#Context menus

UIToolbox.Core.ContextMenu has a general popup menu. ToolBarMenu uses it for its drop-downs.

• AttachTo(target, context) gives an element the menu with one call. The menu shows on a right click, on the Menu key or Shift+F10 while the focus is in the element, and on a long press (LONG_PRESS_MS, 0.5 s) with touch or a pen. One menu can be attached to many elements, each with its own context. DetachFrom(target) removes it.
• ShowDropdown(trigger, side, align) shows the menu next to an element, such as a button. Below or above the trigger, Start puts the left edges in line and End the right edges. Right or left of it, Start puts the top edges in line and End the bottom edges. The side flips when it has no room. A second call for the same trigger closes the menu, so call it from the click handler of the button.
• A menu that a key or ShowDropdown opened gives the focus back to the element when a key or an item closes it.
• A radio item has a RadioGroup name and a dot for the check mark. A click checks it and unchecks the other items of the menu with the same group.
• Destructive shows an item in the danger color. Use it for an item that deletes.
• The menu closes on an item click, a click outside it, or Escape. Callback runs, then ActionTriggered fires, after the menu closes. A checkable item flips Checked before both.
• The predicates get the context object from ShowAt each time the menu opens.
• An item with children has a submenu, with an arrow. The submenu opens to the right of the menu on hover, click, Right or Enter. It moves to stay inside the workspace. A click on a submenu item closes all the menus.
• Up and Down move the highlight and skip disabled items. Enter or Space runs the highlighted item. Left closes a submenu.
• Shortcut is display text, such as Ctrl+Shift+U, Alt+W or F1. ContextMenuComponent shows it; ToolBarMenu runs it. TryParseShortcut reads the modifiers Ctrl (or Cmd), Shift and Alt, and a KeyCode name, a letter, a digit, Del, Esc, Ins, PgUp or PgDn. Case is ignored.
• A & in Text marks the access key, underlined; in an open menu that key runs the item. AccessKey has the key, FormatAccessKey(text, out key) gives the rich text, and KeyChar(keyCode) gives the letter of a key.
• In UXML, MenuItem has text, action, shortcut, checkable, checked, radio-group, destructive and enabled. Child MenuItem, MenuSeparator and MenuLabel elements go in the submenu.
• Outside a workspace the menu shows on the panel root and loads its styles there.
• A gamepad has no button for the context menu. Give the player another way to the same commands, such as a button that calls ShowDropdown.

using UIToolbox;
using UIToolbox.Core.ContextMenu;
using UIToolbox.Utils;
using UnityEngine.UIElements;

public static class WindowMenu
{
    public static void Attach(VisualElement target, WindowDescriptor window)
    {
        var menu = new ContextMenuComponent();
        menu.AddItem(new MenuItem { Text = "Maximize", Action = "maximize",
            EnabledPredicate = ctx => !((WindowDescriptor)ctx!).IsMaximized });
        menu.AddSeparator();
        menu.AddItem(new MenuItem { Text = "Close", Action = "close", Destructive = true });

        menu.ActionTriggered += (action, ctx) =>
        {
            var w = (WindowDescriptor)ctx!;
            if (action == "maximize") AsyncRunner.Run(() => w.MaximizeAsync(), "Menu maximize");
            if (action == "close") AsyncRunner.Run(() => w.CloseAsync(), "Menu close");
        };

        // Right click, the Menu key and a long press
        menu.AttachTo(target, window);
    }
}

A dropdown menu on a button, with a heading and radio items:

var sort = new ContextMenuComponent();
sort.AddLabel("Sort by");
sort.AddRadioItem("Name", "sort", () => SortBy("name"), isChecked: true);
sort.AddRadioItem("Date", "sort", () => SortBy("date"));

var button = new Button { text = "Sort" };
button.clicked += () => sort.ShowDropdown(button, MenuSide.Below, MenuAlign.End);

#Styling

The tab strip uses TabContextMenu (close, close others, close to the right, pin, duplicate, move to a new window). You cannot add items to the tab menu today.