I'm trying to pass a C# object to a WebView2 using AddHostObjectToScript. After not succeeding to retrieve the object from the webview, I've used the debugger and found out that the AddHostObjectToScript call is never completing.
Here is the full code snippet:
[ClassInterface(ClassInterfaceType.AutoDual)]
[ComVisible(true)]
public class Example
{
public string Prop { get; set; } = "example";
}
namespace Example_UWP
{
public sealed partial class MainPage : Page
{
public MainPage()
{
InitializeComponent();
InitializeAsync();
}
public async Task InitializeAsync()
{
await ExampleView.EnsureCoreWebView2Async();
ExampleView.Source = new Uri("http://localhost:3000");
ExampleView.CoreWebView2.OpenDevToolsWindow();
ExampleView.CoreWebView2.AddHostObjectToScript("example", new Example());
}
}
}
The example object is as a result not available in chrome.webview.hostObjects or chrome.webview.hostObjects.sync. The function throws the following error:
The group or resource is not in the correct state to perform the requested operation.
I've tried different alternatives without success, such as:
Keeping a reference to the Example instance in an attribute inside Example_UWP to avoid potential GC
Adding the host object before and after each of the previous steps within InitializeAsync
Wait for the event NavigationCompleted to add the host object.
Wait for 5 seconds before adding the host object.
I'm using Microsoft.Web.WebView2 version 1.0.1264.42
In order to interact with your third-party lib, you need to add a very specific C++ project, Windows Runtime Component (C++/WinRT), to your solution that must be called WinRTAdapter.
Next, you must install a lib to your C++ project from NuGet called Microsoft.Web.WebView2:
After this is done, you must your third-party lib as a reference.
Next, go to your C++ project properties go to Common Properties and choose WebView2:
Here you have to do four changes:
Set Use WebView2 WinRT APIs to No.
Set Use the wv2winrt tool to Yes.
Set Use Javascript case to Yes.
Edit Include filters and add the following ones:
Windows.System.UserProfile
Windows.Globalization.Language
CallJSInterface
CallJSInterface is the name of my third-party's namespace.
You click on OK and build your C++ lib.
After you have built your C++ lib (WinRTAdapter), you must add it to your main project as a reference.
Now, we need to do some changes to be able to invoke the functions from our third-party lib. The first one is to register it. We do it in the same LoadLocalPage() function from before or on NavigationCompleted:
var namespacesName = "CallJSInterface";
var dispatchAdapter = new WinRTAdapter.DispatchAdapter();
core_wv2.AddHostObjectToScript(namespacesName, dispatchAdapter.WrapNamedObject(namespacesName, dispatchAdapter));
Where CallJSInterface is your namespace. After this, you need to register your function in your JS like this:
var callJS;
if (chrome && chrome.webview) {
chrome.webview.hostObjects.options.defaultSyncProxy = true;
chrome.webview.hostObjects.options.forceAsyncMethodMatches = [/Async$/];
chrome.webview.hostObjects.options.ignoreMemberNotFoundError = true;
window.CallJSInterface = chrome.webview.hostObjects.sync.CallJSInterface;
callJS = new CallJSInterface.CallJSCSharp();
}
Where CallJSInterface is one more time your namespace. Now, you can invoke JS like this (the async() is mandatory):
callJS.async().KeepScreenOn()
If you need more details, I have a full tutorial on my website:
https://supernovaic.blogspot.com/2022/10/from-webview-to-webview2-in-uwp.html
Related
I'm trying to access some functions inside my C# .dll library and I'm doing it in node.js. I managed to load the library but having some troubles accessing the functions because they are inside a namespace "CCTalkReader" which contains a class "CREDIT_MANAGER" and inside this class I have my method INIT. How do I call it correctly?
I tried like this:
const CCTalk = new ffi.Library("./CCTalkNoteBill.dll", {
'CCTalkReader':{
'CREDIT_MANAGER':{
'INIT': ["void", []]
}
}
});
CCTalk.INIT();
and this
const CCTalk = new ffi.Library("./CCTalkNoteBill.dll", {
'INIT': ["void", []]
});
CCTalk.INIT();
But I always get
Dynamic Symbol Retrieval Error: Win32 error 127
which I found out means that I don't write the second parameter (function name) correctly. Any Ideas?
I am trying to use a service created by somebody else. I have only the service dll. But the instructions provided to me are not complete. This is an example how to use the service but they missed the instantiation of the variable criteria. How can I figure out what type is the variable? . If possible, I prefer to solve the issue without decompiling the dll.
public static void GetData()
{
//ServiceReference1.ServicesClient client = null;
try
{
criteria.Settings = new CheckCall.CriteriaSettings();
CheckCall.Criteria criteria1 = new CheckCall.Criteria();
criteria1.Settings = new CheckCall.CriteriaSettings();
criteria1.AsgnType = CheckcallAssignTypeEnum.Driver;
criteria1.TractorNumber = "Tractor1";
criteria.Expressions = new List<CheckCall.CriteriaExpression>();
criteria.Expressions.Add(new CheckCall.CriteriaExpression
{
Conjuction = CriteriaSetting.ConjuctionEnum.OrOp,
Criteria = criteria1
});
}
catch(Exception ex)
{
Console.Write(ex);
}
}
You could use JetBrains .Net decompiler - dotPeek.(https://www.jetbrains.com/decompiler/)
Decompile the dll, then add the decompiled project to your solution and debug it. The only problem is wether you will receive a project that can be built after decompilation
If the decompilation is not an option/project has errors after decompilation - you can see the contents of the .dll via Object Browser. Find the .dll in the References, right click on it and choose "View in Object Browser". You will see the namespaces, classes and their methods of the .dll. Enter any of the property names of criteria object (Settings or Expressions) and Object Browser will filter everything out
I am a total beginner in C# programming language. I am trying to use Getter and Setter in order to set the string in ProjectA and the retrieve it in Project B.
Project B uses Windows Forms, and I wasnt to set the value of TextBox
with the retrieved string.
Project A is a Console Project and it just reads out some stuff from
file and stores it in string, which I want to retrieve.
However, this is my call in Project B:
string cardOwner = Transmit.Program.CardOwner;
Debug.WriteLine("Card owner = " + cardOwner);
tb_cardholder.Text = cardOwner;
And this is my Getter / Setter in Project A:
private static string _cardOwner;
public static string CardOwner
{
get
{
return _cardOwner;
}
set
{
_cardOwner = value;
}
}
_cardOwner = System.Text.Encoding.ASCII.GetString(bCardOwner);
But in Project B I get "" empty string.
I have included Project A in Project B (added Reference and wrote "using ProjectA").
Any ideas what's going wrong?
Thanks.
Just because you include a project and use its classes in your project B, it doesn't mean that you also use the instances of these classes.
Take the following class:
public class Test
{
public string Message { get; set; }
}
You can put this class into a DLL project (Tools) and reference it from other projects, like a WinForms project ProjectA and a console project ProjectB.
In both projects, you can write something like:
Test t = new Test() { Message = "Hello" };
That creates a new instance of the Test class, but the two running applications ProjectA and ProjectB do not exchange the data! They are completely separated.
The same is true for class properties.
You can't share information between two different applications so easily. Static properties only share data within the same Application Domain, that is in most simple constellations within the same Windows process.
If you want to transfer data between two different processes, you need to use an explicit mechanism for interprocess communication.
When is this line executed?
_cardOwner = System.Text.Encoding.ASCII.GetString(bCardOwner);
You'll need to put that in a method and call that method (and knowing when the call happens will help you understand why _cardOwner is not set:
public static void Init()
{
_cardOwner = System.Text.Encoding.ASCII.GetString(bCardOwner);
}
Then call this method somewhere that you know will be executed before you need _cardOwner:
Transmit.Program.Init();
string cardOwner = Transmit.Program.CardOwner;
tb_cardholder.Text = cardOwner;
I'm currently trying to load and use the Gephi Toolkit from within a .Net 4 C# website.
I have a version of the toolkit jar file compiled against the IKVM virtual machine, which works as expected from a command line application using the following code:
var controller = (ProjectController)Lookup.getDefault().lookup(typeof(ProjectController));
controller.closeCurrentProject();
controller.newProject();
var project = controller.getCurrentProject();
var workspace = controller.getCurrentWorkspace();
The three instances are correctly instantiated in a form similar to org.gephi.project.impl.ProjectControllerImpl#8ddb93.
If however I run the exact same code, with the exact same using statements & references, the very first line loading the ProjectController instance returns null.
I have tried a couple of solutions
Firstly, I have tried ignoring the Lookup.getDefault().lookup(type) call, instead trying to create my own instances:
var controller = new ProjectControllerImpl();
controller.closeCurrentProject();
controller.newProject();
var project = controller.getCurrentProject();
var workspace = controller.getCurrentWorkspace();
This fails at the line controller.newProject();, I think because internally (using reflector) the same Lookup.getDefault().lookup(type) is used in a constructor, returns null and then throws an exception.
Secondly, from here: Lookup in Jython (and Gephi) I have tried to set the %CLASSPATH% to the location of both the toolkit JAR and DLL files.
Is there a reason why the Lookup.getDefault().lookup(type) would not work in a web environment? I'm not a Java developer, so I am a bit out of my depth with the Java side of this.
I would have thought it possible to create all of the instances myself, but haven't been able to find a way to do so.
I also cannot find a way of seeing why the ProjectController load returned null. No exception is thrown, and unless I'm being very dumb, there doesn't appear to be a method to see the result of the attempted load.
Update - Answer
Based on the answer from Jeroen Frijters, I resolved the issue like this:
public class Global : System.Web.HttpApplication
{
public Global()
{
var assembly = Assembly.LoadFrom(Path.Combine(root, "gephi-toolkit.dll"));
var acl = new AssemblyClassLoader(assembly);
java.lang.Thread.currentThread().setContextClassLoader(new MySystemClassLoader(acl));
}
}
internal class MySystemClassLoader : ClassLoader
{
public MySystemClassLoader(ClassLoader parent)
: base(new AppDomainAssemblyClassLoader(typeof(MySystemClassLoader).Assembly))
{ }
}
The code ikvm.runtime.Startup.addBootClassPathAssemby() didn't seem to work for me, but from the provided link, I was able to find a solution that seems to work in all instances.
This is a Java class loader issue. In a command line app your main executable functions as the system class loader and knows how to load assembly dependencies, but in a web process there is no main executable so that system class loader doesn't know how to load anything useful.
One of the solutions is to call ikvm.runtime.Startup.addBootClassPathAssemby() to add the relevant assemblies to the boot class loader.
For more on IKVM class loading issues see http://sourceforge.net/apps/mediawiki/ikvm/index.php?title=ClassLoader
I have created a fairly simple Activity in Mono for Android project:
[Activity(Label = "AndroidApplication1", MainLauncher = true, Icon = "#drawable/icon")]
public class Activity1 : Activity
{
private string value = "intitial";
[Export]
public string GetString()
{
return value;
}
[Export]
public void SetString(string newValue)
{
value = newValue;
}
}
The activity should only serve as a proof-of-concept, hence its simplicity. Now, I'd like to be able to call the method GetString() from the "normal", Java-based Android application.
In Xamarin's docs, I've read about Java to Managed interop, which seems to be exactly what I'm looking for. If I understand it correctly, when Mono for Android app compiles, it generates Java classes that are referred to as Android Callable Wrappers (ACW). I should be then able to call methods on these ACWs from Java-based Android application.
The question is, how exactly do I reference compiled Mono for Android application (the apk file) from the Java-based Android app?
This is where I'm now stuck and was unable to find any concrete examples. There are similar questions here on SO (this one and this one) and some blogposts, but they just boil down to "use ACWs". But how exactly? Maybe I am missing something obvious here, being no Android guy.
What I've tried is to dynamically load the dex file that I yanked from my Mono for Android apk. I've simply put it on the storage card and then tried to use DexClassLoader from Java-based Android app to load it (I've followed this blog post). The ACW class was found, but when I tried to create its instance, I got the following error:
No implementation found for native Lmno/android/Runtime;.register (Ljava/lang/String;Ljava/lang/Class;Ljava/lang/String;)
I suppose that I have to somehow include Mono for Android runtime to the Java-based app, but I have no idea how.
EDIT:
This is the code I am trying to load the dex with:
DexClassLoader cl = new DexClassLoader(dexInternalStoragePath.getAbsolutePath(),
optimizedDexOutputPath.getAbsolutePath(),
null,
getClassLoader());
try {
Class<?> classActivity1 = cl.loadClass("androidapplication1.Activity1");
// the following line throws the exception
Object a = classActivity1.newInstance();
Method getStringMethod = classActivity1.getMethod("GetString");
Object result = getStringMethod.invoke(angel);
result = null;
} catch (Exception e) {
e.printStackTrace();
}
EDIT2:
I am now reading here that it should be possible to directly start activities written in Mono for Android from Java. It is still not clear to me how to reference the Mono for Android from Java and Googling yields no relevant hits. Really stumped now.
If I'm understanding correctly what you're trying to do, this isn't really possible. As the error message you got implies, an Activity within a Mono for Android application relies on the Mono runtime in order to function properly. The callable wrapper isn't useful on its own in this case, since it's just a thin Java wrapper class that calls into the Mono runtime. You can actually see the generated callable wrappers yourself if you look in the obj/Debug/android/src folder after you build your project. For example:
package androidapplication9;
public class Activity1
extends android.app.Activity
implements
mono.android.IGCUserPeer
{
static final String __md_methods;
static {
__md_methods =
"n_onCreate:(Landroid/os/Bundle;)V:GetOnCreate_Landroid_os_Bundle_Handler\n" +
"";
mono.android.Runtime.register ("AndroidApplication9.Activity1, AndroidApplication9, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null", Activity1.class, __md_methods);
}
public Activity1 ()
{
super ();
if (getClass () == Activity1.class)
mono.android.TypeManager.Activate ("AndroidApplication9.Activity1, AndroidApplication9, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null", "", this, new java.lang.Object[] { });
}
public void onCreate (android.os.Bundle p0)
{
n_onCreate (p0);
}
private native void n_onCreate (android.os.Bundle p0);
java.util.ArrayList refList;
public void monodroidAddReference (java.lang.Object obj)
{
if (refList == null)
refList = new java.util.ArrayList ();
refList.add (obj);
}
public void monodroidClearReferences ()
{
if (refList != null)
refList.clear ();
}
}
That said, due to the way Android works, you could have a Java application start an activity that is defined in a Mono for Android application in the same way you'd start an external Java activity. This relies on both applications being installed, of course, but would result in the Mono for Android application and Mono runtime actually starting up to run that activity.
Edit
Updating to answer the questions you posed in your comment. The ExportAttribute basically just gives you some more control in how the ACW gets generated, allowing you to specify that a particular method or field should be present in the ACW and what name it should have. This can be useful when you want to use things like an android:onClick attribute in a layout, for example, where by default the ACW wouldn't contain the method you want to reference.
You can't get much use out of an ACW outside of the context of a Mono for Android application since the Mono runtime wouldn't be present. Code written in C# is executed on top of the Mono runtime, and not translated into Java behind the scenes during compilation or anything like that. At runtime there are then two runtimes going side by side, Dalvik (Android's runtime) and Mono, and the callable wrappers are there to allow the two to communicate back and forth. Because of that, even a Mono for Android class library would still depend on the Mono runtime, so you cannot use it independently of that runtime.
This diagram shows what the architecture looks like, and how the runtimes relate to each other:
Hope this helps clear things up!