Change NotifyIcon on separate form

Question

I have a form (Form1) that has a NotifyIcon on it. I have another form (Form2) that I would like to change the NotifyIcon's icon from. Whenever I use this code, I get an extra icon that shows up in the system tray, instead of changing the current icon:

Form1 (ico is the name of the NotifyIcon):

public string DisplayIcon
{
    set { ico.Icon = new Icon(System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("Alerts.Icons." + value)); }
}

Form2:

Form1 form1 = new Form1();
form1.DisplayIcon = "on.ico";

I suspect is has something to do with creating a new instance of Form1 on Form2, but I'm not sure how to access "DisplayIcon" without doing this. Thanks.

UDPATE: I'm a little confused on writing the custom property on Form 2, would it be something like:

public Form Form1
{
    set {value;}
}

Answer 1

I assume form1 at one point creates form2. At that point you can pass a reference of form1 to form2 so form2 can access the DisplayIcon property of form1.

So you would end up with something like

//Somewhere in the code of form1
public void btnShowFormTwoClick(object sender, EventArgs e) 
{
    Form2 form2 = new Form2();
    form2.Form1 = this; //if this isn't done within form1 code you wouldn't use this but the form1 instance variable
    form2.Show();
}

//somewhere in the code of form2
public Form1 Form1 { get;set;} //To create the property where the form1 reference is storred.
this.Form1.DisplayIcon = "on.ico";

Answer 2

Your suspicion is correct, you are creating a second instance of Form1 which results in a duplicate NotifyIcon.

You need a reference to Form1 from Form2 in order to set the DisplayIcon property on the correct instance.

A possible solution is to pass the reference from Form1 to Form2 when creating Form2 (I assume you create Form2 from Form1).

For example:

Form2 form2 = new Form2();
form2.Form1 = this; // Form1 is custom property on Form2 that you need to add
form2.Show();

On Form2 the custom property would be defined as:

 //Note the type is Form1, in order to get to your public DisplayIcon property. 
 public Form1 Form1 { get;set;}