Enhance OpenGlControlBase.cs (#17011)

1. Dispose IGlContext correctly
2. Refactor OpenGL initialization check

Author: heku

src/Avalonia.OpenGL/Controls/OpenGlControlBase.cs

@@ -20,6 +20,9 @@ public abstract class OpenGlControlBase : Control
         private Task<bool>? _initialization;
         private OpenGlControlBaseResources? _resources;
         private Compositor? _compositor;
+
+        [MemberNotNullWhen(true, nameof(_resources))]
+        private bool IsInitializedSuccessfully => _initialization is { Status: TaskStatus.RanToCompletion, Result: true };
         protected GlVersion GlVersion => _resources?.Context.Version ?? default;
 
         public OpenGlControlBase()
@@ -29,7 +32,7 @@ public OpenGlControlBase()
 
         private void DoCleanup()
         {
-            if (_initialization is { Status: TaskStatus.RanToCompletion } && _resources != null)
+            if (IsInitializedSuccessfully)
             {
                 try
                 {
@@ -86,14 +89,13 @@ private bool EnsureInitializedCore(
                     ctx = contextFactory.CreateContext(null);
                     if (ctx.TryGetFeature<IGlContextExternalObjectsFeature>(out var externalObjects))
                         _resources = OpenGlControlBaseResources.TryCreate(ctx, surface, interop, externalObjects);
-                    else
-                        ctx.Dispose();
                 }
 
                 if(_resources == null)
                 {
                     Logger.TryGet(LogEventLevel.Error, "OpenGL")?.Log("OpenGlControlBase",
                         "Unable to initialize OpenGL: current platform does not support multithreaded context sharing and shared memory");
+                    ctx?.Dispose();
                     return false;
                 }
             }
@@ -137,15 +139,13 @@ private bool EnsureInitialized()
             if (_initialization != null)
             {
                 // Check if we've previously failed to initialize OpenGL on this platform
-                if (_initialization is { IsCompleted: true, Result: false } ||
-                    _initialization?.IsFaulted == true)
-                    return false;
-
-                // Check if we are still waiting for init to complete
-                if (_initialization is { IsCompleted: false })
+                // or if we are still waiting for init to complete
+                if (!IsInitializedSuccessfully)
+                {
                     return false;
+                }
 
-                if (_resources!.Context.IsLost)
+                if (_resources.Context.IsLost)
                     ContextLost();
                 else 
                     return true;
@@ -157,8 +157,10 @@ async void ContinueOnInitialization()
             {
                 try
                 {
-                    await _initialization;
-                    RequestNextFrameRendering();
+                    if (await _initialization)
+                    {
+                        RequestNextFrameRendering();
+                    }
                 }
                 catch
                 {
@@ -224,7 +226,7 @@ await _compositor.TryGetRenderInterfaceFeature(
 
         public void RequestNextFrameRendering()
         {
-            if ((_initialization == null || _initialization is { Status: TaskStatus.RanToCompletion }) &&
+            if ((_initialization == null || IsInitializedSuccessfully) &&
                 !_updateQueued && _compositor != null)
             {
                 _updateQueued = true;