In the following code, how do I identify which control raised the Click event?
void x_Click(object sender, EventArgs e)
{
//How do I identify the sender?
}
private void fill()
{
for(blah)
{
Button x = new Button();
x.Click += new EventHandler(x_Click);
this.controls.Add(x)
}
}
void x_Click(object sender, EventArgs e)
{
Button who = (Button) sender;
// you can now access who.Text, etc.
}
Related
My program dynamically creates a number of buttons at runtime. All of them get attached to an EventHandler, which links to the same method. How to know which button was pressed when the method executes? I tried using sender.Name, because object sender is a Button at runtime, but it doesn't compile.
List<Button> buttons = new List<Button>();
private void Form1_Load(object sender, EventArgs e)
{
for (int i = 1; i < 3; i++)
{
buttons.Add(new Button() { Name = "btn" + i });
buttons.Last().Click += new EventHandler(btn_Click);
}
}
public void btn_Click(object sender, EventArgs e)
{
MessageBox.Show(sender.Name + " is clicked");
}
You are on the right track.
The problem you have is that in btn_Click the sender is a generic object, so the compiler doesn't know what type it is, so you need to tell it by casting.
public void btn_Click(object sender, EventArgs e)
{
Button senderButton = (Button)sender;
MessageBox.Show(senderButton.Name + " is clicked");
}
I am creating one button on a page dynamically. Now I want to use the button click event on that button.
How can I do this in C# ASP.NET?
Button button = new Button();
button.Click += (s,e) => { your code; };
//button.Click += new EventHandler(button_Click);
container.Controls.Add(button);
//protected void button_Click (object sender, EventArgs e) { }
The easier one for newbies:
Button button = new Button();
button.Click += new EventHandler(button_Click);
protected void button_Click (object sender, EventArgs e)
{
Button button = sender as Button;
// identify which button was clicked and perform necessary actions
}
Simply add the eventhandler to the button when creating it.
button.Click += new EventHandler(this.button_Click);
void button_Click(object sender, System.EventArgs e)
{
//your stuff...
}
It is much easier to do:
Button button = new Button();
button.Click += delegate
{
// Your code
};
You can create button in a simple way, such as:
Button button = new Button();
button.Click += new EventHandler(button_Click);
protected void button_Click (object sender, EventArgs e)
{
Button button = sender as Button;
// identify which button was clicked and perform necessary actions
}
But event probably will not fire, because the element/elements must be recreated at every postback or you will lose the event handler.
I tried this solution that verify that ViewState is already Generated and recreate elements at every postback,
for example, imagine you create your button on an event click:
protected void Button_Click(object sender, EventArgs e)
{
if (Convert.ToString(ViewState["Generated"]) != "true")
{
CreateDynamicElements();
}
}
on postback, for example on page load, you should do this:
protected void Page_Load(object sender, EventArgs e)
{
if (Convert.ToString(ViewState["Generated"]) == "true") {
CreateDynamicElements();
}
}
In CreateDynamicElements() you can put all the elements you need, such as your button.
This worked very well for me.
public void CreateDynamicElements(){
Button button = new Button();
button.Click += new EventHandler(button_Click);
}
Let's say you have 25 objects and want one process to handle any one objects click event. You could write 25 delegates or use a loop to handle the click event.
public form1()
{
foreach (Panel pl in Container.Components)
{
pl.Click += Panel_Click;
}
}
private void Panel_Click(object sender, EventArgs e)
{
// Process the panel clicks here
int index = Panels.FindIndex(a => a == sender);
...
}
So I have a matrix of panels (maybe will change for Picture Boxes in the future), and what i want is that every time i press one of the panels after pressing the button on the toolbox it will change it's background to a certain picture.
Right now what i have is:
private void EtapaInicial_Click(object sender, EventArgs e)
{
EtapaInicialWasClicked = true;
}
private void panel_Click(object sender, EventArgs e)
{
if (EtapaInicialWasClicked)
{
panel1.BackgroundImage = Symbols.EtapaInicialbm;
EtapaInicialWasClicked = false;
}
}
What I would like to change was the panel1 to make it work for every panel (otherwise it will only change panel1 independently of the panel i've clicked), is that possible?
Try the following
private void EtapaInicial_Click(object sender, EventArgs e)
=> EtapaInicialWasClicked = true;
private void panel_Click(object sender, EventArgs e)
{
if (EtapaInicialWasClicked)
{
(sender as Panel).BackgroundImage = Symbols.EtapaInicialbm;
EtapaInicialWasClicked = false;
}
}
Yes it is. You have to loop through each panel
and assign the same event handler but you have to make some changes in the event handler itself
foreach(var p in allPanels)
{
p.Click += panel_Click;
}
Then change your event handler like this
private void panel_Click(object sender, EventArgs e)
{
var p = (Panel)sender;
if (EtapaInicialWasClicked)
{
p .BackgroundImage = Symbols.EtapaInicialbm;
EtapaInicialWasClicked = false;
}
}
Remember the sender argument contains reference to the actual control that initiated the event but you have to cast it first in order to use it.
However if you want to store more data for the event you've just handled you can use the panel.Tag property. This can be used to store EtapaInicialWasClicked for example
Is this possible to display button on Windows Form only when focus is on specific textbox?
Tried that with this approach:
private void button3_Click(object sender, EventArgs e)
{
MessageBox.Show("OK");
}
private void textBox2_Enter(object sender, EventArgs e)
{
button3.Visible = true;
}
private void textBox2_Leave(object sender, EventArgs e)
{
button3.Visible = false;
}
No luck, because button click does not work then, because button is hidden immediately after textbox lost focus, preventing it from firing button3_Click(/*...*/) { /*...*/ } event.
Now I'm doing it like that:
private void button3_Click(object sender, EventArgs e)
{
MessageBox.Show("OK");
}
private void textBox2_Enter(object sender, EventArgs e)
{
button3.Visible = true;
}
private void textBox2_Leave(object sender, EventArgs e)
{
//button3.Visible = false;
DoAfter(() => button3.Visible = false);
}
private async void DoAfter(Action action, int seconds = 1)
{
await Task.Delay(seconds*1000);
action();
}
Form now waits for a second and only then hides button3.
Is there any better approach?
I think you want to display the button only when focus is on specific textbox or the focus is on the button.
To do this you can check the Focused property of button3 in the Leave event of textBox2 and only hide the button if the button doesn't have focus. Note that the button will get focus before the Leave event of textBox2 fires.
You will then need to hide the button in the scenario where button3 loses focus and the focus moves to somewhere other than textBox2. You can use exactly the same technique here by handling the Leave event of button3 and only hiding button3 if textBox2 does not have focus.
The following code should fit your requirements:
private void textBox2_Leave(object sender, EventArgs e)
{
if (!button3.Focused)
{
button3.Visible = false;
}
}
private void button3_Leave(object sender, EventArgs e)
{
if (!textBox2.Focused)
{
button3.Visible = false;
}
}
private void textBox2_Enter(object sender, EventArgs e)
{
button3.Visible = true;
}
private void button3_Click(object sender, EventArgs e)
{
MessageBox.Show("Button clicked");
}
Why not work with the GotFocus and LostFocus event of the TextBox?
private void textBox2_GotFocus(object sender, EventArgs e)
{
button3.Visible = true;
}
Then hide the button on the click event.
private void button3_Click(object sender, EventArgs e)
{
MessageBox.Show("OK");
button3.Visible = false;
}
How about you add a Panel and place the button and text boxes in that panel and when user MouseHovers that Panel then display the button...
This way user would be able to click on the button...
This is the event you are looking for, I think...
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.mousehover(v=vs.110).aspx
UPDATE:
var textboxFocussed = false;
private void textBox2_Enter(object sender, EventArgs e)
{
textboxFocussed = true;
}
private void textBox2_Leave(object sender, EventArgs e)
{
textboxFocussed = false;
}
UPDATE 2
private void Panel_GotFocus(object sender, EventArgs e)
{
button3.Visible = textboxFocussed;
}
private void Panel_LostFocus(object sender, EventArgs e)
{
button3.Visible = false;
}
Here are the details of the Panel Events
you can add Enter event handler for all controls on form at Load. Just make sure to skip the controls on which you want to show the button.
List<string> strControlException = new List<string>();
public Form1()
{
InitializeComponent();
strControlException.Add("btnMain");
strControlException.Add("txtMain");
}
private void Form1_Load(object sender, EventArgs e)
{
for (int i = 0; i < this.Controls.Count;i++ )
{
if (!strControlException.Contains(Controls[i].Name))
{
Controls[i].Enter += new EventHandler(hideButton);
}
}
}
private void txtMain_Enter(object sender, EventArgs e)
{
btnMain.Visible = true;
}
private void hideButton(object sender, EventArgs e)
{
btnMain.Visible = false;
}
btnMain (Button you want to Manipulate) and txtMain (Which controls the vibility of the button) are the controls in contention here
Add more controls on the form to test.
Explanation for the above code :
First initialize a list with the names of controls that should show the Button
On Form Load add an Event handler to all controls (except the one in our list)
In the handler function hide the button. (You might want to perform more logic here based on the control that called this function)
Button is hidden by default and only on textbox Enter event we show the button.
I managed to create textboxes that are created at runtime on every button click. I want the text from textboxes to disappear when I click on them. I know how to create events, but not for dynamically created textboxes.
How would I wire this up to my new textboxes?
private void buttonClear_Text(object sender, EventArgs e)
{
myText.Text = "";
}
This is how you assign the event handler for every newly created textbox :
myTextbox.Click += new System.EventHandler(buttonClear_Text);
The sender parameter here should be the textbox which sent the even you will need to cast it to the correct control type and set the text as normal
if (sender is TextBox) {
((TextBox)sender).Text = "";
}
To register the event to the textbox
myText.Click += new System.EventHandler(buttonClear_Text);
Your question isn't very clear, but I suspect you just need to use the sender parameter:
private void buttonClear_Text(object sender, EventArgs e)
{
TextBox textBox = (TextBox) sender;
textBox.Text = "";
}
(The name of the method isn't particularly clear here, but as the question isn't either, I wasn't able to suggest a better one...)
when you create the textBoxObj:
RoutedEventHandler reh = new RoutedEventHandler(buttonClear_Text);
textBoxObj.Click += reh;
and I think (not 100% sure) you have to change the listener to
private void buttonClear_Text(object sender, RoutedEventArgs e)
{
...
}
I guess the OP wants to clear all the text from the created textBoxes
private void buttonClear_Text(object sender, EventArgs e)
{
ClearSpace(this);
}
public static void ClearSpace(Control control)
{
foreach (var c in control.Controls.OfType<TextBox>())
{
(c).Clear();
if (c.HasChildren)
ClearSpace(c);
}
}
This should do the job :
private void button2_Click(object sender, EventArgs e)
{
Button btn = new Button();
this.Controls.Add(btn);
// adtionally set the button location & position
//register the click handler
btn.Click += OnClickOfDynamicButton;
}
private void OnClickOfDynamicButton(object sender, EventArgs eventArgs)
{
//since you dont not need to know which of the created button is click, you just need the text to be ""
((Button) sender).Text = string.Empty;
}