implemented base audio playback and scrubbing

app/audio/audiohybriddevice.cpp

@@ -0,0 +1,93 @@
+#include "audiohybriddevice.h"
+
+#include <QDebug>
+#include <QtMath>
+
+AudioHybridDevice::AudioHybridDevice(QObject *parent) :
+  QIODevice(parent),
+  device_(nullptr),
+  sample_index_(0)
+{
+
+}
+
+void AudioHybridDevice::Push(const QByteArray& samples)
+{
+  pushed_samples_ = samples;
+  sample_index_ = 0;
+
+  if (!pushed_samples_.isEmpty()) {
+    emit HasSamples();
+  }
+}
+
+void AudioHybridDevice::Stop()
+{
+  // Whatever is happening, stop it
+  pushed_samples_.clear();
+  device_ = nullptr;
+}
+
+void AudioHybridDevice::ConnectDevice(QIODevice *device)
+{
+  // Clear any previous device or pushed sample
+  Stop();
+
+  device_ = device;
+
+  if (device_ != nullptr) {
+    emit HasSamples();
+  }
+}
+
+bool AudioHybridDevice::IsIdle()
+{
+  return device_ == nullptr && pushed_samples_.isEmpty();
+}
+
+qint64 AudioHybridDevice::readData(char *data, qint64 maxSize)
+{
+  // If a device is connected, passthrough to it
+  if (device_ != nullptr) {
+    qint64 read_count = device_->read(data, maxSize);
+
+    // Stop reading this device
+    if (device_->atEnd()) {
+      device_ = nullptr;
+    }
+
+    return read_count;
+  }
+
+  // If there are samples to push, push those
+  if (!pushed_samples_.isEmpty()) {
+    qint64 read_count = qMin(maxSize, pushed_samples_.size() - sample_index_);
+
+    memcpy(data, pushed_samples_.data()+sample_index_, static_cast<size_t>(read_count));
+
+    sample_index_ += read_count;
+
+    if (sample_index_ == pushed_samples_.size()) {
+      pushed_samples_.clear();
+    }
+
+    if (read_count < maxSize) {
+      memset(data + read_count, 0, static_cast<size_t>(maxSize - read_count));
+    }
+
+    return maxSize;
+  }
+
+  memset(data, 0, static_cast<size_t>(maxSize));
+  return maxSize;
+}
+
+qint64 AudioHybridDevice::writeData(const char *data, qint64 maxSize)
+{
+  Q_UNUSED(data)
+  Q_UNUSED(maxSize)
+
+  // This device doesn't support writing
+
+  return -1;
+}