在两个Windows窗体之间切换

Question

I am working on a game that utilizes Windows Forms in C#. I want to be able to use the first form to call a second form. I have this working. Then I would like for the second form to send data back to the first form rather than creating a new instance of the first form. Can this be done? I know I need to have my properties set up so that I can set the variables from one form to the other. I am just not sure how to go about calling the first form without creating a new instance of it. Is there a way that this can be done? For example if I have Form A create an instance of Form B, can I have Form B do some work and send the data back to the original Form A without creating a new instance of Form A?

Answer 1

It's hard to say without knowing your full requirements. But generally I go like this (Somewhat psuedo code).

Form2 dialogForm = new Form2();
if(dialogForm.ShowDialog() == DialogResult.OK)
{
 this.PropertyOnForm1 = dialogForm.PropertyOnForm2
}

This ofcourse relies that your second form is a dialog. You will need to set the dialogresult buttons on Form2, and have a public property that will be accessed from Form1 once the dialog has been completed.

Let me know if this doesn't work and I'll write up a different answer.

Answer 2

If you don't use the Data sent back Form A right away then you could use the Form_Closing event handler Form B and then a public property in Form B also.

In your Form A it could look like this:

public partial class FormA : Form
{
    FormB frmB = new FormB(); // Instantiate FormB so that you could create an event handler in the constructor
    public FormA()
    {
        InitializeComponent();
        // Event Handler for Form Closing
        frmB.FormClosing += new FormClosingEventHandler(frmB_FormClosing);

    }

    void frmB_FormClosing(object sender, FormClosingEventArgs e)
    {
        String fromFormB = frm2.FormBData; // Get Data from Form B when form is about to close
    }

    private void button1_Click(object sender, EventArgs e)
    {
        frmB.ShowDialog(); // Showing Form B
    }
 }

And in your Form B it could look like this:

  private void button1_Click(object sender, EventArgs e)
  {
       // Let just say that the data is sent back once you click a button
        FormBData = "Hello World!"; 
        Close();
   }

   public String FormBData { get; set; }

Answer 3

Since you are creating Form2 in Form1 , you can create a custom event in Form2 and subscribe to it in Form1 at the time that you create Form2 , if you are returning information from Form2 when you are closing it then Edper's or MindingData's answers will work.

Here is a quick and dirty example using EventHandler<TEventArgs>

Form1

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Form2 frm2 = new Form2();
        frm2.myCustomEvent += frm2_myCustomEvent;
        frm2.Show();

    }

    void frm2_myCustomEvent(object sender, string e)
    {
        this.Text = e;
    }
}

Form2

public partial class Form2 : Form
{
    public event EventHandler<string> myCustomEvent;
    int count;
    public Form2()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        count +=1;
        myCustomEvent(sender, count.ToString());
    }
}