Applying the Decorator Pattern to Forms
- by devoured elysium
I am trying to apply the Decorator Design Pattern to the following situation:
I have 3 different kind of forms: Green, Yellow, Red.
Now, each of those forms can have different set of attributes. They can have a minimize box disabled, a maximized box disabled and they can be always on top.
I tried to model this the following way:
Form <---------------------------------------FormDecorator
/\ /\
|---------|-----------| |----------------------|-----------------|
GreenForm YellowForm RedForm MinimizeButtonDisabled MaximizedButtonDisabled AlwaysOnTop
Here is my GreenForm code:
public class GreenForm : Form {
public GreenForm() {
this.BackColor = Color.GreenYellow;
}
public override sealed Color BackColor {
get { return base.BackColor; }
set { base.BackColor = value; }
}
}
FormDecorator:
public abstract class FormDecorator : Form {
private Form _decoratorForm;
protected FormDecorator(Form decoratorForm) {
this._decoratorForm = decoratorForm;
}
}
and finally NoMaximizeDecorator:
public class NoMaximizeDecorator : FormDecorator
{
public NoMaximizeDecorator(Form decoratorForm) : base(decoratorForm) {
this.MaximizeBox = false;
}
}
So here is the running code:
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(CreateForm());
}
static Form CreateForm() {
Form form = new GreenForm();
form = new NoMaximizeDecorator(form);
form = new NoMinimizeDecorator(form);
return form;
}
The problem is that I get a form that isn't green and that still allows me to maximize it. It is only taking in consideration the NoMinimizeDecorator form. I do comprehend why this happens but I'm having trouble understanding how to make this work with this Pattern.
I know probably there are better ways of achieving what I want. I made this example as an attempt to apply the Decorator Pattern to something. Maybe this wasn't the best pattern I could have used(if one, at all) to this kind of scenario. Is there any other pattern more suitable than the Decorator to accomplish this? Am I doing something wrong when trying to implement the Decorator Pattern?
Thanks
