Android引入OpenCV的示例
简介
在移动开发中,如果我们要实现一些图像处理相关的功能,难免要用到OpenCV。而OpenCV是用c++开发的。我们在Android中,需要使用jni的方法去使用它。
引入配置
我们引入jni开发的基本配置方法,已经在另一篇博客中介绍过了,不再赘述。这一次我们无非是要引入第三方的c++库。
首先,我们找到或新建jniLibs文件夹,然后将依赖的动态库和静态库(路径为OpenCV-android-sdk\sdk\native\libs)拷贝到\src\main\jniLibs下面。
然后,找到cpp文件夹。将include文件夹(路径OpenCV-android-sdk\sdk\native\jni\include)拷贝到cpp(路径\app\src\main\cpp)文件夹里。
接着,我们需要引入c++的相关支持。在module的build.gradle里面加入:
externalNativeBuild { cmake { //arguments '-DANDROID_TOOLCHAIN=clang', '-DANDROID_STL=gnustl_static' cppFlags "-std=c++11","-frtti", "-fexceptions" } } ndk{ abiFilters 'armeabi-v7a' }
最后,我们需要在CMakeLists.txt中,加入opencv相关的声明。由于配置比较复杂,在此直接将demo的CMakeLists.txt的内容贴到这里。
# For more information about using CMake with Android Studio, read the # documentation: https://d.android.com/studio/projects/add-native-code.html # Sets the minimum version of CMake required to build the native library. 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. set(CMAKE_VERBOSE_MAKEFILE on) set(libs "${CMAKE_SOURCE_DIR}/src/main/jniLibs") include_directories(${CMAKE_SOURCE_DIR}/src/main/cpp/include) add_library(libopencv_java3 SHARED IMPORTED ) set_target_properties(libopencv_java3 PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_java3.so") add_library(libopencv_calib3d STATIC IMPORTED ) set_target_properties(libopencv_calib3d PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_calib3d.a") add_library(libopencv_core STATIC IMPORTED ) set_target_properties(libopencv_core PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_core.a") add_library(libopencv_features2d STATIC IMPORTED ) set_target_properties(libopencv_features2d PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_features2d.a") add_library(libopencv_flann STATIC IMPORTED ) set_target_properties(libopencv_flann PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_flann.a") add_library(libopencv_highgui STATIC IMPORTED ) set_target_properties(libopencv_highgui PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_highgui.a") add_library(libopencv_imgcodecs STATIC IMPORTED ) set_target_properties(libopencv_imgcodecs PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_imgcodecs.a") add_library(libopencv_imgproc STATIC IMPORTED ) set_target_properties(libopencv_imgproc PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_imgproc.a") add_library(libopencv_ml STATIC IMPORTED ) set_target_properties(libopencv_ml PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_ml.a") add_library(libopencv_objdetect STATIC IMPORTED ) set_target_properties(libopencv_objdetect PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_objdetect.a") add_library(libopencv_photo STATIC IMPORTED ) set_target_properties(libopencv_photo PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_photo.a") add_library(libopencv_shape STATIC IMPORTED ) set_target_properties(libopencv_shape PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_shape.a") add_library(libopencv_stitching STATIC IMPORTED ) set_target_properties(libopencv_stitching PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_stitching.a") add_library(libopencv_superres STATIC IMPORTED ) set_target_properties(libopencv_superres PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_superres.a") add_library(libopencv_video STATIC IMPORTED ) set_target_properties(libopencv_video PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_video.a") add_library(libopencv_videoio STATIC IMPORTED ) set_target_properties(libopencv_videoio PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_videoio.a") add_library(libopencv_videostab STATIC IMPORTED ) set_target_properties(libopencv_videostab PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_videostab.a") add_library(libopencv_ts STATIC IMPORTED ) set_target_properties(libopencv_ts PROPERTIES IMPORTED_LOCATION "${libs}/${ANDROID_ABI}/libopencv_ts.a") set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11 -fexceptions -frtti") #include_directories(D:/Projects/Android/CLMAndroid/OpenCV-android-sdk/sdk/native/jni/include ) #set(OpenCV_DIR D:/Projects/Android/CLMAndroid/OpenCV-android-sdk/sdk/native/jni) #find_package(OpenCV REQUIRED) #target_link_libraries(${OpenCV_LIBS}) 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). src/main/cpp/native-lib.cpp ) # 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 android log libopencv_java3 libopencv_calib3d libopencv_core libopencv_features2d libopencv_flann libopencv_highgui libopencv_imgcodecs libopencv_imgproc libopencv_ml libopencv_objdetect libopencv_photo libopencv_shape libopencv_stitching libopencv_superres libopencv_video libopencv_videoio libopencv_videostab # Links the target library to the log library # included in the NDK. ${log-lib} )
这样配置之后,我们就可以在cpp中,直接使用OpenCV库了。在此贴一个简单的均值滤波:
#include <jni.h> #include <string> #include <opencv2/opencv.hpp> #include <bits/stdc++.h> #include <android/log.h> #include<opencv2/core/core.hpp> #include"opencv2/imgproc/imgproc.hpp" using namespace cv; using namespace std; #define MAKE_ARGB(a, r, g, b) ((a&0xff)<<24) | ((r&0xff)<<16) | ((g&0xff)<<8) | (b&0xff) #define MAKE_RGB565(r, g, b) ((((r) >> 3) << 11) | (((g) >> 2) << 5) | ((b) >> 3)) extern "C" { JNIEXPORT jintArray JNICALL Java_com_live_longsiyang_opencvdemo_OpenCVNativeManager_getBlurImage(JNIEnv *env, jobject thiz, jintArray pixels_, jint w, jint h) { int colorType = CV_8UC4; jint *pixels = env->GetIntArrayElements(pixels_, NULL); Mat imgMat(h, w, colorType, pixels); Mat out(h, w, colorType); blur(imgMat, out, Size(20, 20)); env->ReleaseIntArrayElements(pixels_, pixels, 0); int *outIntImage = new int[w * h]; for (int i = 0; i < w * h; i++) { int a, r, g, b; for (int j = 0; j < 4; j++) { a = out.data[i * 4 + 3]; r = out.data[i * 4 + 2]; g = out.data[i * 4 + 1]; b = out.data[i * 4 + 0]; outIntImage[i] = (int) out.data[i * 4 + j]; } outIntImage[i] = MAKE_ARGB(a,r,g,b); } jintArray result = env->NewIntArray(w * h); env->SetIntArrayRegion(result, 0, w * h, outIntImage); return result; } }
这样我们就能看到一个基本的模糊效果的demo。
import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.TextView; public class MainActivity extends AppCompatActivity { static { System.loadLibrary("native-lib"); } ImageView mIvTest; Button mBtnTest; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mIvTest = (ImageView) findViewById(R.id.img_test); mIvTest.setImageResource(R.drawable.beauty_steward_course_video_thumb_icon); mBtnTest = (Button) findViewById(R.id.btn_test); mBtnTest.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Bitmap srcBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.beauty_steward_course_video_thumb_icon); int w = srcBitmap.getWidth(); int h = srcBitmap.getHeight(); int[] pixels = new int[w*h]; srcBitmap.getPixels(pixels,0,w,0,0,w,h); int[] outPixels = OpenCVNativeManager.getBlurImage(pixels ,w,h); Bitmap destBitmap = Bitmap.createBitmap(w,h, Bitmap.Config.ARGB_8888); destBitmap.setPixels(outPixels,0,w,0,0,w,h); mIvTest.setImageBitmap(destBitmap); } }); findViewById(R.id.btn_reset).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mIvTest.setImageResource(R.drawable.beauty_steward_course_video_thumb_icon); } }); } }
导出.so
在build中找到这个so,这就是我们需要的文件。此外,由于我们使用了opencv相关的库,我们还需要将opencv的相关文件复制出来。将其导入我们需要的工程。
导入之后,我们只需要在module的build.gradle里面加入:
android { ... sourceSets { main { jniLibs.srcDirs = ['src/main/jniLibs'] aidl.srcDirs = ['src/main/aidl'] } } }
之后,我们就可以直接调用
System.loadLibrary("native-lib");
值得注意的是,JNI的方法是与路径名相关的,所以当我们以这样的方法调用native方法时,我们需要路径名匹配。
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