Audio-Router/Audio Router WPF/AudioGraphConnection.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Threading;
using System.Threading.Tasks;
using Windows.Media.Audio;
using System.Windows.Controls;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;

namespace Audio_Router_WPF
{
    public class AudioGraphConnection
    {
        string SourceNames { get; }
        string TargetNames { get; }
        int SamplesPerMS { get; }

        public AudioGraph Graph { get; private set; }

        AudioDeviceOutputNode TargetDevice { get; set; }
        AudioDeviceInputNode SourceDevice { get; set; }

        Dispatcher uiDispatcher { get; set; }

        TextBlock latencyLabel { get; set; } = new TextBlock();

        int quantaCount;

#pragma warning disable CS8618 // Cannot convert null literal to non-nullable reference type.
        public AudioGraphConnection(AudioGraph graph, AudioDeviceOutputNode targetDevice, AudioDeviceInputNode sourceDevice, Dispatcher uiDispatcher)
        {
            Graph = graph;
            TargetDevice = targetDevice;
            SourceDevice = sourceDevice;
            this.uiDispatcher = uiDispatcher;
            SourceNames = sourceDevice.Device.Name;
            TargetNames = targetDevice.Device.Name;

            SamplesPerMS = (int)(Graph.SamplesPerQuantum / (double)Graph.EncodingProperties.SampleRate * 1000);
        }

        /// <summary>
        /// Creates a grid populated with UI controls containing information about this item, i.e. for rendering
        /// </summary>
        /// <returns></returns>
        public Grid GetAsDisplayItem(out Button deletionButton)
        {
            // Create the display elements
            Grid result = new Grid();
            Button destroyButton = new Button()
            {
                Content = "Stop",
                HorizontalAlignment = HorizontalAlignment.Right
            };

            TextBlock label = new TextBlock()
            {
                HorizontalAlignment = HorizontalAlignment.Left
            };
            latencyLabel = new TextBlock()
            {
                Padding = new Thickness(0, 0, 5, 0)
            };
            Slider volumeSlider = new Slider
            {
                Maximum = 5.0,
                Minimum = 0.0,
                Value = 1.0,
                SmallChange = 0.1,
                MinWidth = 250,
                Margin = new Thickness(5, 0, 5, 0)
            };

            StackPanel rightSide = new StackPanel
            {
                Orientation = Orientation.Horizontal
            };

            // Set the base grid to span the full screen width available
            result.HorizontalAlignment = HorizontalAlignment.Stretch;
            result.Margin = new Thickness(1, 1, 1, 5);
            // Add Column definitions
            result.ColumnDefinitions.Add(new ColumnDefinition()); // '*' size; fits the maximum space it can, evenly
            result.ColumnDefinitions.Add(new ColumnDefinition()   // 'auto'; automatically resizes to the total size of the children elements
            {
                Width = GridLength.Auto
            });


            Run sourceDev = new Run()
            {
                Text = SourceNames
            };
            Run arrow = new Run
            {
                Text = "  ",
                FontFamily = new FontFamily("Segoe MDL2 Assets")
            };
            Run targetDev = new Run()
            {
                Text = TargetNames
            };

            // Add the text to the label
            label.Inlines.Add(sourceDev);
            label.Inlines.Add(arrow);
            label.Inlines.Add(targetDev);

            // Register the event 
            destroyButton.Click += DestroyButton_Click;
            result.Children.Add(label);

            volumeSlider.ValueChanged += VolumeSlider_ValueChanged;

            Graph.QuantumProcessed += Graph_QuantumProcessed;
            rightSide.Children.Add(latencyLabel);
            rightSide.Children.Add(volumeSlider);
            rightSide.Children.Add(destroyButton);
            rightSide.HorizontalAlignment = HorizontalAlignment.Right;
            result.Children.Add(rightSide);
            Grid.SetColumn(rightSide, 1);
            deletionButton = destroyButton;
            return result;
        }

        private void Graph_QuantumProcessed(AudioGraph sender, object args)
        {
            // updates aren't urgent, only process after some time (this is 1s, with the Windows default of 10 ms / quanta
            if (quantaCount % 100 == 0)
            {
                if (latencyLabel is null) return;
                string result = (Graph.LatencyInSamples / (double)Graph.SamplesPerQuantum * SamplesPerMS).ToString("0.#") + " ms";
                
                uiDispatcher.Invoke(() =>
                 {
                     try
                     {
                         // Try to set the label, otherwise it may have already been destroyed
                         latencyLabel.Text = result;
                     }
                     catch (NullReferenceException)
                     {

                     }
                 }, DispatcherPriority.Background);
                result = null;
            }
            /// ----------------------
            /// ||    About this:   ||
            /// ----------------------
            /// Running AudioGraph in WPF causes what seems to be the captured audio data to 
            /// never go out of scope (this does not happen in UWP, as shown in the near-identical code from the 
            /// UWP project), so the memory allocations for the project keep increasing.
            /// Stopping the AudioGraph causes these allocations to finalise, so frees up the space.
            /// we can call ResetAllNodes() periodically (i.e.: every 10s (1000 * 10 ms)) to reset the
            /// nodes
            ///
            if (quantaCount == 1000)
            {
                //SourceDevice.Reset();
                Graph.ResetAllNodes();
                // GC.Collect(); // We can let the GC handle itself
            }
            quantaCount++;
            quantaCount %= 1001;
        }

        private void VolumeSlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {
            TargetDevice.OutgoingGain = e.NewValue;
            SourceDevice.OutgoingGain = e.NewValue;
        }

        #pragma warning disable CS8625 // Cannot convert null literal to non-nullable reference type.
        private void DestroyButton_Click(object sender, RoutedEventArgs e)
        {
            Graph.QuantumProcessed -= Graph_QuantumProcessed;
            Graph.ResetAllNodes();
            latencyLabel = null;
            Graph.Stop();
            TargetDevice.Dispose();
            SourceDevice.Dispose();
            Graph.Dispose();
            Graph = null;
            TargetDevice = null;
            SourceDevice = null;
            uiDispatcher = null;
            _ = App.appRef.audioGraphConnections.Remove(this);
            GC.Collect();
        }

        public void OnHide()
        {
            latencyLabel = null;
            Graph.QuantumProcessed -= Graph_QuantumProcessed;
        }
    }
}