使用QT Creator一步一步编写自己的CMake工程

为什么要选择QT Creator？方便，方便，方便~~~~

陆陆续续使用QT已经4,5年了，如果一直还停留在傻瓜化的鼠标添加删除配置阶段，也太Low B了吧，还是赶紧学点高级货，因为Android Studio里面就是CMake，哦嚯嚯，有点儿兴趣了~~~~

学习CMake躲不开CMakeLists.txt的书写，来看看QT Creator向导给我们的内容：

project(TestFaceDetect)#工程名字cmake_minimum_required(VERSION 2.8)#CMAKE版本#源码路径aux_source_directory(. SRC_LIST)#编译成EXEadd_executable(${PROJECT_NAME} ${SRC_LIST})

什么？源文件都没有啊，怎么就编译成了我想要的exe/.out？看上面注释！！！

10:35:07: 为项目TestFaceDetect执行步骤 ...
10:35:07: 正在启动 "C:\Program Files (x86)\CMake\bin\cmake.exe" --build . --target clean
10:35:07: 进程"C:\Program Files (x86)\CMake\bin\cmake.exe"正常退出。
10:35:07: 正在启动 "C:\Program Files (x86)\CMake\bin\cmake.exe" --build . --target all

Scanning dependencies of target TestFaceDetect
[ 33%] Building CXX object CMakeFiles/TestFaceDetect.dir/main.cpp.obj
main.cpp
[100%] Linking CXX executable TestFaceDetect.exe
[100%] Built target TestFaceDetect
10:35:09: 进程"C:\Program Files (x86)\CMake\bin\cmake.exe"正常退出。
10:35:09: Elapsed time: 00:02.

好，知道了最基本的CMakeLists.txt内容，我们more一点，添加一个C++类Person：

#ifndef PERSON_H#define PERSON_H#ifdef _WIN32    #ifdef LIBPERSON_BUILD        #define LIBPERSON_API __declspec(dllexport)    #else        #define LIBPERSON_API __declspec(dllimport)    #endif#else    #define LIBPERSON_API#endif#include <string>using namespace std;//class /*LIBPERSON_API*/ Person{public:    Person(int age, string name);public:    int getAge();    string getName();protected:private:    int age;    string name;};#endif // PERSON_H

#include "person.h"Person::Person(int age, string name){    this->age = age;    this->name = name;}int Person::getAge(){    return age;}string Person::getName(){    return name;}

简单的一个类，在main.cpp中加入调用：

#include <iostream>using namespace std;#include "person.h"int main(int argc, char *argv[]){    cout << "Hello World!" << endl;    Person juan(18,"Juan");    cout<<"My name is "<<juan.getName()<<", "<<juan.getAge()<<" years old!"<<endl;    return 0;}

再次执行编译运行，又一次成功了，输出：

Hello World!
My name is Juan, 18 years old!

你说，这也太简单了，我要尝试把Person类生成静态库调用，“上帝说要有光就有了光”，于是乎，CMakeLists.txt变成了：

project(TestFaceDetect)#工程名字cmake_minimum_required(VERSION 2.8)#CMAKE版本#源码文件（手工指定）set(LIB_SRC person.cpp)set(APP_SRC main.cpp)#将person.cpp编译成静态库add_library(libperson ${LIB_SRC})#将main.cpp编译成exeadd_executable(${PROJECT_NAME} ${APP_SRC})#exe链接时的依赖库target_link_libraries(${PROJECT_NAME} libperson)

编译，也没有问题！！！

怎么？你还不满足？是的，我们都知道，动态库才是我的最爱！！！

好好好，满足你！！！

继续修改CMakeLists.txt 既然上面都已经使用了add_library，会不会右add_shared_library之类的？遗憾的是，没有！！！那就只能在add_library参数上下功夫了，想到这里就对了，我们要得到dll/so库，只需要一个SHARED参数就OK了。

因此，CMakeLists.txt内容变为：

project(TestFaceDetect)#工程名字cmake_minimum_required(VERSION 2.8)#CMAKE版本#源码路径#aux_source_directory(. SRC_LIST)#源码文件（手工指定）set(LIB_SRC person.cpp)set(APP_SRC main.cpp)#编译成EXE#add_executable(${PROJECT_NAME} ${SRC_LIST})#编译成静态库#add_library(${PROJECT_NAME} ${SRC_LIST})#将person.cpp编译成静态库#add_library(libperson ${LIB_SRC})#将person.cpp编译成动态库add_library(libperson SHARED ${LIB_SRC})#将main.cpp编译成exeadd_executable(${PROJECT_NAME} ${APP_SRC})#exe依赖库target_link_libraries(${PROJECT_NAME} libperson)

编译，咦？？？怎么不通过啊？？？

10:06:29: 为项目TestFaceDetect执行步骤 ...
10:06:29: 正在启动 "C:\Program Files (x86)\CMake\bin\cmake.exe" --build . --target all


Scanning dependencies of target libperson
[ 25%] Building CXX object CMakeFiles/libperson.dir/person.cpp.obj
person.cpp
[ 50%] Linking CXX shared library libperson.dll
[ 50%] Built target libperson
Scanning dependencies of target TestFaceDetect
[ 75%] Building CXX object CMakeFiles/TestFaceDetect.dir/main.cpp.obj
main.cpp
NMAKE : fatal error U1073: 不知道如何生成“libperson.lib”
Stop.
NMAKE : fatal error U1077: “"E:\Visual Studio 2015 Enterprise\VC\BIN\nmake.exe"”: 返回代码“0x2”
Stop.
NMAKE : fatal error U1077: “"E:\Visual Studio 2015 Enterprise\VC\BIN\nmake.exe"”: 返回代码“0x2”
Stop.
10:06:31: 进程"C:\Program Files (x86)\CMake\bin\cmake.exe"退出，退出代码 2 。
Error while building/deploying project TestFaceDetect (kit: Desktop Qt 5.4.1 VS12 x86)
When executing step "Make"
10:06:31: Elapsed time: 00:02.

不知道怎么生成lib库，发现生成的dll库确实是没有导出任何函数的，用过VS的都知道需要指明dll导出规则，即Person.h开头的那一段：

#ifdef _WIN32    #ifdef LIBPERSON_BUILD        #define LIBPERSON_API __declspec(dllexport)    #else        #define LIBPERSON_API __declspec(dllimport)    #endif#else    #define LIBPERSON_API#endif

把导出类声明成：

class LIBPERSON_API Person{public:    Person(int age, string name);public:    int getAge();    string getName();protected:private:    int age;    string name;};

CMakeLists.txt变成最终的：

project(TestFaceDetect)#工程名字cmake_minimum_required(VERSION 2.8)#CMAKE版本#源码路径#aux_source_directory(. SRC_LIST)#源码文件（手工指定）set(LIB_SRC person.cpp)set(APP_SRC main.cpp)#编译成EXE#add_executable(${PROJECT_NAME} ${SRC_LIST})#编译成静态库#add_library(${PROJECT_NAME} ${SRC_LIST})#将person.cpp编译成静态库add_library(libperson ${LIB_SRC})#将person.cpp编译成动态库

#宏定义方法，任选一种add_definitions("-DLIBPERSON_BUILD")#set(CMAKE_C_FLAGS "")#c程序的#set(CMAKE_CXX_FLAGS "-DLIBPERSON_BUILD")#c++程序的add_library(libperson SHARED ${LIB_SRC})#将main.cpp编译成exeadd_executable(${PROJECT_NAME} ${APP_SRC})#exe依赖库target_link_libraries(${PROJECT_NAME} libperson)

编译，通过！！！运行结果和静态库一致！！！

OK！！！

高级点，引入外部第三方库：

#引入第三方库include_directories(${PROJECT_SOURCE_DIR}/fcsdk)#首先要添加库，重要add_library(libface  SHARED  IMPORTED)#再设置库的位置#引入dll库，特有的set_target_properties(libface    PROPERTIES    IMPORTED_IMPLIB    ${PROJECT_SOURCE_DIR}/fcsdk/FaceCapture.lib)###set_property(TARGET#    libface#    PROPERTY#    IMPORTED_IMPLIB#    ${PROJECT_SOURCE_DIR}/fcsdk/FaceCapture.lib)#引入第三方so库，任选一#set_property(TARGET#    libface#    PROPERTY#    IMPORTED_LOCATION#    ${PROJECT_SOURCE_DIR}/fcsdk/FaceCapture.so)###set_target_properties(libface#    PROPERTIES#    IMPORTED_LOCATION#    ${PROJECT_SOURCE_DIR}/fcsdk/FaceCapture.so)#将main.cpp编译成exeadd_executable(${PROJECT_NAME} ${APP_SRC})#exe依赖库target_link_libraries(${PROJECT_NAME}    libperson    libface)#引入的第三方库别名

注意，上面的要引入dll需要设置

IMPORTED_IMPLIB (https://cmake.org/cmake/help/v3.0/prop_tgt/IMPORTED_IMPLIB.html)

其他，直接设置

IMPORTED_LOCATION (https://cmake.org/cmake/help/v3.0/prop_tgt/IMPORTED_LOCATION.html)

本文参考：

http://blog.csdn.net/dbzhang800/article/details/6314073

http://blog.csdn.net/fan_hai_ping/article/details/42524205