Navigate from a child form to its sibling form

Question

In a parent form A, there's the following code to call a child form "B":

        Window frmChildB;
        frmChildB = new FormB();
        frmChildB.ShowDialog();

In the same form: the following code to call a child form "C":

        Window frmChildC;
        frmChildC = new FormC();
        frmChildC.ShowDialog();

Now I want to make a button in form B, so that if I click that button, it automatically navigate to form C.

Using a reference object of form C in form B like in the answer of this question should be avoided if possible. The reason is that there are more than ten forms like B, C... and each of them must be able to navigate to another. Having 10 form-referenced objects inside a form isn't good.

I think there must be some way to achieve the effect. Does anyone know about this?

Answer 1

Try creating an Event in frmChildB and Subscribe to it in the Parent. You can then do what you want without having an reference to frmChildC in frmChildB.

---

Look at this MSDN link;

This is very rough but should give you an idea.

creating the event in the child forms

public delegate void SwapEventHandler(object sender, EventArgs e);
public partial class Form2 : Form
{
    public event SwapEventHandler Swap;

    public Form2()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Swap(sender, e);
    }
}

Consumming it in the Parent Form

private void button1_Click(object sender, EventArgs e)
{
    frmChildB = new Form2();
    frmChildB.Name = "frmChildB";
    frmChildB.Swap += new SwapEventHandler(frmChildB_Swap);
    frmChildB.ShowDialog();
}


private void frmChildB_Swap(object sender, EventArgs e)
{
    frmChildB.Swap -= new SwapEventHandler(frmChildB_Swap);
    frmChildB.Close();
    frmChildB.Dispose();
    frmChildB = null;
    frmChildC = new Form2();
    frmChildC.Name = "frmChildC";
    frmChildC.Swap += new SwapEventHandler(frmChildC_Swap);
    frmChildC.ShowDialog();
}

void frmChildC_Swap(object sender, EventArgs e)
{
    frmChildC.Swap -= new SwapEventHandler(frmChildC_Swap);
    frmChildC.Close();
    frmChildC.Dispose();
    frmChildC = null;
    frmChildB = new Form2();
    frmChildB.Name = "frmChildC";
    frmChildB.Swap += new SwapEventHandler(frmChildB_Swap);
    frmChildB.ShowDialog();
}

Answer 2

At a primitive level it appears that you would benefit more from using the standard 'Wizard' pattern than having separate forms for each question. The exception being that instead of just having the typical next and back buttons, you should have buttons to jump to any of the questions. Here is a good tutorial that will walk you through the normal steps of creating a wizard.

Answer 3

If I understand your question correctly, you would like to have a single instance of each of the forms and just navigate back and forth between them.

If this is what you want, you can implement a static FormManager class that creates instances of the forms and shows them as needed. You can even use an enum to further reduce the complexity.

Here is an example of this class (it will need some additional work, but should give you a good idea):

public class FormManager
{
    private static FormB m_FormB;
    public static FormB formB
    {
        get
        {
            if (m_FormB == null)
            {
                m_FormB = new FormB();
            }
            return m_FormB;
        }
    }
    private static FormC m_FormC;
    puClic static FormC formC
    {
        get
        {
            if (m_FormC == null)
            {
                m_FormC = new FormC();
            }
            return m_FormC;
        }
    }

    public enum FormId
    {
        FormB,
        FormC
    }

    public static Form ShowForm(FormId whichForm)
    {
        Form oForm;

        switch (whichForm)
        {
            case FormId.FormB:
                oForm = FormManager.formB;
                break;

            case FormId.FormC:
                oForm = FormManager.formC;
                break;

            default:
                oForm = null;
                break;
        }

        if (oForm != null)
        {
            oForm.ShowDialog();
        }
        return oForm;
    }
}

This can be called from the child forms as:

FormManager.ShowForm(FormManager.FormId.FormB);