Trait Backend

pub trait Backend {
    // Required methods
    fn poll_event(&mut self) -> Option<Event>;
    fn set_title(&mut self, title: String);
    fn refresh(&mut self);
    fn has_colors(&self) -> bool;
    fn screen_size(&self) -> XY<usize>;
    fn move_to(&self, pos: XY<usize>);
    fn print(&self, text: &str);
    fn clear(&self, color: Color);
    fn set_color(&self, colors: ColorPair) -> ColorPair;
    fn set_effect(&self, effect: Effect);
    fn unset_effect(&self, effect: Effect);

    // Provided methods
    fn is_persistent(&self) -> bool { ... }
    fn name(&self) -> &str { ... }
}

Trait defining the required methods to be a backend.

A backend is the interface between the abstract view tree and the actual input/output, like a terminal.

It usually delegates the work to a terminal-handling library like ncurses or termion, or it can entirely simulate a terminal and show it as a graphical window (BearLibTerminal).

When creating a new cursive tree with Cursive::new(), you will need to provide a backend initializer - usually their init() function.

Backends are responsible for handling input and converting it to Event. Input must be non-blocking, it will be polled regularly.

Required Methods

fn poll_event(&mut self) -> Option<Event>

Polls the backend for any input.

Should return immediately:

• None if no event is currently available.
• Some(event) for each event to process.

fn set_title(&mut self, title: String)

Sets the title for the backend.

This usually sets the terminal window title.

fn refresh(&mut self)

Refresh the screen.

This will be called each frame after drawing has been done.

A backend could, for example, buffer any print command, and apply everything when refresh() is called.

fn has_colors(&self) -> bool

Should return true if this backend supports colors.

fn screen_size(&self) -> XY<usize>

Returns the screen size.

fn move_to(&self, pos: XY<usize>)

Move the cursor to the given cell.

The next call to print() will start at this place.

fn print(&self, text: &str)

Print some text at the current cursor.

The cursor will then be moved past the end of the printed text.

fn clear(&self, color: Color)

Clears the screen with the given color.

fn set_color(&self, colors: ColorPair) -> ColorPair

Starts using a new color.

This should return the previously active color.

Any call to print_at from now on should use the given color.

fn set_effect(&self, effect: Effect)

Enables the given effect.

Any call to print_at from now on should use the given effect.

fn unset_effect(&self, effect: Effect)

Disables the given effect.

Provided Methods

fn is_persistent(&self) -> bool

Returns true if the backend has persistent output.

If true, this means that output stays there between calls to refresh(), so only delta needs to be sent.

fn name(&self) -> &str

Returns a name to identify the backend.

Mostly used for debugging.

Implementors

impl Backend for cursive::backends::crossterm::Backend

Available on crate feature crossterm-backend only.

impl Backend for cursive::backends::curses::pan::Backend

Available on crate feature pancurses-backend only.

impl Backend for cursive::backends::puppet::Backend

impl Backend for cursive::backends::termion::Backend

Available on crate feature termion-backend only.

impl Backend for Dummy