Develop Reference

C# How to have a form subscribe to an event which is within a user control within a floy layour panel?

So I have a form on a WinForms app.
On that form is a FlowLayoutPanel.
On the FlowLayout panel is a bunch of user controls each representing rows from a table from a database.
On each control is a button.
How do I have the form subscribe to a button click on one of the controls passing back that rows database info?
This is the control code:
public partial class ctrlLeague : UserControl
{
public League activeLeague = new League();
public event EventHandler<MyEventArgs> ViewLeagueClicked;
public ctrlLeague(League lg)
{
InitializeComponent();
lblLeagueName.Text = lg.leagueName;
activeLeague = lg;
}
private void btnViewLeague_Click(object sender, EventArgs e)
{
ViewLeagueClicked(this, new MyEventArgs(activeLeague));
}
public class MyEventArgs : EventArgs
{
public MyEventArgs(League activeLeague)
{
ActiveLeague = activeLeague;
}
public League ActiveLeague { get; }
}
}
if I put the following into the form constructor it tells me "

You can define your favorite event with delegate and call it wherever you want, here it is called inside btnView_Click.
This means that whenever btnView_Click called, your event is
actually called.
public partial class ctrlLeague : UserControl
{
public League activeLeague = new League();
public event EventViewLeagueClicked ViewLeagueClicked;
public delegate void EventViewLeagueClicked(object Sender);
public ctrlLeague(League lg)
{
InitializeComponent();
lblLeagueName.Text = lg.leagueName;
activeLeague = lg;
}
private void btnViewLeague_Click(object sender, EventArgs e)
{
if (ViewLeagueClicked != null)
ViewLeagueClicked(activeLeague);
}
}
now use
public Form1()
{
InitializeComponent();
League league = new League();
league.leagueName = "Seri A";
//
//These lines are best added in Form1.Designer.cs
//
ctrlLeague control = new ctrlLeague(league);
control.Location = new System.Drawing.Point(350, 50);
control.Name = "ctrlLeague";
control.Size = new System.Drawing.Size(150, 100);
control.ViewLeagueClicked += Control_ViewLeagueClicked;
this.Controls.Add(control);
}
private void Control_ViewLeagueClicked(object Sender)
{
League l = Sender as League;
MessageBox.Show(l.leagueName);
}

Subdialog is shown one more time on each activation of parent Dialog

I developed an app, where the user sects on order from a list. If the order is selected, the EditOrderWindow shows. From this window, the user can add items to the Order by. This is done in a sub dialog AddItemWindow. Works fine for the first order.
However, if a second order is edited, the AddItemWindow shows again after its been closed. For the third order edited it shows three times aso.
I couldn't figure out why this happens, and how to prevent it.
ViewModel
public class ViewModel
{
public ICommand EditOrderCommand { get; set; }
public ICommand AddItemCommand { get; set; }
public event EventHandler<int> EditOrder;
public event EventHandler<int> AddItem;
public event EventHandler<int> ItemAdded;
public ViewModel()
{
//Is fired when an item in the datagrid in Control OrderList is doubleclicked
EditOrderCommand = new ICommand();
EditOrderCommand.Executed += EditOrderCommand_Executed();
//Is fired when the users click on add in EditOrderWindow
AddItemCommand = new ICommand();
AddItemCommand.Executed += AddItemCommand_Executed();
}
private void EditOrderCommand_Executed(object sender, EventArgs e)
{
if (SelectedOrder != null)
{
EditOrder(this, SelectedOrder.Id);
}
}
private void AddItemCommand_Executed(object sender, EventArgs e)
{
AddItem(this, new EventArgs());
}
}
Control: OrderList
public partial class OrderList : UserControl
{
ViewModel vm;
public OrderList()
{
InitializeComponent();
//DataContext is set in xmal
vm = (ViewModel)this.DataContext;
vm.EditOrder += Vm_EditOrder;
}
private void Vm_EditOrder(object sender, int e)
{
EditOrderWindow s = new EditOrderWindow(vm);
s.ShowDialog();
s = null;
}
Window: EditOrderWindow
public partial class EditOrderWindow : Window
{
ViewModel vm;
AddItemWindow aiw;
public EditOrderWindow(ViewModel _vm)
{
InitializeComponent();
vm = _vm;
this.DataContext = vm;
vm.AddItem -= Vm_AddItem;
vm.AddItem += Vm_AddItem;
}
private void Vm_AddItem(object sender, EventArgs e)
{
if (aiw == null)
{
aiw = new AddItemWindow(vm);
}
aiw.ShowDialog();
aiw = null;
}
}
Window: AddItemWindow
public partial class AddItemWindow : Window
{
public AddItemWindow(ViewModel _vm)
{
InitializeComponent();
this.DataContext = _vm;
_vm.ItemAdded -= _vm_ItemAdded;
_vm.ItemAdded += _vm_ItemAdded;
}
private void _vm_ItemAdded(object sender, EventArgs e)
{
this.Close();
}
}

Mousebuttonpressed event Issues C#

I have an issue with a custom event i have created. I have made a Usercontrol that looks the following:
public partial class UCListView : UserControl {
public UCListView() {
InitializeComponent();
}
public event EventHandler SubmitClick;
public event EventHandler MouseButtonUpEvent;
private void SubmitButton_OnClick(object sender, RoutedEventArgs e) {
if (SubmitClick != null)
SubmitClick(this, e);
}
private void MouseButtonUp(object sender, RoutedEventArgs e) {
if (MouseButtonUpEvent != null) {
MouseButtonUpEvent(this, e);
}
}
}
Here is the MouseButtonUp event i have.
The following is where i listen to the event:
public partial class RoundsteelWindow : WindowControls {
private UCListView uc;
public RoundsteelWindow() {
InitializeComponent();
uc = new UCListView();
uc.SubmitClick += new EventHandler(ButtonPressed);
uc.MouseButtonUpEvent += new EventHandler(MousePressed);
stkTest.Children.Add(uc);
base.Test<RoundSteel>(uc, "Roundsteel");
}
}
Here is the WindowControls, where the MousePressed method can be seen. This is the same as the code snippet beneath this code. Really don't see the issue:
public abstract class WindowControls : Window {
public IMaterialWith14Elements _ReturnObject { get; set; }
public double amount { get; set; }
private UCListView _uc;
public void Test<T>(UCListView uc, string type) where T: IMaterialWith14Elements, new() {
_uc = uc;
List<T> test = MaterialLogic.GetList(type) as List<T>;
foreach (T material in test) {
uc.listView.Items.Add(material.Name);
}
}
private string str;
public void MousePressed(object sender, EventArgs eventArgs) {
var item = (sender as ListView).SelectedItem;
if (item != null) {
_ReturnObject = _uc.listView.SelectedItems as FlatSteel ;
str = item.ToString();
_uc.amountText.IsEnabled = true;
}
}
public void ButtonPressed(object sender, EventArgs e) {
if (!string.IsNullOrEmpty(_uc.amountText.Text)) {
amount = _uc.amountText.Text.customParseToDouble();
this.Close();
}
else {
MessageBox.Show("Indtast venligst en værdi.");
}
}
}
Now the problem is the following: With the following code it is working, but this class is not using the windowcontrols. It is called by another class which handles all of the buttons.
private void flatsteelListView_PreviewMouseLeftButtonUp(object sender, RoutedEventArgs e) {
var item = (sender as ListView).SelectedItem;
if (item != null) {
_returnObject = flatsteelListView.SelectedItems as FlatSteel;
str = item.ToString();
amountTextbox.IsEnabled = true;
FindObject(str);
}
}
The first picture shows the working window. This is where there is not used a usercontrol. Actually this is a previous issue i have worked with and got help with here on stackoverflow Help for thisissue.
The second picture is showing the next window using the usercontrol that has been created. The button event works and closes the window. Here comes then the issue, when the listview item is pressed. It is doing the same thing as on the first picture(where it works), but it is giving me a null reference, which doesn't make any sense to me. I have also checked the object sender to see if there was a difference between the sender of these two different windows.
I simply can't figure out why this is not working.
greetings darophi

Your sender is an object of UCListView class which is inherited from UserControl and you are trying to use it like ListView. So as result of operation (sender as ListView) you get null because sender is not an instance of ListView class and not inherits it.

Can I prevent ListBox.RefreshItem(object item) from removing and re-adding the object?

The issue I am having is that when I update my object, the ListBox automatically removes and then re-adds the object to the list, thus calling the index and value changed events. I was able to prevent this by creating a custom ListBox control and when the PropertyChangedEvent was called, I would raise a flag that would prevent those events in the base class from being called. What is happening now is that my entire reference is being replace by a new reference and unless I re-select the item in the ListBox, I have the wrong reference.
What I basically want to do, is to change the Display Value in my object and then have it update only the text in the list box. I do not want it to remove and to re-add the object/reference/whatever it does. It's quite annoying.
Here is the example code I am working with...
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.myListBox1.SelectedValueChanged += this.onchange;
}
private void Form1_Load(object sender, EventArgs e)
{
this.myListBox1.Add(new strobj("z"));
this.myListBox1.Add(new strobj("a"));
this.myListBox1.Add(new strobj("b"));
this.myListBox1.Add(new strobj("f"));
this.myListBox1.Add(new strobj("n"));
this.myListBox1.Add(new strobj("h"));
this.myListBox1.Add(new strobj("p"));
this.myListBox1.Add(new strobj("t"));
this.myListBox1.Add(new strobj("c"));
this.myListBox1.Add(new strobj("q"));
}
private void onchange(object sender, EventArgs e)
{
MessageBox.Show("Hello World");
}
int i = 0;
private void button1_Click(object sender, EventArgs e)
{
if (this.myListBox1.SelectedItem != null)
{
strobj item = (strobj)this.myListBox1.SelectedItem;
item.Name1 = i++.ToString();
}
}
}
public partial class MyListBox
{
public MyListBox()
{
InitializeComponent();
}
public void Add(strobj item)
{
item.OnNameChanged += this.MyDispalyMemberChanged;
this.Items.Add(item);
}
bool refreshing = false;
public void MyDispalyMemberChanged(strobj itemChanged)
{
this.refreshing = true;
this.RefreshItem(this.Items.IndexOf(itemChanged));
this.refreshing = false;
}
protected override void OnSelectedValueChanged(EventArgs e)
{
if (!this.refreshing)
{
base.OnSelectedValueChanged(e);
}
}
}
class strobjCollection : List<strobj>
{
NameChangeEventHandler NameChangedEvent;
}
delegate void NameChangeEventHandler(strobj sender);
public class strobj
{
internal NameChangeEventHandler OnNameChanged;
private string _Name1;
public string Name1
{
get { return this._Name1; }
set
{
this._Name1 = value;
if (this.OnNameChanged != null)
{
this.OnNameChanged(this);
}
}
}
public int i = 0;
public string str = "p";
public strobj(string name)
{
this._Name1 = name;
}
public strobj()
{
this._Name1 = "You did not create this object";
}
public override string ToString()
{
return this._Name1;
}
}

This is what the INotifyPropertyChanged interface was made for.
Instead of raising your custom event, you'd raise the PropertyChanged event with the name of the property you changed set in the event args and the listbox would update.
See MSDN.

No data is set when wpf window is loaded?

I have a issue with passing information from one wpf window to another. For some reason when main window is loaded nothing is set in the label, I need to be able to keep the data in a string to use for anything (label not important but shows what I mean)?
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public string MyData { get; set; }
void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
label1.Content = MyData;
}
public partial class LoginWindow : Window
{
public LoginWindow()
{
InitializeComponent();
}
private void button2_Click(object sender, RoutedEventArgs e)
{
string mytext = "blabla";
MainWindow fromloginwindow = new MainWindow();
fromloginwindow.Mydata = mytext;
}
Or am I doing this the wrong way round?
EDIT:
Please do not go on a tangent about the label its unimportant I need to be able to get and set a string for use anywhere in the MainWindow. Also the string "mytext" is also irrelevant as obviously I will not be setting the string this way.

It sounds like you are running into an event lifecycle issue; the calls to the Loaded event happen pretty quickly and thus, the chance to set the text has passed. Instead, what you should do is either:
1) Bind the Property to the Label in the XAML
public event PropertyChangedEventHandler PropertyChanged;
public MainWindow()
{
InitializeComponent();
DataContext = this;
}
protected string _myData = string.Empty;
public string MyData
{
get { return _myData; }
set { _myData = value; NotifyPropertyChanged("MyData"); }
}
protected void NotifyPropertyChanged(string propName)
{
var methods = PropertyChanged;
if(methods != null)
methods(this, new PropertyChangedEventArgs(propName));
}
<Label Content="{Binding MyData}" />
2) Set the control text via another method (or inside the property declaration):
public void SetLabel(string text)
{
label1.Content = text;
}
protected void button2_Click(object sender, RoutedEventArgs e)
{
MainWindow x = new MainWindow();
x.SetLabel("blabla");
}

The Loaded event occurs before you set MyData, change the code like this:
public partial class MainWindow : Window
{
public MainWindow(string data)
{
MyData = data
InitializeComponent();
}

Have you tried passing the value to the second window through the window's constructor?
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public MainWindow(string data)
: this()
{
label1.Content = data;
}
}
public partial class LoginWindow : Window
{
public LoginWindow()
{
InitializeComponent();
}
private void button2_Click(object sender, RoutedEventArgs e)
{
string mytext = "blabla";
MainWindow fromloginwindow = new MainWindow(mytext);
}
}