QT for Android+OpenCV的配置详细图解

参考：https://blog.csdn.net/u012230798/article/details/86620400
参考：https://blog.csdn.net/bootleader/article/details/80875602

环境：Qt5.5.1+MinGW+Windows8.1
目的：想用Ｑt实现拍照后将图片转换成灰度图，所以进行相关的配置

第一步：准备工作

QT下载：http://download.qt.io/archive/qt/ QT下关于android的配置这里不再赘述，网上超多资料。
opencv下载：https://opencv.org/releases/
下载的最新的一版opencv-4.1.0 Android版，下载后是.zip格式，解压即安装，路径自己选择，注意不要包含中文与空格。

目录打开如下
都准备好之后就可以开始配置了。

第二步：在QT项目中添加库

在项目下的.pro中添加如下代码，把静态链接添加到项目中。

unix {
ANDROID_OPENCV = F:/OpenCV-android-sdk/sdk/native

INCLUDEPATH += $$ANDROID_OPENCV/jni/include/opencv2 \
               $$ANDROID_OPENCV/jni/include

LIBS += $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_calib3d.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_core.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_dnn.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_features2d.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_flann.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_highgui.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_imgcodecs.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_imgproc.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_ml.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_objdetect.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_photo.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_stitching.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_video.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_videoio.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libcpufeatures.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libIlmImf.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibjasper.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibjpeg-turbo.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibpng.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibprotobuf.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibtiff.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibwebp.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libquirc.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libtbb.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libtegra_hal.a \
        $$ANDROID_OPENCV/libs/armeabi-v7a/libopencv_java4.so
}

在电脑系统环境变量中添加对应的路径。（会加的可以略过）
右键我的电脑→属性→高级系统设置
→环境变量→系统变量下的Path→编辑

在变量中添加如下路径，以英文分号间隔，路径要与你电脑上的路径 对应，不要单纯的复制粘贴。

F:\OpenCV-android-sdk\sdk\native\libs\armeabi-v7a;F:\OpenCV-android-sdk\sdk\native\jni;F:\OpenCV-android-sdk\sdk\native\jni\include\opencv2;F:\OpenCV-android-sdk\sdk\native\jni\abi-armeabi-v7a;F:\OpenCV-android-sdk\sdk\native\3rdparty\libs\armeabi-v7a;F:\OpenCV-android-sdk\sdk\native\staticlibs\armeabi-v7a;F:\OpenCV-android-sdk\sdk\native\libs\armeabi-v7a

第三步：添加动态链接库进APK

最后一个库libopencv_java4.so是动态库，要加入到安卓的apk里。
对应下面的图，项目→构建→Build Android APK下的详细→Additional Libraries右侧的Add…选择libopencv_java4.so的路径

加入路径后，项目会自动构建一遍，在.pro 中会出现如下代码

contains(ANDROID_TARGET_ARCH,armeabi-v7a) {
    ANDROID_EXTRA_LIBS = \
        $$PWD/F:/OpenCV-android-sdk/sdk/native/libs/armeabi-v7a/libopencv_java4.so

此时构建是会报错的，原因是找不到该文件，问题就在PWD上面

$$PWD代表项目所在根目录

这是自动生成的，具体原因我不知道，有了解的麻烦不吝赐教。
然后我将该代码段修改成下面的样子就可以找到文件了，项目就可以构建成功了，

注意$$后面有个空格

contains(ANDROID_TARGET_ARCH,armeabi-v7a) {
    ANDROID_EXTRA_LIBS = \
        $$ F:/OpenCV-android-sdk/sdk/native/libs/armeabi-v7a/libopencv_java4.so