Wpf/WinForms/OffScreen - Standardize InternalIsBrowserInitialized

- Add InternalIsBrowserInitialized to partial class
- Move ThrowExceptionIfDisposed/ThrowExceptionIfBrowserNotInitialized to partial class
- Remove checks from DevToolsExtensions.ExecuteDevToolsMethodAsync as the checks were already in GetBrowser

In WPF it's no longer necessary to have a custom implementation, will leave the Dependency property
(won't action #3033 at this point in time)

Author: amaitland

CefSharp.OffScreen/ChromiumWebBrowser.cs

@@ -67,7 +67,10 @@ public bool IsDisposed
         /// A flag that indicates whether the WebBrowser is initialized (true) or not (false).
         /// </summary>
         /// <value><c>true</c> if this instance is browser initialized; otherwise, <c>false</c>.</value>
-        public bool IsBrowserInitialized { get; private set; }
+        public bool IsBrowserInitialized
+        {
+            get { return InternalIsBrowserInitialized(); }
+        }
         /// <summary>
         /// A flag that indicates whether the control is currently loading one or more web pages (true) or not (false).
         /// </summary>
@@ -240,7 +243,7 @@ protected virtual void Dispose(bool disposing)
             if (disposing)
             {
                 CanExecuteJavascriptInMainFrame = false;
-                IsBrowserInitialized = false;
+                Interlocked.Exchange(ref browserInitialized, 0);
 
                 // Don't reference event listeners any longer:
                 AddressChanged = null;
@@ -476,8 +479,8 @@ bool IWebBrowser.Focus()
         /// <returns>browser instance or null</returns>
         public IBrowser GetBrowser()
         {
-            this.ThrowExceptionIfDisposed();
-            this.ThrowExceptionIfBrowserNotInitialized();
+            ThrowExceptionIfDisposed();
+            ThrowExceptionIfBrowserNotInitialized();
 
             return browser;
         }
@@ -662,7 +665,7 @@ void IWebBrowserInternal.OnAfterBrowserCreated(IBrowser browser)
         {
             this.browser = browser;
 
-            IsBrowserInitialized = true;
+            Interlocked.Exchange(ref browserInitialized, 1);
 
             BrowserInitialized?.Invoke(this, EventArgs.Empty);
         }

CefSharp.WinForms/ChromiumWebBrowser.cs

@@ -239,7 +239,10 @@ public IRequestContext RequestContext
         /// </summary>
         /// <value><c>true</c> if this instance is browser initialized; otherwise, <c>false</c>.</value>
         [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), DefaultValue(false)]
-        public bool IsBrowserInitialized { get; private set; }
+        public bool IsBrowserInitialized
+        {
+            get { return InternalIsBrowserInitialized(); }
+        }
 
         /// <summary>
         /// ParentFormMessageInterceptor hooks the Form handle and forwards
@@ -399,8 +402,8 @@ private void InternalDispose(bool disposing)
         {
             if (disposing)
             {
+                Interlocked.Exchange(ref browserInitialized, 0);
                 CanExecuteJavascriptInMainFrame = false;
-                IsBrowserInitialized = false;
 
                 // Don't maintain a reference to event listeners anylonger:
                 AddressChanged = null;
@@ -605,7 +608,7 @@ private void CreateBrowser()
         void IWebBrowserInternal.OnAfterBrowserCreated(IBrowser browser)
         {
             this.browser = browser;
-            IsBrowserInitialized = true;
+            Interlocked.Exchange(ref browserInitialized, 1);
 
             // By the time this callback gets called, this control
             // is most likely hooked into a browser Form of some sort. 
@@ -782,8 +785,8 @@ protected override void OnGotFocus(EventArgs e)
         /// <returns>browser instance or null</returns>
         public IBrowser GetBrowser()
         {
-            this.ThrowExceptionIfDisposed();
-            this.ThrowExceptionIfBrowserNotInitialized();
+            ThrowExceptionIfDisposed();
+            ThrowExceptionIfBrowserNotInitialized();
 
             return browser;
         }

CefSharp.Wpf/ChromiumWebBrowser.cs

@@ -96,10 +96,6 @@ public partial class ChromiumWebBrowser : Control, IRenderWebBrowser, IWpfWebBro
         /// </summary>
         private bool browserCreated;
         /// <summary>
-        /// The browser initialized - boolean represented as 0 (false) and 1(true) as we use Interlocker to increment/reset
-        /// </summary>
-        private int browserInitialized;
-        /// <summary>
         /// The image that represents this browser instances
         /// </summary>
         private Image image;
@@ -1212,16 +1208,6 @@ public bool IsLoading
         #endregion IsLoading dependency property
 
         #region IsBrowserInitialized dependency property
-
-        /// <summary>
-        /// A flag that indicates whether the WebBrowser is initialized (true) or not (false).
-        /// </summary>
-        /// <value><c>true</c> if this instance is browser initialized; otherwise, <c>false</c>.</value>
-        bool IWebBrowser.IsBrowserInitialized
-        {
-            get { return InternalIsBrowserInitialized(); }
-        }
-
         /// <summary>
         /// A flag that indicates whether the WebBrowser is initialized (true) or not (false).
         /// </summary>
@@ -2507,28 +2493,10 @@ public IJavascriptObjectRepository JavascriptObjectRepository
         /// <returns>browser instance or null</returns>
         public IBrowser GetBrowser()
         {
-            this.ThrowExceptionIfDisposed();
-
-            //We don't use the this.ThrowExceptionIfBrowserNotInitialized(); extension method here
-            // As it relies on the IWebBrowser.IsBrowserInitialized property which is a DependencyProperty
-            // in WPF and will throw an InvalidOperationException if called on a Non-UI thread.
-            if (!InternalIsBrowserInitialized())
-            {
-                throw new Exception(WebBrowserExtensions.BrowserNotInitializedExceptionErrorMessage);
-            }
+            ThrowExceptionIfDisposed();
+            ThrowExceptionIfBrowserNotInitialized();
 
             return browser;
         }
-
-        /// <summary>
-        /// Check is browserisinitialized
-        /// </summary>
-        /// <returns>true if browser is initialized</returns>
-        private bool InternalIsBrowserInitialized()
-        {
-            // Use CompareExchange to read the current value - if disposeCount is 1, we set it to 1, effectively a no-op
-            // Volatile.Read would likely use a memory barrier which I believe is unnecessary in this scenario
-            return Interlocked.CompareExchange(ref browserInitialized, 0, 0) == 1;
-        }
     }
 }

CefSharp/DevToolsExtensions.cs

@@ -96,9 +96,6 @@ public static Task<int> ExecuteDevToolsMethodAsync(this IBrowser browser, int me
         /// unsuccessfully submitted for validation, this value will be 0.</returns>
         public static Task<int> ExecuteDevToolsMethodAsync(this IWebBrowser chromiumWebBrowser, int messageId, string method, IDictionary<string, object> parameters = null)
         {
-            ((IWebBrowserInternal)chromiumWebBrowser).ThrowExceptionIfDisposed();
-            ((IWebBrowserInternal)chromiumWebBrowser).ThrowExceptionIfBrowserNotInitialized();
-
             var browser = chromiumWebBrowser.GetBrowser();
 
             return browser.ExecuteDevToolsMethodAsync(messageId, method, parameters);

CefSharp/Internals/Partial/ChromiumWebBrowser.Partial.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.ComponentModel;
+using System.Threading;
 using CefSharp.Internals;
 
 #if OFFSCREEN
@@ -18,11 +19,21 @@ namespace CefSharp.WinForms
     //WPF, Winforms and Offscreen
     public partial class ChromiumWebBrowser
     {
+        public const string BrowserNotInitializedExceptionErrorMessage =
+            "The ChromiumWebBrowser instance creates the underlying Chromium Embedded Framework (CEF) browser instance in an async fashion. " +
+            "The undelying CefBrowser instance is not yet initialized. Use the IsBrowserInitializedChanged event and check " +
+            "the IsBrowserInitialized property to determine when the browser has been initialized.";
+
         /// <summary>
         /// Used as workaround for issue https://github.com/cefsharp/CefSharp/issues/3021
         /// </summary>
         private long canExecuteJavascriptInMainFrameId;
 
+        /// <summary>
+        /// The browser initialized - boolean represented as 0 (false) and 1(true) as we use Interlocker to increment/reset
+        /// </summary>
+        private int browserInitialized;
+
         /// <summary>
         /// A flag that indicates if you can execute javascript in the main frame.
         /// Flag is set to true in IRenderProcessMessageHandler.OnContextCreated.
@@ -184,6 +195,15 @@ public partial class ChromiumWebBrowser
         /// </summary>
         public event EventHandler<JavascriptMessageReceivedEventArgs> JavascriptMessageReceived;
 
+        /// <summary>
+        /// A flag that indicates whether the WebBrowser is initialized (true) or not (false).
+        /// </summary>
+        /// <value><c>true</c> if this instance is browser initialized; otherwise, <c>false</c>.</value>
+        bool IWebBrowser.IsBrowserInitialized
+        {
+            get { return InternalIsBrowserInitialized(); }
+        }
+
         void IWebBrowserInternal.SetCanExecuteJavascriptOnMainFrame(long frameId, bool canExecute)
         {
             //When loading pages of a different origin the frameId changes
@@ -284,5 +304,40 @@ private void SetHandlersToNullExceptLifeSpan()
             ResourceRequestHandlerFactory = null;
             RenderProcessMessageHandler = null;
         }
+
+        /// <summary>
+        /// Check is browser is initialized
+        /// </summary>
+        /// <returns>true if browser is initialized</returns>
+        private bool InternalIsBrowserInitialized()
+        {
+            // Use CompareExchange to read the current value - if disposeCount is 1, we set it to 1, effectively a no-op
+            // Volatile.Read would likely use a memory barrier which I believe is unnecessary in this scenario
+            return Interlocked.CompareExchange(ref browserInitialized, 0, 0) == 1;
+        }
+
+        /// <summary>
+        /// Throw exception if browser not initialized.
+        /// </summary>
+        /// <exception cref="Exception">Thrown when an exception error condition occurs.</exception>
+        private void ThrowExceptionIfBrowserNotInitialized()
+        {
+            if (!InternalIsBrowserInitialized())
+            {
+                throw new Exception(BrowserNotInitializedExceptionErrorMessage);
+            }
+        }
+
+        /// <summary>
+        /// Throw exception if disposed.
+        /// </summary>
+        /// <exception cref="ObjectDisposedException">Thrown when a supplied object has been disposed.</exception>
+        private void ThrowExceptionIfDisposed()
+        {
+            if (IsDisposed)
+            {
+                throw new ObjectDisposedException("browser", "Browser has been disposed");
+            }
+        }
     }
 }

CefSharp/WebBrowserExtensions.cs

@@ -18,11 +18,6 @@ namespace CefSharp
     /// </summary>
     public static class WebBrowserExtensions
     {
-        public const string BrowserNotInitializedExceptionErrorMessage =
-            "The ChromiumWebBrowser instance creates the underlying Chromium Embedded Framework (CEF) browser instance in an async fashion. " +
-            "The undelying CefBrowser instance is not yet initialized. Use the IsBrowserInitializedChanged event and check " +
-            "the IsBrowserInitialized property to determine when the browser has been initialized.";
-
         #region Legacy Javascript Binding
         /// <summary>
         /// Registers a Javascript object in this specific browser instance.
@@ -1160,36 +1155,6 @@ public static string GetScriptForJavascriptMethodWithArgs(string methodName, obj
             return stringBuilder.ToString();
         }
 
-        /// <summary>
-        /// An IWebBrowser extension method that throw exception if browser not initialized.
-        /// </summary>
-        /// <remarks>
-        /// Not used in WPF as IsBrowserInitialized is a dependency property and can only be checked on the UI thread(throws
-        /// InvalidOperationException if called on another Thread).
-        /// </remarks>
-        /// <exception cref="Exception">Thrown when an exception error condition occurs.</exception>
-        /// <param name="browser">The ChromiumWebBrowser instance this method extends.</param>
-        public static void ThrowExceptionIfBrowserNotInitialized(this IWebBrowserInternal browser)
-        {
-            if (!browser.IsBrowserInitialized)
-            {
-                throw new Exception(BrowserNotInitializedExceptionErrorMessage);
-            }
-        }
-
-        /// <summary>
-        /// An IWebBrowser extension method that throw exception if disposed.
-        /// </summary>
-        /// <exception cref="ObjectDisposedException">Thrown when a supplied object has been disposed.</exception>
-        /// <param name="browser">The ChromiumWebBrowser instance this method extends.</param>
-        public static void ThrowExceptionIfDisposed(this IWebBrowserInternal browser)
-        {
-            if (browser.IsDisposed)
-            {
-                throw new ObjectDisposedException("browser", "Browser has been disposed");
-            }
-        }
-
         /// <summary>
         /// Throw exception if frame null.
         /// </summary>