C++ Qt 视频设置窗口代码注释

VideoSettings::VideoSettings(QMediaRecorder *mediaRecorder, QWidget *parent) :
    QDialog(parent),                                            '用父窗口构造对话框'
    ui(new Ui::VideoSettingsUi),                                '创建UI对象'
    mediaRecorder(mediaRecorder)                                '初始化媒体录制器'
{
    ui->setupUi(this);                                          '将UI对象设置为当前对话框的UI'
    //设置音频编解码器
    ui->audioCodecBox->addItem(tr("Default audio codec"), QVariant(QString()));
    foreach (const QString &codecName, mediaRecorder->supportedAudioCodecs()) {
        QString description = mediaRecorder->audioCodecDescription(codecName);
        ui->audioCodecBox->addItem(codecName+": "+description, QVariant(codecName));
    }
    //设置音频采样率
    foreach (int sampleRate, mediaRecorder->supportedAudioSampleRates()) {
        ui->audioSampleRateBox->addItem(QString::number(sampleRate), QVariant(sampleRate));
    }
    ui->audioQualitySlider->setRange(0, int(QMultimedia::VeryHighQuality));    '设置音频质量调节器的范围'
    //设置视频编解码器
    ui->videoCodecBox->addItem(tr("Default video codec"), QVariant(QString()));
    foreach (const QString &codecName, mediaRecorder->supportedVideoCodecs()) {
        QString description = mediaRecorder->videoCodecDescription(codecName);
        ui->videoCodecBox->addItem(codecName+": "+description, QVariant(codecName));
    }
    ui->videoQualitySlider->setRange(0, int(QMultimedia::VeryHighQuality));    '设置视频质量调节器的范围'
    //设置视频分辨率
    ui->videoResolutionBox->addItem(tr("Default"));
    QList<QSize> supportedResolutions = mediaRecorder->supportedResolutions();
    foreach (const QSize &resolution, supportedResolutions) {
        ui->videoResolutionBox->addItem(QString("%1x%2").arg(resolution.width()).arg(resolution.height()),
                                        QVariant(resolution));
    }
    //设置帧率
    ui->videoFramerateBox->addItem(tr("Default"));
    QList<qreal> supportedFrameRates = mediaRecorder->supportedFrameRates();
    qreal rate;
    foreach (rate, supportedFrameRates) {
        QString rateString = QString("%1").arg(rate, 0, 'f', 2);
        ui->videoFramerateBox->addItem(rateString, QVariant(rate));
    }
    //设置容器格式
    ui->containerFormatBox->addItem(tr("Default container"), QVariant(QString()));
    foreach (const QString &format, mediaRecorder->supportedContainers()) {
        ui->containerFormatBox->addItem(format+": "+mediaRecorder->containerDescription(format),
                                        QVariant(format));
    }
}

VideoSettings::~VideoSettings()                                    'VideoSettings类的析构函数'
{
    delete ui;                                                      '释放UI对象的内存'
}

void VideoSettings::changeEvent(QEvent *e)                          '处理窗口事件'
{
    QDialog::changeEvent(e);                                        '调用父类的同名函数处理事件'
    switch (e->type()) {
    case QEvent::LanguageChange:                                    '处理语言改变的事件'
        ui->retranslateUi(this);                                    '重新翻译UI'
        break;
    default:
        break;
    }
}

QAudioEncoderSettings VideoSettings::audioSettings() const           '获取音频编码器设置'
{
    QAudioEncoderSettings settings = mediaRecorder->audioSettings();
    settings.setCodec(boxValue(ui->audioCodecBox).toString());       '设置编解码器'
    settings.setQuality(QMultimedia::EncodingQuality(ui->audioQualitySlider->value()));    '设置音质'
    settings.setSampleRate(boxValue(ui->audioSampleRateBox).toInt());    '设置采样率'
    return settings;                                                '返回设置对象'
}

void VideoSettings::setAudioSettings(const QAudioEncoderSettings &audioSettings)    '设置音频编码器设置'
{
    selectComboBoxItem(ui->audioCodecBox, QVariant(audioSettings.codec()));                '选择编解码器'
    selectComboBoxItem(ui->audioSampleRateBox, QVariant(audioSettings.sampleRate()));      '选择采样率'
    ui->audioQualitySlider->setValue(audioSettings.quality());                             '设置音质'
}

QVideoEncoderSettings VideoSettings::videoSettings() const           '获取视频编码器设置'
{
    QVideoEncoderSettings settings = mediaRecorder->videoSettings();
    settings.setCodec(boxValue(ui->videoCodecBox).toString());       '设置编解码器'
    settings.setQuality(QMultimedia::EncodingQuality(ui->videoQualitySlider->value()));    '设置质量'
    settings.setResolution(boxValue(ui->videoResolutionBox).toSize());    '设置分辨率'
    settings.setFrameRate(boxValue(ui->videoFramerateBox).value<qreal>());   '设置帧率'
    return settings;                                                '返回设置对象'
}

void VideoSettings::setVideoSettings(const QVideoEncoderSettings &videoSettings)    '设置视频编码器设置'
{
    selectComboBoxItem(ui->videoCodecBox, QVariant(videoSettings.codec()));                   '选择编解码器'
    selectComboBoxItem(ui->videoResolutionBox, QVariant(videoSettings.resolution()));         '选择分辨率'
    ui->videoQualitySlider->setValue(videoSettings.quality());                                '设置质量'

    //special case for frame rate
    for (int i = 0; i < ui->videoFramerateBox->count(); ++i) {
        qreal itemRate = ui->videoFramerateBox->itemData(i).value<qreal>();
        if (qFuzzyCompare(itemRate, videoSettings.frameRate())) {
            ui->videoFramerateBox->setCurrentIndex(i);
            break;
        }
    }
}

QString VideoSettings::format() const                                '获取容器格式'
{
    return boxValue(ui->containerFormatBox).toString();              '返回下拉框的值'
}

void VideoSettings::setFormat(const QString &format)                 '设置容器格式'
{
    selectComboBoxItem(ui->containerFormatBox, QVariant(format));    '选择下拉框的值'
}

QVariant VideoSettings::boxValue(const QComboBox *box) const          '获取下拉框的值'
{
    int idx = box->currentIndex();
    if (idx == -1)
        return QVariant();

    return box->itemData(idx);
}

void VideoSettings::selectComboBoxItem(QComboBox *box, const QVariant &value)    '选择下拉框的值'
{
    for (int i = 0; i < box->count(); ++i) {
        if (box->itemData(i) == value) {
            box->setCurrentIndex(i);
            break;
        }
    }
}