Develop Reference

UWP C# How To Handle Event for Dynamically Created Button(s) and Control

in relation to the post UWP C# Add Button Dynamically and Organizing On StackPanel I have additional questions
how do I control these dynamically created button(s)' event? eg. button 1 to turns on LED 1, button 2 to turns on LED 2 etc.
how to selectively remove the button(s) and reorganize the remaining buttons with no empty spaces in between.
Thank you.
Update:
I have a routine to add the client with details such as client IP etc. from the client and to add and display them in a scrollviewer.
How do i link either the clientname or client ip to the dictionary?
private async void AddClientList()
{
await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
ClientListUserControl clientListControl = new ClientListUserControl(this, new ClientList(clientName, receiveIP, DateTime.Now, receivePort, receiveService, receiveDEV, receiveSTS, receiveACT));
ClientList_Panel.Children.Add(clientListControl);
clientListControl.updateDisplay();
});
}

You can also use Tag property of Button to pass the parameter. This property is inherited from FrameworkElement, and generally it is used to get or set an arbitrary object value that can be used to store custom information about this object.
Please refer to following code.
private void ButtonCreateNewButton_Click(object sender, RoutedEventArgs e)
{
Button b = new Button();
b.Height = 30;
b.Width = 100;
b.VerticalAlignment = VerticalAlignment.Top;
b.HorizontalAlignment = HorizontalAlignment.Left;
b.Margin = new Thickness(6, 6, 6, 6);
b.Content = "Button " + buttonCounter;
b.Tag = "LED-" + buttonCounter;
b.Click += Button_Click;
....
buttonCounter++;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var btn = sender as Button;
var led = btn.Tag;
//use led_name as a parameter here, according with this variable to turn on the LED
TurnOnOffLed(led);
}

To your first question:
To handle this, you should introduce a dictionary, where the button is the key and your value is the client. So you can get the linked client in the ClickHandler.
public Dictionary<Button, object> clientDict = new Dictionary<Button, object>();
Note: Here the type of the client is object, because I don`t know what type you have!
You add the button inside of your AddButton routine. Again: I dont know where you get your client from, so I added the value null. Change this to fulfil your requirements. Then you add another ClickHandler and get the linked client:
b.Click += HandleButtonClick;
clientDict.Add(b, null);
private void HandleButtonClick(object sender, RoutedEventArgs e)
{
//Execute whatever you want from your client:
var client = clientDict[sender as Button];
}
To your second question:
You need to add a RemoveMethod, where you get the column and row of the button, which should be deleted. Afterwards you can manipulate all other buttons column and row property. To avoid, that a new added button is not aligned to the others, you need to change the add-process, to make the position of the new button depending on the number of elements in your dictionary. Here an example how the full code could look like:
public int buttonCounter = 1;
public Dictionary<Button, object> clientDict = new Dictionary<Button, object>();
private void RemoveBtn(Button button)
{
var row = Grid.GetRow(button);
var column = Grid.GetColumn(button);
//Rearange
foreach (var btn in clientDict.Keys)
{
var r = Grid.GetRow(btn);
var c = Grid.GetColumn(btn);
if (c > column || (c == column && r > row))
{
if (r != 0)
{
//Set the row new
Grid.SetRow(btn, r - 1);
}
else
{
//Need to set it to a new column
Grid.SetRow(btn, 3);
Grid.SetColumn(btn, c - 1);
}
}
}
myGrid.Children.Remove(button);
clientDict.Remove(button);
}
private void Button_Click(object sender, RoutedEventArgs e)
{
//Create the button
Button b = new Button();
b.Height = 30;
b.Width = 100;
b.VerticalAlignment = VerticalAlignment.Top;
b.HorizontalAlignment = HorizontalAlignment.Left;
b.Margin = new Thickness(20, 20, 0, 0);
b.Content = "Button " + buttonCounter;
b.Click += HandleButtonClick;
clientDict.Add(b, null);
//Calculate the place of the button
int column = (int)(clientDict.Count / 4);
int row = clientDict.Count % 4;
//Check if you need to add a columns
if (row == 0 && myGrid.ColumnDefinitions.Count <= column)
{
ColumnDefinition col = new ColumnDefinition();
col.Width = new GridLength(column, GridUnitType.Auto);
myGrid.ColumnDefinitions.Add(col);
}
//Add the button
myGrid.Children.Add(b);
Grid.SetColumn(b, column);
Grid.SetRow(b, row);
buttonCounter++;
}
private void HandleButtonClick(object sender, RoutedEventArgs e)
{
//Execute whatever you want from you handler:
var client = clientDict[sender as Button];
}
Note: The rearrange process is not performance optimized.

Dynamically adding controls and eventhandlers (asp.net c#)

I'm a computing foundation year student and am designing a basic e-commerce site for a project at uni and have run into a problem that has me banging my head against my desk
So..
I am dynamically creating a shopping basket using asp.net controls in the Page_Load method of the basket page based off what is in a session variable (type dictionary - the key is the product id and the value is the qty).
I can add items from the browse page which has more dynamically added controls based off whatever the user puts in the products table of the database, that works fine.
I can populate the basket with all the details but am struggling with a '-' and '+' button to alter the qty in the basket.
I can assign the event handler to run a method in a class that adds (or removes) 1 item at a time but the problem I face is if I place my code in Page_Load the function works but renders the controls before the event handler fires (so while the dictionary updates, it's not showing the new value - you have to refresh or add another and then you're always 1 behind)
If I place the code in PreRender the event handler doesnt fire.
This is my first ever project in ASP.NET so please go easy on me if I'm barking up the wrong tree with my methodology.
Any ideas or a nudge in the right direction would be gratefully received
Many thanks in advance
EDIT To add a bit more detail
//creating my button
Button tdQtyDownButton = new Button();
tdQtyDownButton.ID = "qtyDown"+ row["prod_id"]; tdQtyDownButton.Text = "-";
tdQtyDownButton.Click += delegate (object sender1, EventArgs e1) {
ShoppingBasket.AddItem((int)row["prod_id"]); };
tdQtyDown.Controls.Add(tdQtyDownButton);
//in seperate ShoppingBasket class file
public static void AddItem(int prod_id)
{
if (HttpContext.Current.Session["basket"] != null)
{
if(!((Dictionary<int, int>)HttpContext.Current.Session["basket"]).ContainsKey(prod_id))
{
((Dictionary<int, int>)HttpContext.Current.Session["basket"]).Add(prod_id, 1);
}
else
{
int currentQty = 0;
((Dictionary<int, int>)HttpContext.Current.Session["basket"]).TryGetValue(prod_id, out currentQty);
((Dictionary<int, int>)HttpContext.Current.Session["basket"]).Remove(prod_id);
((Dictionary<int, int>)HttpContext.Current.Session["basket"]).Add(prod_id, currentQty + 1);
}
}
else
{
CreateBasket();
AddItem( prod_id);
}
}
As i said, it sort of works - I think it's a just a lifecycle issue and probably needs a wholly fresh approach

Assuming you want to add a Button dynamically and handle it's click event :
Button button1 = new Button();
button1.Text = "dynamic button";
button1.Left = 10; button1.Top = 10;
textBox1.Click += new EventHandler(btn_click);
this.Controls.Add(button1);
private void btn_click()
{
}
Update : From your comment,it seems like that you want to refresh your page without reloading it...For that,your easiest approach will be SignalR or you can use the UpdatePanel Control

For Windows Form Application
public partial class Form1 : Form
{
int i = 1;
int j = 1;
int rbCount = 0;
public Form1()
{
InitializeComponent();
}
private void buttonAddRadio_Click(object sender, EventArgs e)
{
RadioButton rb = new RadioButton();
rb.Name = "Radio Button" + i.ToString();
rb.Text = "Radio Button" + i;
rb.Left = 8;
rb.Top = 15 + (rbCount * 27);
rb.AutoSize = true;
rb.Click += new EventHandler(radio_click);
groupBox1.Controls.Add(rb);
i++;
rbCount++;
}
void radio_click(object sender, EventArgs e)
{
MessageBox.Show(((RadioButton)sender).Text);
}
private void buttonAddCheck_Click(object sender, EventArgs e)
{
CheckBox cb = new CheckBox();
cb.Name = "CheckBox" + j.ToString();
cb.Text = "CheckBox" + j;
cb.Left = 8;
cb.Top = 15 + (rbCount * 27);
cb.AutoSize = true;
cb.Click += new EventHandler(checkbox_checked);
groupBox1.Controls.Add(cb);
j++;
rbCount++;
}
void checkbox_checked(object sender, EventArgs e)
{
MessageBox.Show(((CheckBox)sender).Text);
}
}
For ASP.NET Web Application
string[] myArray = new string[] { "Alex", "Bob", "John", "Srinivas", "Zamal", "Rahul" }
foreach (string item in myArray)
{
HyperLink myHyp = new HyperLink();
myHyp.Text = Suspect;
myHyp.NavigateUrl = "User Details.aspx?name=" + HttpUtility.UrlEncode(item));
myPanel.Controls.Add(new LiteralControl("<ul>"));
myPanel.Controls.Add(new LiteralControl("<li>"));
myPanel.Controls.Add(hpSuspect);
myPanel.Controls.Add(new LiteralControl("</li>"));
myPanel.Controls.Add(new LiteralControl("</ul>"));
}
N.B. LiteralControl is used for adding general HTML controls.

Change background of a button when clicking another button

I am currently experimenting in WPF and just created a UniformGrid with 800 buttons which are created in a for loop. All buttons have their own names and share the same click event.
What I want to do now is the following: I want to click the first button (rect0) to change the color of this button and the next one (rect1).
I am totally stuck right now because everything I write into the click event refers to the button I clicked.
public MainWindow()
{
InitializeComponent();
for (int i = 0; i < 800; i++)
{
Button BTN_rect = new Button()
{
Name = "rect" + i,
Background = Brushes.White,
};
BTN_rect.Click += BTN_rect_Click;
Uniform.Children.Add(BTN_rect);
}
}
private void BTN_rect_Click(object sender, RoutedEventArgs e)
{
Button BTN_rect = sender as Button;
BTN_rect.Background = Brushes.Red;
MessageBox.Show(BTN_rect.Name);
}

There are a load of ways to do this.
I took a shortcut and put just 9 buttons in a stackpanel, otherwise the same.
public MainWindow()
{
InitializeComponent();
for (int i = 0; i < 8; i++)
{
Button BTN_rect = new Button()
{
Name = "rect" + i,
Content =Name,
Tag = i,
Background = Brushes.White,
};
BTN_rect.Click += BTN_rect_Click;
sp.Children.Add(BTN_rect);
}
}
private void BTN_rect_Click(object sender, RoutedEventArgs e)
{
Button current = sender as Button;
current.Background = Brushes.Red;
string targetName = $"rect{((int)current.Tag) + 1}";
Button nextButton = sp.Children.OfType<Button>().Where(x => x.Name == targetName).SingleOrDefault();
nextButton.Background = Brushes.Red;
}
Usually, you'd template data into repeated controls rather than add them in code, btw.

How can I retrieve the input values of dynamically created textfields?

Here is my code so far where I have a numericupdown item named numericUpDown and button. Once the user selects a number when they press the button it dynamically created the fields.
private void createPerson_Click(object sender, EventArgs e)
{
Label[] person_Name = new Label[(int)this.numericUpDown.Value];
TextBox[] person_txtinput = new TextBox[(int)this.numericUpDown.Value];
for (int i = 0; i < this.numericUpDown.Value; i++)
{
//create person name label
Person_Name[i] = new Label();
Person_Name[i].Location = new System.Drawing.Point(20, 114 + i * 25);
Person_Name[i].Size = new System.Drawing.Size(120, 15);
Person_Name[i].Text = (i + 1).ToString() + #")" + "Person Name:";
this.Controls.Add(Person_Name[i]);
//create person name textbox
PersonNameTxtInput[i] = new TextBox();
PersonNameTxtInput[i].Location = new System.Drawing.Point(140, 114 + i * 25);
PersonNameTxtInput[i].Size = new System.Drawing.Size(125, 20);
this.Controls.Add(PersonNameTxtInput[i]);
}
}
private void save_Click(object sender, EventArgs e)
{
for (int i = 0; j < this.numericUpDown.Value; i++)
{
MessageBox.Show("" + PersonNameTxtInput[i].Text);
}
}
My question is, how can I get all the values from the textboxes depending on how many fields are created by the user when the save button is pressed?
I have tried using the code within the save button listener however how can i make Label[] person_Name = new Label[(int)this.numericUpDown.Value]; a global variable so i can access it within the save button for loop.

Well, I don't know exactly why you are doing this in this particular way and I must admit it doesn't seem very effective, but you could just do what Ryan_L suggested and iterate through this.Controls like this
for(int i = 0; i < this.Controls.Count; i++)
{
if(this.Controls[i] is TextBox) //skip buttons and labels
{
MessageBox.Show("" + this.Controls[i].Text);
}
}
Now, regarding your question how to define a global variable so you can access it within the save button for loop...just define the two arrays outside of the createPerson_Click event like this:
Label[] person_Name;
TextBox[] person_txtinput;
private void button1_Click(object sender, EventArgs e)
{
person_Name = new Label[(int)this.numericUpDown.Value];
person_txtinput = new TextBox[(int)this.numericUpDown.Value];
//the rest of the code
}
Hope this helps. However, you might want to reconsider your entire approach.

Dynamically create buttons in c# by user at runtime

How to create buttons dynamically after user input in C# (Visual Studio).
There is a text-box to enter how many buttons user wants?
Then my target is to create buttons below the input field as the user wants
then how can I get id's of that buttons?
private void button1_Click(object sender, EventArgs e)
{
List<Button> buttons = new List<Button>();
for (int i = 0; i < n; i++)
{
this.Controls.Add(buttons[i]);
}
}

Here I first added an event handler to the textbox, which is called whenever the text value is changed. The value is converted to the int value and then is used in a for loop statement. You can set your button's potion to the desired value using location property. Using tag or name property you can assign a unique value to your buttons. I hope the code helps.
Look at the code below :
private void Form1_Load(object sender, EventArgs e)
{
textBox1.TextChanged += textBox1_TextChanged;
}
void textBox1_TextChanged(object sender, EventArgs e)
{
var txtBox = sender as TextBox;
if (txtBox == null) return;
var count = Convert.ToInt16(txtBox.Text);
//
var xPosition = 0;
for (var i = 1; i <= count; i++)
{
var button = new Button
{
Tag = string.Format("Btn{0}", i),
Text = string.Format("Button{0}",i),
Location = new Point(xPosition, 0)
};
xPosition = xPosition + 100;
Controls.Add(button);
}

When you are creating Control(in your case Buttons) you can give them Name property. It will be very good if that name will be unique.
var btn = new Button();
btn.Name = "MyBtn";
btn.Text = "Our Button";
this.Controls.Add(btn);
For creation of N buttons you just need to put this in a Loop with N iterations and set btn.Name to something like "Name"+SomeNumber.
To set the Position of the Buttons to below the input you should set btn.Left and btn.Top to the corresponding coordinates.
Then when you need to work with generated Control/Button you can do search by that Name in the following way:
var btn = (Button)this.Controls.Find("MyBtn", true).First();
and do whatever you want with that Control/Button.
But in this case there is some danger as I am not checking if there was found any control with that name. If you write incorrect Name this will throw exception on .First().