How to update contents of rich text box in form1 with values coming from form2 without closing form2?

Question

I want to pass values between two Forms (c# both in active states). How can I do it?

I have two forms: Form1 and Form2.

Form1 contains a rich text box and a button. When I click on that button, Form2 should open and a text in rich text box should be sent to a textbox in Form2 and Form1 should remain opened as well being on back of Form2.

Form2 contains a text box and a button where user edits a text in textbox and when user clicks on a button then the edited text should be sent back to the rich text box in Form1 and the Form2 should close/ stay opened and Form1 should highlight the updated text in rich text box.

How can i do it? Can somebody help me to do this with a simple example?

Answer 1

Please changes the field names as you required. Also following code will update the rich text box value concurrently when textfield value in form2 is changed. You may want to do minor changes to trigger it on button change event.

Add the following method to your From1

private void SetChildFromValueToParent(object obj, EventArgs args)
    {
        //Read the child form's control value and set it to parent form field
        txtBox.Text = ((TextBox)(obj)).Value.ToString();
    }

Add the following logic to your Form1 button click which opens the Form2

private void button1_Click(object sender, EventArgs e)
{
    ChildForm childForm = new ChildForm();

    //Find the textbox control in the child form
    Control[] controls = childForm.Controls.Find("textBox", true);

    if (null != controls[0])
    {
        //Bind the method in the parent form to child form text control's TextChanged event
        controls[0].TextChanged += new System.EventHandler(SetChildFromValueToParent);
    }

    childForm.ShowDialog();
}

EDIT - Getting value on Button Click

   private void SetChildFromValueToParent(object obj, EventArgs args)
        {
             //Read the child form's control value and set it to parent form field
             Form2 from2 = new Form2();
             string richTextBox.Text =  ((TextBox)form2.Controls["textBox1"]).Text;            
        }

Answer 2

In some ways I prefer the first answer, but here's an approach which will help you understand the relationship between the two forms. Note: To get this to work, both richtextboxes will need to be changed from private to internal:

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

    private void btnEditOnForm1_Click(object sender, EventArgs e)
    {
        var form2 = new Form2(richTextBoxOnForm1);
        form2.richTextBoxOnForm2.Text = richTextBoxOnForm1.Text;
        form2.ShowDialog(this);
    }
}

and

public partial class Form2 : Form
{
    private readonly RichTextBox _rtb;

    public Form2(RichTextBox pRTB)
    {
        InitializeComponent();
        _rtb = pRTB;
    }

    private void btnOkOnForm2_Click(object sender, EventArgs e)
    {
        _rtb.Text = richTextBoxOnForm2.Text;
        this.Close();
    }

    private void btnCancelOnForm2_Click(object sender, EventArgs e)
    {
        this.Close();
    }
}

Note how Form2 needs a reference back to the richtextbox on Form1 in order to update it, so you need to tweak the contructor to accept that reference.

Alternatively, you could create a suitable function in Form1 to update the richtextbox there, and call it using

    private void btnOkOnForm2_Click(object sender, EventArgs e)
    {
        ((Form1)this.Owner).UpdateRichTextBoxOnForm1(richTextBoxOnForm2.Text);
        this.Close();
    }

making use of the fact that you included the sender ('this') in the ShowDialog call

        form2.ShowDialog(this);