Module cursive::view

Expand description

Base elements required to build views.

Views are the main building blocks of your UI.

A view can delegate part or all of its responsabilities to child views, forming a view tree. The root of this tree is a StackView handled directly by the Cursive element.

Layout

The layout phase is when the size and location of each view is computed.

Each view is given an area of the screen by the View::layout() method. With this, the view is free to plan its content, including calling View::layout() on its own children.

In order to determine how much space should be given each child, parents can use View::required_size() on them.

Contracts

When building new Views, you should respect these contracts:

By default, View::layout() should be called before any call to View::draw() with the same available size. The only exceptions is when both following conditions are met:
- The available size has not changed since the last call to View::layout()
- View::needs_relayout() returns false
In this case, it is safe to omit the call to View::layout().
The value returned by required_size should be an actually viable size, no matter what the request is. This means calling View::layout() with a size returned by required_size is never an error.