Interface Focusable<S extends Focusable<S>>

Type Parameters:
S - the component's own type, which the setters return
All Superinterfaces:
EventTarget<S>
All Known Subinterfaces:
Button, CalendarView, CheckBox, ColorPicker, ComboBox<T>, CycleButton<T>, DatePicker, DateTimePicker, DropDownButton, Expander, Flyout, GridView<T>, ListView<T>, Menu, NavigationView, PasswordTextBox, RadioButton, ScrollBar, ScrollPanel, Slider, Spinner, SplitPane, TabBar, TableView<T>, TextArea, TextBox, TimePicker, ToggleButton, ToggleSwitch, TreeView<T>
public interface Focusable<S extends Focusable<S>> extends EventTarget<S>
A component that can take keyboard focus and be reached with Tab, such as a button, a text box or a list.

Keyboard input goes to the focused component and bubbles up from it, so containers hear InputEvents.KEY without being focusable themselves. Components that do not implement this interface never take focus.

A component that implements it starts out focusable and tabbable, with tab index 0. To make a custom component focusable, extend CustomComponent and declare implements Focusable<Self>: the class already has every method below. Do not implement this interface any other way.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final EventType<FocusEvent>
    FOCUS_GAINED
    Told after the component gained keyboard focus.
    static final EventType<FocusEvent>
    FOCUS_LOST
    Told after the component lost keyboard focus.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    isFocusable()
    Returns whether the component can take keyboard focus now.
    boolean
    isFocused()
    Returns whether this component has keyboard focus.
    boolean
    isFocusVisible()
    Returns whether this component has keyboard focus that should be shown, as a focus ring or a lit face.
    boolean
    isTabbable()
    Returns whether Tab and Shift+Tab stop at this component.
    boolean
    requestFocus()
    Asks the host to give this component keyboard focus.
    S
    setFocusable(boolean focusable)
    Sets whether the component can take keyboard focus, by a click or by requestFocus().
    S
    setTabbable(boolean tabbable)
    Sets whether Tab and Shift+Tab stop at this component.
    S
    setTabIndex(int tabIndex)
    Sets the tab index.
    int
    tabIndex()
    Returns the tab index.

    Methods inherited from interface EventTarget

    onEvent, onEvent, subscribe

  • Field Details

    • FOCUS_GAINED

      static final EventType<FocusEvent> FOCUS_GAINED
      Told after the component gained keyboard focus. Direct. Default behavior: a text box moves its caret to the end.

    • FOCUS_LOST

      static final EventType<FocusEvent> FOCUS_LOST
      Told after the component lost keyboard focus. Direct.

  • Method Details

    • isFocusable

      boolean isFocusable()
      Returns whether the component can take keyboard focus now.
      Returns:
      true unless turned off with setFocusable(false)

    • setFocusable

      S setFocusable(boolean focusable)
      Sets whether the component can take keyboard focus, by a click or by requestFocus(). Turning it off suits parts of a control that should leave focus where it is, such as the list in a combo box's popup. Turning it off on the focused component clears focus at once, and the component hears FOCUS_LOST.
      Parameters:
      focusable - false to refuse focus
      Returns:
      this component

    • isTabbable

      boolean isTabbable()
      Returns whether Tab and Shift+Tab stop at this component.
      Returns:
      true unless turned off with setTabbable(false)

    • setTabbable

      S setTabbable(boolean tabbable)
      Sets whether Tab and Shift+Tab stop at this component. Only matters while it is focusable.
      Parameters:
      tabbable - false to leave the component out of tab order
      Returns:
      this component

    • tabIndex

      int tabIndex()
      Returns the tab index.
      Returns:
      the tab index; 0 by default

    • setTabIndex

      S setTabIndex(int tabIndex)
      Sets the tab index. Tab visits components in ascending tab index, and components with equal indexes in tree order (depth first, children in the order they were added). Negative values are allowed.
      Parameters:
      tabIndex - the tab index
      Returns:
      this component

    • isFocused

      boolean isFocused()
      Returns whether this component has keyboard focus. At most one component per host has focus.
      Returns:
      true while focused

    • isFocusVisible

      boolean isFocusVisible()
      Returns whether this component has keyboard focus that should be shown, as a focus ring or a lit face. Focus is shown when it came from the keyboard, or from code while the last press was a key's rather than a pointer's, and also once a key is pressed while it has focus; a pointer press hides it again. So a button clicked with the mouse keeps focus without looking focused, and Tab shows where focus is. When the host becomes active again, focus comes back shown as it was. Strata's controls draw their focus rings, lit faces and keyboard cursors only while this is true, and text boxes show their focused look whenever they have focus. Themes can style it through the focus_visible style state.
      Returns:
      true while focused and focus is shown

    • requestFocus

      boolean requestFocus()
      Asks the host to give this component keyboard focus. Fails, changing nothing, unless the component is attached, focusable, visible and enabled, with every ancestor visible and enabled. While a dialog is open, it also fails for a component below the top dialog, so only the dialog's content and overlays opened above it can take focus.
      Returns:
      true if the component now has focus