ElementHost blocks mouse events - wpf

NOTE: I AM TRYING TO SOLVE THE MOUSE ISSUE, NOT THE KEYBOARD PROBLEM, WHICH IS ALREADY SOLVED
So I am creating a Visual Studio 2015 extension, working on the Options pages.
I am using WPF, so I use ElementHost to host a UserControl. At first it wasn't receiving keyboard events, so I implemented the solution at:
WPF TextBox not accepting Input when in ElementHost in Window Forms
A quick run down of the solution:
A) on the UserControl's Loaded event, I do:
var s = HwndSource.FromVisual(this) as HwndSource;
s?.AddHook(ChildHwndSourceHook);
B) In ChildHwndSourceHook(), I do something like:
static IntPtr ChildHwndSourceHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if (msg == WM_GETDLGCODE)
{
handled = true;
return new IntPtr(DLGC_WANTCHARS | DLGC_WANTARROWS | DLGC_HASSETSEL | DLGC_WANTTAB);
}
return IntPtr.Zero;
}
HOWEVER, now mouse over events seem to be being ignored, as the cursor doesn't change when moving it over textboxes or grid splitters, not even on new Windows I create. Very occasionally, though, the mouse events do work, though, and continue to work until I move to another page or close the dialog. That's the weirdest part.
I've tried everything and have scoured Google all day, but I am no closer to understanding why clicks work fine, but mouse over events don't seem to be registered.
I did try REMOVING the message handler, then opening a Window, but it seems once the handler is added, removing it won't fix anything.
Does anyone know how I can get mouse over events to work on my controls? Thanks so much!

I've found success using the method the creator Viasfora used. You can see the code on the GitHub repo here. In particular, look at the TextObfuscationDialog and how it is hosted. I believe there might be something wrong with the VS extension documentation, because I ran into the same problem you did.
EDIT:
I've created a sample project to show this method does work (I'm using it in 2 of my own extensions right now). Hopefully this working code might make it easier for you to implement it in your own project.
You can download the source code from my OneDrive here.
The UIElementDialogPage on MSDN says:
Provides seamless hosting of Windows Presentation Foundation (WPF)
content inside a native dialog running an IsDialogMessage-style
message loop. This class enables tabbing into and out of the WPF child
window handle (HWND), and enables keyboard navigation within the WPF
child HWND.
So while an ElementHost will not function correctly within the message loop of a normal/WinForms DialogPage, the UIElementDialogPage will. There are a number of classes that have UIElement* or similar prefix - they are to help migrate the legacy code of VS from Windows Forms to WPF.

Related

Hosted Winform control does not respond to events from WPF

This is my first question in StackOverflow. Due to lack of reputations, I couldn't post any links or images.
I've been working on the following issue for more than 2 days. Any help would greatly be appreciated.
Before I get into my question, here is what I have and what I'm expecting:
I have a Windows Form which hosts WPF in an ElementHost control.
And then, I have a Winforms UserControl similar to DateTimePicker. This
is hosted inside a WindowsFormsHost control.
The above scenario is un-avoidable for the following reasons:
The authorization dialog to all our applications is developed in
Winforms, and takes a Winforms instance as its parameter. There is no
WPF version introduced yet. Therefore, I had to use an ElementHost to
host my View inside the Windows Form.
The Winforms control hosted inside my WPF is also un-avoidable. We
have our own DateTime Winforms UserControl that behaves similar to
the DateTimePicker Winforms control, but has lot more complexities
involved. So, replacing this control with a WPF version is out of
question.
Expected Functionality:
I have a
WPF control (say, a textbox)
A DateTime Winforms UserControl that I was mentioning above.
And a Cancel button that basically resets the above controls.
When I hit the Cancel button, I'm publishing an event from the ViewModel, say RunViewModel to the WPF UserControl code behind file, say RunView.xaml.cs.
eventAggregator.GetEvent<ResetDateTimeEvent>().Publish(true);
In the code behind file, I've subscribed to the event as follows
eventAggregator.GetEvent<ResetDateTimeEvent>().Subscribe(ResetDateTimeHandler);
The WPF control resets to its default value, but the DateTime UserControl does not reset.
So, for testing purposes, I removed the ElementHost control, and just had my WPF View with a WindowsFormsHost control that hosts the DateTime Winforms UserControl, and a WPF "Cancel" button.
When I click on the button, the value on the DateTime control resets to its default value.
Then, I thought this might be an issue with my DateTime Winforms UserControl.
So, I replaced my DateTime Winforms UserControl with a Winforms Textbox control in my actual application. So now the nesting is as follows:
WinForms-ElementHost-WPF-WindowsFormsHost-Winforms Textbox
Here is the xaml code.
<WindowsFormsHost x:Name="ReportFromDtTmHost" Margin="8,0" Grid.Column="0"
LostFocus="ReportFromDtTmHost_LostFocus">
<WindowsFormsHost.Child>
<winforms:TextBox x:Name="ReportFromDateTime"/>
</WindowsFormsHost.Child>
</WindowsFormsHost>
On Initial load, I’m loading the Textbox with Initial Load Text text
private void Window_Loaded(object sender, EventArgs e)
{
ReportFromDateTime.Text = "Initial Load Text";
}
As I was mentioning above, when I hit the Cancel button, this is what happens:
Publish the event from ViewModel
eventAggregator.GetEvent().Publish(true);
Subscribe to the event in the code behind file (xaml.cs):
eventAggregator.GetEvent().Subscribe(ResetDateTimeHandler);
EventHandler for the published event.
private void ResetDateTimeHandler(bool cancelClicked)
{
ReportFromDateTime.Text = "Reset to Default";
}
As you can see in the above code, I’m resetting the Text on clicking the Cancel button.
During Debugging, I could see the Text property being changed to "Reset to Default", but the UI does not show these changes.
Here is the wierd part:
The Child property on the WindowsFormsHost control is different from the actual “ReportFromDateTime” Textbox control.
While debugging, I could see that the Child and Name property on the WindowsFormsHost control were different.
The Name property is empty,
ReportFromDtTmHost.Child.Name = ""
which rather should be ReportFromDateTime.
It almost seems like the Host and the Child controls are getting re-created.
As far as I see it, I think the extra level of nesting (WinForms-ElementHost-WPF-WindowsFormsHost-Winforms Textbox) might be causing issues during the interoperations between WPF and Winforms.
I’ve done a lot of research and searched lot of links for suggestions. I found none pointing out this issue. Some of them were close. Here are a couple of links:
The this suggests to reproduce the message loop under the “Surrogate Windows Forma Message Loop” section.
Here is one more link that explains the issue with nesting under the Nesting section.
I apologize for being verbose. Just wanted you guys to get a clear picture of my problem. Please let me know if you have any questions regarding the post. Any suggestions would be greatly appreciated.
EDIT:
We were able to resolve the issue, but still, it is a work-around. Here is what we did:
There were two ways to resolve this issue, but both were related to using static.
Static Winforms control:
We used the following static Winforms control
public static class ControlHolder
{
public static TextBox ReportFromDateTimeInstance;
}
In the OnChanged event of the "actual" control, we dump the actual control, ReportFromDateTime to the static control, ReportFromDateTimeInstance.
private void ReportFromDateTime_TextChanged(object sender, EventArgs e)
{
ControlHolder.ReportFromDateTimeInstance = (TextBox)sender;
}
And from then on, wherever we update the actual control (as in ResetDateTimeHandler method), we update the static control
private void ResetDateTimeHandler(bool cancelClicked)
{
ControlHolder.ReportFromDateTimeInstance = "Text changed";
}
This shows the updated value on the Front-End
Static EventAggregator
This work-around was provided by one of our colleague.
In this case, we are using our actual control, ReportFromDateTime, rather than the static control, ControlHolder.ReportFromDateTimeInstance
We used a static event aggregator for publishing/subscribing the ResetDateTimeEvent instead of using the Event Aggregator instance provided by Unity Container. So, instead of
eventAggregator.GetEvent<ResetDateTimeEvent>.Publish(true);
we used:
ResetDateTimeEvent.Instance.Publish(true);
And in the subscription:
ResetDateTimeEvent.Instance.Subscribe(ResetDateTimeHandler);
I know that we need not use a static event aggregator in this scenario since we are using the instance provided by Unity Container (which makes sure that a single instance is shared by all the ViewModels), but this also has resolved the issue.
So, I'm still confused on why the above two scenarios are solving the problem. Is it the static-ness that is solving the issue ?
As I was already saying, I feel that the controls are getting re-created, and by the time we have the controls in hand, they have been already re-created.
Any suggestions would greatly be appreciated.
I've done the same thing before in an app that had a WPF control inside of a WinForms control. The WPF used Prism/Unity (later switched to MEF) to start everything up. However, this created a whole new EventAggregator by default in the bootstrapper, so I had override the default IEventAggregator in the container with a static one b/c the WinForm side had already been created and was using its own IEventAggregator instance. The symptom was similar in that published events were not received.
In a mixed system such as yours, singletons are great for ensuring that everything's feeding off of the same reference, especially when your startup is in stages (WinForms then WPF).
Simple answer: yes, use singletons for shared references between WinForms code and WPF code. Those singletons can be fed into the container in the WPF bootstrapper so that injection still occurs in the WPF side, too.

How to make the Windows OSK open when a TextBox gets focus, instead of requiring users to tap a keyboard icon?

We are working on a WPF application in .NET 4 that will be used with a touch screen. We are trying to use the built-in Windows OSK for our input, and the last remaining issue is to get the keyboard to open up as soon as a text box gets focus. Currently, if a text box gets focus, a small keyboard icon appears (this is the InputPanel icon) and the user has to tap that icon to make the keyboard open up.
Is there a way to skip the icon step, and just have the keyboard open up all the way on focus? Preferably something that can be set or coded in one place and apply to all text boxes globally? It also needs to use the current culture settings of the application thread (which it already appears to be doing).
I haven't been able to find anything in the control panel settings that lets you skip the icon step. I also found some examples online of using the TextInputPanel.CurrentInPlaceState, but when I implemented code to open up a TextInputPanel on preview focus of the main window, I kept getting COM INTEROP exceptions and basically hit a dead end (the Microsoft.Ink.dll is an interop DLL).
Is it possible that there is a registry key that can change the default CurrentInPlaceState to Expanded instead of HoverTarget? I haven't been able to find one in my net searching.
Thanks,
Valerie
EDIT: Here is some code that I put in the main window's code behind, as well as the exception message I keep getting - and I have no idea what it means or how to fix it (my net searches failed me!)
protected override void OnPreviewGotKeyboardFocus(KeyboardFocusChangedEventArgs e)
{
base.OnPreviewGotKeyboardFocus(e);
TextBox textbox = e.NewFocus as TextBox;
TextBox oldTextbox = e.OldFocus as TextBox;
if (oldTextbox != null && boxesToInputs.ContainsKey(oldTextbox))
{
TextInputPanel oldPanel = boxesToInputs[oldTextbox];
oldPanel.Dispose();
boxesToInputs.Remove(oldTextbox);
}
if (textbox != null)
{
// Make sure we've cleaned up old panels, just in case
if (boxesToInputs.ContainsKey(textbox))
{
boxesToInputs[textbox].Dispose();
boxesToInputs.Remove(textbox);
}
TextInputPanel newPanel = new TextInputPanel(((HwndSource)PresentationSource.FromDependencyObject(textbox)).Handle);
newPanel.DefaultInPlaceState = InPlaceState.Expanded;
newPanel.DefaultInputArea = PanelInputArea.Keyboard;
boxesToInputs[textbox] = newPanel;
}
}
And here is the exception message, which occurs when my code calls the TextInputPanel constructor:
Retrieving the COM class factory for component with CLSID {F9B189D7-228B-4F2B-8650-B97F59E02C8C} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))
I verified that the platform target of the WPF app is x86. I ran Dependency Walker and it said that the Microsoft.Ink.dll I was using was 64 bit, and that two delay-loaded dependencies were missing (GPSVC.dll and IESHIMS.dll). I found a 32 bit version of Microsoft.Ink.dll, but I am still getting the same error, and Dependency Walker is saying the same thing - GPSVC.dll and IESHIMS.dll are missing.
I can't target x64, and I'd prefer not to have to put the missing DLLs into my application folder (if that would work?). I hope there is something simple I am missing, because this is a lot of trouble to just get rid of a keyboard hint...
Any help is greatly appreciated - I am a bit of a newb when it comes to working with unmanaged/interop assemblies...
I researched for a similar propose. In my case it was to create a custom OSK. It seems that (by now) it's not possible to create a custom input device. The explanation is in this link:
http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/a813a08a-7960-45fe-bc91-e81cdb75bd10
Moreover, I found a "workaround" which uses Win32 API calls to access SendKey method, and report input independently of the target. The project that I found is:
http://wosk.codeplex.com/
SendKey is also available on WinForms (see http://msdn.microsoft.com/en-us/library/system.windows.forms.sendkeys.aspx ) but I'm not sure if it will produce the same behavior.
I'll checking these options in the following days, but perhaps some of this information might help.
Regards
Herber

WPF User Control On MFC Dialog Showing Hidden Every Once and a While

I am running into a very strange problem that I wanted to see if anyone else has seen. I have a C++ application (compile with CLR support) that has a MFC dialog which hosts a WPF user control. Every once and a while, the WPF user control will not appear when the dialog opens. The control is there as I can press a button on that user control. Obviously, I cannot see it, but the button still responds to a click event if I click the area where the button is supposed to be.
The strange part in all this is how sporadic it happens. Sometimes it happens the first time the user goes into the dialog after starting the application. Other times, it will happen after successfully going into the dialog a few times. We have deinitely not found any pattern to when it will happen. It just happens once and a while. Also, we have seen this across all different operating systems - XP, Vista and Win7.
To correct the problem, simply closing the application and relaunching it norally cures it.
In terms of the code, the standard approach for WPF user controls on MFC dialogs is being used:
// Create the initial object
System::Windows::Interop::HwndSourceParameters^ sourceParams = gcnew System::Windows::Interop::HwndSourceParameters ("BatchSelectionContainer");
sourceParams->PositionX = x;
sourceParams->PositionY = y;
sourceParams->Height = height;
sourceParams->Width = width;
sourceParams->ParentWindow = System::IntPtr(parent);
sourceParams->WindowStyle = WS_VISIBLE | WS_CHILD;
BatchSelectionDialogGlobals::gHwndSource = gcnew System::Windows::Interop::HwndSource(*sourceParams);
BatchSelectionDialogGlobals::gHwndSource->AddHook(gcnew HwndSourceHook(ChildHwndSourceHook));
// Save a reference to the new frame
BatchSelectionDialogGlobals::BatchSelectionFrame = gcnew ProteinSimple::ParticleDetection::Console::BatchSelection();
// Establish an event handler for the buttons
BatchSelectionDialogGlobals::BatchSelectionFrame->EnableExecuteButton += gcnew ProteinSimple::ParticleDetection::Console::BatchSelection::GeneralHandler(&BatchSelectionDialog::EnableExecuteButton);
BatchSelectionDialogGlobals::BatchSelectionFrame->DisableExecuteButton += gcnew ProteinSimple::ParticleDetection::Console::BatchSelection::GeneralHandler(&BatchSelectionDialog::DisableExecuteButton);
// Finalize the visual parts and return the handle
BatchSelectionDialogGlobals::gHwndSource->RootVisual = BatchSelectionDialogGlobals::BatchSelectionFrame;
return (HWND) BatchSelectionDialogGlobals::gHwndSource->Handle.ToPointer();
This is certainly a strange one. I have some of my users that have never seen it, while others it happens many times a day.
It feels like a bug in MFC in how it displays the WPF control. However, I have searched on-line and have never heard anybody describe this problem. The code is not throwing any exceptions, so I am not sure what the problem could be.
I am stumped and would appreciate any insight into the problem.
WPF doesn't draw the stuff as windows-controls as MFC or WinForms do draw - you can check it using Spy++. That's why its not possible/easy to mix WPF and MFC.

Several parts of UI are not painted

We have a very strange behaviour of a WPF application. Sometimes (not very ofen), some parts of the user interface are simply not painted.
Just recently the save button and a text box on the configuration view didn't show up. Even more strange is that after a relogin, what results in a new view instance, the problem is still present.
Sometimes it helps to hover the mouse over the position where the missing controls usually are to get them visible. But switching the tab page and then back to the original one with the missing controls they are all missing again. Other controls won't show up by hoovering the mouse over them.
Another problem is that dialogs are sometimes screwed up. Parts of the dialog are displaced vertically. But when e.g. a text box inside the dialog gets the focus, it is painted correctly while the rest of the dialog stays displaced.
I don't have the slightest clue what causes this problem. Any idea is welcome.
[Edit 1] So far we have seen this always on Windows XP. Windows 7 seems to be Ok. Also switching to Software-Rendering seems to fix the problem on Windows XP but I'm not sure on this.
The problem was solved by switching the RenderMode to SoftwareOnly. It seems to be a .NET 4 issue when running on Windows XP:
public class MyWindow : Window
{
protected void SetSoftwareRendering()
{
System.Windows.Interop.HwndSource hwndSource = PresentationSource.FromVisual( this ) as System.Windows.Interop.HwndSource;
System.Windows.Interop.HwndTarget hwndTarget = hwndSource.CompositionTarget;
hwndTarget.RenderMode = System.Windows.Interop.RenderMode.SoftwareOnly;
}
}
Alternatively one can write
System.Windows.Media.RenderOptions.ProcessRenderMode = System.Windows.Interop.RenderMode.SoftwareOnly;
All windows are inherited from MyWindow and can decide wether or not they want the software rendering. Currently we don't use this flexibility and have it enabled on all instances.
If this happens in other WPF applications too it might be your hardware, driver, OS or .NET software.
If not, the only option is to try and reproduce in a minimal case and on several machines.
Are you able to make a minimal version that has the problem en post the code?

What causes a window to not appear in the taskbar until it's Alt-Tabbed to in Vista?

When our app is started programatically (either through custom action in MSI installer or when starting a new instance) in Windows Vista (also happens in Windows 7 Beta) it won't appear in the taskbar and isn't focused. Alt-tabbing to it will make it appear in the taskbar properly and stay there.
What causes this? I've seen this in some other apps before as well, but not sure why. Out app is .NET WinForms app. Never see this happen in XP, only Vista and 7
Edit: Well, it seems like the only time this happens reproducibly is when it's run by the installer, I believe there's other times it occurs, but I might just be crazy. The launching code is a bit complex to post because we handle various command line launch parameters and it launches a signin form before actually launching the main app etc.
Has anyone had to deal with this scenario before and worked it out?
Try checking your main application form "Form Border" property.
If it's ToolWindow (Fixed or Sizable), try changing it to FixedDialog for example.
This solved the problem in my case.
The usual reason for this is that your main application window doesn't have the window styles that let Windows know it's a main application window (rather than a tool window or a dialog box). So Windows is having to guess based on how the app was started, etc.
Use Spy++ to complare the window styles (especially extended styles) if your window to that of some other window that doesn't have this problem. Are you missing the WS_EX_APPWINDOW style? Are any other styles/extended styles different from other top level windows?
G.So's answer made me find the solution for my problem, wich was caused by the fact that i had my form sizable from launch, but set to borderless in the load void.
If anyone is interested in how i managed to keep the switch to borderless and have it pop up as it should in the taskbar without any dirty hacks.. here it is..
Make a new event from the form on the form's "Shown" event, and put your line of code for switching to borderless in here. Problem solved :)
private void Form1_Shown(object sender, EventArgs e)
{
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
}
and for the lazy ones ;) >>>>
this.Shown += new EventHandler(Form1_Shown);
Thanks again G.So for clearing up what could cause this in the first place.
I stuggled with this issue as well, and found like a previous commenter said, you cannot have anything in the form's Load() event that changes that FormBorderStyle property. Move anything that changes it to the Shown() event.
Well, one solution is to use a hack like this. That's really not what it's for.
Usually the decision of whether a window will be in the taskbar or not is based on the border styles it uses. The article I linked to provides a bit more detail. The article's comment about the window having an owner or not is quite possible highly relevant to your issue, since the window might somehow be getting a different owner when launched by the installer.
That article is in VB but it's all based around API calls so the info it provides is pretty language independent.
Never see this happen in XP, only Vista and 7
Maybe it's a bug in Vista...?
What happens if you call SetForegroundWindow() (or equivalent in .Net)?
Edit
I did of course mean "BringWindowToTop()".
Or do both.
We had this same problem and fixed it by setting the form property showintaskbar property to true.
Weird that all windows os's dont run apps in the same way!
In our situation, this was tracked down to the form's text property being changed within the Load event.
After putting this inside a BeginInvoke, this odd behaviour no longer happened.
Hope this helps anyone else.
Example
private void Form_Load(object sender, EventArgs e)
{
...
...
...
// this needs to be inside a BeginInvoke otherwise it messes with the taskbar visibility
this.BeginInvoke(new Action(() =>
{
this.Text = "Something new";
}));
...
...
...
}
We encountered the same issue, also in Windows 8. Sometimes the form was receiving correctly the focus, but say just ~30% of the time.
We tried different solutions, but actually the one that worked was the following:
private void OnFormShown(object sender, EventArgs e)
{
// Tell Windows that the Form is a main application window
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
// Even if true, enforce the fact that we will the application on the taskbar
this.ShowInTaskbar = true;
// Put the window to the front and than back
this.BringToFront();
this.TopMost = true;
this.TopMost = false;
// 'Steal' the focus.
this.Activate();
}
Moreover, we ensure also not to set the title of the form during the Load event.

Resources