Develop Reference

Why XAML button can't invoke argumentless function

I have function in create.cs
private void FillGrid()
{
ClearingEntities CE = new ClearingEntities();
var Accountss = CE.Accounts;
DataGrid1.ItemsSource = Accountss.ToList();
}
I invoke this function from other .cs files just writing FillGrid(); without any arguments
but from xaml in button Click="FillGrid" gives error
click auto generated functions have
private void Button_Click(object sender, RoutedEventArgs e)
I don't want insert those object sender, RoutedEventArgs e arguments
if I insert those to my function's arguments then other calling should be changed
to
FillGrid([argument],[argument]);
note: it is not event handling function just fill data stuff
how to call FillGrid() from xaml? without changing create.cs

This is just the way Button Event's work.
Read more about EventHandler here
Why don't you just use this:
<Button Click="FillGridClicked" />
//sender = button, RoutedEventArgs = arguments of that event
private void FillGridClicked(object sender, RoutedEventArgs e)
{
FillGrid();
}
Every ClickEventHandler needs these arguments as it is a custom delegate defined that way. If you really want to emit this you need to extend the button and create a custom click handler for yourself. (see this for example)

creating ValueChanged event handler in code behind

I'm using the DoubleUpDown control from WPFToolkit and I'm trying to create an event handler using ValueChanged.
DoubleUpDown dud = new DoubleUpDown();
dud.ValueChanged += new RoutedPropertyChangedEventHandler<double>(DoubleUpDown_ValueChanged);
private void DoubleUpDown_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
}
I get the error message
CS0029 Cannot implicitly convert type
'System.Windows.RoutedPropertyChangedEventHandler double' to
'System.Windows.RoutedPropertyChangedEventHandler object'
Any suggestions on how this can be addressed to ensure no type conflicts? Thanks.

As the erros suggests, ValueChanged is expecting a RoutedPropertyChangedEventHandler<object>, so you would have to do this:
DoubleUpDown dud = new DoubleUpDown();
dud.ValueChanged += new RoutedPropertyChangedEventHandler<object>(DoubleUpDown_ValueChanged);
private void DoubleUpDown_ValueChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
}
And inside the handler you will have to cast the object to a double.
Note:
The author left a comment in the source code about that, here:
Due to a bug in Visual Studio, you cannot create event handlers for
generic T args in XAML, so I have to use object instead.

I've just had a delve through the online source code, and it looks like the declaration of that event is...
public event RoutedPropertyChangedEventHandler<object> ValueChanged
So your signature needs to match that by making it...
private void DoubleUpDown_ValueChanged(object sender, RoutedPropertyChangedEventArgs<object> e)

Is this what you're intending ?
dud.ValueChanged += DoubleUpDown_ValueChanged;
private void DoubleUpDown_ValueChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
if(e != null && Math.Abs((double)e.NewValue) < 0.000000001d)
{
// for example
}
}

i hope this may help you
this.dud.ValueChanged += new System.Windows.RoutedPropertyChangedEventHandler<double>(this.dud_ValueChanged);
private void dud_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)

DateTimePicker Change Value on Click In windows Form Application C#

I Am using a DateTime Picker in WindowsForm Application of C#. I initalize My dateTImePicker with DateTime.Min Value. What I want is that when a user clicks that dropdown It Should Change its value to DateTime.Now Value and show the current value in calendar but I have to first open it then close it and then reopen it to get the required date in calendar. How can I Do it in a single Click? Any Help will be appreciated.
So far I have tried these events:
private void GroupEndingDate_MouseUp(object sender, MouseEventArgs e)
{
GroupEndingDate.Value = DateTime.Now;
}
private void GroupStartingDate_MouseDown(object sender, MouseEventArgs e)
{
GroupStartingDate.Value = DateTime.Now;
}
private void GroupStartingDate_DropDown(object sender, EventArgs e)
{
GroupStartingDate.Value = DateTime.Now;
}

Try this in your dropdown event. This worked for me.
private void Form1_Load(object sender, EventArgs e)
{
dateTimePicker1.Value = DateTime.Now.AddDays(-3);
}
private void dateTimePicker1_DropDown(object sender, EventArgs e)
{
dateTimePicker1.Value = DateTime.Now;
}

The following works just fine for me without having to click the control a second time.
private void dateTimePicker1_DropDown(object sender, EventArgs e)
{
dateTimePicker1.Value = DateTime.Now;
}
But I agree this approach seems a little odd to me. The date will be set every time the control opens up. Why not just initialize it to DateTime.Now in your form's Load event?

How do I make a button show the listbox when clicked?

I am making a form where if a button is clicked it will go to my list box and run the functions I have in there though I am a bit confused on how to make it realise when the button has been clicked and for the listbox to work. Here is my code >_>
private void button1_Click(object sender, EventArgs e)
{
}
public void ListBox_SelectedIndexChanged(object sender, EventArgs e)
{
Ping.PlayConsole();
}

You just need:
private void button1_Click(object sender, EventArgs e)
{
Ping.PlayConsole();
}
It's ok to call the same function under different handlers.

Try this :
private void button1_Click(object sender, EventArgs e)
{
ListBox_SelectedIndexChanged(sender,e);
}
Good Luck !!

private void button1_Click(object sender, EventArgs e)
{
ListBox.Focus();
Ping.PlayConsole();
}

Both event handlers share the same signature void (object , EventArgs), so they are call-compatible.
If you are connecting the event visually using the form designer:
Go to the Property Inspector's Events pane and instead of double-clicking it to create an event handler stub for button1.Click, click the dropdown box icon that appears on the right side. Visual Studio will show all the event handlers present in the form that have a compatible signature, you should be able to choose ListBox_SelectIndexChanged for the button1.Click handler. They will be sharing the same handler.
If you are connecting the handler by code then this should work too:
ListBox1.SelectIndexChanged += new System.EventHandler(ListBox_SelectedIndexChanged);
button1.Click += new System.EventHandler(ListBox_SelectedIndexChanged);

Timer updating pictureBox on click error in C#

I have the following code-
private void button1_Click(object sender, EventArgs e)
{
_soundplayer.Play();
timer1_Tick();
}
private void timer1_Tick()
{
pictureBox1.Image = imageList1.Images[imgIndex++];
}
For some reason this brings back the error in the Form1.Designer.cs -
Error 1 No overload for 'timer1_Tick' matches delegate 'System.EventHandler'
When button1 is clicked the image in pictureBox1 should change every 2 seconds with the timer tick, however I can't get past this error. Please advise.

The Tick event is an event of type EventHandler. It requires two arguments for the event handler:
private void timer1_Tick(object sender, EventArgs e)
{
pictureBox1.Image = imageList1.Images[imgIndex++];
}
Which requires you to modify the Click event handler like this:
private void button1_Click(object sender, EventArgs e)
{
_soundplayer.Play();
timer1_Tick(this, EventArgs.Empty);
}
Using the designer to add event handlers can keep you out of trouble like this. Select the timer, click the lightning bolt icon in the Properties window and double-click Tick.

Start timer, when you clicked on a button. And set timer interval to 2000 milliseconds. Timer_tick event will be created automatically every 2 seconds.
private void timer1_Tick()
{
pictureBox1.Image = imageList1.Images[imgIndex++];
}
private void button1_Click(object sender, EventArgs e)
{
_soundplayer.Play();
timer1_Start();
}