I'm loading user images using Silverlight 3.
Everything works fine and I can set the file stream to a BitmapImage and it gets rendered OK.
The problem is that if I try to load something that's not an image (like a .exe that's been renamed to .png) Silverlight crashes with a System.Exception that says "Catastrophic failure".
The MSDN documentation unhelpfully says that it should be so there msdn link and I should listen to the ImageFailed event (which never gets fired).
Am I missing something there or is the library broken when loading from a stream?
The code I've got loading the image from the source:
var openFileDialog = new OpenFileDialog();
openFileDialog.Filter = "*.jpg;*.jpeg;*.png|*.jpg;*.jpeg;*.png";
openFileDialog.Multiselect = false;
var showDialog = openFileDialog.ShowDialog();
if (showDialog.HasValue && showDialog.Value)
{
using (var reader = openFileDialog.File.OpenRead())
{
var picture = new BitmapImage();
picture.DownloadProgress += (o, e) => System.Threading.SynchronizationContext.Current.Send((oo) => System.Windows.Browser.HtmlPage.Window.Alert("Download progress: " + e.Progress), null);
picture.ImageFailed += (o, e) => System.Threading.SynchronizationContext.Current.Send((oo) => System.Windows.Browser.HtmlPage.Window.Alert("Image failed: " + e.ErrorException), null);
picture.ImageOpened += (o, e) => System.Threading.SynchronizationContext.Current.Send((oo) => System.Windows.Browser.HtmlPage.Window.Alert("Image opened: " + e.OriginalSource), null);
picture.SetSource(reader); // BANG! here without any of the alerts showing up
}
}
That's weird, but you're right, it does behave that way, even on Silverlight 4.
There may be a better option, but one way I've found to work around these exceptions that can't otherwise be handled is to modify the App.Application_UnhandledException() method. This would work for you:
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
// Handle stupid image load exception. Can't think of a better way to do it -- sorry.
if (e.ExceptionObject is System.Exception && e.ExceptionObject.Message.Contains("HRESULT") && e.ExceptionObject.Message.Contains("E_UNEXPECTED"))
{
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
MessageBox.Show("Error loading image.");
});
e.Handled = true;
return;
}
// If the app is running outside of the debugger then report the exception using
// the browser's exception mechanism. On IE this will display it a yellow alert
// icon in the status bar and Firefox will display a script error.
if (!System.Diagnostics.Debugger.IsAttached)
{
// NOTE: This will allow the application to continue running after an exception has been thrown
// but not handled.
// For production applications this error handling should be replaced with something that will
// report the error to the website and stop the application.
e.Handled = true;
Deployment.Current.Dispatcher.BeginInvoke(delegate { ReportErrorToDOM(e); });
}
}
It's a hack and I don't like it, but it's better than an unhandled exception.
BTW, you really ought to file a Connect bug on this behavior. It quite certainly fails the "Law of Least Astonishment". See Tim Heuer's post on how to get the bug filed: http://timheuer.com/blog/archive/2010/05/03/ways-to-give-feedback-on-silverlight.aspx
Related
I am trying to create a software in WPF which hosts a browser (WebView2 currently 1.0.818.41) and also show a OnScreenKeyboard when there is a input field focused in the browser.
I have done this kind of stuff with CefSharp in WPF before but I cannot do it with WebView2 currently. My problem is I do not find a way to send keystrokes from the OnScreenKeyboard (or from the WPF Window) to the Browser.
In CefSharp there we have a function called ChromiumWebBrowser.GetHost().SendKeyEvent() but I cannot find something similar in WebView2.
Am I blind or is this something which is currently not implemented (or maybe not planed)?
Thank you in advance!
There is no direct way. What can be done is execute some JS, which in turn posts a message to WebView. This message can then be caught back in wv2_WebMessageReceived event.
There is extensive documentation on the interop between.NET and JS and interop between JS and .NET WPF Forms here.
A solution would be to inject a sendMessage JS function in the NavigationStarting event:
private void wv2_NavigationStarting(Microsoft.UI.Xaml.Controls.WebView2 sender, Microsoft.Web.WebView2.Core.CoreWebView2NavigationStartingEventArgs args){
var sc = "function sendMessage(txt) { window.chrome.webview.postMessage(txt); }";
wv2.CoreWebView2.AddScriptToExecuteOnDocumentCreatedAsync(sc);
}
Now you collect input fields and add onfocus and onblur events to these input fields for example in the NavigationCompleted event like this:
private void wv2_NavigationCompleted(Microsoft.UI.Xaml.Controls.WebView2 sender, Microsoft.Web.WebView2.Core.CoreWebView2NavigationCompletedEventArgs args){
string script = "const collection ="+
"document.getElementsByTagName(\"input\");" +
"for (let i = 0; i < collection.length; i++){" +
"collection[i].onfocus= ()=>{ sendMessage('onFocus('+collection[i].name')'); }; " +
"collection[i].onblur= (ev)=>{ sendMessage('onBlur('+collection[i].name')'); };"+
"}";
sender.ExecuteScriptAsync(script);
}
Now catch the message in the wv2_WebMessageReceived event:
private void wv2_WebMessageReceived(Microsoft.UI.Xaml.Controls.WebView2 sender, Microsoft.Web.WebView2.Core.CoreWebView2WebMessageReceivedEventArgs args)
{
var postMess = args.TryGetWebMessageAsString();
if (postMess == "onFocus(nameOfField)" )
{
// here activate the button(keyboard)
// store the Name on focusField variable
}
if (postMess == "onBlur" && paneShown)
{
// here deactivate the button(keyboard)
// release the focusField
}
}
Now you can send a click event to the input fields:
private void btn_Clicked(Object sender, EventArgs args)
{
var script = "var field "+
"= document.getElementsByName("+focusField+");" +
" field.value+=field.value"+args.keyValue();
wv2.CoreWebView2.ExecuteScriptAsync(script);
}
wv2 is an instance of WebView2 and the code is typed directly here and not compiled. Hope you get the idea.
I'm new to automating webpage access, so forgive what is probably a remedial question. I'm using C#/Windows.Forms in a console app. I need to programmatically enter the value of an input on a webpage that I cannot modify and that is running javascript. I have successfully opened the page (triggering WebBrowser.DocumentCompleted). I set browser emulation mode to IE11 (in registry), so scripts run without errors. When DocumentCompleted() triggers, I am unable to access the document elements without first viewing the document content via MessageBox.Show(), which is clearly not acceptable for my unattended app.
What do I need to do so that my document elements are accessbile in an unattended session (so I can remove MessageBox.Show() from the code below)? Details below. Thank you.
The input HTML is:
<input class="input-class" on-keyup="handleKeyPress($key)" type="password">
My DocumentCompleted event handler is:
private static void LoginPageCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
WebBrowser wb = ((WebBrowser)sender);
var document = wb.Document;
// I'm trying to eliminate these 3 lines
var documentAsIHtmlDocument = (mshtml.IHTMLDocument)document.DomDocument;
var content = documentAsIHtmlDocument.documentElement.innerHTML;
MessageBox.Show(content);
String classname = null;
foreach (HtmlElement input in document.GetElementsByTagName("input"))
{
classname = input.GetAttribute("className");
if (classname == "input-class")
{
input.SetAttribute("value", password);
break;
}
}
}
The problem for me was that the page I'm accessing is being created by javascript. Even though documentComplete event was firing, the page was still not completely rendered. I have successfully processed the first page by waiting for the document elements to be available and if not available, doing Application.DoEvents(); in a loop until they are, so I know now that I'm on the right track.
This SO Question helped me: c# WebBrowser- How can I wait for javascript to finish running that runs when the document has finished loading?
Note that checking for DocumentComplete does not accurately indicate the availability of the document elements on a page generated by javascript. I needed to keep checking for the elements and running Application.DoEvents() until they became available (after the javascript generated them).
If the problem comes from the creation of a STAThread, necessary to instantiate the underlying Activex component of WebBrowser control, this is
a modified version of Hans Passant's code as shown in the SO Question you linked.
Tested in a Console project.
class Program
{
static void Main(string[] args)
{
NavigateURI(new Uri("[SomeUri]", UriKind.Absolute), "SomePassword");
Console.ReadLine();
}
private static string SomePassword = "SomePassword";
private static void NavigateURI(Uri url)
{
Thread thread = new Thread(() => {
WebBrowser browser = new WebBrowser();
browser.DocumentCompleted += browser_DocumentCompleted;
browser.Navigate(url);
Application.Run();
});
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
}
protected static void browser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
WebBrowser browser = ((WebBrowser)sender);
if (browser.Url == e.Url)
{
while (browser.ReadyState != WebBrowserReadyState.Complete)
{ Application.DoEvents(); }
HtmlDocument Doc = browser.Document;
if (Doc != null)
{
foreach (HtmlElement input in Doc.GetElementsByTagName("input"))
{
if (input.GetAttribute("type") == "password")
{
input.InnerText = SomePassword;
//Or
//input.SetAttribute("value", SomePassword);
break;
}
}
}
Application.ExitThread();
}
}
}
I'm trying to render some html content to a bitmap in a Windows Service.
I'm using System.Windows.Controls.WebBrowser to perform the render. The basic rendering setup works as a standalone process with a WPF window hosting the control, but as a service, at least I'm not getting the LoadCompleted events to fire.
I know that I at least need a Dispatcher or other message pump looping for this WPF control. Perhaps I'm doing it right and there are just additional tricks/incompatibilities necessary for the WebBrowser control. Here's what I've got:
I believe only one Dispatcher needs to be running and that it can run for the life of the service. I believe the Dispatcher.Run() is the actual loop itself and thus needs it's own thread which it can otherwise block. And that thread needs to be [STAThread] in this scenario. Therefore, in a relevant static constructor, I have the following:
var thread = new Thread(() =>
{
dispatcher = Dispatcher.CurrentDispatcher;
Dispatcher.Run();
});
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
where dispatcher is a static field. Again, I think there can only be one but I'm not sure if I'm supposed to be able use Dispatcher.CurrentDispatcher() from anywhere instead and get the right reference.
The rendering operation is as follows. I create, navigate, and dispose of the WebBrowser on dispatcher's thread, but event handler assignments and mres.Wait I think may all happen on the render request-handling operation. I had gotten The calling thread cannot access this object because a different thread owns it but now with this setup I don't.
WebBrowser wb = null;
var mres = new ManualResetEventSlim();
try
{
dispatcher.Invoke(() => { wb = new WebBrowser(); });
wb.LoadCompleted += (s, e) =>
{
// Not firing
};
try
{
using (var ms = new MemoryStream())
using (var sw = new StreamWriter(ms, Encoding.Unicode))
{
sw.Write(html);
sw.Flush();
ms.Seek(0, SeekOrigin.Begin);
// GO!
dispatcher.Invoke(() =>
{
try
{
wb.NavigateToStream(ms);
Debug.Assert(Dispatcher.FromThread(Thread.CurrentThread) != null);
}
catch (Exception ex)
{
// log
}
});
if (!mres.Wait(15 * 1000)) throw new TimeoutException();
}
}
catch (Exception ex)
{
// log
}
}
finally
{
dispatcher.Invoke(() => { if (wb != null) wb.Dispose(); });
}
When I run this, I get my timeout exception every time since the LoadCompleted never fires. I've tried to verify that the dispatcher is running and pumping properly. Not sure how to do that, but I hooked a few of the dispatcher's events from the static constructor and I get some printouts from that, so I think it's working.
The code does get to a wb.NavigateToStream(ms); breakpoint.
Is this bad application of Dispatcher? Is the non-firing of wb.LoadCompleted due to something else?
Thanks!
Here's a modified version of your code which works as a console app. A few points:
You need a parent window for WPF WebBrowser. It may be a hidden window like below, but it has to be physically created (i.e. have a live HWND handle). Otherwise, WB never finishes loading the document (wb.Document.readyState == "interactive"), and LoadCompleted never gets fired. I was not aware of such behavior and it is different from the WinForms version of WebBrowser control. May I ask why you picked WPF for this kind of project?
You do need to add the wb.LoadCompleted event handler on the same thread the WB control was created (the dispatcher's thread here). Internally, WPF WebBrowser is just a wrapper around apartment-threaded WebBrowser ActiveX control, which exposes its events via IConnectionPointContainer interface. The rule is, all calls to an apartment-threaded COM object must be made on (or proxied to) the thread the object was originally created on, because that's what such kind of objects expect. In that sense, IConnectionPointContainer methods are no different to other methods of WB.
A minor one, StreamWriter automatically closes the stream it's initialized with (unless explicitly told to not do so in the constructor), so there is no need to for wrapping the stream with using.
The code is ready to compile and run (it requires some extra assembly references: PresentationFramework, WindowsBase, System.Windows, System.Windows.Forms, Microsoft.mshtml).
using System;
using System.Text;
using System.Threading;
using System.Diagnostics;
using System.Windows;
using System.Windows.Threading;
using System.Windows.Controls;
using System.IO;
using System.Runtime.InteropServices;
using mshtml;
namespace ConsoleWpfApp
{
class Program
{
static Dispatcher dispatcher = null;
static ManualResetEventSlim dispatcherReady = new ManualResetEventSlim();
static void StartUIThread()
{
var thread = new Thread(() =>
{
Debug.Print("UI Thread: {0}", Thread.CurrentThread.ManagedThreadId);
try
{
dispatcher = Dispatcher.CurrentDispatcher;
dispatcherReady.Set();
Dispatcher.Run();
}
catch (Exception ex)
{
Debug.Print("UI Thread exception: {0}", ex.ToString());
}
Debug.Print("UI Thread exits");
});
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
}
static void DoWork()
{
Debug.Print("Worker Thread: {0}", Thread.CurrentThread.ManagedThreadId);
dispatcherReady.Wait(); // wait for the UI tread to initialize
var mres = new ManualResetEventSlim();
WebBrowser wb = null;
Window window = null;
try
{
var ms = new MemoryStream();
using (var sw = new StreamWriter(ms, Encoding.Unicode)) // StreamWriter automatically closes the steam
{
sw.Write("<b>Hello, World!</b>");
sw.Flush();
ms.Seek(0, SeekOrigin.Begin);
// GO!
dispatcher.Invoke(() => // could do InvokeAsync here as then we wait anyway
{
Debug.Print("Invoke Thread: {0}", Thread.CurrentThread.ManagedThreadId);
// create a hidden window with WB
window = new Window()
{
Width = 0,
Height = 0,
Visibility = System.Windows.Visibility.Hidden,
WindowStyle = WindowStyle.None,
ShowInTaskbar = false,
ShowActivated = false
};
window.Content = wb = new WebBrowser();
window.Show();
// navigate
wb.LoadCompleted += (s, e) =>
{
Debug.Print("wb.LoadCompleted fired;");
mres.Set(); // singal to the Worker thread
};
wb.NavigateToStream(ms);
});
// wait for LoadCompleted
if (!mres.Wait(5 * 1000))
throw new TimeoutException();
dispatcher.Invoke(() =>
{
// Show the HTML
Console.WriteLine(((HTMLDocument)wb.Document).documentElement.outerHTML);
});
}
}
catch (Exception ex)
{
Debug.Print(ex.ToString());
}
finally
{
dispatcher.Invoke(() =>
{
if (window != null)
window.Close();
if (wb != null)
wb.Dispose();
});
}
}
static void Main(string[] args)
{
StartUIThread();
DoWork();
dispatcher.InvokeShutdown(); // shutdown UI thread
Console.WriteLine("Work done, hit enter to exit");
Console.ReadLine();
}
}
}
Maybe the Webbrowser Control needs Desktop Interaction for rendering the content:
My feeling say that using WPF controls and in particular particulary the Webbrowser-Control (=Wrapper around the IE ActiveX control) isn't the best idea.. There are other rendering engines that might be better suited for this task: Use chrome as browser in C#?
In my wpf application, I have a menu. When I click on one of the elements of the menu, I change my screen data, which is quite a long process.
I tried to disable the main window when I do such a loading, using this method :
private void SetNavigation(MainContentTypeEnum enumVal, int id, ICheckState vm)
{
var parent = Window.GetWindow(this);
var tmpCursor = parent.Cursor;
parent.Cursor = Cursors.Wait;
parent.IsEnabled = false;
BackgroundWorker bw = new BackgroundWorker();
bw.WorkerReportsProgress = true;
bw.DoWork += (o, args) =>
{
try
{
Dispatcher d = args.Argument as Dispatcher;
d.Invoke(new Action(() =>
{
Navigation.Navigator.SetContol(enumVal, id, vm);
}));
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
};
bw.RunWorkerCompleted += (o, args) =>
{
parent.IsEnabled = true;
parent.Cursor = tmpCursor;
};
bw.RunWorkerAsync(Dispatcher.CurrentDispatcher);
}
This method works on the very first call, the form is disabled, and then enabled when data is loaded. But on next calls, it doesn't work anymore, everything freezes until the operation completes. I tried setting a breakpoint, and the method is correctly hit and executed. I don't understant why it only works one time...
Have you an idea ?
Thanks in advance!
Edit: A bit of precision: this code is part of a usercontrol, which is why I call the parent using Window.GetWindow(this);
Edit2: Setting a Thread.Sleep(1000); just before invoking the dispatcher does the job. My guess is that the parent.IsEnabled instruction is not executed quickly enough... but why ?
Edit3: Having made some timings, my data retrieval is quite quick. It seems that the problem exists on the binding phase. I set the value to the bound property, and the method returns. However, the UI still frozen for a moment after that.
After some digging into exception handling in silverlight and reading some useful blogs like this
Silverlight exception handling using WCF RIA Services and WCF Services I ended up implementing similar idea in the App.xaml.cs to show an error page and call another wcf service method to log the error to the event viewer:
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
if (!System.Diagnostics.Debugger.IsAttached)
{
var errorPage = new Error();
errorPage.Show();
string errorMsg = string.Format("{0} {1}", e.ExceptionObject.Message, e.ExceptionObject.StackTrace);
EventHandler<WriteIntoEventLogCompletedEventArgs> callback = (s, ev) =>
{
bool result = ev.Result;
};
(new ServiceProxy<ApplicationServiceClient>()).CallService<WriteIntoEventLogCompletedEventArgs>(callback, errorMsg);
e.Handled = true;
}
}
and this is what I have in Error.xaml.cs:
private void OKButton_Click(object sender, RoutedEventArgs e)
{
this.DialogResult = true;
}
that basically will close the error page when user clicks on OK.
Everything works fine most of the cases.The problem happens when one of the callbacks to the wcf service cause an exception.The error page will be shown nicely and when user clicks ok, error page will get closed. But the background is still showing the busy indicator and the original service callback is still waiting for the response.I need to somehow terminate it.
I would be appriciative if anybody could help.
Thanks,
Sil
--
Thanks a lot for your helpful reply.I used the same idea and in the original service callback method added a code to check e.Error and if it is not null,close the window(it is a child window) with the busyindicator and everything works perfect now. Thanks again. Sil
My guess is that the original service callback may be completing but in an error condition. You may need to detect the error condition and set the IsBusy property of the busyindicator back to False.
Couple of things to check
Is the original service callback atleast returning successfully? You can check this by placing a breakpoint into the original service callback method.
Have you correctly handled the error condition in your callback method. For example -
void proxy_GetUserCompleted(object sender, GetUserCompletedEventArgs e)
{
if (e.Error != null)
{
getUserResult.Text = "Error getting the user.";
}
else
{
getUserResult.Text = "User name: " + e.Result.Name + ", age: " + e.Result.Age + ", is member: " + e.Result.IsMember;
}
}
Reference - http://msdn.microsoft.com/en-us/library/cc197937(v=VS.95).aspx