QT中cmakelist项目学习插件功能_qt cmakelist

最近在ubuntu中利用qt creator学习qt的插件功能，网上资料较少，记录一下。本文基础建立于在 Qt Creator 上创建 ROS 项目并新建/导入 ROS 包

项目构造如上图，要实现的功能是在rbs_plugins中生成插件文件(.so格式)，并在rbs_viz中载入该插件。

一、生成插件

在rbs_plugins中添加插件文件：plugininterface.h(接口文件)  myplugin.h(自己定义的插件类文件) my_plugin.cpp

plugininterface.h代码如下：

// rbs_plugins/plugininterface.h
#ifndef PLUGININTERFACE_H
#define PLUGININTERFACE_H
 
#include <QStringList>
#include <QtPlugin>
#include <QJsonObject>
 
class PluginInterface
{
public:
    virtual ~PluginInterface() {}
    virtual void doSomething() = 0;
};
 
#define PluginInterface_iid "id123"      //必须为接口设置id，id随意就行
Q_DECLARE_INTERFACE(PluginInterface, PluginInterface_iid)
 
#endif // PLUGININTERFACE_H

myplugin.h:

// rbs_plugins/myplugin.h
#ifndef MYPLUGIN_H
#define MYPLUGIN_H
 
#include <QObject>
#include "plugininterface.h"
 
class MyPlugin : public QObject, public PluginInterface
{
    Q_OBJECT
    Q_INTERFACES(PluginInterface)
    Q_PLUGIN_METADATA(IID "id123")  //id必须与刚刚接口的id一致
public:
    MyPlugin(QObject *parent = nullptr) : QObject(parent) {}
    void doSomething() override;  //函数必须实现，不能空着
 
};
 
#endif // MYPLUGIN_H

myplugin.cpp:

// rbs_plugins/myplugin.cpp
#include "../include/rbs_plugins/myplugin.h"
#include <QDebug>
 
void MyPlugin::doSomething()
{
    qDebug() << "MyPlugin is doing something!";
}
 
extern "C" PluginInterface* myplugin_instance() {
    return new MyPlugin;
}

最重要的是配置cmakelist文件，配置不对会显示meta data载入错误的提示：

cmake_minimum_required(VERSION 3.0.2)
project(rbs_plugins)
 
 
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
 
find_package(catkin REQUIRED COMPONENTS
  roscpp
)
find_package(Qt6 REQUIRED Core Widgets)
set(QT_LIBRARIES Qt6::Widgets)
#add
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
 
catkin_package()
 
file(GLOB QT_FORMS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} ui/*.ui)
file(GLOB QT_RESOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} resources/*.qrc)
file(GLOB_RECURSE QT_MOC RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}/../rbs_plugins/ FOLLOW_SYMLINKS include/rbs_viz/*.hpp *.h)
 
QT_ADD_RESOURCES(QT_RESOURCES_CPP ${QT_RESOURCES})
QT_WRAP_UI(QT_FORMS_HPP ${QT_FORMS})
QT_WRAP_CPP(QT_MOC_HPP ${QT_MOC})
 
file(GLOB_RECURSE QT_SOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}/../rbs_plugins/ FOLLOW_SYMLINKS src/*.cpp)
 
 
add_library(myplugin SHARED ${QT_SOURCES} ${QT_RESOURCES_CPP} ${QT_FORMS_HPP} ${QT_MOC_HPP})
target_link_libraries(myplugin PRIVATE Qt6::Core ${QT_LIBRARIES} ${catkin_LIBRARIES} ${VTK_LIBRARIES})
install(TARGETS myplugin LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}/rbs_plugins)

点击重新构建，可以在项目的该路径下看到插件的生成（catkin_rbs/devel/lib/libmyplugin.so）

二、加载插件

将刚刚的接口头文件plugininterface.h移到rbs_viz中的include文件夹中，并在需要载入的cpp文件里#include plugininterface.h，用以下代码进行试验：

QString pluginPath = "/xxx/xxx/catkin_rbs/devel/lib/libmyplugin.so"; //插件所在路径
    QPluginLoader pluginLoader(pluginPath);
    QObject *plugin = pluginLoader.instance();
 
    if (plugin) {
        myPlugin = qobject_cast<PluginInterface *>(plugin);
        if (myPlugin) {
            qDebug() << "BasePageApi插件加载成功！";
            myPlugin->doSomething();
            myPlugin->doSomething();
            return;
        } else {
            qDebug() << "无法转换为插件接口";
        }
    } else {
        qDebug() << "插件加载失败：" << pluginLoader.errorString();
    }
 
    if (QMessageBox::critical(nullptr, "警告", "BasePageApi插件加载失败！", QMessageBox::Ok) == QMessageBox::Ok) {
        qDebug() << "BasePageApi插件加载失败！！";
    }

运行结果：