Dec 07, 2016 Both the Qt and Eclipse IDE’s can handle CMake projects easily. Both of these IDE’s are cross platform which makes porting a lot easier. There are plenty of tutorials for creating a project using OpenCV, just like this one for Eclipse: Using OpenC. But first and foremost,i just can't seem to setup opencv2.0.0a or the 2.3.1 version its been 4 days, i have posted my query on the opencv's sourceforge forum, in the yahoo group of opencv though there some guys helped, but that also didn't solve the problem All the other guides are for 2.x but not 2.3 or for visual studio, including all that.
This tutorial has been created to help you use OpenCV library within your Android project.
This guide was written with Windows 7 in mind, though it should work with any other OS supported byOpenCV4Android SDK.
This tutorial assumes you have the following installed and configured:
- JDK
- Android SDK and NDK
- Eclipse IDE
- ADT and CDT plugins for Eclipse
If you need help with anything of the above, you may refer to our @ref tutorial_android_dev_intro guide.
This tutorial also assumes you have OpenCV4Android SDK already installed on your development machineand OpenCV Manager on your testing device correspondingly. If you need help with any of these, youmay consult our @ref tutorial_O4A_SDK tutorial.
If you encounter any error after thoroughly following these steps, feel free to contact us viaOpenCV4Android discussion group or OpenCV Q&Aforum . We'll do our best to help you out.
Using OpenCV Library Within Your Android Project
In this section we will explain how to make some existing project to use OpenCV. Starting with 2.4.2release for Android, OpenCV Manager is used to provide apps with the best available version ofOpenCV. You can get more information here:
Android OpenCV Manager
and in theseslides.Java
Application Development with Async Initialization
Using async initialization is a recommended way for application development. It uses the OpenCVManager to access OpenCV libraries externally installed in the target system.
-# Add OpenCV library project to your workspace. Use menuFile -> Import -> Existing project in your workspace.
-# In application project add a reference to the OpenCV Java SDK inProject -> Properties -> Android -> Library -> Add select OpenCV Library - 2.4.9.
In most cases OpenCV Manager may be installed automatically from Google Play. For the case, whenGoogle Play is not available, i.e. emulator, developer board, etc, you can install it manually usingadb tool. See
Manager Selection
for details.There is a very base code snippet implementing the async initialization. It shows basic principles.See the '15-puzzle' OpenCV sample for details.@code{.java}public class Sample1Java extends Activity implements CvCameraViewListener {
}@endcodeIt this case application works with OpenCV Manager in asynchronous fashion. OnManagerConnectedcallback will be called in UI thread, when initialization finishes. Please note, that it is notallowed to use OpenCV calls or load OpenCV-dependent native libs before invoking this callback. Loadyour own native libraries that depend on OpenCV after the successful OpenCV initialization. DefaultBaseLoaderCallback implementation treat application context as Activity and calls Activity.finish()method to exit in case of initialization failure. To override this behavior you need to overridefinish() method of BaseLoaderCallback class and implement your own finalization method.
Application Development with Static Initialization
According to this approach all OpenCV binaries are included into your application package. It isdesigned mostly for development purposes. This approach is deprecated for the production code,release package is recommended to communicate with OpenCV Manager via the async initializationdescribed above.
-# Add the OpenCV library project to your workspace the same way as for the async initializationabove. Use menu File -> Import -> Existing project in your workspace, press Browse button andselect OpenCV SDK path (
OpenCV-2.4.9-android-sdk/sdk
).-# In the application project add a reference to the OpenCV4Android SDK inProject -> Properties -> Android -> Library -> Add select OpenCV Library - 2.4.9;
-# If your application project doesn't have a JNI part, just copy the corresponding OpenCVnative libs from
<OpenCV-2.4.9-android-sdk>/sdk/native/libs/<target_arch>
to your projectdirectory to folder libs/<target_arch>
.-# The last step of enabling OpenCV in your application is Java initialization code before callingOpenCV API. It can be done, for example, in the static section of the Activity class:@code{.java}static {if (!OpenCVLoader.initDebug()) {// Handle initialization error}}@endcodeIf you application includes other OpenCV-dependent native libraries you should load themafter OpenCV initialization:@code{.java}static {if (!OpenCVLoader.initDebug()) {// Handle initialization error} else {System.loadLibrary('my_jni_lib1');System.loadLibrary('my_jni_lib2');}}@endcode
Native/C++
To build your own Android application, using OpenCV as native part, the following steps should betaken:
-# You can use an environment variable to specify the location of OpenCV package or just hardcodeabsolute or relative path in the
jni/Android.mk
of your projects.-# The file jni/Android.mk
should be written for the current application using the common rulesfor this file.-# The following line:@code{.make}include C:WorkOpenCV4AndroidOpenCV-2.4.9-android-sdksdknativejniOpenCV.mk@endcodeShould be inserted into the
jni/Android.mk
file after this line:@code{.make}include $(CLEAR_VARS)@endcode-# Several variables can be used to customize OpenCV stuff, but you don't need to use them whenyour application uses the async initialization via the OpenCV Manager API.-# The file
Application.mk
should exist and should contain lines:@code{.make}APP_STL := gnustl_staticAPP_CPPFLAGS := -frtti -fexceptions@endcodeAlso, the line like this one:@code{.make}APP_ABI := armeabi-v7a@endcodeShould specify the application target platforms.-# Either use @ref tutorial_android_dev_intro_ndk 'manual' ndk-build invocation or@ref tutorial_android_dev_intro_eclipse 'setup Eclipse CDT Builder' to build native JNI libbefore (re)building the Java part and creatingan APK.
Hello OpenCV Sample
Here are basic steps to guide you trough the process of creating a simple OpenCV-centricapplication. It will be capable of accessing camera output, processing it and displaying the result.
-# Open Eclipse IDE, create a new clean workspace, create a new Android projectFile --> New --> Android Project-# Set name, target, package and minSDKVersion accordingly. The minimal SDK version for build withOpenCV4Android SDK is 11. Minimal device API Level (for application manifest) is 8.-# Allow Eclipse to create default activity. Lets name the activity HelloOpenCvActivity.-# Choose Blank Activity with full screen layout. Lets name the layout HelloOpenCvLayout.-# Import OpenCV library project to your workspace.-# Reference OpenCV library within your project properties.
-# Edit your layout file as xml file and pass the following layout there:@code{.xml}
Dev C++ Ide Download
-# Add the following permissions to the
AndroidManifest.xml
file:@code{.xml}-# Set application theme in AndroidManifest.xml to hide title and system buttons.@code{.xml}@endcode-# Add OpenCV library initialization to your activity. Fix errors by adding required imports.@code{.java}private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {@Overridepublic void onManagerConnected(int status) {switch (status) {case LoaderCallbackInterface.SUCCESS:{Log.i(TAG, 'OpenCV loaded successfully');mOpenCvCameraView.enableView();} break;default:{super.onManagerConnected(status);} break;}}};
-# Defines that your activity implements CvCameraViewListener2 interface and fix activity relatederrors by defining missed methods. For this activity define onCreate, onDestroy and onPause andimplement them according to the code snippet below. Fix errors by adding required imports.@code{.java}private CameraBridgeViewBase mOpenCvCameraView;
-# Run your application on device or emulator.
Lets discuss some most important steps. Every Android application with UI must implement Activityand View. By the first steps we create blank activity and default view layout. The simplestOpenCV-centric application must implement OpenCV initialization, create its own view to show previewfrom camera and implements CvCameraViewListener2 interface to get frames from camera and process it.
First of all we create our application view using xml layout. Our layout consists of the only onefull screen component of class org.opencv.android.JavaCameraView. This class is implemented insideOpenCV library. It is inherited from CameraBridgeViewBase, that extends SurfaceView and usesstandard Android camera API.
After creating layout we need to implement Activity class. OpenCV initialization process has beenalready discussed above. In this sample we use asynchronous initialization. Implementation ofCvCameraViewListener interface allows you to add processing steps after frame grabbing from cameraand before its rendering on screen. The most important function is onCameraFrame. It is callbackfunction and it is called on retrieving frame from camera. The callback input is object ofCvCameraViewFrame class that represents frame from camera.
@note Do not save or use CvCameraViewFrame object out of onCameraFrame callback. This object doesnot have its own state and its behavior out of callback is unpredictable!
It has rgba() and gray()methods that allows to get frame as RGBA and one channel gray scale Mat respectively. It expectsthat onCameraFrame function returns RGBA frame that will be drawn on the screen.