asked on

Context Menus 101

I have added a Context Menu (popup) to a Windows Form.

At runtime....when I right-click on the associated control....the popup menu activates and shows "Add"

But when I click on Add...nothing happens because I have not associated an event handler for the click on Add.

How do I do this?

ASKER CERTIFIED SOLUTION

Timbo87

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Tom Knowlton

ASKER

I am actually adding the pop-up menu items at runtim using the ContextMenu popup event:

private void contextMenuTreeMod_Popup(object sender, System.EventArgs e)
            {
                  // Define the MenuItem objects to display for the TextBox.
                  MenuItem menuItem1 = new MenuItem("&Add");

                  // Clear all previously added MenuItems.
                  contextMenuTreeMod.MenuItems.Clear();

                  if(contextMenuTreeMod.SourceControl == treeViewInventory)
                  {
                        // Add MenuItems to display for the TextBox.
                        contextMenuTreeMod.MenuItems.Add(menuItem1);
                  }
            }

My intent is for THIS method to fire when the user clicks on ADD..........but the method is not WIRED to the CLICK EVENT

            protected void menuItem1_Click(System.Object sender, System.EventArgs e)
            {
                  // Insert code to handle Click event.
                  MessageBox.Show("Add something to");
            }

Tom Knowlton

ASKER

Ohhhhhh...........I get it.....duh...............

This works:

            private void contextMenuTreeMod_Popup(object sender, System.EventArgs e)
            {
                  // Define the MenuItem objects to display for the TextBox.
                  MenuItem menuItem1 = new MenuItem("&Add");

                  menuItem1.Click += new EventHandler(menuItem1_Click); //////////////////////////////////// JUST NEEDED TO ADD THIS PART......AS YOU SUGGESTED.....////////////////////////

                  // Clear all previously added MenuItems.
                  contextMenuTreeMod.MenuItems.Clear();

                  if(contextMenuTreeMod.SourceControl == treeViewInventory)
                  {
                        // Add MenuItems to display for the TextBox.
                        contextMenuTreeMod.MenuItems.Add(menuItem1);
                  }
            }

            protected void menuItem1_Click(System.Object sender, System.EventArgs e)
            {
                  // Insert code to handle Click event.
                  MessageBox.Show("Add something to");
            }

Tom Knowlton

ASKER

Let me ask you this:

How would I UNWIRE the ADD click event from one method............. and then REWIRE the ADD click event to some other method:

My best guess:

private void contextMenuTreeMod_Popup(object sender, System.EventArgs e)
{
// Define the MenuItem objects to display for the TextBox.
MenuItem menuItem1 = new MenuItem("&Add");

menuItem1.Click += new EventHandler(menuItem1_Click); //////////////////////////////////// JUST NEEDED TO ADD THIS PART......AS YOU SUGGESTED.....////////////////////////

//CAN I USE -= to unassign the event handler?????????????????

// Clear all previously added MenuItems.
contextMenuTreeMod.MenuItems.Clear();

if(contextMenuTreeMod.SourceControl == treeViewInventory)
{
// Add MenuItems to display for the TextBox.
contextMenuTreeMod.MenuItems.Add(menuItem1);
}
}

protected void menuItem1_Click(System.Object sender, System.EventArgs e)
{
// Insert code to handle Click event.
MessageBox.Show("Add something to");
}

protected void menuItem1Alt_Click(System.Object sender, System.EventArgs e)
{
// Insert code to handle Click event.
MessageBox.Show("ALTERNATE Add something to");
}

Timbo87

Yes, you can use -= to remove delegates. You can also wire up multiple event handlers if you need to.

Tom Knowlton

ASKER

wire-up multiple event handlers?

you mean several differnt event handlers for one click....and the one that gets used depends on something?

can you explain?

Timbo87

Multicasting is the ability to call multiple methods with a single delegate.

EventHandler a = new EventHandler(method1);
EventHandler b = new EventHandler(method2);
EventHandler c = new EventHandler(method3);

menuItem.Click = a + b + c;

Then you can add or remove them with += or -=.

Tom Knowlton

ASKER

Interesting.