Struct Screen 

pub struct Screen<W: Write> { /* private fields */ }

The image on the terminal, and the promise to take it back.

Generic over its sink for super::chrome::Chrome’s reason, which is sharper here: every byte this writes is invisible to every other kind of test, and the one that matters most — an image left in the terminal’s memory after the process has gone — is invisible to the reader too.

Implementations

impl<W: Write> Screen<W>

pub fn new(out: W, allowed: bool) -> Self

A screen that will draw if allowed, and never otherwise.

pub fn mapping(&self, cell: Option<(u16, u16)>) -> Maps

Whether a map could appear at all, given what the terminal has just said one cell measures — None when it will not say.

The one predicate, asked here rather than in two places: this is the half of the answer only the screen knows, and the cell size is the half only the terminal knows, and #656 was those two halves being combined nowhere. Asked every frame, because only one of them is a constant: a window can lose its pixel fields without the program at the other end changing — a tmux client attaching, a pane moving between displays.

pub fn show(&mut self, view: &View, pane: Pane, now: Instant) -> Result<Drawn>

Draws the map of whatever the cursor is on, if anything has changed since the last one.

Answers what it left on the screen rather than Ok(()): see Drawn, and #656 for what a silent decline costs.

Errors

Anything the terminal refuses.

pub fn hide(&mut self) -> Result<()>

Takes the image down, if one is up.

Called whenever the map cannot be right: an overlay is over it, the terminal has no room, or the reader turned it off. Forgetting the fingerprint with it is the part that is easy to miss — a map hidden behind the help page and then unhidden is the same picture, so a show that only compared fingerprints would leave the pane blank for as long as nothing else changed.

Errors

Anything the terminal refuses.

pub fn restore(&mut self) -> Result<()>

Puts back everything this took, and can be called twice.

The state being given back here lives in another program’s memory: an image is stored by the terminal, and a process that exits without deleting one leaves a megabyte behind with nothing alive to notice. #619’s rule — a state that cannot be given back is a state you do not take — with the same answer, an id and a delete.

Errors

Anything the terminal refuses.

Trait Implementations

impl<W: Debug + Write> Debug for Screen<W>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.