# AndroidCamera2ShowOpenCVMat **Repository Path**: KouMeanSun/android-camera2-show-open-cvmat ## Basic Information - **Project Name**: AndroidCamera2ShowOpenCVMat - **Description**: An android camera2 demo project, show how to show c++ opencv draw result mat on application surface synchronized。 一个同步展示android c++ 利用opencv 绘制完图像返回给camera2 展示的 demo 工程。 - **Primary Language**: Unknown - **License**: Not specified - **Default Branch**: master - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2021-07-15 - **Last Updated**: 2021-07-16 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README # AndroidCamera2ShowOpenCVMat #### 介绍 An android camera2 demo project, show how to show c++ opencv draw result mat on application surface synchronized。 一个同步展示android c++ 利用opencv 绘制完图像返回给camera2 展示的 demo 工程。 ##1.CMakeLists.txt 代码： ```# For more information about using CMake with Android Studio, read the # documentation: https://d.android.com/studio/projects/add-native-code.html # Sets the minimum version of CMake required to build the native library. cmake_minimum_required(VERSION 3.4.1) # Creates and names a library, sets it as either STATIC # or SHARED, and provides the relative paths to its source code. # You can define multiple libraries, and CMake builds them for you. # Gradle automatically packages shared libraries with your APK. add_library( # Sets the name of the library. native-lib # Sets the library as a shared library. SHARED # Provides a relative path to your source file(s). native-lib.cpp) # Searches for a specified prebuilt library and stores the path as a # variable. Because CMake includes system libraries in the search path by # default, you only need to specify the name of the public NDK library # you want to add. CMake verifies that the library exists before # completing its build. #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) # Specifies libraries CMake should link to your target library. You # can link multiple libraries, such as libraries you define in this # build script, prebuilt third-party libraries, or system libraries. # 自定义的头文件路径设置 include_directories(${CMAKE_SOURCE_DIR}/include) set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -L${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}") target_link_libraries( native-lib log opencv_java3 android ) ``` ##2.jniLibs里要放入opencv 的 so库 ##3.java层主要代码： ``` //RGBA output Image.Plane Y_plane = image.getPlanes()[0]; //Y int Y_rowStride = Y_plane.getRowStride(); Image.Plane U_plane = image.getPlanes()[1]; //U int UV_rowStride = U_plane.getRowStride(); Image.Plane V_plane = image.getPlanes()[2]; //V // pass the current device's screen orientation to the c++ part int currentRotation = getWindowManager().getDefaultDisplay().getRotation(); boolean isScreenRotated = currentRotation != Surface.ROTATION_90; long imageTimestamp = image.getTimestamp() + cameraTimestampsShiftWrtSensors; int imageWidth = image.getWidth(); int imageHeight = image.getHeight(); Log.i(TAG, "image width: " + imageWidth + " height: " + imageHeight); // pass image to c++ part onImageAvailableNative(imageWidth, imageHeight, Y_rowStride, Y_plane.getBuffer(), UV_rowStride, U_plane.getBuffer(), V_plane.getBuffer(), mSurface, imageTimestamp, isScreenRotated, virtualCamDistance); c++层主要代码： uint8_t *srcYPtr = reinterpret_cast(env->GetDirectBufferAddress(bufferY)); uint8_t *srcUPtr = reinterpret_cast(env->GetDirectBufferAddress(bufferU)); uint8_t *srcVPtr = reinterpret_cast(env->GetDirectBufferAddress(bufferV)); if(srcYPtr == NULL || srcVPtr == NULL || srcUPtr == NULL) { LOGE("blit NULL pointer ERROR"); return false; } cv::Mat mYuv(height * 3 / 2, width, CV_8UC1); unsigned char *data = mYuv.data; memcpy(data,srcYPtr,height * rowStrideY); data += height * rowStrideY; memcpy(data,srcVPtr,height / 2 * rowStrideUV); ANativeWindow *win = ANativeWindow_fromSurface(env, surface); ANativeWindow_acquire(win); ANativeWindow_Buffer buf; int rotatedWidth = height; // 360 int rotatedHeight = width; // 640 ANativeWindow_setBuffersGeometry(win, width, height, 0); if (int32_t err = ANativeWindow_lock(win, &buf, NULL)) { LOGE("ANativeWindow_lock failed with error code %d\n", err); ANativeWindow_release(win); return false; } // LOGI("buf.stride: %d", buf.stride); uint8_t *dstPtr = reinterpret_cast(buf.bits); Mat dstRgba(height, buf.stride, CV_8UC4, dstPtr); // TextureView buffer, use stride as width Mat srcRgba(height, width, CV_8UC4); Mat rotatedRgba(rotatedHeight, rotatedWidth, CV_8UC4); // convert YUV to RGBA cv::cvtColor(mYuv, srcRgba, CV_YUV2RGBA_NV21); // Rotate 90 degree ,顺时针90度 cv::rotate(srcRgba, rotatedRgba, cv::ROTATE_90_CLOCKWISE); //顺时针270度 cv::rotate(rotatedRgba, srcRgba, cv::ROTATE_90_COUNTERCLOCKWISE); char charbuf[22]; sprintf(charbuf, "gmy"); cv::putText(srcRgba, charbuf, cv::Point(10, 30), cv::FONT_HERSHEY_PLAIN, 1.5, cv::Scalar(255, 0, 255), 2, 8); // copy to TextureView surface uchar *dbuf = dstRgba.data; uchar *sbuf = srcRgba.data; for (int i = 0; i < srcRgba.rows; i++) { dbuf = dstRgba.data + i * buf.stride * 4; memcpy(dbuf, sbuf, srcRgba.cols * 4); //TODO: threw a SIGSEGV SEGV_ACCERR once sbuf += srcRgba.cols * 4; } ANativeWindow_unlockAndPost(win); ANativeWindow_release(win); bool finishFlag = true; return finishFlag; ``` ##4:主要原理就是通过JNI传递一个Surface给c++，然后创建ANativeWindow，通过ANativeWindow锁住画布，然后opencv 绘制画面，绘制完毕之后 ANativeWindow再 解锁，post出去，把画面数据发送给Surface对应的TextureView。这样就能够实现同步显示c++绘制的图像了。 ##5.Demo链接：[码云链接](https://gitee.com/KouMeanSun/android-camera2-show-open-cvmat/new/master?readme=true) ，[gitHub链接](https://github.com/KouMeanSun/AndroidCamera2ShowOpenCVMat)