18.1 How ConstraintLayout Works

In common with all other layouts, ConstraintLayout is responsible for managing the positioning and sizing behavior of the visual components (also referred to as widgets) it contains. It does this based on the constraint connections that are set on each child widget.

In order to fully understand and use ConstraintLayout, it is important to gain an appreciation of the following key concepts:

•Constraints

•Margins

•Opposing Constraints

•Constraint Bias

•Chains

•Chain Styles

•Guidelines

•Groups

•Barriers

•Flow

18.1.1 Constraints

Constraints are essentially sets of rules that dictate the way in which a widget is aligned and distanced in relation to other widgets, the sides of the containing ConstraintLayout and special elements called guidelines. Constraints also dictate how the user interface layout of an activity will respond to changes in device...