采用libvlc做一个视频播放器(续)-注册事件回调

一、功能介绍

在前面文章里已经介绍过，如何调用libvlc提供的API快速开发一款简单的视频播放器(https://juejin.cn/post/7023552394798006279) 这篇文章继续完善视频播放器的基本功能。 增加播放进度条、播放时间进度显示、实时获取播放过程中的状态等等。

libvlc提供了事件回调，注册相应的事件之后，在回调里可以得到各种事件,比如: 开始播放状态、停止播放、暂停播放、播放进度等等。

事件注册示例代码:

//创建事件管理器
libvlc_event_manager_t * eventManager = libvlc_media_player_event_manager(vlc_mediaPlayer);

//订阅事件
attachEvents(eventManager);

//订阅事件
void Widget::attachEvents(libvlc_event_manager_t *eventManager)
{
    // 事件列表
    QList<libvlc_event_e> events = {
        libvlc_MediaPlayerPositionChanged,
        libvlc_MediaPlayerTimeChanged,
        libvlc_MediaPlayerLengthChanged,
        libvlc_MediaPlayerPaused,
        libvlc_MediaPlayerPlaying,
        libvlc_MediaPlayerStopped,
        libvlc_MediaPlayerEndReached,
        libvlc_MediaParsedChanged
    };

    // 订阅事件
    for (const libvlc_event_e &e : events)
    {
        libvlc_event_attach(eventManager, e, vlcEvents, nullptr);
    }
}


void Widget::vlcEvents(const libvlc_event_t *event, void *param)
{
    qint64 pos=0;
    switch (event->type){
    case libvlc_MediaPlayerTimeChanged:
         //获取当前媒体播放的位置
         pos=event->u.media_player_time_changed.new_time;
         pThis->ui->label_t1->setText(QTime(0, 0, 0,0).addMSecs(int(pos)).toString(QString::fromLatin1("HH:mm:ss:zzz")));
         pThis->ui->horizontalSlider_pos->setValue(pos);
         break;
    case libvlc_MediaPlayerPositionChanged:
         //qDebug() << "Position: " << event->u.media_player_position_changed.new_position << endl;
         break;
    case libvlc_MediaPlayerLengthChanged:
         qDebug() << "Length:"<< event->u.media_player_length_changed.new_length;
         break;
    case libvlc_MediaPlayerEndReached:
         qDebug() << "VLC播放完毕.";
         break;
    case libvlc_MediaPlayerStopped:
         qDebug() << "VLC停止播放";
         break;
    case libvlc_MediaPlayerPlaying:
         qDebug() << "VLC开始播放";
         break;
    case libvlc_MediaPlayerPaused:
         qDebug() << "VLC暂停播放";
         break;
    case libvlc_MediaParsedChanged: //获取媒体信息
          qDebug() << "获取媒体信息";
         break;
    }
}

最终运行效果:

二、完整实现代码

2.1 widget.cpp

#include "widget.h"
#include "ui_widget.h"

Widget* Widget::pThis = nullptr;

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    pThis=this;

    ui->setupUi(this);

    //创建并初始化libvlc实例
    vlc_base=libvlc_new(0,nullptr);

    this->setWindowTitle("libvlc设计的视频播放器");
}


Widget::~Widget()
{
    delete ui;
}

//选择视频
void Widget::on_pushButton_open_clicked()
{
    /*选择文件*/
    QString filename=QFileDialog::getOpenFileName(this,"选择打开的文件","D:/",tr("*.*"));

    std::replace(filename.begin(), filename.end(), QChar('/'), QChar('\\'));
    qDebug()<<"播放的媒体:"<<filename;

    /*为特定文件路径创建媒体*/
    if(vlc_media)libvlc_media_release(vlc_media);
    vlc_media=libvlc_media_new_path(vlc_base,filename.toUtf8().data());
    if(vlc_media==nullptr)
    {
        qDebug()<<"libvlc_media_new_path 执行错误.";
        return;
    }

    /*根据给定的媒体对象创建一个播放器对象*/
    if(vlc_mediaPlayer)libvlc_media_player_release(vlc_mediaPlayer);
    vlc_mediaPlayer=libvlc_media_player_new_from_media(vlc_media);

    //创建事件管理器
    eventManager = libvlc_media_player_event_manager(vlc_mediaPlayer);

    //订阅事件
    attachEvents(eventManager);

    /*设置给予媒体播放器媒体输出的win32/win64窗口句柄*/
    libvlc_media_player_set_hwnd(vlc_mediaPlayer, (void *)ui->widget->winId());

    /*播放媒体文件*/
    if(vlc_mediaPlayer)libvlc_media_player_play(vlc_mediaPlayer);

    //等待VLC解析文件.否则下面的时间获取不成功
    QThread::msleep(500);

    //获取媒体文件总长度 ms
    libvlc_time_t length = libvlc_media_player_get_length(vlc_mediaPlayer);
    qDebug()<<"媒体文件总长度:"<<length;
    ui->label_t2->setText(QTime(0, 0, 0,0).addMSecs(int(length)).toString(QString::fromLatin1("HH:mm:ss:zzz")));
    ui->horizontalSlider_pos->setMaximum(length);
    ui->horizontalSlider_pos->setMinimum(0);
}


//暂停与继续
void Widget::on_pushButton_pause_clicked()
{
    if(vlc_mediaPlayer)libvlc_media_player_pause(vlc_mediaPlayer);
}

//停止
void Widget::on_pushButton_stop_clicked()
{
    if(vlc_mediaPlayer)libvlc_media_player_stop(vlc_mediaPlayer);
}


//订阅事件
void Widget::attachEvents(libvlc_event_manager_t *eventManager)
{
    // 事件列表
    QList<libvlc_event_e> events = {
        libvlc_MediaPlayerPositionChanged,
        libvlc_MediaPlayerTimeChanged,
        libvlc_MediaPlayerLengthChanged,
        libvlc_MediaPlayerPaused,
        libvlc_MediaPlayerPlaying,
        libvlc_MediaPlayerStopped,
        libvlc_MediaPlayerEndReached,
        libvlc_MediaParsedChanged
    };

    // 订阅事件
    for (const libvlc_event_e &e : events)
    {
        libvlc_event_attach(eventManager, e, vlcEvents, nullptr);
    }
}


void Widget::vlcEvents(const libvlc_event_t *event, void *param)
{
    qint64 pos=0;
    switch (event->type){
    case libvlc_MediaPlayerTimeChanged:
         //获取当前媒体播放的位置
         pos=event->u.media_player_time_changed.new_time;
         pThis->ui->label_t1->setText(QTime(0, 0, 0,0).addMSecs(int(pos)).toString(QString::fromLatin1("HH:mm:ss:zzz")));
         pThis->ui->horizontalSlider_pos->setValue(pos);
         break;
    case libvlc_MediaPlayerPositionChanged:
         //qDebug() << "Position: " << event->u.media_player_position_changed.new_position << endl;
         break;
    case libvlc_MediaPlayerLengthChanged:
         qDebug() << "Length:"<< event->u.media_player_length_changed.new_length;
         break;
    case libvlc_MediaPlayerEndReached:
         qDebug() << "VLC播放完毕.";
         break;
    case libvlc_MediaPlayerStopped:
         qDebug() << "VLC停止播放";
         break;
    case libvlc_MediaPlayerPlaying:
         qDebug() << "VLC开始播放";
         break;
    case libvlc_MediaPlayerPaused:
         qDebug() << "VLC暂停播放";
         break;
    case libvlc_MediaParsedChanged: //获取媒体信息
          qDebug() << "获取媒体信息";
         break;
    }
}

2.2 widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <vlc/vlc.h>
#include <QDebug>
#include <QFileDialog>
#include <QMoveEvent>
#include <QTime>
#include <QThread>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
    void attachEvents(libvlc_event_manager_t *eventManager);
private slots:
    void on_pushButton_open_clicked();

    void on_pushButton_pause_clicked();

    void on_pushButton_stop_clicked();
protected:
    static void vlcEvents(const libvlc_event_t *ev, void *param);
private:
    Ui::Widget *ui;
    static Widget *pThis;
    libvlc_instance_t *vlc_base=nullptr;
    libvlc_media_t *vlc_media=nullptr;
    libvlc_media_player_t *vlc_mediaPlayer=nullptr;
    libvlc_event_manager_t *eventManager;
};
#endif // WIDGET_H