Fix: UI crash on app exit and refactor: UI _drawAction became a method

.github/workflows/pr.yml

@@ -1,4 +1,4 @@
-name: Test and Publish NuGet
+name: Run tests
 
 # Trigger the workflow on PRs
 on:

src/Spice86/ViewModels/MainWindowViewModel.cs

@@ -54,14 +54,15 @@ public sealed partial class MainWindowViewModel : ViewModelBase, IPauseStatus, I
  [ObservableProperty]
  private Configuration _configuration;
  private bool _disposed;
+ private bool _renderingTimerInitialized;
+ private bool _drawingSemaphoreSlimDisposed;
  private Thread? _emulatorThread;
  private bool _isSettingResolution;
  private string _lastExecutableDirectory = string.Empty;
  private bool _closeAppOnEmulatorExit;
  private bool _isAppClosing;
 
  private static Action? _uiUpdateMethod;
- private Action? _drawAction;
  private readonly Timer _drawTimer = new(1000.0 / ScreenRefreshHz);
  private readonly SemaphoreSlim? _drawingSemaphoreSlim = new(1, 1);
 
@@ -138,8 +139,6 @@ public double Scale {
  set => SetProperty(ref _scale, Math.Max(value, 1));
  }
 
- private bool _isDrawThreadInitialized;
-
  [ObservableProperty]
  private Cursor? _cursor = Cursor.Default;
 
@@ -262,7 +261,7 @@ private async Task StartNewExecutable(string? filePath = null) {
  File.Exists(filePath)) {
  await RestartEmulatorWithNewProgram(filePath);
  }
- else if (_hostStorageProvider.CanOpen == true) {
+ else if (_hostStorageProvider.CanOpen) {
  FilePickerOpenOptions options = new() {
  Title = "Start Executable...",
  AllowMultiple = false,
@@ -334,25 +333,32 @@ public void ShowColorPalette() {
  [RelayCommand]
  public void ResetTimeMultiplier() => TimeMultiplier = Configuration.TimeMultiplier;
 
- private void InitializeRenderingThread() {
- if (_isDrawThreadInitialized || _disposed || _isSettingResolution || _isAppClosing || _uiUpdateMethod is null || Bitmap is null || RenderScreen is null) {
+ private void InitializeRenderingTimer() {
+ if (_renderingTimerInitialized) {
+ return;
+ }
+ _renderingTimerInitialized = true;
+ _drawTimer.Elapsed += (_, _) => DrawScreen();
+ _drawTimer.Start();
+ }
+
+ private void DrawScreen() {
+ if (_disposed || _isSettingResolution || _isAppClosing || _uiUpdateMethod is null || Bitmap is null || RenderScreen is null) {
  return;
  }
- _drawAction = () => {
+ if (!_drawingSemaphoreSlimDisposed) {
  _drawingSemaphoreSlim?.Wait();
- try {
- using ILockedFramebuffer pixels = Bitmap.Lock();
- var uiRenderEventArgs = new UIRenderEventArgs(pixels.Address, pixels.RowBytes * pixels.Size.Height / 4);
- RenderScreen.Invoke(this, uiRenderEventArgs);
- } finally {
+ }
+ try {
+ using ILockedFramebuffer pixels = Bitmap.Lock();
+ var uiRenderEventArgs = new UIRenderEventArgs(pixels.Address, pixels.RowBytes * pixels.Size.Height / 4);
+ RenderScreen.Invoke(this, uiRenderEventArgs);
+ } finally {
+ if (!_drawingSemaphoreSlimDisposed) {
  _drawingSemaphoreSlim?.Release();
  }
- _uiDispatcher.Post(static () => _uiUpdateMethod.Invoke(), DispatcherPriority.Render);
- };
-
- _drawTimer.Elapsed += (_, _) => _drawAction.Invoke();
- _drawTimer.Start();
- _isDrawThreadInitialized = true;
+ }
+ _uiDispatcher.Post(static () => _uiUpdateMethod.Invoke(), DispatcherPriority.Render);
  }
 
  public double MouseX { get; set; }
@@ -433,16 +439,21 @@ public void SetResolution(int width, int height) => _uiDispatcher.Post(() => {
  if (Width != width || Height != height) {
  Width = width;
  Height = height;
+ if (_drawingSemaphoreSlimDisposed) {
+ return;
+ }
  _drawingSemaphoreSlim?.Wait();
  try {
  Bitmap?.Dispose();
  Bitmap = new WriteableBitmap(new PixelSize(Width, Height), new Vector(96, 96), PixelFormat.Bgra8888, AlphaFormat.Opaque);
  } finally {
- _drawingSemaphoreSlim?.Release();
+ if (!_drawingSemaphoreSlimDisposed) {
+ _drawingSemaphoreSlim?.Release();
+ }
  }
  }
  _isSettingResolution = false;
- InitializeRenderingThread();
+ InitializeRenderingTimer();
  }, DispatcherPriority.MaxValue);
 
  public event EventHandler<UIRenderEventArgs>? RenderScreen;
@@ -456,16 +467,18 @@ public void Dispose() {
  private void Dispose(bool disposing) {
  if (!_disposed) {
  if (disposing) {
- DisposeDrawThread();
+ _windowActivator.CloseDebugWindow();
+ _drawTimer.Stop();
+ _drawTimer.Dispose();
  _uiDispatcher.Post(() => {
  Bitmap?.Dispose();
  Cursor?.Dispose();
  }, DispatcherPriority.MaxValue);
+ _drawingSemaphoreSlimDisposed = true;
  _drawingSemaphoreSlim?.Dispose();
  PlayCommand.Execute(null);
  IsMachineRunning = false;
  DisposeEmulator();
- _windowActivator.CloseDebugWindow();
  if (_emulatorThread?.IsAlive == true) {
  _emulatorThread.Join();
  }
@@ -474,13 +487,6 @@ private void Dispose(bool disposing) {
  }
  }
 
- private void DisposeDrawThread() {
- _drawAction = null;
- _drawTimer.Stop();
- _drawTimer.Dispose();
- _isDrawThreadInitialized = false;
- }
-
  private void DisposeEmulator() => _programExecutor?.Dispose();
 
  [RelayCommand]