I am developing a C# WinForms application. On the FormLoad event, I dynamically create and add to the form 100 buttons without text, but with names like button1, button2 etc. Also, onto these buttons, after their creation, I dynamically link a unique event handler for the ButtonClick event. How can I access the button's properties from within the event handler (more specifically the button name)?
If I use this.Name, I get the name of the form, and not the name of the button.
Later Edit: (for those who might wonder here in search of solutions)
private void function1()
{
Button a = new Button();
a.Name = "button" + (i * j).ToString();
a.Click += new EventHandler(OnFieldButtonClicked);
}
private void OnFieldButtonClicked(object sender, EventArgs e)
{
Button button = (Button)sender;
MessageBox.Show(button.Name);
}
The sender argument is the event handler encapsulates an instance of the object that has triggered the event:
Button button = (Button) sender;
String text = button.Text;
Related
The problem we are having is accessing the click event for a button which is created in the click event of another button i.e. clicking the first button generates a new panel and controls, and we now want the button on this newly created panel to perform an action.
The controls have been declared at the top of the class as follows:
Panel createElementPage = null;
TextBox elementDescription = null;
TextBox elementName = null;
Button continueButton = null;
AuditSystem audit;
Here is an excerpt of the method that generates the new panel, the part that defines the continueButton is written as follows:
public void CE_Click(object sender, EventArgs e)
{
createElementPage.Controls.Add(elementDescription);
continueButton = new Button();
continueButton.Text = "Continue";
continueButton.Location = new Point(700, 500);
continueButton.Size = new Size(100, 50);
createElementPage.Controls.Add(continueButton);
}
We want to access the continueButton's click event handler but the method we have written does not seem to be working. This is what we have so far:
private void continueButton_Click(object sender, EventArgs e)
{
Console.WriteLine(" something");
}
Clicking the button yields no results, and we have tried a few solutions such as implementing a seperate eventHandler method. Does anybody have a fix for this?
You have to actually subscribe to the event:
continueButton.Click += continueButton_Click;
Events need to be told what they should handle. Without that, they won't "listen" to anything.
Friendly note: be careful when adding handlers "on demand" like this (i.e. outside of the designer). It doesn't really apply here (you have a new button each time), but it's fairly easy to accidentally subscribe to a control's event multiple times, and your handler will fire multiple times as a result. It's just nice to be aware of :)
I have a windows form application with multiple buttons. I need to retrieve the text property of any button clicked in order to create a query to the database. the only way I know is to create a button click event and cast the sender as button then do a switch case for each button Id which seems very hectic since I probably will have more than 100 buttons in the entire application. So my question is there a generic key press method I can create which can retrieve the text property of any button pressed/clicked on the form? Please excuse me if the question is not very clear. Any help will be appreciate
Use a single click event handler for all similar kind of buttons. This way there will be click event subscribed for every button but only one method which will be executed for all buttons. You can determine which button was pressed as follows.
Using sender object as follows;
private void button_Click(object sender, EventArgs e)
{
var buttonText = ((Button)sender).Text;
//Query using buttonText
}
Update:
Above answer will still require you to subscribe click event for each button. If you don't want that then have a look at following approach;
You could use (ClickTransparentButton or) disable (Enabled=false) all these buttons and add click event on parent Form. Once you get click event you can get button which was clicked as follows;
private void Form1_Click(object sender, EventArgs e)
{
var p = PointToClient(Cursor.Position);
var control = GetChildAtPoint(p);
if(control is Button)
{
var buttonText = ((Button)control).Text;
//Query using buttonText
}
}
But this has few disadvantages such as, you will not be able to operate these buttons using keyboard.
and more...
Create some function as buttons click handler:
private void buttonClickHandler(object sender, EventArgs e)
{
string buttonName = (sender as Button).Text;
}
2A. Connect Click event of every button to this handler.
2B. To automate connection of button click handler use something like that:
private void connectButtonsHandlers()
{
foreach(var c in this.Controls)
{
if(c is Button)
{
(c as Button).Click += buttonClickHandler;
}
}
}
Add this code to form constructor to perform connection at program start.
I have 10 buttons, 0-9 (button0, button1, button2...). When I click any of these buttons, I would like to perform the same routine on them. I would like to know how to, upon clicking of any of these buttons, direct them to the routine below.
private void button0_Click(object sender, EventArgs e)
{
int newValue;
newValue = Convert.ToInt32(Button.text);
}
I have already gone into the properties of each button, then events, and changed the click event to button0_Click (I would have thought this would add "handles button1.click, button2.click, etc." after "private void button0_Click(object sender, EventArgs e)" but if it does that in the background, that's ok as long as it works.)
I also need to know how to identify the button that has been pressed, which is where I'm at with "Convert.ToInt32(Button.text)" (e.g. button2.text = "2").
You can select the same event handler for all the buttons in the designer (in the event tab of the properties window, select the event and there'll be a drop down with all your defined event handlers).
To get which button has been clicked on, cast the sender argument to a Button and you'll have it.
Button button = (Button)sender;
int value = int.Parse( button.Text );
Edit: Also, the "Handles control.event" syntax only exists in Visual Basic.
Edit: Check out the generated code (Form1.Designer.cs, for example) to see how the events are hooked up.
The C# language doesn't use handles to bind events (as VB does). The code for the actual binding is in the generated code for the form, i.e. in the background as you put it.
The sender property is a reference to the control where the event happened. You just need to cast it to the actual type of the control:
private void button0_Click(object sender, EventArgs e)
{
Button button = (Button)sender;
int newValue = Convert.ToInt32(button.text);
}
As an alternative to using the text of the button (for example if you want to translate the application to different languages, or simply don't want to rely on the text), you can put whatever you like in the Tag property of each button, and retrieve it in the event handler.
You could wire them all up to the same event handler an extract the button from sender e.g.
private void button0_Click(object sender, EventArgs e)
{
var button = sender as Button
if (button != null)
{
int newValue = Convert.ToInt32(Button.text);
}
}
I would like to know , how it is able to identify, which button is clicked, if i have 3 buttons.
Thanks & regards
I don't know anything about your program, other than it having 3 buttons. So, here are our buttons:
Button b1 = new Button();
b1.Name = b1.Text = "Button 1";
Button b2 = new Button();
b2.Name = b2.Text = "Button 2";
Button b3 = new Button();
b3.Name = b3.Text = "Button 3";
Now each button needs to open a messagebox displaying their name when clicked. This is where we're going to use Button_Click event. Each button's Click event can have an unique method which is being called when the button is clicked, or all the buttons can use the same method. I'll provide you with both ways.
Method 1: Same method for each button. This method is going to do nothing but display the pressed button's name.
private void Global_Button_Click(object sender, EventArgs e)
{
MessageBox.Show(((Button)sender).Name + " was pressed!");
}
Whenever a button is clicked, this method gets called and the button is given as object sender parameter. Notice that we must cast it to (Button)sender before using it as a button.
There's still one thing to do. This doesn't get called automatically for each button, it's just a method. Instead, we must tell our buttons to call this when they're clicked. This is what events are for:
b1.Click += Global_Button_Click;
b2.Click += Global_Button_Click;
b3.Click += Global_Button_Click;
Method 2: Unique method for each button. This method is only required if your buttons do more than just print the name of the button. So, if the button click needs to do something unique for different buttons, use this.
It works the same as method one, but instead of defining one method for all buttons, we define 3 methods, one for each.
private void Button1_Click(object sender, EventArgs e)
{
MessageBox.Show("Button 1 was pressed!");
// here you can add more code which will be executed when button 1 is clicked
}
private void Button2_Click(object sender, EventArgs e)
{
MessageBox.Show("Button 2 was pressed!");
// code for button 2
}
private void Button3_Click(object sender, EventArgs e)
{
MessageBox.Show("Button 3 was pressed!");
// code for button 3
}
Now lastly we need to tell the buttons to use these methods when they're clicked, and again we use events. This time, different method for each button:
b1.Click += Button1_Click;
b2.Click += Button2_Click;
b3.Click += Button3_Click;
Usually the buttons have seperate event handlers but in case you have three buttons sharing the same event handler, then use command name/command arguments to differentiate between them. The event handler will have an CommandEventArgs through which you can collect the command names and command arguments
I have a Windows form named Form1 and panel within this form named panel1. I use the panel only to place buttons there so that I can group them and work with them separately from the other buttons in my Form1. For the purpose of my program I need to handle every button click made from the buttons inside panel1. For this purpose I use the same code snippet:
public Form1()
{
InitializeComponent();
// Set a click event handler for the button in the panel
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += HandleClick;
}
}
What I need to do is to have a way to identify which button exactly has been clicked. For this purpose I played a little bit with my handler method:
private void HandleClick(object o, EventArgs e)
{
MessageBox.Show("HI" + o.ToString());
}
which gave me some hope because I get this:
It's the second part - Text: button4 which is actually enough information to continue with my work. But I can't find a way to get this piece of information without some complicated string manipulations. So is there a way to get this or other unique information about the button been clicked given the way I have written my code?
private void HandleClick(object sender, EventArgs e)
{
var btn = sender as Button;
if (btn != null)
{
MessageBox.Show(btn.Text);
}
}
One option is to cast the object to a Button, but rather than doing the casting you can change how the event handler is assigned so that you don't need to cast in the first place:
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += (_,args)=> HandleClick(button, args);
}
Then just change the signature of HandleClick to:
private void HandleClick(Button button, EventArgs e);
You need to cast sender to the Button class so you can access its properties:
Button b = (Button)sender;
MessageBox.Show(b.Text);