This section provides guidance on developing layout templates for Backdrop.
A layout is a collection of files that defines how various elements are arranged on a page. Layouts are a new feature in Backdrop (relative to Drupal 7); their closest analogy is the functionality that was provided by the D7 Panels module.
Backdrop's primary tool for positioning content is through layouts and blocks. Each piece of content on a page is called a "block". A collection of blocks on a page is a "layout". A "layout template" is the template that defines the regions in which pieces of content may be placed. A single layout places blocks within its layout template.
Each piece of content in this case is called a "block". Blocks may be placed multiple times in a single "Layout", and each block maintains separate settings. Each layout created saves to a configuration file, including all the settings for the blocks contained within it.
The Layout module provides two distinct ways of rendering pages; it both creates pages and wraps existing pages in layout templates. It is capable of creating a stand-alone page that is created at any custom path specified by the user, and it can also "wrap" the content of any path provided by a module. In the case where a custom path is created, Layout module registers the path in the menu system through
hook_menu(). For wrapping module-provided pages, Layout module declares itself as the system-wide "route handler", as checked in menu_execute_active_handler(). Layout module then becomes responsible for calling the module-provided content as a block, and positions other blocks around the existing content.
Although Backdrop comes with many predefined layout templates for different arrangements of blocks (single-column, various types of multi-column), you can define your own layout templates as described in the following section.