在Android中使用OpenCv-白红宇

在Android中使用OpenCv

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发布时间：2019-05-02

本文共 4648 字，大约阅读时间需要 15 分钟。

编译环境:ubuntu 10.10

opencv版本:2.2

1.首先需要下载以下文件:

OpenCV-2.2.0.tar.bz2

android-ndk-r4-linux-x86-crystax-4.tar.bz2

2.ubuntu需要以下包

sudo apt-get install build-essential

sudo apt-get install cmake

sudo apt-get install libgtk2.0-dev

sudo apt-get install swig

sudo apt-get install libpython2.6 python-dev python2.6-dev

3.解压缩opencv后,在其目录进行以下操作

cd release

cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_PYTHON_SUPPORT=ON

-D BUILD_EXAMPLES=ON ..

make

编译完成后安装进系统库中

sudo make install

sudo ldconfig

如果想测试效果可以进入samples/c目录中执行

. build_all.sh

来编译示例程序,然后运行find_obj来看看opencv中surf的效果

4.接下来是编译android的版本

在编译之前需要解压缩

android-ndk-r4-linux-x86-crystax-4.tar.bz2到用户目录下,因为opencv默认在用户目录下寻找,当然大家也可以更改配置文件

进入android目录中,执行以下操作:

mkdir build

cd build

cmake ..

make

这就编译好android的库文件了,下面来新建一个android程序来测试一下

5.创建一个android工程,工程名为opencvtest,包名为com.opencvtest

在工程的根目录下创建一个jni文件夹,然后分别创建Android.mk和hello-jni.cpp两个文件

Android.mk的内容如下:

LOCAL_PATH:= $(call my-dir)

 
 include $(CLEAR_VARS)
 
 include /home/ms/opencv/OpenCV-2.2.0/android/build/android-opencv.mk
 LOCAL_LDLIBS += $(OPENCV_LIBS)
 LOCAL_C_INCLUDES += $(OPENCV_INCLUDES)
 
 LOCAL_MODULE := hello-jni
 LOCAL_SRC_FILES := hello-jni.cpp
 
 include $(BUILD_SHARED_LIBRARY)

其中需要注意的是要更改

include /home/ms/opencv/OpenCV-2.2.0到自己的opencv目录下

hello-jni.cpp的内容如下:

#include<jni.h>

 #include  <cstdlib>
 #include  <stdexcept>
 #include  <string>
 
 #include  <opencv2/core/core.hpp>
 #include  <opencv2/features2d/features2d.hpp>
 #include  <opencv2/highgui/highgui.hpp>
 #include  <opencv2/imgproc/imgproc.hpp>
 #include  <opencv2/calib3d/calib3d.hpp>
 #include  <opencv2/imgproc/imgproc_c.h>
 
 static CvScalar colors[]=
 { 
            
     { 
            { 
            0,0,255}},
     { 
            { 
            0,128,255}},
     { 
            { 
            0,255,255}},
     { 
            { 
            0,255,0}},
     { 
            { 
            255,128,0}},
     { 
            { 
            255,255,0}},
     { 
            { 
            255,0,0}},
     { 
            { 
            255,0,255}},
     { 
            { 
            255,255,255}}
 };
 
 extern "C"
 jint Java_com_opencvtest_opencvtest_getKeypointNum(JNIEnv* env,jobject thiz)
 { 
            
     IplImage* object  = cvLoadImage(  "/sdcard/src.jpg", CV_LOAD_IMAGE_GRAYSCALE);
 
     if(object!= NULL){ 
            
         CvSURFParams params = cvSURFParams(500, 1);
         CvMemStorage* storage  = cvCreateMemStorage(0);
         IplImage* object_color  = cvCreateImage(cvGetSize(object), 8, 3);
         CvSeq *objectKeypoints  = 0;
         CvSeq *objectDescriptors  = 0;
 
         cvCvtColor( object, object_color, CV_GRAY2BGR);
         cvExtractSURF( object, 0,&objectKeypoints,&objectDescriptors, storage, params);
 
      for(  int i = 0; i< objectKeypoints->total; i++)
      { 
            
      CvSURFPoint* r  = (CvSURFPoint*)cvGetSeqElem( objectKeypoints, i);
      CvPoint center;
      int radius;
      center.x = cvRound(r->pt.x);
      center.y = cvRound(r->pt.y);
      radius = cvRound(r->size*1.2/9.*2);
      cvCircle( object_color, center, radius, colors[0], 1, 8, 0  );
      }
 
         cvSaveImage(  "/sdcard/src_surf.jpg" , object_color);
 
         return objectKeypoints->total;
     }
 
     return 0;
 }

需要注意的是,如果创建的工程名和我不一样的话,需要更改JNI函数的函数名

更改好之后在工程的根目录下运行

~/android-ndk-r4-crystax/ndk-build

即可进行编译,

~/android-ndk-r4-crystax指向了我自己的目录,大家可以根据自己的情况修改

编译完成后会创建libs和obj两个目录出来,同时需要注意的是要刷新android的工程来同步这两个目录下的内容

最后更改opencvtest.java文件来调用JNI,我的代码如下:

package com.opencvtest;

 
 import android.app.Activity;
 import android.os.Bundle;
 import android.widget.TextView;
 
 public class opencvtestextends Activity{ 
            
     
     private TextView mTextView;
     
     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState){ 
            
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         
         mTextView =  (TextView)  this.findViewById(R.id.textview);
         
         mTextView.setText(Integer.toString(getKeypointNum()));
     }
     
     public nativeint getKeypointNum();
 
     static { 
            
         System.loadLibrary("hello-jni");
     }
 }