Manually adding / removing call backs

HybridWebView/HybridWebView.cs

@@ -1,4 +1,5 @@
-using System.Text.Json;
+using System.Reflection;
+using System.Text.Json;
 
 namespace HybridWebView
 {
@@ -94,13 +95,21 @@ private void InvokeDotNetMethod(JSInvokeMethodData invokeData)
                 throw new NotImplementedException($"The {nameof(JSInvokeTarget)} property must have a value in order to invoke a .NET method from JavaScript.");
             }
 
-            var invokeMethod = JSInvokeTarget.GetType().GetMethod(invokeData.MethodName!, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.InvokeMethod);
-            if (invokeMethod == null)
+            object containingClass = JSInvokeTarget;
+            MethodInfo invokeMethod = JSInvokeTarget.GetType().GetMethod(invokeData.MethodName, BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance | BindingFlags.InvokeMethod);
+
+            if(invokeMethod is null)
             {
-                throw new InvalidOperationException($"The method {invokeData.MethodName} couldn't be found on the {nameof(JSInvokeTarget)} of type {JSInvokeTarget.GetType().FullName}.");
+                (object containingClass, MethodInfo method)? localMethod = LocalRegisteredCallbacks.Where(x => x.Key.Equals(invokeData.MethodName)).Select(x => x.Value).FirstOrDefault();
+
+                if(localMethod is not null)
+                {
+                    invokeMethod = localMethod.Value.method;
+                    containingClass = localMethod.Value.containingClass;
+                }
             }
 
-            if (invokeData.ParamValues != null && invokeMethod.GetParameters().Length != invokeData.ParamValues.Length)
+            if (invokeData.ParamValues is not null && invokeMethod.GetParameters().Length != invokeData.ParamValues.Length)
             {
                 throw new InvalidOperationException($"The number of parameters on {nameof(JSInvokeTarget)}'s method {invokeData.MethodName} ({invokeMethod.GetParameters().Length}) doesn't match the number of values passed from JavaScript code ({invokeData.ParamValues.Length}).");
             }
@@ -110,7 +119,24 @@ private void InvokeDotNetMethod(JSInvokeMethodData invokeData)
                     .Zip(invokeMethod.GetParameters(), (s, p) => JsonSerializer.Deserialize(s, p.ParameterType))
                     .ToArray();
 
-            var returnValue = invokeMethod.Invoke(JSInvokeTarget, paramObjectValues);
+            invokeMethod.Invoke(containingClass, paramObjectValues);
+        }
+
+
+        internal readonly Dictionary<string, (object containingClass, MethodInfo method)> LocalRegisteredCallbacks = new();
+        public void AddLocalCallback(object containingClass, string methodName)
+        {
+            MethodInfo action = containingClass.GetType().GetMethod(methodName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance | BindingFlags.InvokeMethod);
+
+            if (LocalRegisteredCallbacks.ContainsKey(action.Name))
+                LocalRegisteredCallbacks.Remove(action.Name);
+
+            LocalRegisteredCallbacks.Add(action.Name, (containingClass, action));
+        }
+        public void RemoveLocalCallback(string methodName)
+        {
+            if (LocalRegisteredCallbacks.ContainsKey(methodName))
+                LocalRegisteredCallbacks.Remove(methodName);
         }
 
         private sealed class JSInvokeMethodData

MauiCSharpInteropWebView/MainPage.xaml.cs

@@ -12,6 +12,9 @@ public MainPage()
         BindingContext = this;
 
         myHybridWebView.JSInvokeTarget = new MyJSInvokeTarget(this);
+
+        // Register in the constructor or anywhere else
+        myHybridWebView.AddLocalCallback(this, nameof(AddLocalCallBackTest));
     }
 
     public string CurrentPageName => $"Current hybrid page: {_currentPage}";
@@ -26,6 +29,11 @@ private async void OnSendRawMessageToJS(object sender, EventArgs e)
         _ = await myHybridWebView.EvaluateJavaScriptAsync($"SendToJs('Sent from .NET, the time is: {DateTimeOffset.Now}!')");
     }
 
+    private async void AddLocalCallBackTest(string message, int value)
+    {
+        WriteToLog($"I'm a .NET method called from JavaScript with message='{message}' and value={value}, using a local registration");
+    }
+
     private async void OnInvokeJSMethod(object sender, EventArgs e)
     {
         var sum = await myHybridWebView.InvokeJsMethodAsync<int>("JsAddNumbers", 123, 456);
@@ -76,5 +84,6 @@ private enum HybridAppPageID
         MainPage = 0,
         RawMessages = 1,
         MethodInvoke = 2,
+        ManualRegister = 3,
     }
 }

MauiCSharpInteropWebView/MauiCSharpInteropWebView.csproj

@@ -48,6 +48,10 @@
 		<MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
 	</ItemGroup>
 
+	<ItemGroup>
+	  <None Remove="Resources\Raw\hybrid_root\localMethodinvoke.html" />
+	</ItemGroup>
+
 	<ItemGroup>
 		<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="7.0.0" />
 	</ItemGroup>
@@ -56,4 +60,10 @@
 	  <ProjectReference Include="..\HybridWebView\HybridWebView.csproj" />
 	</ItemGroup>
 
+	<ItemGroup>
+	  <MauiAsset Update="Resources\Raw\hybrid_root\localmethodinvoke.html">
+	    <LogicalName>%(RecursiveDir)%(Filename)%(Extension)</LogicalName>
+	  </MauiAsset>
+	</ItemGroup>
+
 </Project>

MauiCSharpInteropWebView/Resources/Raw/hybrid_root/hybrid_app.html

@@ -10,7 +10,7 @@
 <body>
     <h1>HybridWebView demo: Main page</h1>
     <div class="navBar">
-        Main page | <a href="/rawmessages.html">Raw messages</a> | <a href="/methodinvoke.html">Method invoke</a>
+        Main page | <a href="/rawmessages.html">Raw messages</a> | <a href="/methodinvoke.html">Method invoke</a> | <a href="/localmethodinvoke.html">Local method invoke</a>
     </div>
     <div>
         Welcome to the HybridWebView demo for .NET MAUI!

MauiCSharpInteropWebView/Resources/Raw/hybrid_root/localMethodinvoke.html

@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+
+<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
+<head>
+    <meta charset="utf-8" />
+    <title></title>
+    <script>
+        function JsAddNumbers(a, b) {
+            var sum = a + b;
+            Log('Called from .NET with values (' + a + ', ' + b + '), and returning the sum: ' + sum);
+            return sum;
+        }
+
+        function CallDotNetMethod() {
+            Log('Calling a method in .NET with some parameters');
+
+            HybridWebView.SendInvokeMessageToDotNet("AddLocalCallBackTest", ["msg from js", 987]);
+        }
+    </script>
+    <script src="_hwv/HybridWebView.js"></script>
+    <script src="js/extra_code.js"></script>
+    <link href="styles/my-styles.css" rel="stylesheet" />
+</head>
+<body>
+    <h1>HybridWebView demo: Method invoke</h1>
+    <div class="navBar">
+        <a href="/">Main page</a> | <a href="/rawmessages.html">Raw messages</a> | <a href="/methodinvoke.html">Method invoke</a> | Local method invoke
+    </div>
+    <div>
+        Methods can be invoked in both directions:
+
+        <ul>
+            <li>JavaScript can invoke .NET methods by calling <code>HybridWebView.SendInvokeMessageToDotNet("DotNetMethodName", ["param1", 123]);</code>.</li>
+            <li>.NET can invoke JavaScript methods by calling <code>var sum = await webView.InvokeJsMethodAsync<int>("JsAddNumbers", 123, 456);</code>.</li>
+        </ul>
+    </div>
+    <div>
+        <button type="button" onclick="CallDotNetMethod()">Call .NET method with some parameters</button>
+    </div>
+    <h2>
+        JS message log:
+    </h2>
+    <div>
+        <textarea id="messageLog" style="width: 90%; height: 10em;"></textarea>
+    </div>
+    <script>
+        // Notify .NET code which page we're on
+        HybridWebView.SendRawMessageToDotNet("page:3");
+    </script>
+</body>
+</html>

MauiCSharpInteropWebView/Resources/Raw/hybrid_root/methodinvoke.html

@@ -24,7 +24,7 @@
 <body>
     <h1>HybridWebView demo: Method invoke</h1>
     <div class="navBar">
-        <a href="/">Main page</a> | <a href="/rawmessages.html">Raw messages</a> | Method invoke
+        <a href="/">Main page</a> | <a href="/rawmessages.html">Raw messages</a> | Method invoke | <a href="/localmethodinvoke.html">Local method invoke</a>
     </div>
     <div>
         Methods can be invoked in both directions:

MauiCSharpInteropWebView/Resources/Raw/hybrid_root/rawmessages.html

@@ -22,7 +22,7 @@
 <body>
     <h1>HybridWebView demo: Raw messages</h1>
     <div class="navBar">
-        <a href="/">Main page</a> | Raw messages | <a href="/methodinvoke.html">Method invoke</a>
+        <a href="/">Main page</a> | Raw messages | <a href="/methodinvoke.html">Method invoke</a> | <a href="/localmethodinvoke.html">Local method invoke</a>
     </div>
     <div>
         Raw messages are sent as a raw string from JavaScript to .NET with no further processing.