Struct Previews 

pub struct Previews { /* private fields */ }

Where the previews of a tree on this thread report, shared with the host that hands the compositor each window’s live picture there: the same handle, so a preview that moves moves its picture.

A host that shows a shell’s views in the compositor’s process installs one handle (install) before it lays the tree out; the preview reports into it on every layout. With none installed, a preview reports nowhere and costs one thread-local read.

It keeps the rects a well keeps (Wells), apart from the tree’s wells: a preview moves nothing on the desk.

Implementations

impl Previews

pub fn new() -> Previews

A handle with no preview on it.

pub fn picture(&self, window: &str) -> Option<Rect>

Where the preview of window window stands, in the layout’s logical coordinates, as of the last layout that placed it.

pub fn pictures(&self) -> BTreeMap<String, Rect>

Every preview on screen, by window, as of the last layout.

pub fn is_empty(&self) -> bool

Whether any preview stands on a tree at all: empty after a layout that placed none.

pub fn generation(&self) -> u64

Moves with every layout that placed a preview, so a reader knows whether its last answer still stands.

pub fn place(&self, window: &str, rect: Rect)

Record rect as the preview of window window.

pub fn remove(&self, window: &str)

Forget the preview of window window: it left the screen.

pub fn clear(&self)

Forget every preview: a layout that placed none leaves none on screen.

Trait Implementations

impl Clone for Previews

fn clone(&self) -> Previews

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Previews

fn default() -> Previews

Returns the “default value” for a type.