ContextMenu

A menu opened by a secondary click on an element, for the actions that apply to that element.

Import

use limn::{Component, ContextMenu, ContextMenuEntry, ContextMenuItem};

Usage

A context menu wraps the element it belongs to, where that element is built. It adds no layout and no primary-click target, and the child keeps its own focus and selection. The tree opens and closes the menu, so the host keeps no open flag: it only handles the item’s ID.

fn view(palette: ComponentPalette) -> Element {
    ContextMenu::new(
        "file-row",
        file_row(palette),
        vec![
            ContextMenuEntry::Item(
                ContextMenuItem::new("file:copy", "Copy").icon(Icon::File).shortcut("Ctrl+C"),
            ),
            ContextMenuEntry::Separator,
            ContextMenuEntry::Item(ContextMenuItem::new("file:delete", "Delete").icon(Icon::Trash)),
        ],
        palette,
    )
    .render()
}

fn update(state: &mut State, action: &UiAction) {
    if let UiAction::Clicked { id } = action {
        match id.as_str() {
            "file:copy" => state.copy(),
            "file:delete" => state.delete(),
            _ => {}
        }
    }
}

The first argument names the area the menu belongs to. The menu opens when the window’s backend sends UiEvent::ContextMenu { position } over that area, or UiEvent::ContextMenuKeyboard while a control inside it has focus; see Backend.

Items

ContextMenuItem::new("paste", "Paste").enabled(state.can_paste)

icon puts a glyph before the label and shortcut keycaps after it. enabled(false) draws the item muted and takes it out of reach. A long label wraps; in a very narrow window the shortcut is left out whole, never cut.

Keyboard

Motion

The menu fades in and settles, and fades out; see Animation.

Actions

A click outside the menu closes it and reports nothing: it does not reach the control under the pointer. A wheel or trackpad scroll outside it closes it too, and scrolls what is under the pointer.

Accessibility

While the menu is open the platform is told each item is a menu item named by its label, and that a disabled one is there and cannot be used. A separator says nothing.

Limits

• Its items are actions in one list: no submenus, check boxes, radio items or a second line that says why an item is disabled. For those, the host opens a DropdownMenu with at(point) where the secondary click was, and catches the menu key itself.