Android-JNI static Loading OpenCV

Android-JNI static Loading OpenCV
JNI static Loading OpenCV

Address: http://blog.csdn.net/caroline_wendy

Steps:

1. Prepare the OpenCV-Android Library

Copy the OpenCV sdk to the working folder.

Download the latest android-sdk of OpenCV:OpenCV-2.4.9-android-sdk;

PutSdk folder,CopyTo the working directory. the sdk folder contains three folders: native, java, and etc.

2. Load the OpenCV-Android Library

Import)Java folder in the working directory,Set as the library of the current project.

[Project name] Right-click-> Android-> Add Library-> select the added Library.NoSelect Is Library.

3. Create JniClientClass.

IncludeMethod), YesMultiple. <喎?http: www.bkjia.com kf ware vc " target="_blank" class="keylink"> VcD48cD48L3A + PHByZSBjbGFzcz0 = "brush: java;">/*****/package com. example. hellomyjni;/*** @ author Administrator **/public class JniClient {static public native String sayName (); static public native int [] grayImage (int [] pixels, int w, int h );}
Use the command line to generate the header file.

Go to the project folder and generate the JNI header file. Run the following command:

"Javah-classpath bin/classes-d jni com. example. hellomyjni. JniClient"

Or javah-classpath D:/eclipse-android/android-sdk/platforms/android-17/android. jar; bin/classes-d jni com. example. mycamera. CartoonifierView

Contains the Android library.

Command Parsing:

Generate a header file using javah;

-The classpath class position (bin/classes) is a. class file;

-D jni needs to generate JNI classes (com. example. hellomyjni. JniClient), including [package]. [classname].

Other references: http://blog.csdn.net/caroline_wendy/article/details/39032551

4. Modify the JNI configuration file

You need to create in the jni folderApplication. mk is mainly responsible for the use of C ++ standards (APP_STL) and libraries to be compiled.

APP_STL := gnustl_staticAPP_CPPFLAGS := -frtti -fexceptionsAPP_ABI := armeabi-v7a

Modify Android. mk. OPENCV_LIB_TYPE: = STATIC is not required.

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)#OPENCV_LIB_TYPE:=STATICOPENCV_INSTALL_MODULES:=oninclude C:/Users/Administrator/android-workspace/opencv-sdk/native/jni/OpenCV.mkLOCAL_MODULE    := HelloMyJniLOCAL_SRC_FILES := HelloMyJni.cppLOCAL_LDLIBS +=  -llog -ldl#LOCAL_C_INCLUDES += ./LOCAL_SRC_FILES += ./sayname.cppinclude $(BUILD_SHARED_LIBRARY)

5. JNI Functions

#include 
 
  #include 
  
   using namespace cv;#include "com_example_hellomyjni_JniClient.h"#include "sayname.h"JNIEXPORT jstring JNICALL Java_com_example_hellomyjni_JniClient_sayName  (JNIEnv *env, jclass) {string str = sayname();return env->NewStringUTF(str.c_str());}JNIEXPORT jintArray JNICALL Java_com_example_hellomyjni_JniClient_grayImage  (JNIEnv *env, jclass, jintArray buf, jint w, jint h ) {jint *cbuf;cbuf = env->GetIntArrayElements(buf, false);if (cbuf == NULL) {return 0;}Mat imgData(h, w, CV_8UC4, (unsigned char*) cbuf);uchar* ptr = imgData.ptr(0);for (int i = 0; i < w * h; i++) {int grayScale = (int) (ptr[4 * i + 2] * 0.299 + ptr[4 * i + 1] * 0.587+ ptr[4 * i + 0] * 0.114);ptr[4 * i + 1] = grayScale;ptr[4 * i + 2] = grayScale;ptr[4 * i + 0] = grayScale;}int size = w * h;jintArray result = env->NewIntArray(size);env->SetIntArrayRegion(result, 0, size, cbuf);env->ReleaseIntArrayElements(buf, cbuf, 0);return result;}
  
 

Add OpenCV header file checkTo avoid file errors.

6. Modify MainActivity

Call the JNI function.

package com.example.hellomyjni;import org.opencv.android.OpenCVLoader;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Bitmap.Config;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.widget.ImageView;import android.widget.TextView;public class MainActivity extends Activity{private ImageView iv;private Bitmap bmp;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);TextView tv = (TextView) findViewById(R.id.text_view);tv.setText(JniClient.sayName()); //recall JNIiv = (ImageView) findViewById(R.id.image_view);bmp = BitmapFactory.decodeResource(getResources(), R.drawable.shoes);int w = bmp.getWidth();int h = bmp.getHeight();int[] pixels = new int[w * h];bmp.getPixels(pixels, 0, w, 0, 0, w, h);int[] resultInt = JniClient.grayImage(pixels, w, h); //recall JNIBitmap resultImg = Bitmap.createBitmap(w, h, Config.ARGB_8888);resultImg.setPixels(resultInt, 0, w, 0, 0, w, h);iv.setImageBitmap(resultImg);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}static {if (!OpenCVLoader.initDebug()) {    } else {        System.loadLibrary("HelloMyJni");    }}}

7. Output