error: invalid use of incomplete type ‘class QVideoWidget‘ QVideoWidget 报错_d:\sdlxfinalcode\qs_client\mainwindow.cpp:6: error

QVideoWidget 报错

报错原代码：
m_videoWidget = new QVideoWidget(this);

m_videoWidget = new QVideoWidget(this);

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报错：error: invalid use of incomplete type ‘class QVideoWidget’
m_videoWidget = new QVideoWidget(this);
^

解决：

使用new QVideoWidget(this)时，.h头文件声明最好不要使用include QWidget 虽然可以通过声明，但运行cpp代码会有上述报错。

#include <QWidget>

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建议使用:

#include <QtMultimediaWidgets>
或  #include <QVideoWidget>
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具体代码

QT实现视频播放器,pro 文件中有：QT += core gui multimedia multimediawidgets quickwidgets

头文件 mainwindow.h：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

#include <QVideoWidget>
#include <QMediaPlayer>
#include <QMediaPlaylist>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected:
    QMediaPlayer *m_player = nullptr;
    QMediaPlaylist *m_playlist = nullptr;
    QVideoWidget *m_videoWidget = nullptr;
};

#endif // MAINWINDOW_H



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QT实现视频播放器,c文件 mainwindow.cpp：

#include "mainwindow.h"
#include <QMediaMetaData>
#include <QtWidgets>


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    setMinimumSize(1200,1000);
    m_player = new QMediaPlayer(this);
    m_player->setAudioRole(QAudio::VideoRole);
   m_videoWidget = new QVideoWidget(this);
    m_player->setVideoOutput(m_videoWidget);
    m_videoWidget->move(100,100);
    m_videoWidget->resize(700,440);

m_videoWidget->setAspectRatioMode(Qt::IgnoreAspectRatio);
    QBoxLayout *displayLayout = new QHBoxLayout;
    displayLayout->addWidget(m_videoWidget, 2);

    QString spath("E:\\data\\code\\Qt_project_try\\03_QDialog\\video\\3min.wmv");
    QUrl pathurl = QUrl::fromUserInput(spath);
    m_player->setMedia(pathurl);
    m_player->play();

    QPushButton *btn =new QPushButton;
    QPushButton *openButton = new QPushButton(tr("muda"), this);
    btn->setParent(this);
    btn->setText("sb");
    btn->move(30,300);
    btn->resize(50,50);
    QBoxLayout *layout = new QVBoxLayout;
    layout->addLayout(displayLayout);
    layout->addWidget(openButton);
    layout->addWidget(btn);

    setLayout(layout);

    connect(btn,&QPushButton::clicked,[=](){

        m_player->setMedia(pathurl);
        m_player->play();
        qDebug() << "通过按键视频也能播放";
    });
}

MainWindow::~MainWindow()
{


}



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