- Use Android Studio instead of Ecliplse. - Use new Gradle-based OpenCV for Android SDK.pull/24653/head
Rostislav Vasilikhin
1 year ago
committed by
Alexander Smorkalov
@ -1,255 +0,0 @@ |
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OpenCV4Android SDK {#tutorial_O4A_SDK} |
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================== |
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|
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@prev_tutorial{tutorial_android_dev_intro} |
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@next_tutorial{tutorial_dev_with_OCV_on_Android} |
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|
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| | | |
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| -: | :- | |
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| Original author | Vsevolod Glumov | |
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| Compatibility | OpenCV >= 3.0 | |
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|
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@warning |
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This tutorial is deprecated. |
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|
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This tutorial was designed to help you with installation and configuration of OpenCV4Android SDK. |
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|
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This guide was written with MS Windows 7 in mind, though it should work with GNU Linux and Apple Mac |
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OS as well. |
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|
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This tutorial assumes you have the following software installed and configured: |
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|
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- JDK |
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- Android SDK and NDK |
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- Eclipse IDE |
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- ADT and CDT plugins for Eclipse |
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|
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If you need help with anything of the above, you may refer to our @ref tutorial_android_dev_intro guide. |
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|
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If you encounter any error after thoroughly following these steps, feel free to contact us via |
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[OpenCV4Android](https://groups.google.com/group/android-opencv/) discussion group or OpenCV [Q&A |
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forum](https://forum.opencv.org). We'll do our best to help you out. |
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|
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General info |
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------------ |
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|
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OpenCV4Android SDK package enables development of Android applications with use of OpenCV library. |
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|
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The structure of package contents looks as follows: |
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|
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OpenCV-2.4.9-android-sdk |
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|_ apk |
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| |_ OpenCV_2.4.9_binary_pack_armv7a.apk |
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| |_ OpenCV_2.4.9_Manager_2.18_XXX.apk |
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| |
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|_ doc |
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|_ samples |
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|_ sdk |
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| |_ etc |
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| |_ java |
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| |_ native |
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| |_ 3rdparty |
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| |_ jni |
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| |_ libs |
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| |_ armeabi |
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| |_ armeabi-v7a |
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| |_ x86 |
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| |
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|_ LICENSE |
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|_ README.android |
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|
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- `sdk` folder contains OpenCV API and libraries for Android: |
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- `sdk/java` folder contains an Android library Eclipse project providing OpenCV Java API that can |
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be imported into developer's workspace; |
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- `sdk/native` folder contains OpenCV C++ headers (for JNI code) and native Android libraries |
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(\*.so and \*.a) for ARM-v5, ARM-v7a and x86 architectures; |
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- `sdk/etc` folder contains Haar and LBP cascades distributed with OpenCV. |
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- `apk` folder contains Android packages that should be installed on the target Android device to |
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enable OpenCV library access via OpenCV Manager API (see details below). |
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|
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On production devices that have access to Google Play Market (and Internet) these packages will |
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be installed from Market on the first start of an application using OpenCV Manager API. But |
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devkits without Market or Internet connection require this packages to be installed manually. |
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Install the Manager.apk and optional binary_pack.apk if it needed. See `Manager Selection` |
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for details. |
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|
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@note Installation from Internet is the preferable way since OpenCV team may publish updated |
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versions of this packages on the Market. |
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|
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- `samples` folder contains sample applications projects |
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and their prebuilt packages (APK). Import them into Eclipse workspace (like described below) and |
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browse the code to learn possible ways of OpenCV use on Android. |
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|
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- `doc` folder contains various OpenCV documentation in PDF format. It's also available online at |
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<http://docs.opencv.org>. |
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@note The most recent docs (nightly build) are at <http://docs.opencv.org/4.x>. Generally, it's more |
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up-to-date, but can refer to not-yet-released functionality. |
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@todo I'm not sure that this is the best place to talk about OpenCV Manager |
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|
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Starting from version 2.4.3 OpenCV4Android SDK uses OpenCV Manager API for library initialization. |
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OpenCV Manager is an Android service based solution providing the following benefits for OpenCV |
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applications developers: |
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|
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- Compact apk-size, since all applications use the same binaries from Manager and do not store |
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native libs within themselves; |
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- Hardware specific optimizations are automatically enabled on all supported platforms; |
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- Automatic updates and bug fixes; |
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- Trusted OpenCV library source. All packages with OpenCV are published on Google Play; |
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|
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|
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Manual OpenCV4Android SDK setup |
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------------------------------- |
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|
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### Get the OpenCV4Android SDK |
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|
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-# Go to the [OpenCV download page on |
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SourceForge](http://sourceforge.net/projects/opencvlibrary/files/) and download |
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the latest available version. This tutorial is based on this package: [OpenCV-2.4.9-android-sdk.zip](http://sourceforge.net/projects/opencvlibrary/files/opencv-android/2.4.9/OpenCV-2.4.9-android-sdk.zip/download). |
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-# Create a new folder for Android with OpenCV development. For this tutorial we have unpacked |
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OpenCV SDK to the `C:\Work\OpenCV4Android\` directory. |
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|
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@note Better to use a path without spaces in it. Otherwise you may have problems with ndk-build. |
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|
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-# Unpack the SDK archive into the chosen directory. |
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|
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You can unpack it using any popular archiver (e.g with 7-Zip): |
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|
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 |
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|
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On Unix you can use the following command: |
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@code{.bash} |
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unzip ~/Downloads/OpenCV-2.4.9-android-sdk.zip |
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@endcode |
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|
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### Import OpenCV library and samples to the Eclipse |
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|
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-# Start Eclipse and choose your workspace location. |
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|
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We recommend to start working with OpenCV for Android from a new clean workspace. A new Eclipse |
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workspace can for example be created in the folder where you have unpacked OpenCV4Android SDK |
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package: |
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|
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 |
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|
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-# Import OpenCV library and samples into workspace. |
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|
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OpenCV library is packed as a ready-for-use [Android Library |
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Project](http://developer.android.com/guide/developing/projects/index.html#LibraryProjects). You |
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can simply reference it in your projects. |
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|
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Each sample included into the `OpenCV-2.4.9-android-sdk.zip` is a regular Android project that |
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already references OpenCV library. Follow the steps below to import OpenCV and samples into the |
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workspace: |
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|
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- Right click on the Package Explorer window and choose Import... option from the context |
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menu: |
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|
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 |
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|
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- In the main panel select General --\> Existing Projects into Workspace and press Next |
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button: |
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|
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 |
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|
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- In the Select root directory field locate your OpenCV package folder. Eclipse should |
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automatically locate OpenCV library and samples: |
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|
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 |
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|
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- Click Finish button to complete the import operation. |
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|
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@note OpenCV samples are indeed **dependent** on OpenCV library project so don't forget to import it to your workspace as well. |
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|
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After clicking Finish button Eclipse will load all selected projects into workspace, and you |
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have to wait some time while it is building OpenCV samples. Just give a minute to Eclipse to |
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complete initialization. |
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|
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 |
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|
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Once Eclipse completes build you will have the clean workspace without any build errors: |
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|
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 |
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|
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@anchor tutorial_O4A_SDK_samples |
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### Running OpenCV Samples |
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|
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At this point you should be able to build and run the samples. Keep in mind, that face-detection and |
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Tutorial 2 - Mixed Processing include some native code and require Android NDK and NDK/CDT plugin |
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for Eclipse to build working applications. If you haven't installed these tools, see the |
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corresponding section of @ref tutorial_android_dev_intro. |
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|
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**warning** |
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|
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Please consider that some samples use Android Java Camera API, which is accessible with an AVD. |
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|
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@note Recent *Android SDK tools, revision 19+* can run ARM v7a OS images but they available not for |
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all Android versions. |
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|
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Well, running samples from Eclipse is very simple: |
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|
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- Connect your device with adb tool from Android SDK or create an emulator with camera support. |
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- See [Managing Virtual Devices](http://developer.android.com/guide/developing/devices/index.html) document for help |
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with Android Emulator. |
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- See [Using Hardware Devices](http://developer.android.com/guide/developing/device.html) for |
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help with real devices (not emulators). |
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|
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- Select project you want to start in Package Explorer and just press Ctrl + F11 or select option |
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Run --\> Run from the main menu, or click Run button on the toolbar. |
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|
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@note Android Emulator can take several minutes to start. So, please, be patient. \* On the first |
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run Eclipse will ask you about the running mode for your application: |
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|
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 |
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|
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- Select the Android Application option and click OK button. Eclipse will install and run the |
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sample. |
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|
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Chances are that on the first launch you will not have the [OpenCV |
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Manager](https://docs.google.com/a/itseez.com/presentation/d/1EO_1kijgBg_BsjNp2ymk-aarg-0K279_1VZRcPplSuk/present#slide=id.p) |
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package installed. In this case you will see the following message: |
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|
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 |
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|
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To get rid of the message you will need to install OpenCV Manager and the appropriate |
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OpenCV binary pack. Simply tap Yes if you have *Google Play Market* installed on your |
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device/emulator. It will redirect you to the corresponding page on *Google Play Market*. |
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|
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If you have no access to the *Market*, which is often the case with emulators - you will need to |
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install the packages from OpenCV4Android SDK folder manually. See `Manager Selection` for |
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details. |
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@code{.sh} |
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<Android SDK path>/platform-tools/adb install <OpenCV4Android SDK path>/apk/OpenCV_2.4.9_Manager_2.18_armv7a-neon.apk |
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@endcode |
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|
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@note armeabi, armv7a-neon, arm7a-neon-android8, mips and x86 stand for platform targets: |
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- armeabi is for ARM v5 and ARM v6 architectures with Android API 8+, |
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- armv7a-neon is for NEON-optimized ARM v7 with Android API 9+, |
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- arm7a-neon-android8 is for NEON-optimized ARM v7 with Android API 8, |
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- mips is for MIPS architecture with Android API 9+, |
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- x86 is for Intel x86 CPUs with Android API 9+. |
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|
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@note |
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If using hardware device for testing/debugging, run the following command to learn its CPU |
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architecture: |
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@code{.sh} |
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adb shell getprop ro.product.cpu.abi |
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@endcode |
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If you're using an AVD emulator, go Window \> AVD Manager to see the list of available devices. |
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Click Edit in the context menu of the selected device. In the window, which then pop-ups, find |
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the CPU field. |
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|
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@note |
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You may also see section `Manager Selection` for details. |
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|
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When done, you will be able to run OpenCV samples on your device/emulator seamlessly. |
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|
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- Here is Sample - image-manipulations sample, running on top of stock camera-preview of the |
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emulator. |
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|
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 |
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|
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What's next |
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----------- |
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|
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Now, when you have your instance of OpenCV4Adroid SDK set up and configured, you may want to proceed |
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to using OpenCV in your own application. You can learn how to do that in a separate @ref tutorial_dev_with_OCV_on_Android tutorial. |
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@ -1,384 +1,113 @@ |
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Android Development with OpenCV {#tutorial_dev_with_OCV_on_Android} |
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=============================== |
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|
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@prev_tutorial{tutorial_O4A_SDK} |
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@prev_tutorial{tutorial_android_dev_intro} |
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@next_tutorial{tutorial_android_dnn_intro} |
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|
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| | | |
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| -: | :- | |
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| Original author | Vsevolod Glumov | |
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| Compatibility | OpenCV >= 3.0 | |
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|
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@warning |
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This tutorial is deprecated. |
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| Original authors | Alexander Panov, Rostislav Vasilikhin | |
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| Compatibility | OpenCV >= 4.9.0 | |
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|
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This tutorial has been created to help you use OpenCV library within your Android project. |
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|
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This guide was written with Windows 7 in mind, though it should work with any other OS supported by |
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OpenCV4Android SDK. |
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This guide was checked on Ubuntu but contains no platform-dependent parts, therefore should be compatible with any OS supported by Android Studio and OpenCV4Android SDK. |
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|
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This tutorial assumes you have the following installed and configured: |
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|
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- Android Studio |
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- JDK |
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- Android SDK and NDK |
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- Eclipse IDE |
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- ADT and CDT plugins for Eclipse |
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- OpenCV for Android SDK from official [release page on Github](https://github.com/opencv/opencv/releases) |
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or [SourceForge](https://sourceforge.net/projects/opencvlibrary/). Advanced: as alternative the SDK may be |
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built from source code by [instruction on wiki](https://github.com/opencv/opencv/wiki/Custom-OpenCV-Android-SDK-and-AAR-package-build). |
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|
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If you need help with anything of the above, you may refer to our @ref tutorial_android_dev_intro guide. |
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|
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This tutorial also assumes you have OpenCV4Android SDK already installed on your development machine |
||||
and OpenCV Manager on your testing device correspondingly. If you need help with any of these, you |
||||
may consult our @ref tutorial_O4A_SDK tutorial. |
||||
|
||||
If you encounter any error after thoroughly following these steps, feel free to contact us via |
||||
[OpenCV4Android](https://groups.google.com/group/android-opencv/) discussion group or OpenCV [Q&A |
||||
forum](https://forum.opencv.org) . We'll do our best to help you out. |
||||
|
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Using OpenCV Library Within Your Android Project |
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------------------------------------------------ |
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|
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In this section we will explain how to make some existing project to use OpenCV. Starting with 2.4.2 |
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release for Android, *OpenCV Manager* is used to provide apps with the best available version of |
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OpenCV. You can get more information here: `Android OpenCV Manager` and in these |
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[slides](https://docs.google.com/a/itseez.com/presentation/d/1EO_1kijgBg_BsjNp2ymk-aarg-0K279_1VZRcPplSuk/present#slide=id.p). |
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If you encounter any error after thoroughly following these steps, feel free to contact us via OpenCV [forum](https://forum.opencv.org). We'll do our best to help you out. |
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|
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### Java |
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Hello OpenCV sample |
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------------------- |
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|
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#### Application Development with Async Initialization |
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In addition to this instruction you can use some video guide, for example [this one](https://www.youtube.com/watch?v=bR7lL886-uc&ab_channel=ProgrammingHut) |
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|
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Using async initialization is a **recommended** way for application development. It uses the OpenCV |
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Manager to access OpenCV libraries externally installed in the target system. |
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1. Open Android Studio and create empty project by choosing ***Empty Views Activity*** |
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|
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-# Add OpenCV library project to your workspace. Use menu |
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File -\> Import -\> Existing project in your workspace. |
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 |
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|
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Press Browse button and locate OpenCV4Android SDK (`OpenCV-2.4.9-android-sdk/sdk`). |
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2. Setup the project: |
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- Choose ***Java*** language |
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- Choose ***Groovy DSL*** build configuration language |
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- Choose ***Minumum SDK*** to the same version number as was used during OpenCV 4 Android build |
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- If you don't know it, you can find it in file `OpenCV-android-sdk/sdk/build.gradle` at `android -> defaultConfig -> minSdkVersion` |
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|
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 |
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 |
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|
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-# In application project add a reference to the OpenCV Java SDK in |
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Project -\> Properties -\> Android -\> Library -\> Add select OpenCV Library - 2.4.9. |
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|
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 |
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3. Click ***File -> New -> Import module...*** and select OpenCV SDK path |
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|
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In most cases OpenCV Manager may be installed automatically from Google Play. For the case, when |
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Google Play is not available, i.e. emulator, developer board, etc, you can install it manually using |
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adb tool. See `Manager Selection` for details. |
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 |
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|
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There is a very base code snippet implementing the async initialization. It shows basic principles. |
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See the "15-puzzle" OpenCV sample for details. |
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@code{.java} |
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public class Sample1Java extends Activity implements CvCameraViewListener { |
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4. Set module name as `OpenCV` and press `Finish` |
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|
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private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) { |
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@Override |
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public void onManagerConnected(int status) { |
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switch (status) { |
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case LoaderCallbackInterface.SUCCESS: |
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{ |
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Log.i(TAG, "OpenCV loaded successfully"); |
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mOpenCvCameraView.enableView(); |
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} break; |
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default: |
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{ |
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super.onManagerConnected(status); |
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} break; |
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} |
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} |
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}; |
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 |
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|
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@Override |
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public void onResume() |
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{ |
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super.onResume(); |
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OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_6, this, mLoaderCallback); |
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5. OpenCV also provides experiemental Kotlin support. Please add Android Kotlin plugin to `MyApplication/OpenCV/build.gradle` file: |
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@code{.gradle} |
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plugins { |
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id 'org.jetbrains.kotlin.android' version '1.7.10' #version may differ for your setup |
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} |
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|
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... |
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} |
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@endcode |
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It this case application works with OpenCV Manager in asynchronous fashion. OnManagerConnected |
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callback will be called in UI thread, when initialization finishes. Please note, that it is not |
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allowed to use OpenCV calls or load OpenCV-dependent native libs before invoking this callback. Load |
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your own native libraries that depend on OpenCV after the successful OpenCV initialization. Default |
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BaseLoaderCallback 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 override |
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finish() method of BaseLoaderCallback class and implement your own finalization method. |
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|
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#### Application Development with Static Initialization |
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|
||||
According to this approach all OpenCV binaries are included into your application package. It is |
||||
designed mostly for development purposes. This approach is deprecated for the production code, |
||||
release package is recommended to communicate with OpenCV Manager via the async initialization |
||||
described above. |
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|
||||
-# Add the OpenCV library project to your workspace the same way as for the async initialization |
||||
above. Use menu File -\> Import -\> Existing project in your workspace, press Browse button and |
||||
select OpenCV SDK path (`OpenCV-2.4.9-android-sdk/sdk`). |
||||
|
||||
 |
||||
|
||||
-# In the application project add a reference to the OpenCV4Android SDK in |
||||
Project -\> Properties -\> Android -\> Library -\> Add select OpenCV Library - 2.4.9; |
||||
|
||||
 |
||||
|
||||
-# If your application project **doesn't have a JNI part**, just copy the corresponding OpenCV |
||||
native libs from `<OpenCV-2.4.9-android-sdk>/sdk/native/libs/<target_arch>` to your project |
||||
directory to folder `libs/<target_arch>`. |
||||
|
||||
In case of the application project **with a JNI part**, instead of manual libraries copying you |
||||
need to modify your Android.mk file: add the following two code lines after the |
||||
"include $(CLEAR_VARS)" and before |
||||
"include path_to_OpenCV-2.4.9-android-sdk/sdk/native/jni/OpenCV.mk" |
||||
@code{.make} |
||||
OPENCV_CAMERA_MODULES:=on |
||||
OPENCV_INSTALL_MODULES:=on |
||||
@endcode |
||||
The result should look like the following: |
||||
@code{.make} |
||||
include $(CLEAR_VARS) |
||||
Like this: |
||||
 |
||||
If you don't do this, you may get an error: |
||||
@code |
||||
Task failed with an exception. |
||||
----------- |
||||
* Where: |
||||
Build file '/home/alexander/AndroidStudioProjects/MyApplication/opencv/build.gradle' line: 4 |
||||
|
||||
# OpenCV |
||||
OPENCV_CAMERA_MODULES:=on |
||||
OPENCV_INSTALL_MODULES:=on |
||||
include ../../sdk/native/jni/OpenCV.mk |
||||
* What went wrong: |
||||
A problem occurred evaluating project ':opencv'. |
||||
> Plugin with id 'kotlin-android' not found. |
||||
@endcode |
||||
After that the OpenCV libraries will be copied to your application `libs` folder during the JNI |
||||
build.v |
||||
The fix was found [here](https://stackoverflow.com/questions/73225714/import-opencv-sdk-to-android-studio-chipmunk) |
||||
|
||||
Eclipse will automatically include all the libraries from the `libs` folder to the application |
||||
package (APK). |
||||
6. OpenCV project uses `aidl` and `buildConfig` features. Please enable them in |
||||
`MyApplication/OpenCV/build.gradle` file to `android` block: |
||||
|
||||
-# The last step of enabling OpenCV in your application is Java initialization code before calling |
||||
OpenCV API. It can be done, for example, in the static section of the Activity class: |
||||
@code{.java} |
||||
static { |
||||
if (!OpenCVLoader.initDebug()) { |
||||
// Handle initialization error |
||||
} |
||||
} |
||||
@endcode |
||||
If you application includes other OpenCV-dependent native libraries you should load them |
||||
**after** OpenCV initialization: |
||||
@code{.java} |
||||
static { |
||||
if (!OpenCVLoader.initDebug()) { |
||||
// Handle initialization error |
||||
} else { |
||||
System.loadLibrary("my_jni_lib1"); |
||||
System.loadLibrary("my_jni_lib2"); |
||||
} |
||||
@code{.gradle} |
||||
buildFeatures{ |
||||
aidl true |
||||
buildConfig true |
||||
} |
||||
@endcode |
||||
|
||||
### Native/C++ |
||||
|
||||
To build your own Android application, using OpenCV as native part, the following steps should be |
||||
taken: |
||||
|
||||
-# You can use an environment variable to specify the location of OpenCV package or just hardcode |
||||
absolute 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 rules |
||||
for this file. |
||||
|
||||
For detailed information see the Android NDK documentation from the Android NDK archive, in the |
||||
file `<path_where_NDK_is_placed>/docs/ANDROID-MK.html`. |
||||
|
||||
-# The following line: |
||||
@code{.make} |
||||
include C:\Work\OpenCV4Android\OpenCV-2.4.9-android-sdk\sdk\native\jni\OpenCV.mk |
||||
@endcode |
||||
Should 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 when |
||||
your application uses the async initialization via the OpenCV Manager API. |
||||
|
||||
@note These variables should be set **before** the "include .../OpenCV.mk" line: |
||||
@code{.make} |
||||
OPENCV_INSTALL_MODULES:=on |
||||
Like this: |
||||
 |
||||
If you don't do this, you may get an error: |
||||
@code |
||||
JavaCameraView.java:15: error: cannot find symbol import org.opencv.BuildConfig; ^ symbol: class BuildConfig location: package org.opencv |
||||
@endcode |
||||
The fix was found [here](https://stackoverflow.com/questions/76374886/error-cannot-find-symbol-import-org-opencv-buildconfig-android-studio) and [here](https://forum.opencv.org/t/task-compiledebugjavawithjavac-failed/13667/4) |
||||
|
||||
Copies necessary OpenCV dynamic libs to the project libs folder in order to include them |
||||
into the APK. |
||||
@code{.make} |
||||
OPENCV_CAMERA_MODULES:=off |
||||
@endcode |
||||
Skip native OpenCV camera related libs copying to the project libs folder. |
||||
@code{.make} |
||||
OPENCV_LIB_TYPE:=STATIC |
||||
@endcode |
||||
Perform static linking with OpenCV. By default dynamic link is used and the project JNI lib |
||||
depends on libopencv_java.so. |
||||
|
||||
-# The file `Application.mk` should exist and should contain lines: |
||||
@code{.make} |
||||
APP_STL := gnustl_static |
||||
APP_CPPFLAGS := -frtti -fexceptions |
||||
@endcode |
||||
Also, the line like this one: |
||||
@code{.make} |
||||
APP_ABI := armeabi-v7a |
||||
@endcode |
||||
Should specify the application target platforms. |
||||
|
||||
In some cases a linkage error (like |
||||
`"In function 'cv::toUtf16(std::basic_string<...>... undefined reference to 'mbstowcs'"`) |
||||
happens when building an application JNI library, depending on OpenCV. The following line in the |
||||
`Application.mk` usually fixes it: |
||||
@code{.make} |
||||
APP_PLATFORM := android-9 |
||||
@endcode |
||||
7. Add the module to the project: |
||||
- Click ***File -> Project structure... -> Dependencies -> All modules -> + (Add Dependency button) -> Module dependency*** |
||||
- Choose `app` |
||||
- Select `OpenCV` |
||||
|
||||
-# 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 lib |
||||
before (re)building the Java part and creating |
||||
an APK. |
||||
|
||||
Hello OpenCV Sample |
||||
------------------- |
||||
|
||||
Here are basic steps to guide you through the process of creating a simple OpenCV-centric |
||||
application. 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 project |
||||
File --\> New --\> Android Project |
||||
-# Set name, target, package and minSDKVersion accordingly. The minimal SDK version for build with |
||||
OpenCV4Android 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} |
||||
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
||||
xmlns:tools="http://schemas.android.com/tools" |
||||
xmlns:opencv="http://schemas.android.com/apk/res-auto" |
||||
android:layout_width="match_parent" |
||||
android:layout_height="match_parent" > |
||||
|
||||
<org.opencv.android.JavaCameraView |
||||
android:layout_width="fill_parent" |
||||
android:layout_height="fill_parent" |
||||
android:visibility="gone" |
||||
android:id="@+id/HelloOpenCvView" |
||||
opencv:show_fps="true" |
||||
opencv:camera_id="any" /> |
||||
|
||||
</LinearLayout> |
||||
@endcode |
||||
-# Add the following permissions to the `AndroidManifest.xml` file: |
||||
@code{.xml} |
||||
</application> |
||||
|
||||
<uses-permission android:name="android.permission.CAMERA"/> |
||||
|
||||
<uses-feature android:name="android.hardware.camera" android:required="false"/> |
||||
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false"/> |
||||
<uses-feature android:name="android.hardware.camera.front" android:required="false"/> |
||||
<uses-feature android:name="android.hardware.camera.front.autofocus" android:required="false"/> |
||||
@endcode |
||||
-# Set application theme in AndroidManifest.xml to hide title and system buttons. |
||||
@code{.xml} |
||||
<application |
||||
android:icon="@drawable/icon" |
||||
android:label="@string/app_name" |
||||
android:theme="@android:style/Theme.NoTitleBar.Fullscreen" > |
||||
@endcode |
||||
-# Add OpenCV library initialization to your activity. Fix errors by adding required imports. |
||||
@code{.java} |
||||
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) { |
||||
@Override |
||||
public void onManagerConnected(int status) { |
||||
switch (status) { |
||||
case LoaderCallbackInterface.SUCCESS: |
||||
{ |
||||
Log.i(TAG, "OpenCV loaded successfully"); |
||||
mOpenCvCameraView.enableView(); |
||||
} break; |
||||
default: |
||||
{ |
||||
super.onManagerConnected(status); |
||||
} break; |
||||
} |
||||
} |
||||
}; |
||||
|
||||
@Override |
||||
public void onResume() |
||||
{ |
||||
super.onResume(); |
||||
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_6, this, mLoaderCallback); |
||||
} |
||||
@endcode |
||||
-# Defines that your activity implements CvCameraViewListener2 interface and fix activity related |
||||
errors by defining missed methods. For this activity define onCreate, onDestroy and onPause and |
||||
implement them according to the code snippet below. Fix errors by adding required imports. |
||||
@code{.java} |
||||
private CameraBridgeViewBase mOpenCvCameraView; |
||||
|
||||
@Override |
||||
public void onCreate(Bundle savedInstanceState) { |
||||
Log.i(TAG, "called onCreate"); |
||||
super.onCreate(savedInstanceState); |
||||
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); |
||||
setContentView(R.layout.HelloOpenCvLayout); |
||||
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.HelloOpenCvView); |
||||
mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE); |
||||
mOpenCvCameraView.setCvCameraViewListener(this); |
||||
} |
||||
|
||||
@Override |
||||
public void onPause() |
||||
{ |
||||
super.onPause(); |
||||
if (mOpenCvCameraView != null) |
||||
mOpenCvCameraView.disableView(); |
||||
} |
||||
|
||||
public void onDestroy() { |
||||
super.onDestroy(); |
||||
if (mOpenCvCameraView != null) |
||||
mOpenCvCameraView.disableView(); |
||||
} |
||||
|
||||
public void onCameraViewStarted(int width, int height) { |
||||
} |
||||
|
||||
public void onCameraViewStopped() { |
||||
} |
||||
|
||||
public Mat onCameraFrame(CvCameraViewFrame inputFrame) { |
||||
return inputFrame.rgba(); |
||||
} |
||||
@endcode |
||||
-# Run your application on device or emulator. |
||||
 |
||||
|
||||
Lets discuss some most important steps. Every Android application with UI must implement Activity |
||||
and View. By the first steps we create blank activity and default view layout. The simplest |
||||
OpenCV-centric application must implement OpenCV initialization, create its own view to show preview |
||||
from 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 one |
||||
full screen component of class org.opencv.android.JavaCameraView. This class is implemented inside |
||||
OpenCV library. It is inherited from CameraBridgeViewBase, that extends SurfaceView and uses |
||||
standard Android camera API. |
||||
 |
||||
|
||||
After creating layout we need to implement Activity class. OpenCV initialization process has been |
||||
already discussed above. In this sample we use asynchronous initialization. Implementation of |
||||
CvCameraViewListener interface allows you to add processing steps after frame grabbing from camera |
||||
and before its rendering on screen. The most important function is onCameraFrame. It is callback |
||||
function and it is called on retrieving frame from camera. The callback input is object of |
||||
CvCameraViewFrame class that represents frame from camera. |
||||
8. Before using any OpenCV function you have to load the library first. If you application includes other OpenCV-dependent native libraries you should load them ***after*** OpenCV initialization. |
||||
Library is loaded at app start: |
||||
@snippet samples/android/tutorial-1-camerapreview/src/org/opencv/samples/tutorial1/Tutorial1Activity.java ocv_loader_init |
||||
Like this: |
||||
 |
||||
|
||||
@note Do not save or use CvCameraViewFrame object out of onCameraFrame callback. This object does |
||||
not have its own state and its behavior out of callback is unpredictable! |
||||
9. Choose a device to check the sample on and run the code by pressing `run` button |
||||
|
||||
It has rgba() and gray() |
||||
methods that allows to get frame as RGBA and one channel gray scale Mat respectively. It expects |
||||
that onCameraFrame function returns RGBA frame that will be drawn on the screen. |
||||
 |
||||
|
||||
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