qt 如何制作动态库插件

首先

首先第一点要确定我们的接口是固定的，也就是要确定

c 复制代码

#ifndef RTSPPLUGIN_H
#define RTSPPLUGIN_H
#include "rtspplugin_global.h"
typedef void (*func_callback)(uint8_t* data,
                              int len,
                              uint32_t ssrc,
                              uint32_t ts,
                              const char* ipfrom,
                              uint16_t fport);
extern "C"
{
RTSPPLUGIN_EXPORT const char* func_name();
RTSPPLUGIN_EXPORT int func_no();
//类型，接入类型？
RTSPPLUGIN_EXPORT int func_access();
RTSPPLUGIN_EXPORT void* create(const char* ip, uint16_t port, func_callback callback);
RTSPPLUGIN_EXPORT int  start(void *server);
RTSPPLUGIN_EXPORT void stop(void* server);
}
#endif // RTSPPLUGIN_H

使用extern "C" 来保持接口能被正确的找到函数名

rtspplugin_global.h 文件定义宏

c 复制代码

#include <QtCore/qglobal.h>

#if defined(RTSPPLUGIN_LIBRARY)
#  define RTSPPLUGIN_EXPORT Q_DECL_EXPORT
#else
#  define RTSPPLUGIN_EXPORT Q_DECL_IMPORT
#endif

文件实现如下,需要定义一个结构体，将需要保存的数据结构都放在里面

c 复制代码

#include "rtspplugin.h"
#include <string>
extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/pixdesc.h>
#include <libavutil/hwcontext.h>
#include <libavutil/opt.h>
#include <libavutil/avassert.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>

}

typedef struct rtsplugin
{
    struct SwsContext* img_convert_ctx = NULL;
    AVFormatContext* input_ctx = NULL;
    int video_stream, ret;
    AVStream* video = NULL;
    //AVCodecContext* decoder_ctx = NULL;
    //AVCodec* decoder = NULL;
    AVPacket packet;
    enum AVHWDeviceType type;
    std::string url;
}rtsplugin;
const char* func_name()
{
    return "rtspclient";
}
int func_no()
{
    return 10;
}
void* create(const char* ip, uint16_t port, func_callback callback)
{
    rtsplugin* pi = new rtsplugin();
    return pi;
}
int  start(void *client)
{
    return 0;
}
void stop(void* client)
{
}

qt的pro文件如下

c 复制代码

QT -= gui
#QT += core gui widgets
TEMPLATE = lib
DEFINES += RTSPPLUGIN_LIBRARY

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
INCLUDEPATH += ../VT_qt/win64/
DESTDIR = ../
# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    rtspplugin.cpp

HEADERS += \
    rtspplugin_global.h \
    rtspplugin.h


win32{
    DEFINES += WIN32_LEAN_AND_MEAN
    LIBS += -L../VT_qt/win64/
    DESTDIR = ../VT_qt/bin64/


    ## FFmpeg
    LIBS += -lavformat      \
            -lavdevice      \
            -lavcodec       \
            -lswresample    \
            -lswscale       \
            -lavutil        \
            -lopencv_world450d



}

# Default rules for deployment.
unix {
    target.path = /usr/lib
}
!isEmpty(target.path): INSTALLS += target

编译完成，正确生成动态库

调用

生成exe文件

pro文件如下

c 复制代码

TEMPLATE = app
CONFIG += console c++11
CONFIG -= app_bundle



win32{
    DEFINES += WIN32_LEAN_AND_MEAN
    DESTDIR = ../VT_qt/bin64/
}

#CONFIG -= qt
QT       += core

SOURCES += \
        main.cpp

c 复制代码

#include <QCoreApplication>
#include <QLibrary>
#include <QDebug>

using namespace std;
typedef void(*func_callback)(uint8_t* data,
    int len,
    uint32_t ssrc,
    uint32_t ts,
    const char* ipfrom,
    uint16_t fport);

typedef  const char* (*func_name)();
typedef int (*func_no)();
typedef int (*func_access)();
//接入型插件，必须create， start stop
typedef void* (*create)(const char* ip, uint16_t port, func_callback callback);
typedef int (*start)(void *server);
typedef void (*stop)(void* server);
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QString library_path = QCoreApplication::applicationDirPath() + "/rtspplugin.dll";
    QLibrary* L = new QLibrary(library_path);

    if( nullptr == L) return -1;

    if(! L->load()){
        qDebug() << "[error:]" << L->errorString();
        delete L;
        L = NULL;
    }

    func_name funcname = (func_name)L->resolve("func_name");
    const char* name = funcname();
    qDebug()<<name;
    func_no   funcno = (func_no)L->resolve("func_no");
    int no = funcno();
    qDebug()<<no;

    L->unload();

    return a.exec();

}

只是个示例，不要忘了释放，释放要在动态库里面释放，

主要的申请和释放改一下

c 复制代码

void* create(const char* url, func_callback callback)
{
    PluginContext* con = (PluginContext*) malloc(sizeof(PluginContext));
    con->url = url;
    return con;
}
void Release(void* context)
{
    free(context);
}

ok, 成功执行，没有问题