MenuDynamicListItem

A list item without a fixed list. Left and right call your callback, and the string it returns becomes the displayed value. Pressing select raises a separate event.

Example usage

// The title for the menu item.
string title = "Dynamic list item.";

// The initial selected list item text.
string initialSelectedText = "0";

// Create the callback function for when the left/right arrow
// keys are pressed. Returning a new string value which will become the new
// selected text.
string ChangeCallback(MenuDynamicListItem item, bool left)
{
    // Left will be true when the left arrow key was pressed
    // and false if the right arrow key was pressed.
    if (left)
        return (int.Parse(item.CurrentItem) - 1).ToString();

    return (int.Parse(item.CurrentItem) + 1).ToString();
}

// Use the ChangeCallback function from above to create a new callback delegate.
MenuDynamicListItem.ChangeItemCallback callback = new MenuDynamicListItem.ChangeItemCallback(ChangeCallback);

// optional description
string description = "Description for this dynamic item. Pressing left will make the value smaller, pressing right will make the value bigger.";

// Create the dynamic list item using the variables above.
MenuDynamicListItem dynList = new MenuDynamicListItem(title, initialSelectedText, callback, description);

// Add a menu item to a menu:
menu.AddMenuItem(dynList);

A clamped counter

The callback can clamp, step or format the value however you like.

string VolumeCallback(MenuDynamicListItem item, bool left)
{
    int value = int.Parse(item.CurrentItem.Replace("%", ""));
    value = MathUtil.Clamp(left ? value - 5 : value + 5, 0, 100);
    return $"{value}%";
}

menu.AddMenuItem(new MenuDynamicListItem(
    "Volume",
    "50%",
    new MenuDynamicListItem.ChangeItemCallback(VolumeCallback),
    "Changes in steps of 5%, between 0% and 100%."
));

Reacting to a dynamic list item

// Fires after your callback returned a new value.
menu.OnDynamicListItemCurrentItemChange += (_menu, _item, _oldValue, _newValue) =>
{
    Debug.WriteLine($"'{_item.Text}' went from {_oldValue} to {_newValue}.");
};

// Fires when the user presses select on the item.
menu.OnDynamicListItemSelect += (_menu, _item, _currentItem) =>
{
    Debug.WriteLine($"'{_item.Text}' was pressed while showing {_currentItem}.");
};

Constructors

Constructor	Description
`MenuDynamicListItem(string text, string initialValue, ChangeItemCallback callback)`	Creates a dynamic list item without a description.
`MenuDynamicListItem(string text, string initialValue, ChangeItemCallback callback, string description)`	Creates a dynamic list item with a description.

Parameter	Type	Description
text	string	The text on the left side of the item.
initialValue	string	The value shown before the user changes anything.
callback	ChangeItemCallback	Returns the next value.
description	string	Shown below the menu while the item is highlighted.

ChangeItemCallback

public delegate string ChangeItemCallback(MenuDynamicListItem item, bool left);

Runs on every left or right press. The returned string becomes the new CurrentItem.

Parameter	Type	Description
item	MenuDynamicListItem	The item being changed. `item.CurrentItem` holds the current value.
left	bool	True for the left control, false for the right control.

Properties

Property	Type	Default value	Description
HideArrowsWhenNotSelected	bool	false	Hides the left and right arrows while the item is not highlighted.
CurrentItem	string	`initialValue` argument	The value being displayed. Can be set.
Callback	ChangeItemCallback	`callback` argument	Called on left and right to get the next value.

Methods

MenuDynamicListItem has no methods of its own.