How do I prevent Multiple forms from opening?
I do .show on the form but the user can click the main form and the button again and another instance of form opens.
Two options, depending on what you need:
Use ShowDialog instead of Show, which will open a modal window. This is the obvious solution if you don't need your main form to be active while the child form is open.
Or keep track of the window you opened already in the main form and do nothing if it's already open. This will be needed if you want the user to be able to use the main form while the child form is already open, maybe to open other forms.
do something like:
SingleForm myform = null;
void ShowMyForm_Click(object sender, EventArgs e)
{ if (myform == null)
{
myform = new SingleForm();
}
myform.Show();
myform.BringToFront();
}
Force your form object to adhere to the singleton pattern
I prefer to use Generics and lazy loading to handle my forms. Since all of my forms inherit from a base class, I can use the same method to bring forms to the front, send them to the back, destroy them, start them, etc.
If you keep a form manager class that's responsible for managing any loaded forms, you can bring whatever form to the front that you want, or prevent specific forms from being able to come back unless certain criteria are met.
public void LoadForm<T>() where T : MyNameSpace.MyBaseForm
{
// Load all your code in this joint and just call it when you
// need a form. In here, you can determine if a copy of the form
// already exists and then bring it forward or not
}
Disable the main form until the child form goes away, or disable the button.
button_onClick(object Sender, EventArgs e)
{
Button btn = sender as Button;
btn.Enabled = false;
Form myform = new MyForm();
myform.Show();
}
Of course, you really should be using form.ShowDialog() rather than form.Show() if you want modal behavior.
Related
I have 5 child forms in my c# application. one of the child forms named childFormopens another form subForm. What i want is, when subForm is open, user cannot click or do anything inside the application without closing subForm. But this should be contained in the application only. i.e When user wants to switch to another application without closing subForm he/she wont see subForm anymore, again if user switches to the c# application the subForm form must be on top and rest of the control must be disabled.
to create and show the subForm from within the childForm i wrote a button_click event
Imagine your form contains an editbox, a Button and a close Button (x).
This may help if we have the same SDK.
Button.click += delegate{
Subform();
}
Public void Subform(){
Button closebutton = Resource.Id...;
Button Enter = Resource.id...;
Edittext Edit = Resource.Id...;
Enter.enabled = false;
Edit.editable = false;
Closebutton.click += delegate{
Mainform();
}
}
Maybe be a stupid question but say i have an Winform App with 2 clickable buttons (button_1 and button_2), each containing a piece of code. If I open the app, I want to click button_1 then button_2, and close the application. What i am wandering is there any way to insert a method that will call button_1 then button_2 on load (and possibly close the app?) that could be inserted into say Form1_Load?
Don't "click the buttons" automatically. Invoke the logical actions which the buttons invoke automatically. If that logic is currently in the buttons' click events in the code-behind, refactor it into a common location.
For example, your click event might end up with something like:
protected void Button1_Click()
{
SomeObject.DoSomething();
}
Then you can invoke the same action from the form's load event:
protected void Form_Load()
{
SomeObject.DoSomething();
}
Following that, still in the form load event, you can then close the application as well:
protected void Form_Load()
{
SomeObject.DoSomething();
Application.Exit();
}
Though it seems really unnecessary to load up an entire form just to do something without user interaction and then exit. A console application would be much simpler:
static void Main()
{
SomeObject.DoSomething();
}
Then you don't have a UI to worry about, you don't have to attach code to events, you don't even have to forcibly close the application. It'll just execute the code and exit.
I am new to C#, I am creating a application in which there is a need of using two forms
one is Mainform and other is DialogForm.
The DialogForm has two buttons btnYes and btnNo.
whenever the user clicks the close button, FormClosing Event invokes in which I am calling the DialogForm as shown below:
DialogForm ex = new DialogForm();
ex.ShowDialog(this);
Now I want to give e.cancel=false for btnYes and e.cancel=true for btnNo. (this explained by my sir, only basics)
I know how to give functions to a Button which is in same Form but I dont know how to if the Form is different.
I have gone through some links but as I am new to c#, I can't understand it.
If you atleast provide me some links that would be appreciable.
Thanks in advance.
Forms have a property DialogResult. You can set it in the button event handlers.
DialogResult = DialogResult.Yes;
// or
DialogResult = DialogResult.No;
Then you can call the form like this
if (ex.ShowDialog(this) == DialogResult.Yes) {
// Do something
} else {
// Do something else
}
You can also set the CancelButton property of the form in the properties window. Microsoft says:
Gets or sets the button control that is clicked when the user presses the ESC key.
The form has also an AcceptButton property. Microsoft says:
Gets or sets the button on the form that is clicked when the user presses the ENTER key.
I have a Win form application (VS 2010 / C#) and I'm trying to figure out how to refresh pages without a refresh button. Currently I can refresh a page (basically to reset the data bindings) with a refresh button containing code something like this (this.refresh() does not seem to work for some reason):
this.Hide();
AccountSettings AS = new AccountSettings();
AS.ShowDialog();
An example I have is a page with numerous settings including data grids with CellClick events. When I click a cell I can make changes to a database. I hit close to go back to the Settings page but the only way for me to see the changes are to refresh() the page via the button.
So the short of it is, is there any way to refresh a form page from another form page?
For instance, when I click the Save button or close the child window.
Maybe pass the original form as an argument to the second form:
Form2 frm2 = new Form2(this);
And in Form2:
Form1 frm1;
public Form2(Form1 frm1)
{
InitializeComponent();
this.frm1 = frm1;
}
And then have in Form2:
frm1.Update();
Refresh on winform controls repaints the control itself. I find it useful to create a method that just loads my controls with the proper data, and then call it as necessary. (Including Form load)
private void ResetData()
{
//code to update settings
}
If you are showing the form that is closing as a dialog also you can take advantage of that, and check the status of the dialog instead of just opening it.
Form2 dlg = new Form2();
if (dlg.ShowDialog == System.Windows.Forms.DialogResult.OK) {
//code that updates your data
ResetData();
}
If its not a dialog there are a few things you could do and how your application works would make one method better than others. Here is just one example.
If your changes are something you don't need access to data from the other window to update you can handle the closed event of the form you create.
Create a class level variable to hold the form that is opened, so that you can also remove the event handlers you create:
private Form2 frm;
To create an instance of the form, and add the close event handler:
frm = new Form2();
frm.FormClosed += OnForm2Closed;
The event handler method:
private void OnForm2Closed(object sender, FormClosedEventArgs e)
{
ResetData();
frm.FormClosed -= OnForm2Closed;
}
I have custom control which I am rendering inside dialogue box.
this custom control has a link lable lnkLable. I want to close the opened window when I click on lnkLable.
right now I am finding the parent of my conrol which will be dialogue control in the end and then calling the dispose method of that, which I don't feel very good technique to do this.
Use the Close() method on the form to close it.
private void button1_Click(object sender, EventArgs e)
{
Control btn = sender as Control;
Form frm = btn.Parent as Form;
frm.Close();
}
If it's a modal dialog you can also close it by calling the Hide() method because modal dialogs are automatically destroyed the modal pump exits, and the pump will exit when the dialog is hidden.
Rather try using Control.FindForm Method
You have to remember that the control might not be directly on the form, but inside another container, like a panel, in which case the parent of your control will not be the form.
Once yuo have the instance of the form, rather use Form.Close Method