClass("java/lang/Exception");
env->ThrowNew(je, e.what());
return;
} catch (...) {
AndroidBitmap_unlockPixels(env, bitmap);
LOGE("nMatToBitmap caught unknown exception (...)");
jclass je = env->FindClass("java/lang/Exception");
env->ThrowNew(je, "Unknown exception in JNI code {nMatToBitmap}");
return;
}
}
#endif //__ANDROID__
实现灰度转换
这里使用OpenCv的cvtColor方法进行转换
Java代码：
public class MainActivity extends AppCompatActivity {
// Used to load the 'native-lib' library on application startup.
static {
System.loadLibrary("native-lib");
}
private ImageView imgIcon;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imgIcon = (ImageView) findViewById(R.id.img_icon);
}
/**
* 将Bitmap转换为灰度图
*/
public native void converImage2Gray(Bitmap bitmap);
public void onClick(View view) {
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
converImage2Gray(bitmap);
imgIcon.setImageBitmap(bitmap);
}
}
C++代码：
#include <jni.h>
#include <string>
#include "utils.cpp"
extern "C"
JNIEXPORT void JNICALL
Java_com_itfitness_opencvincludedemo_MainActivity_converImage2Gray(JNIEnv *env, jobject instance,
jobject bitmap) {
//源图像
Mat src;
//将Bitmap转换为Mat
BitmapToMat(env,bitmap,src, JNI_FALSE);
//转换的灰度图
Mat gray_image;
cvtColor(src, gray_image, COLOR_BGR2GRAY );
//将Mat转换为Bitmap
MatToBitmap(env,gray_image,bitmap, JNI_FALSE);
//释放Mat
src.release();
gray_image.release();
}
效果展示
