I'm trying to capture keypress events anywhere in my WPF application, regardless of which UI element has the focus. Currently I'm having no luck. Can anyone suggest some strategies that I might not have tried? Or, ideally, provide an answer like "oh that's easy, you just do this".
It's a distributed application, which has a chat system. The effect that I'm looking for is that the user can start typing a chat message at any time, without switching to a standard chat box. I'll display their message in the application myself, using FormattedText objects. This is important because it means there are no text input elements in the application anywhere.
My XAML structure looks roughly like:
<MainWindow>
<Canvas 1>
<Canvas 2>
<Image 1 />
</Canvas 2>
<Image 2 />
</Canvas 1>
</MainWindow>
I programmatically add elements into Canvas 2, and manipulate Image 2, which is why it has that structure.
I've tried adding KeyDown, KeyUp and the Preview events to MainWindow and Canvas 1, but none of them seem to fire (I check with breakpoints). I've also, after reading another related question here, tried manually setting the focus on the main window in the Loaded() method.
I realise there are many related questions on this site, but they haven't helped me because:
there aren't any answers (will my question be answered?)
they assume a text entry widget and are interested in bubbling up events
they want a keybinding for a small number of keys - I would like to capture any key
they are interested in detecting if a control/shift/alt key is down after they've already captured the event
Thank you for taking the time to read my long winded post, and thank you for suggestions.
Update (After Rachel's comment) When I put in a TextBox and set the focus to the TextBox, a key event method at the MainWindow level will fire. So that works as advertised.
However, I would really like to not have an explicit text entry widget in the application at all. I would like the user to be able to just start typing to compose a message.
A little bit of tinkering got me this:
XAML:
<Window x:Class="KeyInput.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="100" Width="225">
<Canvas>
<Grid>
<Label Name="test" Content="Empty" />
</Grid>
</Canvas>
</Window>
CS:
using System.Windows;
using System.Windows.Input;
namespace KeyInput
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.KeyDown += new KeyEventHandler(OnButtonKeyDown);
}
private void OnButtonKeyDown(object sender, KeyEventArgs e)
{
test.Content = test.Content + e.Key.ToString();
}
}
}
This prints out stuff like "Shift" So you'd obviously have to use switches... but it has a Text Box that collects key presses.
I managed to work it out, inspired by answers from Rachel and WernerCD. As they both demonstrated, having the event capture at the MainWindow level does work. The problem was that I neglected to mention that I had a dialog before the MainWindow loaded, which seems to interfere with normal keyboard focus on the MainWindow. Putting explicit Keyboard.focus() in the Loaded() method is too soon. I fixed the problem by putting Keyboard.focus() in the MainWindow_ContentRendered() method.
All is now well (until the next issue anyway). Thank you for the help.
I usually add a PreviewKeyDown event to the MainWindow.
Perhaps your problem is you don't have any control that accepts keyboard focus on your application. Do you get the same results if you add a TextBox to the MainWindow and have focus set there?
Related
We have a WPF desktop application which needs to show some custom message windows. I am having trouble getting them to be read aloud properly by screen readers such as JAWS from Freedom Scientific.
I want to achieve the same behavior as when showing a system message box. For comparison, System.Windows.MessageBox.Show("my message", "My Caption); is announced by JAWS as "My caption dialog. My message. OK Button". This is perfect.
When my message windows are opened (containing only a TextBlock and OK Button), the window title is announced and the OK button is announced as having focus but the TextBlock message is not announced.
Here's a simple test application which shows the issue. Our real app has icons and other status text, of course.
<Window x:Class="Jaws_MessageBox_Test.MyMessageBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Jaws_MessageBox_Test"
mc:Ignorable="d"
Title="MyMessageBox" Height="300" Width="300">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<TextBlock x:Name="mainLabel" Grid.Row="0">Hi there, this is a test to see if JAWS will read the main textbloc when shown.</TextBlock>
<Button Grid.Row="1" Margin="5" HorizontalAlignment="Right" Padding="10,0,10,0" IsDefault="True" x:Name="closeButton" Click="closeButton_Click">_Close</Button>
</Grid>
</Window>
When I show this using:
var mb = new MyMessageBox();
mb.ShowDialog();
The screen reader announces: "MyMessageBox. Close Button" so it's not reading the TextBlock like the system message box does.
What I've found using the Windows SDK inspect and accevent tools is that
The system message box accessibility type is 'Dialog' but the WPF dialog's accessibility type is 'Window'. This might matter. There is no UI Automation Control Type of Dialog https://msdn.microsoft.com/en-us/library/ms749005(v=vs.110).aspx . Is this a bug or limitation in WPF perhaps?
I have tried setting various 'AutomationProperties' attached properties on my window so that the AutomationPeer will have better info but none of those are read when the ShowDialog runs.
Since TextBlock cannot receive input focus, there's no way to even get the text read by tabbing. I temporarily use a read-only TextBox instead to get focus but the experience is still wrong and our blind users should not have to tab around just to have a simple status message read to them.
As part of the experimenting, I also tried creating my own derived AutomationPeer for the message window but none of the Core method content is read automatically when the dialog is launched. The automation child list does have the title bar object listed as the first child whereas that's the last child for the system message box though I don't see a way to change that right now.
I'd greatly appreciate any help for creating a WPF-based custommessage box with full, proper accessibility for blind users.
You have to tell the automation API that your Window is a MessageBox.
To do that add this code to your Window
protected override AutomationPeer OnCreateAutomationPeer()
{
return new MessageBoxWindowAutomationPeer(this);
}
and add this class to your project
public class MessageBoxWindowAutomationPeer : WindowAutomationPeer
{
private const string WC_DIALOG = "#32770";
public MessageBoxWindowAutomationPeer(Window owner)
: base(owner)
{
}
protected override string GetClassNameCore()
{
return WC_DIALOG;
}
protected override string GetLocalizedControlTypeCore()
{
return "Dialogfeld";
}
protected override bool IsContentElementCore()
{
return true;
}
protected override bool IsControlElementCore()
{
return true;
}
}
As we don't need localization in our app "DialogFeld" is the german localized control type. Localizing that one is the part you would have to find out by yourself. ;-)
Set the AutomationProperties.HelpText on the run inside the Textblock
So for Example:
<TextBlock>
<Run Text="aTextString" AutomationProperties.HelpText="ATextString"/>
</TextBlock>
or
<TextBlock>
<Run Text="aTextString" AutomationProperties.HelpText="{Binding Text, RelativeSource={RelativeSource self}}"/>
</TextBlock>
OK from reading around the problem is with Jaws not WPF, as it tends not to read static text on Labels and TextBlocks - strange behaviour.
A workaround might be to use a TextBox, set the BorderStyle = None and place a rectangle on top of it, with fill = White, Opacity = 0.01. This will stop the user being able to focus on the TextBox and means the text will not be static and Jaws should read the text automatically . . .
One thing, does it have to be Jaws that reads the Dialogs that your App pops up?
Have you looked at using system.speech.synthesis.speechsynthesizer to speak the text when the dialog pops up - just a thought!
I don't know if this is correct solution but this works as required on JAWS 18.
<Window ...>
<UserControl>
<StackPanel>
<TextBlock Name="MessageText" ... />
<Button Name="OKButton" ...../>
</StackPanel>
</UserControl>
</Window>
and then focusing the button when window is loaded.
So I wrapped stackpanel inside the usercontrol element.
I have what should be a very simple desktop application I'm working on but I'm having issues doing a few basic tasks. I'm using Visual Studio 2013.
I have created a project from a blank WPF template. I created a new Page, named Page1.xaml, to go along with the default MainWindow.xaml Window.
In my MainWindow.xaml window I have Grid and inside the grid is an Image.
<Grid MouseDown="Grid_MouseDown_1" Cursor="Hand" >
<Image Name="ImageIntro" Source="images/Stories-intro.jpg" Stretch="None" />
</Grid>
The Grid has a MouseDown event so that I can detect when a user clicks anywhere inside the Grid.
private void Grid_MouseDown_1(object sender, MouseButtonEventArgs e)
{
}
Pretty basic and that all works and compiles as intended.
The issue I have is that I'm unable to load the Page1.xaml inside my window on MainWindow.xaml. I don't want to open a separate window, I just want the content on Page1.xaml to be displayed inside the visible window of MainWindow.xaml.
I tried using the following but I get an error when I click the on my link: An unhandled exception of type 'System.NullReferenceException' occurred
private void Grid_MouseDown_1(object sender, MouseButtonEventArgs e)
{
Uri uri = new Uri("Page1.xaml", UriKind.Relative);
NavigationService ns = NavigationService.GetNavigationService(this);
ns.Navigate(uri);
}
This is not a browser application, it's simply a desktop application. The first screen (MainWindow.xaml) should just click thru to display the second screen (Page1.xaml).
I want the Page1.xaml content to take up the entire Window of MainWindow.xaml (sorry, but I can't stress that enough, I don't want a frame or any content from MainWindow.xaml showing when the user is on Page1.xaml).
I'm pretty new to Desktop apps but I have extensive knowledge with .Net C# for web applications. I'm not against changing the flow of what I have if there's a better way to accomplish this. For example, perhaps I shouldn't be using a Window to Page navigation and should instead use a Window to Window or something else.
I would imagine this would be a relatively simple task, but I haven't found anything that works yet so hopefully someone on here can explain it.
create a frame in Main Window
then in your event hander
Page1 mypage=new Page1();//object of the page 1
frame.Navigate(mypage);//pass it to frame navigate method
Read this MSDN link, the requirements for that to work say that this (in your code) must be a Frame. I don't see any XAML code here, but I'm guessing this is a Window. You need a frame to host the navigation, so your MainWindow should probably just the frame, and the contents of your current window should be "Page0".
Thanks Everyone who helped, here is the solution I used (I wanted to make sure a code example was here for anyone who has this same issue in the future).
I added a Frame to my MainWindow.xaml page:
<Grid MouseDown="Grid_MouseDown_1" Cursor="Hand" >
<Image Name="ImageIntro" Source="images/Stories-intro.jpg" Stretch="None" />
<Frame Name="Frame1" Content="" HorizontalAlignment="Left" VerticalAlignment="Top"/>
</Grid>
Then I added the following to my event:
private void Grid_MouseDown_1(object sender, MouseButtonEventArgs e)
{
Page1 mypage = new Page1();
Frame1.Navigate(mypage);
}
This allowed me to click on my link and the new page, Page1.xaml appeared. There was also a navigation bar that appeared at the top and the content didn't completely take up the MainWindow.xaml window but I think I can fiddle around with the settings and get it to where I want it.
Much thanks to Filippo B, Nauman Ahmad, and CodingGorilla for the assist.
I'm having a WPF application which I can minimize to tray. When I normal-click it, the window shows again.
Now I'm wondering how to create a simple ContextMenu?
The ContextMenu has to get filled with x options which onclick will run a function. For now I just need an 'Exit'-item linked to an 'Exit_Click' method.
Something I've tried is:
ContextMenu menu = (ContextMenu)this.FindResource("NotifierContextMenu");
menu.IsOpen = true;
menu doesn't know of any IsOpen value.
Other examples like to use a lot of different things. One of them requires me to create a HostManager for some reason.
I just need a simple ContextMenu. How can I achieve this?
As #H.B. mentioned Hardcodet's NotifyIcon is pretty darn good for WPF Taskbar icons. Sucks you don't get that out of the box with WPF but you might as well use it and address your issue than wait for Microsoft to fix it(They really should just add that library into standards)
Now to solve your issue(Using above solution):
Download the solution
Build the library
Add it to your source control if you have one and add a reference to it(Hardcodet.Wpf.TaskbarNotification.dll) in your project
Now in your MainWindow.xaml you could just have something like:
<Window ...
xmlns:tb="http://www.hardcodet.net/taskbar"
...>
...
<Grid>
<tb:TaskbarIcon>
<tb:TaskbarIcon.ContextMenu>
<ContextMenu>
<MenuItem Click="Exit_Click"
Header="Exit" />
</ContextMenu>
</tb:TaskbarIcon.ContextMenu>
</tb:TaskbarIcon>
...
</Grid>
</Window>
and MainWindow.xaml.cs with the click handler like you needed:
private void Exit_Click(object sender, RoutedEventArgs e) {
Application.Current.Shutdown();
}
I do recommend spending some time looking at the examples coming with the source code of the library to familiarize yourself with your available options. Trust me wpf has it way too easy when it comes to helper libraries. Try some of qt helper libraries and you'll know what "buried in there somewhere" literally means in opensource helpers.
I am trying to migrate an existing Winforms project into WPF. However: there are some user controls I need to leave as WinForm controls.
I have added a WinForms UserControl into a WPF Window. It consists of a RichTextBox and some buttons and labels. This is subclassed into various further user controls.
When I embed the UserControl into a WPF window it renders - but none of the buttons appear to do anything. When underlying processes update e.g. the RichTextBox it does not display the content. Yet when I inspect the textbox in debug I can see the content (though I have to click on 'base' to see this.)
[ One difference I have spotted - though it may not be relevant - is that when this control is on a WPF and non-working Visual Studio shows the object as 'sealed' but when in the original Winforms project when it is fully working it does not show as sealed. ]
I have added code to change the text in the labels - and they also firmly refuse to update: yet again I can see the text if I examine the label in debug mode.
This stack overflow question may address the same issue:
WindowsFormsHost Winform pdfviewer control problem
but the answer didn't make a lot of sense to me:
It mentioned replacing
new Window { Content = CreateContent(), Title = title }.Show();
But this is not a piece of code I recognise: I am using a xaml file with code behind and it's called up using
System.Windows.Application app = new System.Windows.Application();
app.Run(new FormWPFApp());
(where FormWPFApp is my name for the WPF window)
Here is the xaml header:-
<Window x:Class="ZedApp.FormWPFApp"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Printers="clr-namespace:ZedApp.UserControls.Printers"
xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
Title="Conversion version" Height="661" Width="1559" Loaded="Window_Loaded">
Here is the xaml I use for the two UserControls (they both inherit from the same base class) :-
<WindowsFormsHost Height="430" HorizontalAlignment="Left" Margin="192,32,0,0" Name="windowsFormsHostTicketPrinter" VerticalAlignment="Top" Width="324" Grid.Row="1" Grid.Column="1">
<Printers:TicketPrinter x:Name="ticketPrinter">
</Printers:TicketPrinter>
</WindowsFormsHost>
<WindowsFormsHost Height="430" HorizontalAlignment="Left" Margin="522,32,0,0" Name="windowsFormsHostJournalPrinter" VerticalAlignment="Top" Width="324" Grid.Row="1" Grid.Column="1">
<Printers:JournalPrinter x:Name="journalPrinter">
</Printers:JournalPrinter>
</WindowsFormsHost>
[Another thing I have noticed is a method that clears the Rich Text Box on one of the windows starts kicking out errors of the following type if run under WindowsFormsHost in WPF -
"Invoke or BeginInvoke cannot be called on a control until the window handle has been created."
private void ClearRichTextBox(RichTextBox rtbToClear)
{
if (rtbToClear.IsHandleCreated)
{
if (rtbToClear.InvokeRequired)
{
this.Invoke(new Action<RichTextBox>(ClearRichTextBox), new object[] {rtbToClear});
return;
}
rtbToClear.Clear();
}
}
]
What is the likely cause of this behaviour and what do I need to do to get the elements within the User Control working?
Proper input interop with WinForms requires some cooperation between the host and the WPF input system. The topic Message Loops Between Win32 and WPF in the SDK explains this well. In your setup, the easiest way to make this happen is to use code like this:
Window w = new Window1();
System.Windows.Forms.Integration.ElementHost.EnableModelessKeyboardInterop(w);
w.Show();
ElementHost.EnableModelessKeyboardInterop() essentially registers an input hook with the WinForms Application object (which normally runs the message loop) and calls ComponentDispatcher.RaiseThreadMessage().
I've been pounding away at this issue for a little while, and have only found part of the solution.
I'm trying to set up a TabControl so that I can in some cases prevent the user from changing the currently selected tab. When the user is prevented from changing the currently selected tab, then they are shown a dialog box.
I have already read the following documents:
WPF - reset ListBox scroll position when ItemsSource changes
http://wizardsofsmart.net/uncategorized/itemssourcechanged-event-using-attached-dependency-properties/
http://joshsmithonwpf.wordpress.com/2009/09/04/how-to-prevent-a-tabitem-from-being-selected/
http://social.expression.microsoft.com/Forums/en-US/wpf/thread/f7b46018-1e97-4bbe-ada8-49b75dbc1da2/
I have implemented the solution indicated in the 3rd link (though all of the above create the same error seen below). And it works, but...
Things mess up thoroughly if the user does the following:
attempts to change the tab when such an action is disallowed. The MessageBox pops up with the error.
the user clicks "OK" and is returned to the original window.
the user tries again to change the tab. No MessageBox appears.
if the user minimizes the window, and then maximizes it again, then the MessageBox that was supposed to appear earlier appears.
the user clicks "OK" and is returned to the original window... but the tab has been changed to the one they selected before, even though they should not be able to change tabs.
This is obviously not ideal behavior. Why isn't the MessageBox appearing the second time, and why is the tab changing when it should be disallowed from doing so?
If I remove the MessageBox part, it works fine.
Here is the code for the TabControl.SelectionChanged event handler:
bool _isChanging = false;
private void tabControlForNavigation_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (!_isChanging && canChangeTabs.IsChecked.HasValue)
{
_isChanging = true;
bool canLeave = canChangeTabs.IsChecked.Value; //normally this would be replaced by a check in the ViewModel
if (!canLeave)
{
int prevIndex = tabControlForNavigation.Items.IndexOf(tabControlForNavigation.SelectedContent);
tabControlForNavigation.SelectedIndex = prevIndex;
MessageBox.Show("Can't change tabs!"); //if I comment out this line, everything works fine.
}
_isChanging = false;
}
}
I am using MVVM to implement this. The Window looks like this:
<Window x:Class="TestTabControlSwitching.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow"
Height="350"
Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<CheckBox x:Name="canChangeTabs"
Content="Can Change Tabs"
IsChecked="True" />
<TabControl x:Name="tabControlForNavigation"
Grid.Row="1"
IsSynchronizedWithCurrentItem="True"
ItemsSource="{Binding Collection}"
SelectedItem="{Binding SelectedItem}"
SelectionChanged="tabControlForNavigation_SelectionChanged"
Margin="4"
HorizontalAlignment="Stretch">
<TabControl.ItemTemplate>
<DataTemplate>
<ContentPresenter Content="{Binding Path=Name}" />
</DataTemplate>
</TabControl.ItemTemplate>
</TabControl>
</Grid>
I'm omitting the rest of the code for sake of brevity- there is a pretty straight-forward ViewModel structure backing the window.
As you noticed, the problem is the MessageBox inside the event handler. The focus will change to the MessageBox and you can get all kind of undesired effects. I've had my own problems with this.
Here is a couple of SO question on the same subject
WPF: Does MessageBox Break PreviewMouseDown?
Wpf stop routing event when MessageBox appear?
If you must display a message to the user then an alternate approach might be to create a new Window which you style like a MessageBox and then call Show (not ShowDialog) on it inside the event handler.
I know this post is a bit old, but I have a very easy way to accomplish this:
Use the tab_Enter event and create a method that performs your check and displays a MessageBox to the user and then set myTabs.SelectedIndex to the prior index. A simple example:
private void someTab_Enter(object sender, EventArgs e)
{
if (myCondition)
{
MessageBox.Show("Sorry, myCondition will not let you move to this tab.");
myTabs.SelectedIndex = someOtherTabIndex;
}
}
This was a very detailed question. I had the same problem you had (i.e. the message box doesn't display on 2nd or 3rd selection changed until you minimize and maximize the window) and after much debugging and multiple google searches, stumbled on the below linked MSDN forum post.
[TabControl SelectionChanged Strange Behaviour?]
Please ignore the poorly formatted question and answer. But as mentioned in the answer, putting it inside a dispatcher and focussing the selected tab after setting the index resolved the issue for me.
You are missing an easy trick. Just make focusable=False for the Tab header.
<TabItem Header="MY TAB" Focusable="False">
You could bind this property to your view model.
<TabItem Header="MY TAB" Focusable="{Binding Bool_CanHasCheeseBurger}">