111 获取视频数据

第三步，实现获取视频数据的功能。

111.1 实现功能

C:\Users\Minwei\Projects\Qt\Monitor\monitordialog.h：

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...
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#include <QNetworkAccessManager>
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#include <QNetworkReply>
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#include "face.h"
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...
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class MonitorDialog : public QDialog
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{
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    ...
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signals:
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    void recognize(QImage const& frame);
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    ...
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private slots:
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    ...
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    void on_m_streamReply_readyRead();
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    ...
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private:
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    ...
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    QNetworkAccessManager* m_access;
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    QNetworkReply* m_streamReply;
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    QByteArray m_streamData;
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    Face* m_face;
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    QThread* m_thread;
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    ...
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};
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...

C:\Users\Minwei\Projects\Qt\Monitor\monitordialog.cpp：

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...
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#include <QThread>
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...
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MonitorDialog::MonitorDialog(QWidget *parent)
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    ...
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    , m_access(new QNetworkAccessManager(this))
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    , m_streamReply(Q_NULLPTR)
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    , m_face(new Face)
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    , m_thread(new QThread(this))
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    ...
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{
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    ...
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    connect(this, SIGNAL(recognize(QImage const&)),
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        m_face, SLOT(recognize(QImage const&)));
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    m_face->moveToThread(m_thread);
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    m_thread->start();
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    ...
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}
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MonitorDialog::~MonitorDialog()
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{
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    ...
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    m_thread->terminate();
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    m_thread->wait();
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    ...
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}
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void MonitorDialog::on_m_btnStream_clicked()
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{
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    m_streamReply = m_access->get(QNetworkRequest(QUrl(
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        "http://192.168.0.111:8080?action=stream")));
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    connect(m_streamReply, SIGNAL(readyRead()),
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        this, SLOT(on_m_streamReply_readyRead()));
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}
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...
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void MonitorDialog::on_m_streamReply_readyRead()
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{
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    m_streamData += m_streamReply->readAll();
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    int begin = m_streamData.indexOf("\xff\xd8", 0);
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    if (begin == -1)
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    {
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        m_streamData.clear();
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        return;
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    }
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    int end = m_streamData.indexOf("\xff\xd9", begin + 2);
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    if (end == -1)
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        return;
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    QImage frame;
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    if (!frame.loadFromData(m_streamData.mid(begin, end + 2), "JPG"))
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    {
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        m_streamData.clear();
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        return;
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    }
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    m_streamData.clear();
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    ui->m_labStream->setPixmap(QPixmap::fromImage(frame));
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    emit recognize(frame);
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}
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...

111.2 测试验证

运行效果如图所示：