I need to restore the state after the back button is pressed. I'm currently doing this:
<ListView Name="listView" ItemsSource="{Binding MyItems}" Loaded="ListView_Loaded" />
private async void ListView_Loaded(object sender, RoutedEventArgs e) {
await Task.Delay(100);
listView.ScrollIntoView(myItem);
}
When I skip Task.Delay the ScrollIntoView call is ignored because the placeholder for myItem is not initialized yet.
Which ListView event I need to subscribe to instead?
Why not call this inside OnNavigatedTo function of page.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
listView.ScrollIntoView(listView.Items[0]);
}
Related
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
This is a test program. I just created a simple Windows application form with one button, and if the button is clicked, I need it to do something. So, I wrote my code as:
IWebDriver driver;
public Form1()
{
InitializeComponent();
}
public void SetupTest()
{
driver = new FirefoxDriver();
}
private void button1_Click(object sender, EventArgs e)
{
driver.Navigate().GoToUrl("webaddress");
driver.FindElement(By.TagName("Atlast")).Click();
Thread.Sleep(5000);
}
I have included all of the dependencies (both code and references), but I am getting the following error when I click the button:
Object reference not set to an instance of an object. in driver.navigate part of my code..
What mistake did I make here? Can anyone please help me out with this?
private void button1_Click(object sender, EventArgs e)
{
SetupTest()
driver.Navigate().GoToUrl("webaddress");
driver.FindElement(By.TagName("Atlast")).Click();
Thread.Sleep(5000);
}
You need to be calling SetupTest in your button click code. Why? This is where you are creating your new instance of the IWebDriver, therefore it needs to be called otherwise any references to driver will simply refer to null (by default).
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.
Hi how can i bind to this observablecollection
(Mainpage.xaml.cs)
public ObservableCollection tabs = new ObservableCollection();
in xaml? I've tried
(Mainpage.xaml)
But without any luck
a common pattern would be to set a DataContext in you loaded event, assuming you want to bind it to a TabControl called tabs_control on your page:
public MainPage()
{
InitializeComponent();
Loaded += OnLoaded;
}
protected void OnLoaded(object sender, RoutedEventArgs e)
{
//Initialize tabs collection
tab_control.ItemsSource = tabs;
}
Obviously you should substitute the actually control you want to bind to.
EDIT
Base on your comments, what you could do is just setup the control to be the data context, then your XAML binding should work. so instead of above you would do this:
protected void OnLoaded(obejct sender, RoutedEventArgs e)
{
this.DataContext = this;
}
then in your XAMl you could do this:
<TabControl ItemsSource={Binding tabs} ... />
Use WPF's binding syntax for XAML.
<YourControl ItemSource="{Binding tabs} />
You also need to set the DataContext of the top level control (grid, canvas etc) to be a type that owns the tabs collection (that type in the case you didn't rename your window's class, would be Window1.
So, for example, combining that with the XAML fragment above:
<Grid DataContext="Window1">
....
....
<YourControl ItemSource="{Binding tabs} />
....
....
</Grid>