Android 通過cmake的方式接入opencv的方法步驟
簡述
上篇 我們通過Java sdk的方式已經將opencv接入到專案中了,如果想使用opencv sdk 提供的 C++ 標頭檔案與 .so動態庫,自己封裝jni這樣使用上篇的方式顯然是不能實現的。所以本篇我們介紹通過cmake的方式接入opencv。
接入步驟
1、新建jni專案
具體建立過程參考上篇:通過Java sdk方式接入opencv 。
2、匯入so庫
在專案app/src/main目錄下新建jniLibs,並將解壓後的opencv sdk 目錄下對應的路徑 sdk/native/libs 中的檔案複製到jniLibs中。
2、匯入cpp檔案
將opencv sdk 目錄下對應的路徑 sdk/native/jni/include 中的檔案複製到cpp目錄中。
3、修改CMakeLists
將src/main/cpp 中的CMakeLists移動到app目錄下。
2.修改CMakeLists中的內容
# For more information about using CMake with Android Studio,read the # documentation: https://d.android.com/studio/projects/add-native-code.html # 設定CMAKE的版本號 cmake_minimum_required(VERSION 3.4.1) # 設定include資料夾的地址 include_directories(${CMAKE_SOURCE_DIR}/src/main/cpp/include) # 設定opencv的動態庫 add_library(libopencv_java4 SHARED IMPORTED) set_target_properties(libopencv_java4 PROPERTIES IMPORTED_LOCATION ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libopencv_java4.so) add_library( # Sets the name of the library. native-lib #.so庫名 可自定義 # Sets the library as a shared library. SHARED # Provides a relative path to your source file(s). src/main/cpp/native-lib.cpp) 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) target_link_libraries( # Specifies the target library. native-lib libopencv_java4 # Links the target library to the log library # included in the NDK. ${log-lib})
修改app 中的build.gradle檔案 defaultConfig 中配置cmake和ndk
externalNativeBuild { cmake { cppFlags "-std=c++11" arguments "-DANDROID_STL=c++_shared" } } ndk{ abiFilters "armeabi-v7a","arm64-v8a" }
android 中配置jniLibs
sourceSets{ main{ jniLibs.srcDirs = ['src/main/jniLibs'] } }
android 中配置cmake和ndk相關
externalNativeBuild { cmake { path file('CMakeLists.txt') version "3.10.2" } } splits { abi { enable true reset() include 'x86','x86_64','armeabi-v7a','arm64-v8a' //select ABIs to build APKs for universalApk true //generate an additional APK that contains all the ABIs } }
如果是老專案則不必配置splits否則會報錯,只需要幹掉下面的程式碼
splits { abi { enable true reset() include 'x86','arm64-v8a' //select ABIs to build APKs for universalApk true //generate an additional APK that contains all the ABIs } }
最終配置完的程式碼為:
apply plugin: 'com.android.application' apply plugin: 'kotlin-android' apply plugin: 'kotlin-android-extensions' android { compileSdkVersion 29 defaultConfig { applicationId "com.jd.opencv" minSdkVersion 23 targetSdkVersion 29 versionCode 1 versionName "1.0" testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" externalNativeBuild { cmake { cppFlags "-std=c++11" arguments "-DANDROID_STL=c++_shared" } } ndk{ abiFilters "armeabi-v7a","arm64-v8a" } } sourceSets{ main{ jniLibs.srcDirs = ['src/main/jniLibs'] } } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),'proguard-rules.pro' } } externalNativeBuild { cmake { path file('CMakeLists.txt') version "3.10.2" } } splits { abi { enable true reset() include 'x86','arm64-v8a' //select ABIs to build APKs for universalApk true //generate an additional APK that contains all the ABIs } } project.ext.versionCodes = ['armeabi': 1,'armeabi-v7a': 2,'arm64-v8a': 3,'mips': 5,'mips64': 6,'x86': 8,'x86_64': 9] android.applicationVariants.all { variant -> variant.outputs.each { output -> output.versionCodeOverride = project.ext.versionCodes.get(output.getFilter(com.android.build.OutputFile.ABI),0) * 1000000 + android.defaultConfig.versionCode } } } dependencies { implementation fileTree(dir: 'libs',include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation 'androidx.appcompat:appcompat:1.1.0' implementation 'androidx.core:core-ktx:1.2.0' implementation 'androidx.constraintlayout:constraintlayout:1.1.3' testImplementation 'junit:junit:4.12' androidTestImplementation 'androidx.test.ext:junit:1.1.1' androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0' }
使用
我們將一張彩色圖片通過 opencv 處理成一張灰色的照片。
1、編寫處理照片的程式碼。
建立native程式碼
object NativeLibUtils{ init { System.loadLibrary("native-lib") } external fun bitmap2Grey(pixels: IntArray,w: Int,h: Int): IntArray }
建立 jni 程式碼
#include <jni.h> #include <jni.h> #include <string> #include<opencv2/opencv.hpp> #include<iostream> #include <opencv2/imgproc/types_c.h> #include <unistd.h> using namespace cv; using namespace std; extern "C" JNIEXPORT jintArray JNICALL Java_com_mp5a5_opencv_NativeLibUtils_bitmap2Gray(JNIEnv *env,jobject instance,jintArray pixels,jint w,jint h) { jint *cur_array; jboolean isCopy = static_cast<jboolean>(false); cur_array = env->GetIntArrayElements(pixels,&isCopy); if (cur_array == NULL) { return 0; } Mat img(h,w,CV_8UC4,(unsigned char *) cur_array); cvtColor(img,img,CV_BGRA2GRAY); cvtColor(img,CV_GRAY2BGRA); int size = w * h; jintArray result = env->NewIntArray(size); env->SetIntArrayRegion(result,size,(jint *) img.data); env->ReleaseIntArrayElements(pixels,cur_array,0); return result; }
呼叫 native 程式碼來實現彩色圖片轉換成灰色圖片
private fun showGrayImg() { val w = bitmap.width val h = bitmap.height val pixels = IntArray(w * h) bitmap.getPixels(pixels,h) val resultData: IntArray = NativeLibUtils.bitmap2Gray(pixels,h) val resultImage = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888) resultImage.setPixels(resultData,h) iv_image.setImageBitmap(resultImage) }
完整轉換的程式碼
class OpenCvActivity : AppCompatActivity(),View.OnClickListener { private lateinit var bitmap: Bitmap override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_opencv) bitmap = BitmapFactory.decodeResource(resources,R.mipmap.person) iv_image.setImageBitmap(bitmap) btn_btn1.setOnClickListener(this) btn_btn2.setOnClickListener(this) } override fun onClick(v: View?) { v?.id?.let { when (it) { R.id.btn_btn1 -> { showGrayImg() } R.id.btn_btn2 -> { showRgbImg() } } } } private fun showRgbImg() { bitmap = BitmapFactory.decodeResource(resources,R.mipmap.person) iv_image.setImageBitmap(bitmap) } private fun showGrayImg() { val w = bitmap.width val h = bitmap.height val pixels = IntArray(w * h) bitmap.getPixels(pixels,h) val resultData: IntArray = NativeLibUtils.bitmap2Gray(pixels,h) val resultImage = Bitmap.createBitmap(w,Bitmap.Config.ARGB_8888) resultImage.setPixels(resultData,h) iv_image.setImageBitmap(resultImage) } }
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> <ImageView android:id="@+id/iv_image" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_above="@id/ll_location" app:srcCompat="@mipmap/person" /> <LinearLayout android:id="@+id/ll_location" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:orientation="horizontal"> <Button android:id="@+id/btn_btn1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="灰度圖" /> <Button android:id="@+id/btn_btn2" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="色圖" /> </LinearLayout> </RelativeLayout>
顯示效果:
效果圖
Demo 的 Github 地址 https://github.com/Mp5A5/AndroidOpenCv
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