Compact Framework and forms management.

This was my first experience with the Microsoft Compact Framework. The application is developed in Visual Studio 2005 and is targeted to run on Pocket PC 2003 devices. Basically, I had to extend a simple application that had only one form to add some functionality and a few more forms. I understand that the forms in Compact Framework are treated a bit differently compared to a desktop application. What to use for navigation between forms, Show() or ShowDialog()? I decided to use Show() because I have only about 5 forms, most of those are very simple and also, my application will be the only one running on the device. So I thought, if I create each form once and keep them all in memory, just showing and hiding them, it may use more memory, which I do not care that much about, but be easier on the device battery. Okay, I may be saying total nonsense here - I have about 7 days Compact Framework development experience at this very moment.

So I have a dictionary where all existing forms are kept.

private static Dictionary _applicationForms = new Dictionary();

And the function that gets the form from the dictionary by name.

internal static Form GetFormByName(string formName)
{
 if (_applicationForms.ContainsKey(formName))
 {
  return _applicationForms[formName];
 }
 else
 {
  Form newForm = CreateFormByName(formName);
  AddFormIfNotExists(newForm);
  return newForm;
 }
}

And the function to create a form if it has not been yet created.

private static Form CreateFormByName(string name)
{
 Form form = new Form();

 switch (name)
 { 
  case Constants.frmFirst:
   form = new frmFirst();
   break;
   
   ...
   
  case Constants.frmLast:
   form = new frmLast();
   break;
  default:
   form = new frmLast();
   break;
 }
 return form;
}

And the function to add the form to the dictionary if it is not there.

internal static void AddFormIfNotExists(Form frm)
{
 if (!_applicationForms.ContainsKey(frm.Name))
 {
  _applicationForms.Add(frm.Name, frm);
 }
}

And when I need to show another form, I get it from the dictionary and show, and hide the current form.

internal static void ShowFromForm(Form source, string targetName)
{
 Form frm = GetFormByName(targetName);
 frm.Show();
 source.Hide();
}

There's a bit more to it, sometimes I need to find which form is currently visible etc, but these are the core things. Stupid? Good enough? I don't know ...

by Evgeny. Also posted on my website