CMake、OpenCV 和单元测试

cmake_minimum_required (VERSION 3.8)

project (“CMakeTriangles”)set (CMAKE_TOOLCHAIN_FILE “D:/Tools/vcpkg/scripts/buildsystems/vcpkg.cmake”)

set (OpenCV_DIR

“D:/Tools/vcpkg/installed/x86-windows/share/opencv”)

find_package(OpenCV REQUIRED)

# Add source to this project’s executable.

add_executable (CMakeTriangles “CMakeTriangles.cpp”)

target_link_libraries (CMakeTriangles ${OpenCV_LIBS})

# TODO: Add tests and install targets if needed.

在系统中使用硬编码路径获取 CMakeLists.txt 文件，是绝对不可取的，我们稍后会给出建议的方案。现在让我们看看如何使用 OpenCV 制作 CMake  标志。以下是 CMakeTriangles.cpp 的代码：

#include <opencv2/core/core.hpp>

#include <opencv2/highgui/highgui.hpp>

#include <opencv2/imgproc.hpp>

#include <iostream>
using namespace cv;

using namespace std;
int main()

{

Mat image = Mat::zeros(400, 600, CV_8UC3);

image.setTo(Scalar(255, 255, 255));

fillConvexPoly(image, vector<Point>{ Point(200, 300), Point(400, 300), Point(300, 50) }, Scalar(128, 128, 128));

fillConvexPoly(image, vector<Point>{ Point(200, 300), Point(300, 175), Point(300, 50) }, Scalar(255, 0, 0));

fillConvexPoly(image, vector<Point>{ Point(400, 300), Point(305, 255), Point(305, 50) }, Scalar(0, 0, 255));

fillConvexPoly(image, vector<Point>{ Point(205, 300), Point(260, 240), Point(395, 300) }, Scalar(0, 255, 0));

imshow(“CMake Trianges!!”, image);

waitKey(0);

return 0;}

劳动成果惊人！? （课后作业留给大家：使用 OpenCV 图像处理功能制作一个 CMake 标志）

考虑到 CMakeLists.txt 文件和 CMakeTriangles.cpp 文件，我们可以很容易地运行编译：

cmake -S. -BBuild -A “Win32” cd Build && cmake –build .

现在让我们从 CMakeLists.txt 文件中删除硬编码的值

cmake_minimum_required (VERSION 3.8)

project (“CMakeTriangles”)
find_package(OpenCV REQUIRED)
# Add source to this project’s executable.

add_executable (CMakeTriangles “CMakeTriangles.cpp”)

target_link_libraries (CMakeTriangles ${OpenCV_LIBS})

# TODO: Add tests and install targets if needed.

有了这个新的 CMakeLists.txt 文件，项目编译也相应有了些改变：

cmake -S. -BBuild -A “Win32” -DOpenCV_DIR=<relativepath>/vcpkg/installed/x86-windows/share/opencv -DCMAKE_TOOLCHAIN_FILE=

<relativepath> /vcpkg/scripts/buildsystems

/vcpkg.cmakecd Build && cmake –build .

这里 <relativepath> 是相对于已安装的 vcpkg 文件夹的。使用这种方法，你将能在构建文件夹中找到运行程序所需的所有 DLL.

你现在可以双击这个可执行文件，显示如上图。由于 vcpkg、CMake 和OpenCV 都是跨平台的工具，Windows、Linux 和 Mac 都可以支持，因此我们能够按照上面的步骤编译并运行 CMake triangles 映像。

我们该如何添加测试？

作为架构师，我支持在开发周期中尽早添加单元测试。一种测试驱动的方法，是在编写代码之前就添加测试，这种方法可能适用于某些项目，但我反对软件开发中的任何“过度狂热”。让我们重构我们的单片代码，使其更易于单元测试（读者注意：建议在重构之前添加测试）。经过紧张地重构，我们的项目现在被拆分了 CMakeTrianglesLib.cpp、CMakeTriangles.h 和CMakeTriangles.cpp。其中 CMakeTriangles.h 是：

#pragma once
#include <opencv2/core/core.hpp>

#include <opencv2/highgui/highgui.hpp>

#include <opencv2/imgproc.hpp>

#include <iostream>
using namespace cv;

using namespace std;

#include <iostream>
Mat CreateImageWithBackground(int rows, int cols, int type, Scalar background);
void CreateConvexPolygonsOnImage(Mat image, vector<vector<Point>> points, vector<Scalar> backgrounds);
void DisplayWindowWithTitle(Mat image, string title);

CMakeTriangleslib.cpp 是:

#include “CMakeTriangles.h”
Mat CreateImageWithBackground(int rows, int cols, int type, Scalar background)

{

Mat image = Mat::zeros(rows, cols, type);

image.setTo(background);

return image;

}
void CreateConvexPolygonsOnImage(Mat image, vector<vector<Point>> points, vector<Scalar> backgrounds)

{

if (points.size() != backgrounds.size())

return; // No change in the image
for (auto i = 0UL; i < points.size(); ++i)

{

fillConvexPoly(image, points[i], backgrounds[i]);

}

}
void DisplayWindowWithTitle(Mat image, string title)

{      imshow(title, image);

}

CMakeTriangles.cpp 是：

#include “CMakeTriangles.h”
int main()

{

auto image = CreateImageWithBackground(400, 600, CV_8UC3, Scalar(255, 255, 255));
CreateConvexPolygonsOnImage(image, {

{ Point(200, 300), Point(400, 300), Point(300, 50) }, // Grey inner triangle           { Point(200, 300), Point(300, 175), Point(300, 50) }, // Blue left triangle

{ Point(400, 300), Point(305, 255), Point(305, 50) }, // Red right triangle

{ Point(205, 300), Point(260, 240), Point(395, 300)} }, // Green lower triangle

//Grey,                          Blue     Red                Green           { Scalar(128, 128, 128), Scalar(255, 0, 0), Scalar(0, 0, 255), Scalar(0, 255, 0) });

DisplayWindowWithTitle(image, “CMake Triangles Refactored!!”);

waitKey(0);

return 0;}

CMakeLists.txt 变成：

cmake_minimum_required (VERSION 3.8)

project (“CMakeTrianglesRefactored”)
find_package(OpenCV REQUIRED)
add_library (CMakeTrianglesLib “CMakeTrianglesLib.cpp” “CMakeTriangles.h”)

target_include_directories(CMakeTrianglesLib PRIVATE ${OpenCV_INCLUDE_DIRS})
add_executable (CMakeTriangles “CMakeTriangles.cpp”)
target_link_libraries (CMakeTriangles CMakeTrianglesLib ${OpenCV_LIBS})

编译现在生成一个额外的库文件，如下所示：