Module embedded_layout::layout

Layouts - arrange multiple views

A layout is a piece of code that arranges views on the display according to rules of the particular layout algorithm.

Implementing layouts

In embedded-layout, layout objects aren’t special in any way. There is no Layout trait to implement, no required API to provide. Instead, as a developer, you may decide how to make your layout as comfortable as possible.

A layout works on a group of View objects, in the form of a [ViewGroup]. The ViewGroup provides an interface to access view objects of any type.

As an example, a (admittedly not very useful) layout that aligns all views in a ViewGroup to the (0, 0) point, would look something like this:

use embedded_layout::view_group::ViewGroup;

struct MyLayout;

impl MyLayout {
   pub fn arrange(view_group: &mut impl ViewGroup) {
       for idx in 0..view_group.len() {
           let view = view_group.at_mut(idx);
           let by = -view.bounds().top_left;
           // Because `ViewGroup` returns a `&[mut] dyn View`, we need to call the object-safe
           // version of `translate`.
           view.translate_impl(by);
       }
   }
}

As you can see, you can choose not to take ownership of the ViewGroup. If you do, make sure you also implement View and Drawable (you probably don’t want to implement ViewGroup) for your layout object and you provide a way to retrieve the original ViewGroup object!

For a more (but not really) complex example, you may check the source of LinearLayout.

Modules

linear

Linear layout