- Qt 5.5
- Qt Multimedia
- Spectrum Example
- mainwidget.cpp Example File
- Qt 5.5.1 Reference Documentation

# mainwidget.cpp Example File

spectrum/app/mainwidget.cpp

    /****************************************************************************
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    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
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    #include "engine.h"
    #include "levelmeter.h"
    #include "mainwidget.h"
    #include "waveform.h"
    #include "progressbar.h"
    #include "settingsdialog.h"
    #include "spectrograph.h"
    #include "tonegeneratordialog.h"
    #include "utils.h"

    #include <QLabel>
    #include <QPushButton>
    #include <QHBoxLayout>
    #include <QVBoxLayout>
    #include <QStyle>
    #include <QMenu>
    #include <QFileDialog>
    #include <QTimerEvent>
    #include <QMessageBox>

    const int NullTimerId = -1;

    MainWidget::MainWidget(QWidget *parent)
        :   QWidget(parent)
        ,   m_mode(NoMode)
        ,   m_engine(new Engine(this))
    #ifndef DISABLE_WAVEFORM
        ,   m_waveform(new Waveform(this))
    #endif
        ,   m_progressBar(new ProgressBar(this))
        ,   m_spectrograph(new Spectrograph(this))
        ,   m_levelMeter(new LevelMeter(this))
        ,   m_modeButton(new QPushButton(this))
        ,   m_recordButton(new QPushButton(this))
        ,   m_pauseButton(new QPushButton(this))
        ,   m_playButton(new QPushButton(this))
        ,   m_settingsButton(new QPushButton(this))
        ,   m_infoMessage(new QLabel(tr("Select a mode to begin"), this))
        ,   m_infoMessageTimerId(NullTimerId)
        ,   m_settingsDialog(new SettingsDialog(
                m_engine->availableAudioInputDevices(),
                m_engine->availableAudioOutputDevices(),
                this))
        ,   m_toneGeneratorDialog(new ToneGeneratorDialog(this))
        ,   m_modeMenu(new QMenu(this))
        ,   m_loadFileAction(0)
        ,   m_generateToneAction(0)
        ,   m_recordAction(0)
    {
        m_spectrograph->setParams(SpectrumNumBands, SpectrumLowFreq, SpectrumHighFreq);

        createUi();
        connectUi();
    }

    MainWidget::~MainWidget()
    {

    }

    //-----------------------------------------------------------------------------
    // Public slots
    //-----------------------------------------------------------------------------

    void MainWidget::stateChanged(QAudio::Mode mode, QAudio::State state)
    {
        Q_UNUSED(mode);

        updateButtonStates();

        if (QAudio::ActiveState != state && QAudio::SuspendedState != state) {
            m_levelMeter->reset();
            m_spectrograph->reset();
        }
    }

    void MainWidget::formatChanged(const QAudioFormat &format)
    {
       infoMessage(formatToString(format), NullMessageTimeout);

    #ifndef DISABLE_WAVEFORM
        if (QAudioFormat() != format) {
            m_waveform->initialize(format, WaveformTileLength,
                                   WaveformWindowDuration);
        }
    #endif
    }

    void MainWidget::spectrumChanged(qint64 position, qint64 length,
                                     const FrequencySpectrum &spectrum)
    {
        m_progressBar->windowChanged(position, length);
        m_spectrograph->spectrumChanged(spectrum);
    }

    void MainWidget::infoMessage(const QString &message, int timeoutMs)
    {
        m_infoMessage->setText(message);

        if (NullTimerId != m_infoMessageTimerId) {
            killTimer(m_infoMessageTimerId);
            m_infoMessageTimerId = NullTimerId;
        }

        if (NullMessageTimeout != timeoutMs)
            m_infoMessageTimerId = startTimer(timeoutMs);
    }

    void MainWidget::errorMessage(const QString &heading, const QString &detail)
    {
        QMessageBox::warning(this, heading, detail, QMessageBox::Close);
    }

    void MainWidget::timerEvent(QTimerEvent *event)
    {
        Q_ASSERT(event->timerId() == m_infoMessageTimerId);
        Q_UNUSED(event) // suppress warnings in release builds
        killTimer(m_infoMessageTimerId);
        m_infoMessageTimerId = NullTimerId;
        m_infoMessage->setText("");
    }

    void MainWidget::audioPositionChanged(qint64 position)
    {
    #ifndef DISABLE_WAVEFORM
        m_waveform->audioPositionChanged(position);
    #else
        Q_UNUSED(position)
    #endif
    }

    void MainWidget::bufferLengthChanged(qint64 length)
    {
        m_progressBar->bufferLengthChanged(length);
    }

    //-----------------------------------------------------------------------------
    // Private slots
    //-----------------------------------------------------------------------------

    void MainWidget::showFileDialog()
    {
        const QString dir;
        const QStringList fileNames = QFileDialog::getOpenFileNames(this, tr("Open WAV file"), dir, "*.wav");
        if (fileNames.count()) {
            reset();
            setMode(LoadFileMode);
            m_engine->loadFile(fileNames.front());
            updateButtonStates();
        } else {
            updateModeMenu();
        }
    }

    void MainWidget::showSettingsDialog()
    {
        m_settingsDialog->exec();
        if (m_settingsDialog->result() == QDialog::Accepted) {
            m_engine->setAudioInputDevice(m_settingsDialog->inputDevice());
            m_engine->setAudioOutputDevice(m_settingsDialog->outputDevice());
            m_engine->setWindowFunction(m_settingsDialog->windowFunction());
        }
    }

    void MainWidget::showToneGeneratorDialog()
    {
        m_toneGeneratorDialog->exec();
        if (m_toneGeneratorDialog->result() == QDialog::Accepted) {
            reset();
            setMode(GenerateToneMode);
            const qreal amplitude = m_toneGeneratorDialog->amplitude();
            if (m_toneGeneratorDialog->isFrequencySweepEnabled()) {
                m_engine->generateSweptTone(amplitude);
            } else {
                const qreal frequency = m_toneGeneratorDialog->frequency();
                const Tone tone(frequency, amplitude);
                m_engine->generateTone(tone);
                updateButtonStates();
            }
        } else {
            updateModeMenu();
        }
    }

    void MainWidget::initializeRecord()
    {
        reset();
        setMode(RecordMode);
        if (m_engine->initializeRecord())
            updateButtonStates();
    }

    //-----------------------------------------------------------------------------
    // Private functions
    //-----------------------------------------------------------------------------

    void MainWidget::createUi()
    {
        createMenus();

        setWindowTitle(tr("Spectrum Analyser"));

        QVBoxLayout *windowLayout = new QVBoxLayout(this);

        m_infoMessage->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
        m_infoMessage->setAlignment(Qt::AlignHCenter);
        windowLayout->addWidget(m_infoMessage);

    #ifdef SUPERIMPOSE_PROGRESS_ON_WAVEFORM
        QScopedPointer<QHBoxLayout> waveformLayout(new QHBoxLayout);
        waveformLayout->addWidget(m_progressBar);
        m_progressBar->setMinimumHeight(m_waveform->minimumHeight());
        waveformLayout->setMargin(0);
        m_waveform->setLayout(waveformLayout.data());
        waveformLayout.take();
        windowLayout->addWidget(m_waveform);
    #else
    #ifndef DISABLE_WAVEFORM
        windowLayout->addWidget(m_waveform);
    #endif // DISABLE_WAVEFORM
        windowLayout->addWidget(m_progressBar);
    #endif // SUPERIMPOSE_PROGRESS_ON_WAVEFORM

        // Spectrograph and level meter

        QScopedPointer<QHBoxLayout> analysisLayout(new QHBoxLayout);
        analysisLayout->addWidget(m_spectrograph);
        analysisLayout->addWidget(m_levelMeter);
        windowLayout->addLayout(analysisLayout.data());
        analysisLayout.take();

        // Button panel

        const QSize buttonSize(30, 30);

        m_modeButton->setText(tr("Mode"));

        m_recordIcon = QIcon(":/images/record.png");
        m_recordButton->setIcon(m_recordIcon);
        m_recordButton->setEnabled(false);
        m_recordButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        m_recordButton->setMinimumSize(buttonSize);

        m_pauseIcon = style()->standardIcon(QStyle::SP_MediaPause);
        m_pauseButton->setIcon(m_pauseIcon);
        m_pauseButton->setEnabled(false);
        m_pauseButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        m_pauseButton->setMinimumSize(buttonSize);

        m_playIcon = style()->standardIcon(QStyle::SP_MediaPlay);
        m_playButton->setIcon(m_playIcon);
        m_playButton->setEnabled(false);
        m_playButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        m_playButton->setMinimumSize(buttonSize);

        m_settingsIcon = QIcon(":/images/settings.png");
        m_settingsButton->setIcon(m_settingsIcon);
        m_settingsButton->setEnabled(true);
        m_settingsButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        m_settingsButton->setMinimumSize(buttonSize);

        QScopedPointer<QHBoxLayout> buttonPanelLayout(new QHBoxLayout);
        buttonPanelLayout->addStretch();
        buttonPanelLayout->addWidget(m_modeButton);
        buttonPanelLayout->addWidget(m_recordButton);
        buttonPanelLayout->addWidget(m_pauseButton);
        buttonPanelLayout->addWidget(m_playButton);
        buttonPanelLayout->addWidget(m_settingsButton);

        QWidget *buttonPanel = new QWidget(this);
        buttonPanel->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
        buttonPanel->setLayout(buttonPanelLayout.data());
        buttonPanelLayout.take(); // ownership transferred to buttonPanel

        QScopedPointer<QHBoxLayout> bottomPaneLayout(new QHBoxLayout);
        bottomPaneLayout->addWidget(buttonPanel);
        windowLayout->addLayout(bottomPaneLayout.data());
        bottomPaneLayout.take(); // ownership transferred to windowLayout

        // Apply layout

        setLayout(windowLayout);
    }

    void MainWidget::connectUi()
    {
        CHECKED_CONNECT(m_recordButton, SIGNAL(clicked()),
                m_engine, SLOT(startRecording()));

        CHECKED_CONNECT(m_pauseButton, SIGNAL(clicked()),
                m_engine, SLOT(suspend()));

        CHECKED_CONNECT(m_playButton, SIGNAL(clicked()),
                m_engine, SLOT(startPlayback()));

        CHECKED_CONNECT(m_settingsButton, SIGNAL(clicked()),
                this, SLOT(showSettingsDialog()));

        CHECKED_CONNECT(m_engine, SIGNAL(stateChanged(QAudio::Mode,QAudio::State)),
                this, SLOT(stateChanged(QAudio::Mode,QAudio::State)));

        CHECKED_CONNECT(m_engine, SIGNAL(formatChanged(const QAudioFormat &)),
                this, SLOT(formatChanged(const QAudioFormat &)));

        m_progressBar->bufferLengthChanged(m_engine->bufferLength());

        CHECKED_CONNECT(m_engine, SIGNAL(bufferLengthChanged(qint64)),
                this, SLOT(bufferLengthChanged(qint64)));

        CHECKED_CONNECT(m_engine, SIGNAL(dataLengthChanged(qint64)),
                this, SLOT(updateButtonStates()));

        CHECKED_CONNECT(m_engine, SIGNAL(recordPositionChanged(qint64)),
                m_progressBar, SLOT(recordPositionChanged(qint64)));

        CHECKED_CONNECT(m_engine, SIGNAL(playPositionChanged(qint64)),
                m_progressBar, SLOT(playPositionChanged(qint64)));

        CHECKED_CONNECT(m_engine, SIGNAL(recordPositionChanged(qint64)),
                this, SLOT(audioPositionChanged(qint64)));

        CHECKED_CONNECT(m_engine, SIGNAL(playPositionChanged(qint64)),
                this, SLOT(audioPositionChanged(qint64)));

        CHECKED_CONNECT(m_engine, SIGNAL(levelChanged(qreal, qreal, int)),
                m_levelMeter, SLOT(levelChanged(qreal, qreal, int)));

        CHECKED_CONNECT(m_engine, SIGNAL(spectrumChanged(qint64, qint64, const FrequencySpectrum &)),
                this, SLOT(spectrumChanged(qint64, qint64, const FrequencySpectrum &)));

        CHECKED_CONNECT(m_engine, SIGNAL(infoMessage(QString, int)),
                this, SLOT(infoMessage(QString, int)));

        CHECKED_CONNECT(m_engine, SIGNAL(errorMessage(QString, QString)),
                this, SLOT(errorMessage(QString, QString)));

        CHECKED_CONNECT(m_spectrograph, SIGNAL(infoMessage(QString, int)),
                this, SLOT(infoMessage(QString, int)));

    #ifndef DISABLE_WAVEFORM
        CHECKED_CONNECT(m_engine, SIGNAL(bufferChanged(qint64, qint64, const QByteArray &)),
                m_waveform, SLOT(bufferChanged(qint64, qint64, const QByteArray &)));
    #endif
    }

    void MainWidget::createMenus()
    {
        m_modeButton->setMenu(m_modeMenu);

        m_generateToneAction = m_modeMenu->addAction(tr("Play generated tone"));
        m_recordAction = m_modeMenu->addAction(tr("Record and play back"));
        m_loadFileAction = m_modeMenu->addAction(tr("Play file"));

        m_loadFileAction->setCheckable(true);
        m_generateToneAction->setCheckable(true);
        m_recordAction->setCheckable(true);

        connect(m_loadFileAction, SIGNAL(triggered(bool)), this, SLOT(showFileDialog()));
        connect(m_generateToneAction, SIGNAL(triggered(bool)), this, SLOT(showToneGeneratorDialog()));
        connect(m_recordAction, SIGNAL(triggered(bool)), this, SLOT(initializeRecord()));
    }

    void MainWidget::updateButtonStates()
    {
        const bool recordEnabled = ((QAudio::AudioOutput == m_engine->mode() ||
                                    (QAudio::ActiveState != m_engine->state() &&
                                     QAudio::IdleState != m_engine->state())) &&
                                    RecordMode == m_mode);
        m_recordButton->setEnabled(recordEnabled);

        const bool pauseEnabled = (QAudio::ActiveState == m_engine->state() ||
                                   QAudio::IdleState == m_engine->state());
        m_pauseButton->setEnabled(pauseEnabled);

        const bool playEnabled = (/*m_engine->dataLength() &&*/
                                  (QAudio::AudioOutput != m_engine->mode() ||
                                   (QAudio::ActiveState != m_engine->state() &&
                                    QAudio::IdleState != m_engine->state())));
        m_playButton->setEnabled(playEnabled);
    }

    void MainWidget::reset()
    {
    #ifndef DISABLE_WAVEFORM
        m_waveform->reset();
    #endif
        m_engine->reset();
        m_levelMeter->reset();
        m_spectrograph->reset();
        m_progressBar->reset();
    }

    void MainWidget::setMode(Mode mode)
    {
        m_mode = mode;
        updateModeMenu();
    }

    void MainWidget::updateModeMenu()
    {
        m_loadFileAction->setChecked(LoadFileMode == m_mode);
        m_generateToneAction->setChecked(GenerateToneMode == m_mode);
        m_recordAction->setChecked(RecordMode == m_mode);
    }