I'm writing C#/XAML UWP App.
I want to handle KeyDown event for a whole page in my app. That is, no matter what specific control on the page has focus (e.g. a TextBox, a ListView, etc. ), whenever user presses a key while on that page, I want global for the whole Page KeyDown event to be fired. In theory this should be simple - subscribing to KeyDown event when the page is navigated to or loaded, for example:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
KeyDown += SettingsPage_KeyDown;
}
In practice this does't work for all the pages, even for quite simple ones and I can't understand why. I hooked up Window.Current.CoreWindow.KeyDown event which works always and properly,
but I'd like to know what's wrong with Page's KeyDown event. Obviously there may be hundredts of reasons why this doesn't work, but are there any common? I tried setting focus to page (Programmatic, Keyboard) and still
there seems to be no rule when this event works and when it doesn't.
I am using the next code in an application for Windows IoT, and it works:
public sealed partial class YourPage: Page
{
public YourPage() //Constructor
{
this.InitializeComponent();
//Add this line
Window.Current.CoreWindow.KeyDown += CoreWindow_KeyDown;
}
void CoreWindow_KeyDown(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args)
{
//todo
}
}
You could also add the KeyDown attribute in the XAML:
<Page
x:Class="WESS1.Page1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:WESS1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" KeyDown="SettingsPage_KeyDown">
And in the code behind file:
public sealed partial class SettingsPage: Page
{
public SettingsPage() //Constructor
{
this.InitializeComponent();
}
private void SettingsPage_KeyDown(object sender, KeyRoutedEventArgs e)
{
// e.g. check the value of e.Key
}
}
Related
I've been developing with codenameone for over a year, and I never ran into this problem before, I feel like I'm losing my mind. I just redesigned one part of an app I'm working on, and now the ActionListeners aren't firing. I'm attaching them to a Button and a SpanButton in the code:
ActionListener goToDoc = new ActionListener() {
String mDocId = docId;
#Override
public void actionPerformed(ActionEvent evt) {
mStateMachine.currentExpertId = mDocId;
mStateMachine.showForm("DoctorDetails", null);
}
};
name.addActionListener(goToDoc);
Util.downloadImageToStorage(mStateMachine.URL_PREFIX+"images/doctors/"+(String)value.get("doc_pic"),
"doc_post_pic_"+(String)value.get("doc_id")+".png", new Callback<Image>() {
#Override
public void onSucess(Image img) {
pic.setIcon(img.scaledWidth(mStateMachine.getProportionalWidth(.23)));
StateMachine.applyGreenBorder(pic);
pic.addActionListener(goToDoc);
pic.getParent().revalidate();
}
#Override
public void onError(Object sender, Throwable err, int errorCode, String errorMessage) {
System.out.println("Unable to download expert profile picture");
}
});
When I debug the code, the components do show that the ActionListener is attached, but the actionPerformed method is never reached, no matter how many times I click on the buttons. I experience this problem both on the simulator and on an Android device. I have yet to test on an iPhone.
Did you set a parent to be a lead component or focusable?
The reason the click event wasn't firing was because the Components weren't enabled, possibly a bug in the BUI Builder. After checking off the 'Enabled' and 'Focusable' checkboxes in the GUI Builder, and seeing they were unchecked every time I went back to that form, I just used component.setFocusable(true) and component.setEnabled(true) in the code, and it worked fine after that.
I've attached the KeyDown event to a ListView in my Win 10 UWP app. I want to make VirtualKey.Enter have a special effect, but the event is not firing for this particular key. Neither does it for Space, Arrow up or down. This I guess because the listview already has defined a special behaviour for those keys.
I'd like to override some of those keys though, or at least trigger additional actions. Even attaching events to those key with modifiers (e.g. Shift+ArrowDown) would not work because the events still are not firing.
I read that for WPF that there is a PreviewKeyDown-event which one can attach to. I can't find that event for UWP though. Are there any other options?
Stephanie's answer is a good one and it works in the general case. However, as Nilzor observed it will not work in the case of a ListView for the Enter key. For some reason the ListView handles the KeyDown event in case Enter is pressed.
A better way to handle key events when dealing with a ListView, as the question asks, is this.
private void ListView_Loaded(object sender, RoutedEventArgs e)
{
(sender as ListView).AddHandler(UIElement.KeyDownEvent, new KeyEventHandler(ListView_KeyDown), true);
}
private void ListView_KeyDown(object sender, KeyRoutedEventArgs args)
{
if (args.Key == Windows.System.VirtualKey.Enter)
{
}
}
Notice the last argument in the AddHandler function. This specifies whether we want to handle events already handled by a previous element in the visual tree.
Of course don't forget to unsubscribe from the event when appropriate
Here is one way to do it : subscribe to the global Window.Current.CoreWindow.KeyDown event.
Then save the focus state of your listview and react accordingly.
Here is the code :
public sealed partial class MainPage : Page
{
bool hasFocus = false;
public MainPage()
{
this.InitializeComponent();
Window.Current.CoreWindow.KeyDown += CoreWindow_KeyDown;
}
private void CoreWindow_KeyDown(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args)
{
if(hasFocus)
{
Debug.Write("Key down on list");
}
}
private void myList_GotFocus(object sender, RoutedEventArgs e)
{
hasFocus = true;
}
private void myList_LostFocus(object sender, RoutedEventArgs e)
{
hasFocus = false;
}
You will also need to subscribe to the focus events in xaml, for your ListView :
<ListView .... GotFocus="myList_GotFocus" LostFocus="myList_LostFocus"/>
Corcus's solution doesn't work for me. What is working is handling PreviewKeyDown directly from XAML. Works well for SPACE or ENTER key:
XAML:
<ListView PreviewKeyDown="BookmarksListView_PreviewKeyDown">
Code behind:
private void BookmarksListView_PreviewKeyDown(object sender, KeyRoutedEventArgs e)
{
if (e.Key == Windows.System.VirtualKey.Enter)
{
// DO YOUR STUFF...
e.Handled = true;
}
}
You can use AddHandler method.
private void KeyEnterEventHandler(object sender, KeyRoutedEventArgs e)
{
if (e.OriginalKey == Windows.System.VirtualKey.Enter)
{
PlayFromListView();
}
}
private void LoadListView()
{
foreach (var music in playListStorageFile.PlayList)
{
ListViewItem item = new ListViewItem();
item.AddHandler(FrameworkElement.KeyDownEvent, new KeyEventHandler(KeyEnterEventHandler), true);
TextBlock mytext = new TextBlock();
mytext.Text = music.Nro.ToString() + " - " + music.Name;
mytext.Tag = music.Nro;
item.Content = mytext;
lvMusics.Items.Add(item);
}
}
https://learn.microsoft.com/en-us/uwp/api/windows.ui.xaml.uielement.addhandler?view=winrt-18362
I have a situation where manipulation events emanating from offscreen (think bezel of surface pro) are not being registered when the app is in fullscreen mode. However, they are registering as expected when the application is "maximized" (I put that in quotes because I know it's no longer officially a "thing" to be maximized).
To reproduce, create the blank application and add the code at the end of this post.
Swipe from top down, and notice an absence of any manipulation events being fired. Now click the exit full screen button then the maximize button and repeat the experiment, and you will see that manipulation events now properly fire.
It is important to start dragging offscreen.
Is this by design? Is there a gotcha that I'm not aware of? Is it a bug?
The following Xaml file:
<Page
x:Class="EdgeSwipeDetect.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:EdgeSwipeDetect"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="Green"
ManipulationMode="TranslateInertia,TranslateY"
ManipulationStarted="Grid_ManipulationStarted"
ManipulationCompleted="Grid_ManipulationCompleted"
ManipulationDelta="Grid_ManipulationDelta" />
</Page>
Code behind:
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
CoreApplicationViewTitleBar coreTitleBar = CoreApplication.GetCurrentView().TitleBar;
coreTitleBar.ExtendViewIntoTitleBar = true;
var appView = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView();
appView.TryEnterFullScreenMode();
}
private void Grid_ManipulationStarted(object sender, ManipulationStartedRoutedEventArgs e)
{
Debug.WriteLine("ManipulationStarted");
}
private void Grid_ManipulationCompleted(object sender, ManipulationCompletedRoutedEventArgs e)
{
Debug.WriteLine("ManipulationCompleted");
}
private void Grid_ManipulationDelta(object sender, ManipulationDeltaRoutedEventArgs e)
{
Debug.WriteLine("ManipulationDelta");
}
}
I have a radgrid, for date column i have created a custom user control for filtering. I need to create a close button to close the user control. There are no close events which i can call. I don't want to make visibility collapsed. I started with something below:
public partial class DateFilterControl : UserControl, IFilteringControl
{
public event CloseEventHandler Close;
public delegate void CloseEventHandler();
private void Button_Click(object sender, RoutedEventArgs e)
{
this.Close();
}
}
It is throwing nullreference exception which is obvious to come. What code do i need to put to close the user control?
use Messaging Service. With this you can close the window in ViewModel so no need to give close function in Backend. Add Command property to Cancel button
<Button Content="Cancel" Command="{Binding CancelCommand}"/>
Now in the ViewModel add the RelayCommand property in that add
Messenger.Default.Send<bool>(true, typeof(XViewModel));
Now in the BackEnd of this userControl adds following in the constructor.
Messenger.Default.Register<bool>(this, typeof(ScheduleViewModel), (b) =>
{
if (b == true)
{
this.DialogResult = true;
}
});
Now u can close the Window...
This will surely helps u...
I have a user control
public partial class ButtonControl : UserControl
which has two controls of label and picturebox
this.pictureBox1 = new System.Windows.Forms.PictureBox();
this.text = new System.Windows.Forms.Label();
I have used this control in a windows form
this.appointmentButton = new DentalSoft.UI.Controls.ButtonControl();
created an event
this.appointmentButton.Click += new System.EventHandler(this.appointmentButton_Click);
but the problem is, if i click on the image or the label inside of the control, the click event doesn't fire.
I want to fire this click event no matter where the user clicks inside of the control. Is it possible?
Yes it is a simple matter. When you click on the child controls they receive the click event and the user control does not. So you can subscribe to the child control click events and when they occur simply raise the usercontrol click event and it will appear to click no matter where the mouse is positioned.
Just double click on the picturebox and the label to create the click event handlers then add a line of code to call the parent usercontrol OnClick method.
private void text_Click(object sender, EventArgs e)
{
this.OnClick(new EventArgs());
}
private void pictureBox1_Click(object sender, EventArgs e)
{
this.OnClick(new EventArgs());
}
I solved this problem the following way. I wanted to changes the background images of the parent PictureBox when the child Label was clicked. I played around some and found I could call the event handler in the following way.
private void Label_Click(object sender, EventArgs e)
{
Label label = (Label)sender;
Box_Click(label.Parent, e);
}
private void Box_Click(object sender, EventArgs e)
{
//
PictureBox box = sender as PictureBox;
//
if (isMine[int.Parse(box.Name)])
{
box.Image = Image.FromFile(#"..\..\images\BoxRedX.jpg");
MessageBox.Show("Game Over");
}
else
{
box.Image = Image.FromFile(#"..\..\images\BoxGray.jpg");
}
}
As you can see I grab the Child and using it to reference its parent and send it to the parents click event. This is the code I used to work in my project. The important method is the first on listed. The second is there for clarity to see how it passed and worked.