private async Task RenderWaveformAsync(bool withDelay)
{
// Note: This function does not set CurrentWaveform to null to allow the old
// one to stay visible until the new calculation is complete (when called by InvalidateWaveform).
renderWaveformCts?.Cancel();
renderWaveformCts?.Dispose();
renderWaveformCts = new CancellationTokenSource();
try
{
IsLoading = true;
if (withDelay)
{
await Task.Delay(300, renderWaveformCts.Token);
}
if (audioFile == null) // no longer available
{
IsLoading = false;
return;
}
double viewLeft = sequencer.CurrentViewLeftPositionTime - MusicTimeOffset;
double viewRight = sequencer.CurrentViewRightPositionTime - MusicTimeOffset;
double padding = (viewRight - viewLeft) / 4; // use the width of one viewport on each side as padding
double waveformLeft = Math.Max(0, viewLeft - padding);
double waveformRight = viewRight + padding;
Waveform result = await WaveformGenerator.CreateWaveformAsync(audioFile.CreateStream(),
sequencer.TimePixelScale,
waveformLeft,
waveformRight,
renderWaveformCts.Token);
Debug.WriteLine($"Time per sample: {result.TimePerSample}, Sample count: {result.Minimums.Length}");
CurrentWaveform = result;
IsLoading = false;
}
catch (OperationCanceledException) { }
}
public async Task LoadFileAsync(string fileName)
{
try { audioFile = new BufferedAudioFile(fileName); }
catch (Exception e)
{
System.Windows.MessageBox.Show("Could not load music file: " + Path.GetFileName(fileName) + Environment.NewLine + Environment.NewLine + e.Message, "Problem opening file",
System.Windows.MessageBoxButton.OK, System.Windows.MessageBoxImage.Warning);
return;
}
MusicFileName = fileName;
// TODO progress inidicator for file loading
audioFile.LoadIntoMemoryAsync(null).Forget();
audioPlayback.Init(audioFile.CreateStream(infinite: true));
// Initialize our user-facing value from the playback device (which apparently gets its value from Windows).
MusicVolume = LoudnessHelper.VolumeFromLoudness(audioPlayback.Volume);
CurrentWaveform = null;
await RenderWaveformAsync(false);
Notify(nameof(MusicDuration));
}
