Develop Reference

Event recognition C# WPF

I got an Problem with Events. I got a first Window which looks like this:
using System.Windows;
namespace EventsTests
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
/*Binding Event to MainWindow
dont work until you will help*/
MainWindow mw = new MainWindow();
mw.RaiseEvent += raiseEvent_EventHandler;
}
public void raiseEvent_EventHandler()
{
MessageBox.Show("MAINWINDOW Event Fired");
}
private void Button_Click(object sender, RoutedEventArgs e)
{
SecondPage sp = new SecondPage();
sp.Show();
}
}
}
Now the seconde Page don´t do very much:
using System.Windows;
namespace EventsTests
{
/// <summary>
/// Interaction logic for SecondPage.xaml
/// </summary>
public partial class SecondPage : Window
{
SecondPageViewModel spvm = new SecondPageViewModel();
public SecondPage()
{
this.DataContext = spvm;
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
spvm.raiseEventActivate();
}
}
}
And at last I have the SecondPageViewModel:
namespace EventsTests
{
public delegate void raiseEventEventHandler();
class SecondPageViewModel
{
public event raiseEventEventHandler raiseEvent;
public void raiseEventActivate()
{
if(raiseEvent != null)
{
raiseEvent();
}
}
}
}
Now I want, when I click the button on the second page, the Event is fired an the MainWindow recognise the event.
With this code i get the Error:
Error 1 Cannot assign to 'RaiseEvent' because it is a 'method group'
Can someone help me? Or give me an example?
Thanks for every hint ;)

RaiseEvent is not your event, it's a method of the Window.
I think you want to do this:
SecondPage sp = new SecondPage();
sp.raiseEvent += raiseEvent_EventHandler;
sp.Show();
That is, register an event handler with the second page event.
Though I wouldn't advocate event handlers for this. While I don't know what you are trying to achieve I'd rather do something like pass a ViewModel object to the SecondPage and the main window can respond to state changes on that ViewModel.
In WPF, I always aim for zero code behind.
In response to discussion, how one VM could have reference to another. First pass the VM in:
SecondPageViewModel spvm;
public SecondPage(SecondPageViewModel model)
{
spvm = model;
this.DataContext = spvm;
InitializeComponent();
}
Then the SecondpageVM takes a MainVM as a paramter in the constuctor:
SecondPage sp = new SecondPage(new SecondPageViewModel(mainVM));
Updates to the main model are done within the SecondPageViewModel. The second page itself has no references to it.
ThirdPage tp = new ThirdPage(new ThirdPageViewModel(spvm))
Third page VM can access main page VM via property on second page vm: spvm.MainVm

In MainWindow you're trying to subscribe to a Window method, instead of your raiseEvent. And certainly you don't need to instantiate another MainWindow...
Your MainWindow code should be something like this:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public void raiseEventFromSecondPage_EventHandler()
{
MessageBox.Show("MAINWINDOW Event Fired");
}
private void Button_Click(object sender, RoutedEventArgs e)
{
SecondPage sp = new SecondPage();
sp.raiseEventFromSecondPage += raiseEventFromSecondPage_EventHandler();
sp.Show();
}
}
You then need that SecondPage exposes the raiseEvent. This will be a different event from the one in its ViewModel, but you'll chain both.
public partial class SecondPage : Window
{
SecondPageViewModel spvm = new SecondPageViewModel();
public event raiseEventEventHandler raiseEventFromSecondPage;
public SecondPage()
{
this.DataContext = spvm;
spvm.raiseEvent += raiseEvent_EventHandler;
InitializeComponent();
}
public void raiseEvent_EventHandler()
{
if (raiseEventFromSecondPage != null)
raiseEventFromSecondPage();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
spvm.raiseEventActivate();
}
}

Order of form_load method execution

I am creating a winforms application which uses Gmaps.net. I am unable to alter the order in which on Load methods are being called. For some reason the map_load is being called before the man_Load. Is there any way to change the order of this ?
If I can provide any more information to help just ask.
Thanks!
Dan.
public partial class main : Form
{
public main()
{
InitializeComponent();
}
private void main_Load(object sender, EventArgs e)
{
MessageBox.Show("main_load");
}
private void map_Load(object sender, EventArgs e)
{
MessageBox.Show("map_load");
}
}

It seems that you used the WinForms designer to create the map. The code behind is in the InitializeComponent() method and seems that the map is being loaded before the MainForm is loaded.
My recommendation is to create the map, once the MainForm has been loaded:
public partial class main : Form
{
public main()
{
InitializeComponent();
}
private void main_Load(object sender, EventArgs e)
{
Control map = CreateMap();
map.Docking = DockStyle.Fill;
this.Controls.Add(map);
}
private Control CreateMap()
{
// Create a new GMaps.NET object, intialize it and return
}
}
Hope it helps.

Trouble trying to create a DatePicker in GTK#

I'm new to GTK# (and desktop development for that matter) and I can't figure out what seems like to be a simple task. :(
I can't get a simple date picker to work. I have a main window with a single text box entry and a single button. When the button is clicked it opens a new window with the calendar widget and when the user double-clicks a date it then should return the selected date to the text box entry on the main window.
Here is my code, what am I missing?
MainWindow.cs
using System;
using Gtk;
public partial class MainWindow: Gtk.Window
{
public MainWindow (): base (Gtk.WindowType.Toplevel)
{
Build ();
}
protected void OnDeleteEvent (object sender, DeleteEventArgs a)
{
Application.Quit ();
a.RetVal = true;
}
private DateTest1.CalendarTest datePicker;
protected void OnButton1Clicked (object sender, EventArgs e)
{
datePicker = new DateTest1.CalendarTest();
datePicker.DestroyEvent += new DestroyEventHandler(datePickerDestroyed);
datePicker.ShowAll();
}
public void datePickerDestroyed(object sender, EventArgs e)
{
entry1.Text = datePicker.DatePicked.ToString();
}
}
CalendarTest.cs
using System;
namespace DateTest1
{
public partial class CalendarTest : Gtk.Window
{
public DateTime DatePicked;
public CalendarTest () :
base(Gtk.WindowType.Toplevel)
{
this.Build ();
}
protected void OnCalendar1DaySelectedDoubleClick (object sender, EventArgs e)
{
var datePicker = (Gtk.Calendar)sender;
DatePicked = datePicker.Date;
this.Destroy();
}
}
}

You have to use the Destroyed event, not the DestroyEvent ;)
That is, use this:
datePicker.Destroyed += new EventHandler(datePickerDestroyed);
See also this question.

Metro app how to create grouped GridView in the C# code behind

In my metro app I need to show groups of VariableSizeWrapGrid on a GridView. Doing this is straight forward in XAML(by creating ItemsPanelTemplate and GroupStyle). But is there a way to do the same in C# code behind.

From here:
using System;
using System.Windows;
using System.Windows.Data;
namespace GroupingSample
{
public partial class Window1 : System.Windows.Window
{
public Window1()
{
InitializeComponent();
}
CollectionView myView;
private void AddGrouping(object sender, RoutedEventArgs e)
{
myView = (CollectionView)CollectionViewSource.GetDefaultView(myItemsControl.ItemsSource);
if (myView.CanGroup == true)
{
PropertyGroupDescription groupDescription
= new PropertyGroupDescription("#Type");
myView.GroupDescriptions.Add(groupDescription);
}
else
return;
}
private void RemoveGrouping(object sender, RoutedEventArgs e)
{
myView = (CollectionView)CollectionViewSource.GetDefaultView(myItemsControl.ItemsSource);
myView.GroupDescriptions.Clear();
}
}
}
The key here is that you get the default view off of the ItemsSource and set the grouping on that. This line:
myView = (CollectionView)CollectionViewSource.GetDefaultView(myItemsControl.ItemsSource);

Simple Isolated Storage Problem

I am trying to do a simple test with Isolated Storage so I can use it for a Windows Phone 7 application I am making.
The test I am creating sets a creates a key and value with one button, and with the other button sets that value equal to a TextBlock's text.
namespace IsoStore
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
}
public class AppSettings
{
IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;
private void button1_Click(object sender, RoutedEventArgs e)
{
appSettings.Add("email", "someone#somewhere.com");
}
private void button2_Click(object sender, RoutedEventArgs e)
{
textBlock1.Text = (string)appSettings["email"];
}
}
}
}
This way gives me this error:
Cannot access a non-static member of outer type 'IsoStore.MainPage' via nested type 'IsoStore.MainPage.AppSettings'
So I tried this:
namespace IsoStore
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
}
public class AppSettings
{
IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;
private void button1_Click(object sender, RoutedEventArgs e)
{
appSettings.Add("email", "someone#somewhere.com");
}
}
private void button2_Click(object sender, RoutedEventArgs e)
{
textBlock1.Text = (string)appSettings["email"];
}
}
}
And instead I get this error:
The name 'appSettings' does not exist in the current context
So what obvious problem am I overlooking here?
Thanks so much for your time.

appSettings is out of scope for button2_Click
Update Since IsolatedStorageSettings.ApplicationSettings is Static anyway there's no need for the reference at all. Just directly access it.
namespace IsoStore
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
IsolatedStorageSettings.ApplicationSettings.Add("email", "someone#somewhere.com");
}
private void button2_Click(object sender, RoutedEventArgs e)
{
textBlock1.Text = (string)IsolatedStorageSettings.ApplicationSettings["email"];
}
}
}

Try this code, as there isn't any need to define AppSettings class.
namespace IsoStore
{
public partial class MainPage : PhoneApplicationPage
{
IsolatedStorageSettings appSettings;
// Constructor
public MainPage()
{
InitializeComponent();
appSettings = IsolatedStorageSettings.ApplicationSettings;
}
private void button1_Click(object sender, RoutedEventArgs e)
{
appSettings.Add("email", "someone#somewhere.com");
}
private void button2_Click(object sender, RoutedEventArgs e)
{
textBlock1.Text = (string)appSettings["email"];
}
}
}