How can I lock (and make it look faded) a parent form while the child form is active? I tried to make the child form topmost but that just made it always visible and I can still edit the parent form. I want to be unable to operate on the main form while the child form is running in VS2012, C#. This is the code I used to call the second form...
private void checkButton_Click(object sender, EventArgs e)
{
Form2 newForm = new Form2(this);
newForm.Show();
}
One very simple way is to use ShowDialog() instead of Show() on the child form. This will prevent any interaction with the main form. This is also a neat way of passing back results. There are many other ways, of course.
Example:
private void checkButton_Click(object sender, EventArgs e)
{
Form2 newForm = new Form2(this);
newForm.ShowDialog();
}
See MSDN for further details: https://msdn.microsoft.com/en-us/library/c7ykbedk(v=vs.110).aspx
Just add Hide() for Current Running Form,
private void checkButton_Click(object sender, EventArgs e)
{
Form2 newForm = new Form2(this);
this.Hide();//hide old form
newForm.Show();
}
You can use Form.ShowDialog to create dialog which will open on top of parent form and will not allow to edit parent until you close child
private void checkButton_Click(object sender, EventArgs e)
{
Form2 newForm = new Form2(this);
newForm.ShowDialog(this);
}
You might wanna run the form2 in separate thread and set topmost = true, the form1 will function unblocked, but the form2 will run whatever you want unblocked too. Is this what you want?
namespace TestModal
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Thread thrd = new Thread(newwindow);
thrd.IsBackground = true;
thrd.Start();
}
private void newwindow()
{
Form2 frm2 = new Form2();
frm2.TopMost = true;
frm2.ShowDialog();
}
}
}
Related
I designed a form for login that named as form1, and have 2 more form form2,form3
form2 items showing in panel from form1
and what I want to do
when I click the button in panel ( the item from form2 ) want to show form2 and hide form1 but the code isnt working
private void button1_Click(object sender, EventArgs e)
{
Form1 frm1 = new Form1();
Form3 frm3 = new Form3();
frm1.Hide();
frm3.Show();
};
form3 is opening but form1 isnt hiding
Its not hiding because you created a new instance for form1 which is already instantiated.
You must call the Hide() method on the same instance used to call the Show() method.
If you added this code inside form1 class ,then change it like this
private Form1 frm1
public Form2()
{
frm1 = new Form1()
}
private void button_show_form1_Click(object sender, EventArgs e)
{
frm1.Show();
};
private void button1_Click(object sender, EventArgs e)
{
Form3 frm3 = new Form3();
frm3.Show();
frm1.Hide();
};
You creating both forms in your codesnipped. Form1 is not the form you want to close, i think. frm1 is only another instance of Form1, but not the openend instance von Form1. You must have anywhere another instance of Form1. You must use the right referenz to the right instance.
It is important to know that WinForms create an instance of the startup form. In our case the startup form would be Form1. So, when you say
Form1 frm1 = new Form1();
You're actually creating a new (second) instance of Form1. This means that, in code, there are two different Form1's.
What we want to do is check with our application to get the instance of Form1 that already exists.
// This goes in Form2. It returns an instance of Form1, if it exists.
private Form getForm1()
{
// Application holds information about our application, such as which forms are currently open.
var formCollection = System.Windows.Forms.Application.OpenForms;
// Now we loop through the open forms in search of the form we want, Form1.
foreach (Form frm in formCollection)
{
if (frm.Name.Equals("Form1"))
{
return frm;
}
}
return null;
}
Now that we can get the existing instance of Form1 we can use it to make the form hidden.
private void button1_Click(object sender, EventArgs e)
{
var form1 = getForm1();
if (form1 != null) form1.Hide();
}
Something to know here is that when a form is hidden it is not closed. So, we need to make sure that Form1 becomes visible again. For example, we can set Form1 to be visible when Form2 closes.
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
// The question mark (?) checks to see if the result of
// getForm1() is null. Same thing that is happening in
// button1_click
getForm1()?.Show();
}
Complete Form2 Code
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
var frm1 = getForm1();
var frm3 = new Form3();
if (frm1 != null) frm1.Hide();
frm3.Show();
}
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
// The question mark (?) checks to see if the result of getForm1() is null. Same thing that is happening in button1_click
getForm1()?.Show();
}
// This goes in Form2. It returns an instance of Form1, if it exists.
private Form getForm1()
{
// Application holds information about our application, such as which forms are currently open.
// Note that Open and Visible have different definitions.
var formCollection = System.Windows.Forms.Application.OpenForms;
// Now we loop through the open forms in search of the form we want, Form1.
foreach (Form frm in formCollection)
{
if (frm.Name.Equals("Form1"))
{
return frm;
}
}
return null;
}
}
After open FORM 2.dialog from FORM 1, I want to close FORM 1 via button from FORM 2.
FORM 1
private void btnaddIPrange_Click(object sender, EventArgs e)
{
new form2().ShowDialog();
}
FORM 2
private void btnIPRangeCancel_Click(object sender, EventArgs e)
{
//close FORM 1(I don't know the code to close it)
this.Close();
}
Form2 will need a reference to Form1. You can do that several ways.
For example, in Form1 you set the Owner property of the new Form2 instance to this:
private void btnaddIPrange_Click(object sender, EventArgs e)
{
Form2 myForm = new Form2(); // Creates instance of Form2.
myForm.Owner = this; // Assigns reference to this instance of Form1 to the Owner property of Form2.
myForm.Show(); // Opens Form2 instance.
// You can also call myForm.Show(this);
// instead of the above two lines to automatically assign this form as the owner.
}
Then in Form2:
private void btnIPRangeCancel_Click(object sender, EventArgs e)
{
if(this.Owner != null) // Check for null.
this.Owner.Close(); // Closes Form1 instance.
this.Close(); // Closes current Form2 instance.
}
If all your forms are members of the same parent form, you can just call:
var ParentalForm = this.ParentForm as Foo_MainForm;
Make sure the child forms are public/internal members on the form.
Then:
ParentalForm.Foo_FormWantingClosed.Close();
Or in just one line:
(this.ParentForm as Foo_MainForm).Foo_FormWantingClosed.Close();
Off the top of my head.
Another idea! Since the form1 is sender, you can cast the object as form1 and close it directly. For instance:
private void OpenForm2(object sender, EventArgs e)
{
var callingForm = sender as form1;
if (callingForm != null)
{
callingForm.Close();
}
this.Close();
}
My Winform application has 3 form: MainForm, Form1 and Form2.
MainForm has an UserControl; when application starts, it calls MainForm, MainForm will be loaded and added Form1 onto UserControl:
private void MainForm_Load(object sender, EventArgs e)
{
Form1 frm = new Form1() { Dock = DockStyle.Fill, TopLevel = false, Visible = true };
xtraUserControl1.Controls.Add(frm);
}
On Form1, I use delegate:
public delegate void Tranferdata(string txt);
public Tranferdata _tranfer;
private void Gettxt(string txt)
{
tbx_Recieve.Text = txt;
}
Form1 has a button to call Form2:
private void button1_Click(object sender, EventArgs e)
{
Form2 frm2 = new Form2();
frm2.ShowDialog(this);
}
Form2 will send value to Form1 after closed, Code on Form2:
private void Form2_FormClosed(object sender, FormClosedEventArgs e)
{
using (Form1 frm1 = (Form1)this.Owner)
{
frm1._tranfer(tbx_Numb.Text);
}
}
private void button1_Click_1(object sender, EventArgs e)
{
this.Close();
}
But my code doesn't work correctly. It crashed at 'using (Form1 frm1 = (Form1)this.Owner)' and show the System.InvalidCastException.
How can I fix this?
The reason it crashed on that line is because you didn't set Form1 to be the owner of Form2.
To fix, first have Form1 as a class variable and not as a local variable:
Form1 form1;
private void MainForm_Load(object sender, EventArgs e)
{
form1 = new Form1() { Dock = DockStyle.Fill, TopLevel = false, Visible = true };
xtraUserControl1.Controls.Add(form1);
}
Then you can use it to assign Form2's owner when you create it:
private void button1_Click(object sender, EventArgs e)
{
Form2 frm2 = new Form2();
frm2.Owner = form1;
frm2.ShowDialog(this);
}
And also, like Ron Beyer mentioned in his comment, consider removing the using statement, it will close Form1, it doesn't sound like that's what you want to do.
Now, while that approach will work, there are some questions that you should consider here:
Why did you choose to use the "Owner" property in the first place? Do you really need it? Having Form1 as the owner of Form2 means that Form2 will close when Form1 is closed. Since you use ShowDialog on Form2 it will block the user from closing Form1 while Form2 is showing so it seems unneeded.
If the reason for using the Owner property is just for the sake of using the delegate than you could have just added a property to Form2 to be of type Form1, which would have given you type safety and superior code.
But there is even a better way: MainForm can register to the Closed event for Form2 and call the method on Form1. This will remove unneeded dependencies (Form2 and Form1 will not know about each other at all) making the code healthier.
I found the solution to this problem:
In the Form 2:
public void SetParent(Form1 frm)
{
frm1 = frm;
}
and call it in Form 1 at event call form2:
private void button1_Click(object sender, EventArgs e)
{
Form2 frm2 = new Form2();
frm2.SetParent(this);
frm2.ShowDialog();
}
Whenever I need to show another Form, I always instantiate a new Form Object to show another Form (then hiding the current form).
/*Code in Form1*/
private void button1_Click(object sender, EventArgs e)
{
Form2 frm2 = new Form2();
frm2.Show();
this.Hide();
}
After I instantiated and showed the second Form, I want to dispose the previous form (to free up some memory usage) but it is not working on the main context form.
However, the Dispose() method is working on other WinForms which is
not the main context form.
/*Code in Form2*/
private void button1_Click(object sender, EventArgs e)
{
Form1 frm1 = new Form1();
frm1.Show();
this.Dispose();
}
Is it possible to instantiate a Form Object once only, then eventually to call/show it whenever I need it?
You can start your own ApplicationContext, and pass that to every form you want to make the MainForm. You shouldn't keep forms in memory and open and close them at will in my opinion. This could lead to potential memory leaks.
ApplicationContext ac = new ApplicationContext();
ac.MainForm = new Form1(ac);
Application.Run(ac);
(You will put this in the place of Application.Run(new Form1());)
In Form1, when you want to make Form2 the main form:
ac.MainForm = new Form2(ac);
this.Close();
This way, the form can be disposed (since you called Close() and used Show it will automatically dispose) and memory can be cleared. The instance of Form2 will be the new main form.
/*Code in Form1*/
Form2 frm2; // --> Inside the class
private void button1_Click(object sender, EventArgs e)
{
if (frm2 == null)frm2 = new Form2();
frm2.Show();
this.Hide();
}
.
/*Code in Form2*/
Form1 frm1;
//Constructor
public Form2(Form1 frm)
{
frm1= frm;
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
frm1.Show();
this.Hide();
}
I would create a class called "FormHandler"
this may have a method like
here some prototype code (not tested)
public static class FormHandler
{
private static readonly Dictionary<string,Form> Instances = new Dictionary<string,Form>();
public TForm CreateFrom<TForm>()
{
string typeName = typeof(TForm).FullName;
if(Instances.ContainsKey(typeName))
{
return Instances[typeName]
}
else
{
// Create Instace with Activator.CreateInstance,
// and bind the dispose event to remove the form from the collection
// on dispose . Also make sure that you unbind the dispose Event
[...]
}
}
Now the buttonClick would just call
FormHandler.CreateForm<Form2>().Show();
with seperating the code to a new class you can avoid copy and paste in all buttons
How to Add or Remove a control from another form that is active and currently showing? I am using the following code:
private void button2_Click(object sender, EventArgs e)
{
Form1 frm1 = new Form1();
frm1.Controls.RemoveByKey("button1");
}
But it is not working because of new initialization of Form1.
If the form, from which a control is to be removed, is a child of another form you can access the form through the OwnedForms property. And after accessing it, you can remove controls from it. For example
Form1
private void button1_Click(object sender, EventArgs e)
{
var form = new Form3 { Owner = this };
form.Show();
}
private void button2_Click(object sender, EventArgs e)
{
if(OwnedForms.Length > 0)
{
var form = OwnedForms[0];
//assuming there's a control with id 'One':
form.Controls.RemoveByKey("One");
}
}
From the comments, it is clear that Form2 does not have a reference to Form1.
You didn't post any code on how you are displaying Form2, but here is an example on how it could work by passing the reference through the constructor:
public class Form2 : Form {
private Form1 _Form1;
public TestForm(Form1 form1) {
InitializeComponent();
_Form1 = form1; // <- this is the reference from Form1
}
}
Then your removing action on Form2 would look like this:
private void button2_Click(object sender, EventArgs e) {
_Form1.Controls.RemoveByKey("button1");
}
When creating Form2 from Form1, this is an example on how it would be passed:
private Form2 _Form2;
private void button1_Click(object sender, EventArgs e) {
_Form2 = new Form2(this); // <- this is the reference of Form1 you are passing
_Form2.Show();
}
As you already know you need the one instance of Form1.
If this is your main form and you used the Visual Studio wizard to create a Windows Forms Application you can look in the Program class. There is usually the main form built.
Now you need to assign the new Form1() expression to a variable and assign it to the second form with button button2.