audiosource example: Refactor push mode

Factor out a function to calculate the level from the data
to make it clearer that push does not require reimplementing
a QIODevice.
Complements a71362d9ef7098c1d7869b3768a0990a61474980.

Change-Id: I4899b96d1e8d0336f960e514bfd355a894522aa8
Reviewed-by: André de la Rocha <andre.rocha@qt.io>
(cherry picked from commit 28932bcc4c40a6c5f96bf2beb860c916c1161056)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 16 insertions, 10 deletions

diff --git a/examples/multimedia/audiosource/audiosource.cpp b/examples/multimedia/audiosource/audiosource.cpp
index c2b9547b4..1f84ae63a 100644
--- a/examples/multimedia/audiosource/audiosource.cpp
+++ b/examples/multimedia/audiosource/audiosource.cpp
@@ -81,7 +81,7 @@ qint64 AudioInfo::readData(char * /* data */, qint64 /* maxlen */)
     return 0;
 }
 
-qint64 AudioInfo::writeData(const char *data, qint64 len)
+qreal AudioInfo::calculateLevel(const char *data, qint64 len) const
 {
     const int channelBytes = m_format.bytesPerSample();
     const int sampleBytes = m_format.bytesPerFrame();
@@ -98,8 +98,12 @@ qint64 AudioInfo::writeData(const char *data, qint64 len)
             ptr += channelBytes;
         }
     }
+    return maxValue;
+}
 
-    m_level = maxValue;
+qint64 AudioInfo::writeData(const char *data, qint64 len)
+{
+    m_level = calculateLevel(data, len);
 
     emit levelChanged(m_level);
 
@@ -210,18 +214,18 @@ void InputTest::toggleMode()
         m_audioInput->start(m_audioInfo.data());
     } else {
         m_modeButton->setText(tr("Enable pull mode"));
-        auto io = m_audioInput->start();
+        auto *io = m_audioInput->start();
         connect(io, &QIODevice::readyRead,
-            [&, io]() {
-                qint64 len = m_audioInput->bytesAvailable();
-                const int BufferSize = 4096;
-                if (len > BufferSize)
-                    len = BufferSize;
+            [this, io]() {
+                static const qint64 BufferSize = 4096;
+                const qint64 len = qMin(m_audioInput->bytesAvailable(), BufferSize);
 
                 QByteArray buffer(len, 0);
                 qint64 l = io->read(buffer.data(), len);
-                if (l > 0)
-                    m_audioInfo->write(buffer.constData(), l);
+                if (l > 0) {
+                    const qreal level = m_audioInfo->calculateLevel(buffer.constData(), l);
+                    m_canvas->setLevel(level);
+                }
             });
     }
 
diff --git a/examples/multimedia/audiosource/audiosource.h b/examples/multimedia/audiosource/audiosource.h
index 7fde1b2cb..fce664fd9 100644
--- a/examples/multimedia/audiosource/audiosource.h
+++ b/examples/multimedia/audiosource/audiosource.h
@@ -79,6 +79,8 @@ public:
     qint64 readData(char *data, qint64 maxlen) override;
     qint64 writeData(const char *data, qint64 len) override;
 
+    qreal calculateLevel(const char *data, qint64 len) const;
+
 signals:
     void levelChanged(qreal level);