Added the option to include the OpenGL error code description when constructing OpenGlException

src/Avalonia.OpenGL/EglContext.cs

@@ -31,14 +31,14 @@ namespace Avalonia.OpenGL
         public void MakeCurrent()
         {
             if (!_egl.MakeCurrent(_disp.Handle, IntPtr.Zero, IntPtr.Zero, Context))
-                throw new OpenGlException("eglMakeCurrent failed");
+                throw OpenGlException.GetFormattedException("eglMakeCurrent", _egl);
         }
         
         public void MakeCurrent(EglSurface surface)
         {
-            var surf = ((EglSurface)surface)?.DangerousGetHandle() ?? OffscreenSurface;
+            var surf = surface?.DangerousGetHandle() ?? OffscreenSurface;
             if (!_egl.MakeCurrent(_disp.Handle, surf, surf, Context))
-                throw new OpenGlException("eglMakeCurrent failed");
+                throw OpenGlException.GetFormattedException("eglMakeCurrent", _egl);
         }
     }
 }

src/Avalonia.OpenGL/EglDisplay.cs

@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel;
 using System.Runtime.InteropServices;
 using Avalonia.Platform.Interop;
 using static Avalonia.OpenGL.EglConsts;
@@ -34,11 +33,11 @@ namespace Avalonia.OpenGL
             if (_display == IntPtr.Zero)
                 _display = _egl.GetDisplay(IntPtr.Zero);
             
-            if(_display == IntPtr.Zero)
-                throw new OpenGlException("eglGetDisplay failed");
-            
+            if (_display == IntPtr.Zero)
+                throw OpenGlException.GetFormattedException("eglGetDisplay", _egl);
+
             if (!_egl.Initialize(_display, out var major, out var minor))
-                throw new OpenGlException("eglInitialize failed");
+                throw OpenGlException.GetFormattedException("eglInitialize", _egl);
 
             foreach (var cfg in new[]
             {
@@ -113,7 +112,7 @@ namespace Avalonia.OpenGL
             var shareCtx = (EglContext)share;
             var ctx = _egl.CreateContext(_display, _config, shareCtx?.Context ?? IntPtr.Zero, _contextAttributes);
             if (ctx == IntPtr.Zero)
-                throw new OpenGlException("eglCreateContext failed");
+                throw OpenGlException.GetFormattedException("eglCreateContext", _egl);
             var surf = _egl.CreatePBufferSurface(_display, _config, new[]
             {
                 EGL_WIDTH, 1,
@@ -121,7 +120,7 @@ namespace Avalonia.OpenGL
                 EGL_NONE
             });
             if (surf == IntPtr.Zero)
-                throw new OpenGlException("eglCreatePbufferSurface failed");
+                throw OpenGlException.GetFormattedException("eglCreatePBufferSurface", _egl);
             var rv = new EglContext(this, _egl, ctx, surf);
             rv.MakeCurrent(null);
             return rv;
@@ -130,14 +129,14 @@ namespace Avalonia.OpenGL
         public void ClearContext()
         {
             if (!_egl.MakeCurrent(_display, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero))
-                throw new OpenGlException("eglMakeCurrent failed");
+                throw OpenGlException.GetFormattedException("eglMakeCurrent", _egl);
         }
 
         public EglSurface CreateWindowSurface(IntPtr window)
         {
             var s = _egl.CreateWindowSurface(_display, _config, window, new[] {EGL_NONE, EGL_NONE});
             if (s == IntPtr.Zero)
-                throw new OpenGlException("eglCreateWindowSurface failed");
+                throw OpenGlException.GetFormattedException("eglCreateWindowSurface", _egl);
             return new EglSurface(this, _egl, s);
         }
 

src/Avalonia.OpenGL/EglInterface.cs

@@ -1,7 +1,6 @@
 using System;
 using Avalonia.Platform;
 using Avalonia.Platform.Interop;
-using static Avalonia.OpenGL.EglConsts;
 
 namespace Avalonia.OpenGL
 {
@@ -32,8 +31,12 @@ namespace Avalonia.OpenGL
             var lib = dyn.LoadLibrary(library);
             return (s, o) => dyn.GetProcAddress(lib, s, o);
         }
-        
+
         // ReSharper disable UnassignedGetOnlyAutoProperty
+        public delegate int EglGetError();
+        [EntryPoint("eglGetError")]
+        public EglGetError GetError { get; }
+
         public delegate IntPtr EglGetDisplay(IntPtr nativeDisplay);
         [EntryPoint("eglGetDisplay")]
         public EglGetDisplay GetDisplay { get; }

src/Avalonia.OpenGL/GlInterface.cs

@@ -19,7 +19,10 @@ namespace Avalonia.OpenGL
         public T GetProcAddress<T>(string proc) => Marshal.GetDelegateForFunctionPointer<T>(GetProcAddress(proc));
 
         // ReSharper disable UnassignedGetOnlyAutoProperty
-        
+        public delegate int GlGetError();
+        [EntryPoint("glGetError")]
+        public GlGetError GetError { get; }
+
         public delegate void GlClearStencil(int s);
         [EntryPoint("glClearStencil")]
         public GlClearStencil ClearStencil { get; }

src/Avalonia.OpenGL/OpenGlException.cs

@@ -1,12 +1,50 @@
 using System;
+using System.Reflection;
 
 namespace Avalonia.OpenGL
 {
     public class OpenGlException : Exception
     {
+        public int? ErrorCode { get; private set; }
+
         public OpenGlException(string message) : base(message)
         {
+        }
+
+        private OpenGlException(string message, int errorCode) : base(message)
+        {
+            ErrorCode = errorCode;
+        }
+
+        public static OpenGlException GetFormattedException(string funcName, EglInterface egl)
+        {
+            return GetFormattedException(typeof(EglConsts).GetFields(), funcName, 0x3000, 0x301F, egl.GetError());
+        }
+
+        public static OpenGlException GetFormattedException(string funcName, GlInterface gl)
+        {
+            return GetFormattedException(typeof(GlConsts).GetFields(), funcName, 0x0500, 0x0505, gl.GetError());
+        }
+
+        private static OpenGlException GetFormattedException(
+            FieldInfo[] fields, string funcName, int minValue, int maxValue, int errorCode)
+        {
+            foreach (var field in fields)
+            {
+                int value = (int)field.GetValue(null);
+                if (value < minValue || value > maxValue)
+                {
+                    continue;
+                }
+
+                if (value == errorCode)
+                {
+                    return new OpenGlException(
+                        $"{funcName} failed with error {field.Name} (0x{errorCode.ToString("X")})", errorCode);
+                }
+            }
 
+            return new OpenGlException($"{funcName} failed with error 0x{errorCode.ToString("X")}", errorCode);
         }
     }
 }