Flow

Overview

The flow element, is a composite that lays out its children much like the way text is laid out: lay out each element from left to right, fitting as much elements as possible following each child’s maximum horizontal limit. Once a row is full, move to the next row and do the same until the end of the row is filled. Repeat the procedure until all the elements are laid out. The height of each row is determined by the maximum vertical limit of all the elements to be laid out in that row.

The following graphic depicts a simplified layout scenario for child elements a to r.

The child elements arranged in a flow composite are automatically re-flowed when the view size changes.

flow_composite

Create a flow_composite with an indeterminate (dynamic) number of elements to have elements laid out using flow.

Notation

c: Instance of type flow_composite

The flow_composite is essentially a std::vector<element_ptr> that the client uses to manage the composite’s elements. The client is responsible for the lifetime of the container, c. You use flow_composite just as you would a std::vector, such as using push_back to add a child element. Remember that the items are element_ptr instances.

Expression

flow_composite c;

Example

c.push_back(share(child));

share turns an element object into an element_ptr held by the std::vector<element_ptr> in flow_composite.

flow

Once we have a flow_composite, we can place its contents in a flow element.

Notation

c: Instance of flow_composite

Expression

flow(c)

Semantics

Returns instance of Composite.