Layouts is a feature of the Panels module that allows an administrator to define and use custom layouts based on a basic layout builder in the backend. These layouts can be used to build Panels pages. By integrating them with Panelizer to overwrite node rendering with Panels pages content builders are able to define content pages using a layout of their choosing. To enter the layout backend visit admin/structure/panels/layouts.
Creating a new Layout/Edit an existing Layout
To add a Layout visit the backend at admin/structure/panels/layouts and click "Add flexible Layout" at the top (see 1):
You can also edit or delete layouts by choosing the corresponding action to the right of the layout overview (see 2). The filter widget above the layout list can be used to restrict the number of layouts shown.
When creating a new Layout or editing an existing one a layout builder is displayed:
On the top half of the layout builder basic settings for the layout are configured, including name, description and Category (layouts can be filtered by Category in the overview so make sure to enter a reasonable category!).
The layout builder itself always contains a canvas which is the content area of a drupal page later on. The canvas has a number of settings like size, padding, margins etc that can be configured by pressing the grey arrow to the left of it.
Layouts are built out of columns, rows and regions. Every region can contain panels panes (content) on the page, columns and rows are used to layout only. To add a column or row to an element in the layout builder, click the grey arrow left to the element. Every element in the layout can have specific settings again that can be configured in the same way as the canvas settings. Width of elements can be configured by moving the grey slider between elements.
A preview option is available throughout the process.
Adding/Restricting Layout use on Content Types
By default every layout is usable with every content type so a layout for a Go4 page could be used on a Region page. If access to layouts should be restricted on a content type level the Panelizer configuration has to be changed. Navigate to /admin/config/content/panelizer and edit the allowed content for a content type by pressing the "Allowed content" link on the right. Configure the allowed layouts by selecting/deselecting them in the "Select allowed Layouts" tab: