c6fdfe669e
- Update page title for each piece of documentation to use the vernacular concept rather than the class name for the component. - Treat all instances of class names as proper nouns and mark them as code names. PiperOrigin-RevId: 155705022
4.0 KiB
App Bars
AppBarLayout is the ViewGroup used to wrap the app bar that provides many of the
Material Design features and interactions for app bars, namely responsiveness
to scrolling.
Design & API Documentation
- Material Design guidelines: App Bars
- Material Design guidelines: Scrolling techniques
- Class definition
- Class overview
As a container for Toolbars, and other views, it works with
CoordinatorLayout
in order to respond to scrolling techniques. AppBarLayout depends heavily on
being used as a direct child of the CoordinatorLayout and reacts to a sibling
that supports scrolling
(e.g. NestedScrollView,
RecyclerView).
Flags are added to each child of the AppBarLayout to control how they will
respond to scrolling. These are interpreted by the AppBarLayout.LayoutParams.
Available flags are:
Views using the scroll flag should be declared and visually positioned before
other views in the AppBarLayout. This ensures that they are able to exit at the
top of the screen, leaving behind fixed, or pinned, elements.
Related Concepts
The app bar is a way of referencing a specific type of Toolbar. It's not a separate Android class. This UI element is often used to provide branding for the app as well as a place to handle common actions like navigation, search, and menus. These are accessible via text or buttons in the Toolbar. A Toolbar that provides some of these features is often referred to as the app bar. They are programatically identical and use the Toolbar class.
The app bar was previously termed action bar, and there are methods that utilize this name (e.g. getSupportActionBar). Other than use of the action bar APIs, references to this prominent Toolbar element should be app bar.
A CollapsingToolbarLayout is often used as a wrapper around the Toolbar to provide additional UI features in relation to scrolling.