Android: Fix for crashes issue of the Spectrum example

The Spectrum app does not crash anymore after the fix.

Fixes: QTBUG-96953
Change-Id: Ia555bdd21c3bc1ab0ada585c49441d6f8f548f8d
Reviewed-by: Samuel Mira <samuel.mira@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit b9d508b7bb15d067c50ed6fbee8cae2cd6ee3cd0)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 51 insertions, 5 deletions

diff --git a/examples/multimedia/spectrum/engine.cpp b/examples/multimedia/spectrum/engine.cpp
index 2a6a50168..bbbe08a67 100644
--- a/examples/multimedia/spectrum/engine.cpp
+++ b/examples/multimedia/spectrum/engine.cpp
@@ -252,6 +252,9 @@ void Engine::startRecording()
 
 void Engine::startPlayback()
 {
+    if (!m_audioOutput)
+        initialize();
+
     if (m_audioOutput) {
         if (QAudioDevice::Output == m_mode &&
             QAudio::SuspendedState == m_state) {
@@ -409,6 +412,7 @@ void Engine::audioStateChanged(QAudio::State state)
                 break;
             }
             if (QAudio::NoError != error) {
+                emitError(error);
                 reset();
                 return;
             }
@@ -466,8 +470,8 @@ void Engine::reset()
     stopRecording();
     stopPlayback();
     setState(QAudioDevice::Input, QAudio::StoppedState);
-    setFormat(QAudioFormat());
     m_generateTone = false;
+    setFormat(QAudioFormat());
     delete m_file;
     m_file = nullptr;
     delete m_analysisFile;
@@ -586,6 +590,7 @@ void Engine::stopRecording()
         m_audioInput->disconnect();
     }
     m_audioInputIODevice = nullptr;
+    m_notifyTimer->stop();
 
 #ifdef DUMP_AUDIO
     dumpData();
@@ -600,6 +605,7 @@ void Engine::stopPlayback()
         m_audioOutput->disconnect();
         setPlayPosition(0);
     }
+    m_notifyTimer->stop();
 }
 
 void Engine::setState(QAudio::State state)
@@ -707,6 +713,32 @@ void Engine::setLevel(qreal rmsLevel, qreal peakLevel, int numSamples)
     emit levelChanged(m_rmsLevel, m_peakLevel, numSamples);
 }
 
+void Engine::emitError(QAudio::Error error)
+{
+    QString errorString;
+    switch (error) {
+    case QAudio::NoError:
+        errorString = tr("NoError");
+        break;
+    case QAudio::OpenError:
+        errorString = tr("OpenError: An error occurred opening the audio device.");
+        break;
+    case QAudio::IOError:
+        errorString = tr("IOError: An error occurred during read/write of audio device.");
+        break;
+    case QAudio::UnderrunError:
+        errorString = tr("UnderrunError: Audio data is not being fed"
+                        "to the audio device at a fast enough rate.");
+        break;
+    case QAudio::FatalError:
+        errorString = tr("FatalError: A non-recoverable error has occurred,"
+                        "the audio device is not usable at this time.");
+        break;
+    }
+
+    emit errorMessage(tr("Audio Device"), errorString);
+}
+
 #ifdef DUMP_DATA
 void Engine::createOutputDir()
 {
diff --git a/examples/multimedia/spectrum/engine.h b/examples/multimedia/spectrum/engine.h
index 449884251..7f7028bab 100644
--- a/examples/multimedia/spectrum/engine.h
+++ b/examples/multimedia/spectrum/engine.h
@@ -112,7 +112,6 @@ public:
      * Stop any ongoing recording or playback, and reset to ground state.
      */
     void reset();
-
     /**
      * Load data from WAV file
      */
@@ -266,6 +265,7 @@ private:
     void calculateLevel(qint64 position, qint64 length);
     void calculateSpectrum(qint64 position);
     void setLevel(qreal rmsLevel, qreal peakLevel, int numSamples);
+    void emitError(QAudio::Error error);
 
 #ifdef DUMP_DATA
     void createOutputDir();
diff --git a/examples/multimedia/spectrum/mainwidget.cpp b/examples/multimedia/spectrum/mainwidget.cpp
index 2dbfda9ab..b72b01bac 100644
--- a/examples/multimedia/spectrum/mainwidget.cpp
+++ b/examples/multimedia/spectrum/mainwidget.cpp
@@ -96,6 +96,7 @@ MainWidget::MainWidget(QWidget *parent)
     ,   m_loadFileAction(nullptr)
     ,   m_generateToneAction(nullptr)
     ,   m_recordAction(nullptr)
+    ,   m_errorOccurred(false)
 {
     m_spectrograph->setParams(SpectrumNumBands, SpectrumLowFreq, SpectrumHighFreq);
 
@@ -158,6 +159,8 @@ void MainWidget::infoMessage(const QString &message, int timeoutMs)
 void MainWidget::errorMessage(const QString &heading, const QString &detail)
 {
     QMessageBox::warning(this, heading, detail, QMessageBox::Close);
+    m_errorOccurred = true;
+    reset();
 }
 
 void MainWidget::timerEvent(QTimerEvent *event)
@@ -190,6 +193,7 @@ void MainWidget::bufferLengthChanged(qint64 length)
 
 void MainWidget::showFileDialog()
 {
+    m_errorOccurred = false;
     const QString dir;
     const QStringList fileNames = QFileDialog::getOpenFileNames(this, tr("Open WAV file"), dir, "*.wav");
     if (fileNames.count()) {
@@ -214,6 +218,7 @@ void MainWidget::showSettingsDialog()
 
 void MainWidget::showToneGeneratorDialog()
 {
+    m_errorOccurred = false;
     m_toneGeneratorDialog->exec();
     if (m_toneGeneratorDialog->result() == QDialog::Accepted) {
         reset();
@@ -228,12 +233,14 @@ void MainWidget::showToneGeneratorDialog()
             updateButtonStates();
         }
     } else {
+        setMode(NoMode);
         updateModeMenu();
     }
 }
 
 void MainWidget::initializeRecord()
 {
+    m_errorOccurred = false;
     reset();
     setMode(RecordMode);
     if (m_engine->initializeRecord())
@@ -413,17 +420,18 @@ void MainWidget::updateButtonStates()
                                 (QAudio::ActiveState != m_engine->state() &&
                                  QAudio::IdleState != m_engine->state())) &&
                                 RecordMode == m_mode);
-    m_recordButton->setEnabled(recordEnabled);
+    m_recordButton->setEnabled(m_errorOccurred ? false : recordEnabled);
 
     const bool pauseEnabled = (QAudio::ActiveState == m_engine->state() ||
                                QAudio::IdleState == m_engine->state());
-    m_pauseButton->setEnabled(pauseEnabled);
+    m_pauseButton->setEnabled(m_errorOccurred ? false : pauseEnabled);
 
     const bool playEnabled = (/*m_engine->dataLength() &&*/
                               (QAudioDevice::Output != m_engine->mode() ||
                                (QAudio::ActiveState != m_engine->state() &&
                                 QAudio::IdleState != m_engine->state())));
-    m_playButton->setEnabled(playEnabled);
+
+    m_playButton->setEnabled(m_errorOccurred ? false : playEnabled);
 }
 
 void MainWidget::reset()
@@ -435,6 +443,10 @@ void MainWidget::reset()
     m_levelMeter->reset();
     m_spectrograph->reset();
     m_progressBar->reset();
+    if (m_errorOccurred) {
+        setMode(Mode::NoMode);
+        updateButtonStates();
+    }
 }
 
 void MainWidget::setMode(Mode mode)
diff --git a/examples/multimedia/spectrum/mainwidget.h b/examples/multimedia/spectrum/mainwidget.h
index d2340daae..0eae08af0 100644
--- a/examples/multimedia/spectrum/mainwidget.h
+++ b/examples/multimedia/spectrum/mainwidget.h
@@ -152,6 +152,8 @@ private:
     QAction*                m_loadFileAction;
     QAction*                m_generateToneAction;
     QAction*                m_recordAction;
+    bool                    m_errorOccurred;
+
 };
 
 #endif // MAINWIDGET_H