Examples: update list of input devices in AudioRecorder example

Update the input device list when adding/removing an audio input
device (such as a Bluetooth microphone). Also try to restore the
previously selected device if it is still present in the new list.

Task-number: QTBUG-123023
Pick-to: 6.5
Change-Id: Icaaa208bfdb333045d93d1676b365e3c73cdf7f4
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
(cherry picked from commit 7a06020c0acdd81afccd46af30d2c42582dc64c4)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 8b3e1820c4d1a57417c18739ca9cce7a9bbab527)

2 files changed, 27 insertions, 5 deletions

diff --git a/examples/multimedia/audiorecorder/audiorecorder.cpp b/examples/multimedia/audiorecorder/audiorecorder.cpp
index f529dd3e6..4131d5d51 100644
--- a/examples/multimedia/audiorecorder/audiorecorder.cpp
+++ b/examples/multimedia/audiorecorder/audiorecorder.cpp
@@ -74,11 +74,10 @@ void AudioRecorder::init()
     // m_probe->setSource(m_audioRecorder);
 
     // audio devices
-    ui->audioDeviceBox->addItem(tr("Default"), QVariant(QString()));
-    for (auto device : QMediaDevices::audioInputs()) {
-        auto name = device.description();
-        ui->audioDeviceBox->addItem(name, QVariant::fromValue(device));
-    }
+    m_mediaDevices = new QMediaDevices(this);
+    connect(m_mediaDevices, &QMediaDevices::audioInputsChanged, this,
+            &AudioRecorder::updateDevices);
+    updateDevices();
 
     // audio codecs and container formats
     updateFormats();
@@ -194,6 +193,25 @@ void AudioRecorder::displayErrorMessage()
     ui->statusbar->showMessage(m_audioRecorder->errorString());
 }
 
+void AudioRecorder::updateDevices()
+{
+    const auto currentDevice = boxValue(ui->audioDeviceBox).value<QAudioDevice>();
+    int currentDeviceIndex = 0;
+
+    ui->audioDeviceBox->clear();
+
+    ui->audioDeviceBox->addItem(tr("Default"), {});
+    for (const auto &device : m_mediaDevices->audioInputs()) {
+        const auto name = device.description();
+        ui->audioDeviceBox->addItem(name, QVariant::fromValue(device));
+
+        if (device.id() == currentDevice.id())
+            currentDeviceIndex = ui->audioDeviceBox->count() - 1;
+    }
+
+    ui->audioDeviceBox->setCurrentIndex(currentDeviceIndex);
+}
+
 void AudioRecorder::updateFormats()
 {
     if (m_updatingFormats)
diff --git a/examples/multimedia/audiorecorder/audiorecorder.h b/examples/multimedia/audiorecorder/audiorecorder.h
index 47d7ed1e2..2ce71c162 100644
--- a/examples/multimedia/audiorecorder/audiorecorder.h
+++ b/examples/multimedia/audiorecorder/audiorecorder.h
@@ -14,6 +14,7 @@ namespace Ui {
 class AudioRecorder;
 }
 class QAudioBuffer;
+class QMediaDevices;
 QT_END_NAMESPACE
 
 class AudioLevel;
@@ -38,6 +39,7 @@ private slots:
     void updateProgress(qint64 pos);
     void displayErrorMessage();
 
+    void updateDevices();
     void updateFormats();
 
 private:
@@ -48,6 +50,8 @@ private:
 
     QMediaCaptureSession m_captureSession;
     QMediaRecorder *m_audioRecorder = nullptr;
+    QMediaDevices *m_mediaDevices = nullptr;
+
     QList<AudioLevel *> m_audioLevels;
     bool m_outputLocationSet = false;
     bool m_updatingFormats = false;