Added crossterm backend. (#335)

Add a backend using the crossterm library.

.gitignore

@@ -6,3 +6,4 @@ tags
 *.bk
 TODO.txt
 *.rustfmt
+.idea

.travis.yml

@@ -5,5 +5,5 @@ rust:
     - nightly
 script:
     - cargo check --all-features
-    - cargo build --verbose --features "markdown pancurses-backend termion-backend"
-    - cargo test --verbose --features "markdown pancurses-backend termion-backend"
+    - cargo build --verbose --features "markdown pancurses-backend termion-backend crossterm-backend"
+    - cargo test --verbose --features "markdown pancurses-backend termion-backend crossterm-backend"

Cargo.toml

@@ -66,6 +66,10 @@ version = "0.4.1"
 optional = true
 version = "1.5.1"
 
+[dependencies.crossterm]
+optional = true
+version = "0.9.2"
+
 [target.'cfg(unix)'.dependencies]
 signal-hook = "0.1.8"
 
@@ -80,6 +84,7 @@ markdown = ["pulldown-cmark"]
 ncurses-backend = ["ncurses", "maplit", "term_size"]
 pancurses-backend = ["pancurses", "maplit", "term_size"]
 termion-backend = ["termion"]
+crossterm-backend = ["crossterm"]
 unstable_scroll = []
 
 [lib]

src/backend/crossterm.rs

@@ -0,0 +1,302 @@
+//! Backend using the pure-rust crossplatform crossterm library.
+//!
+//! Requires the `crossterm-backend` feature.
+
+#![cfg(feature = "crossterm")]
+
+use crate::vec::Vec2;
+use crate::{backend, theme};
+use crossterm::{
+    cursor, input, terminal, AlternateScreen, AsyncReader, Attribute,
+    ClearType, Color, Colored, InputEvent as CInputEvent,
+    KeyEvent as CKeyEvent, MouseButton as CMouseButton,
+    MouseEvent as CMouseEvent, Terminal, TerminalCursor,
+};
+
+use crate::event::{Event, Key, MouseButton, MouseEvent};
+use std::cell::{Cell, RefCell};
+use std::io::{self, Stdout, Write};
+
+/// Backend using crossterm
+pub struct Backend {
+    current_style: Cell<theme::ColorPair>,
+    last_button: Option<MouseButton>,
+    // reader to read user input async.
+    async_reader: AsyncReader,
+    alternate_screen: AlternateScreen,
+    stdout: RefCell<Stdout>,
+    cursor: TerminalCursor,
+    terminal: Terminal,
+}
+
+impl Backend {
+    /// Creates a new crossterm backend.
+    pub fn init() -> std::io::Result<Box<dyn backend::Backend>>
+    where
+        Self: Sized,
+    {
+        let alternate_screen = AlternateScreen::to_alternate(true)?;
+
+        let input = input();
+        let async_reader = input.read_async();
+        input.enable_mouse_mode().unwrap();
+
+        cursor().hide();
+
+        Ok(Box::new(Backend {
+            current_style: Cell::new(theme::ColorPair::from_256colors(0, 0)),
+            last_button: None,
+            async_reader,
+            alternate_screen,
+            stdout: RefCell::new(io::stdout()),
+            terminal: terminal(),
+            cursor: cursor(),
+        }))
+    }
+
+    fn apply_colors(&self, colors: theme::ColorPair) {
+        with_color(&colors.front, |c| self.write(Colored::Fg(*c)));
+        with_color(&colors.back, |c| self.write(Colored::Bg(*c)));
+    }
+
+    fn write<T>(&self, content: T)
+    where
+        T: std::fmt::Display,
+    {
+        write!(self.stdout.borrow_mut(), "{}", format!("{}", content)).unwrap()
+    }
+
+    fn map_key(&mut self, event: CInputEvent) -> Event {
+        match event {
+            CInputEvent::Keyboard(key_event) => {
+                return match key_event {
+                    CKeyEvent::Esc => Event::Key(Key::Esc),
+                    CKeyEvent::Backspace => Event::Key(Key::Backspace),
+                    CKeyEvent::Left => Event::Key(Key::Left),
+                    CKeyEvent::Right => Event::Key(Key::Right),
+                    CKeyEvent::Up => Event::Key(Key::Up),
+                    CKeyEvent::Down => Event::Key(Key::Down),
+                    CKeyEvent::Home => Event::Key(Key::Home),
+                    CKeyEvent::End => Event::Key(Key::End),
+                    CKeyEvent::PageUp => Event::Key(Key::PageUp),
+                    CKeyEvent::PageDown => Event::Key(Key::PageDown),
+                    CKeyEvent::Delete => Event::Key(Key::Del),
+                    CKeyEvent::Insert => Event::Key(Key::Ins),
+                    CKeyEvent::F(n) => Event::Key(Key::from_f(n)),
+                    CKeyEvent::Char('\n') => Event::Key(Key::Enter),
+                    CKeyEvent::Char('\t') => Event::Key(Key::Tab),
+                    CKeyEvent::Char(c) => Event::Char(c),
+                    CKeyEvent::Ctrl('c') => Event::Exit,
+                    CKeyEvent::Ctrl(c) => Event::CtrlChar(c),
+                    CKeyEvent::Alt(c) => Event::AltChar(c),
+                    _ => Event::Unknown(vec![]),
+                };
+            }
+            CInputEvent::Mouse(mouse_event) => {
+                return match mouse_event {
+                    CMouseEvent::Press(btn, x, y) => {
+                        let position = (x - 1, y - 1).into();
+
+                        let event = match btn {
+                            CMouseButton::Left => {
+                                MouseEvent::Press(MouseButton::Left)
+                            }
+                            CMouseButton::Middle => {
+                                MouseEvent::Press(MouseButton::Middle)
+                            }
+                            CMouseButton::Right => {
+                                MouseEvent::Press(MouseButton::Right)
+                            }
+                            CMouseButton::WheelUp => MouseEvent::WheelUp,
+                            CMouseButton::WheelDown => MouseEvent::WheelDown,
+                        };
+
+                        if let MouseEvent::Press(btn) = event {
+                            self.last_button = Some(btn);
+                        }
+
+                        return Event::Mouse {
+                            event,
+                            position,
+                            offset: Vec2::zero(),
+                        };
+                    }
+                    CMouseEvent::Release(x, y)
+                        if self.last_button.is_some() =>
+                    {
+                        let event =
+                            MouseEvent::Release(self.last_button.unwrap());
+                        let position = (x - 1, y - 1).into();
+
+                        return Event::Mouse {
+                            event,
+                            position,
+                            offset: Vec2::zero(),
+                        };
+                    }
+                    CMouseEvent::Hold(x, y) if self.last_button.is_some() => {
+                        let event =
+                            MouseEvent::Hold(self.last_button.unwrap());
+                        let position = (x - 1, y - 1).into();
+
+                        return Event::Mouse {
+                            event,
+                            position,
+                            offset: Vec2::zero(),
+                        };
+                    }
+                    _ => {
+                        log::warn!(
+                            "Unknown mouse button event {:?}!",
+                            mouse_event
+                        );
+                        Event::Unknown(vec![])
+                    }
+                };
+            }
+            _ => {
+                log::warn!("Unknown mouse event {:?}!", event);
+                Event::Unknown(vec![])
+            }
+        }
+    }
+}
+
+impl backend::Backend for Backend {
+    fn poll_event(&mut self) -> Option<Event> {
+        self.async_reader.next().map(|event| self.map_key(event))
+    }
+
+    fn finish(&mut self) {
+        self.cursor.goto(1, 1);
+        self.terminal.clear(ClearType::All);
+        self.write(Attribute::Reset);
+        input().disable_mouse_mode();
+        cursor().show();
+    }
+
+    fn refresh(&mut self) {
+        self.stdout.borrow_mut().flush().unwrap();
+    }
+
+    fn has_colors(&self) -> bool {
+        // TODO: color support detection?
+        true
+    }
+
+    fn screen_size(&self) -> Vec2 {
+        let size = self.terminal.terminal_size();
+        return Vec2::new(size.0 as usize + 1, size.1 as usize + 1);
+    }
+
+    fn print_at(&self, pos: Vec2, text: &str) {
+        self.cursor.goto(pos.x as u16, pos.y as u16);
+        self.write(text);
+    }
+
+    fn print_at_rep(&self, pos: Vec2, repetitions: usize, text: &str) {
+        if repetitions > 0 {
+            let mut out = self.stdout.borrow_mut();
+
+            self.cursor.goto(pos.x as u16, pos.y as u16);
+
+            // as I (Timon) wrote this I figured out that calling `write_str` for unix was flushing the stdout.
+            // Current work aground is writing bytes instead of a string to the terminal.
+            out.write(text.as_bytes()).unwrap();
+
+            let mut dupes_left = repetitions - 1;
+            while dupes_left > 0 {
+                out.write(text.as_bytes()).unwrap();
+                dupes_left -= 1;
+            }
+        }
+    }
+
+    fn clear(&self, color: theme::Color) {
+        self.apply_colors(theme::ColorPair {
+            front: color,
+            back: color,
+        });
+
+        self.terminal.clear(ClearType::All);
+    }
+
+    fn set_color(&self, color: theme::ColorPair) -> theme::ColorPair {
+        let current_style = self.current_style.get();
+
+        if current_style != color {
+            self.apply_colors(color);
+            self.current_style.set(color);
+        }
+
+        return current_style;
+    }
+
+    fn set_effect(&self, effect: theme::Effect) {
+        match effect {
+            theme::Effect::Simple => (),
+            theme::Effect::Reverse => self.write(Attribute::Reverse),
+            theme::Effect::Bold => self.write(Attribute::Bold),
+            theme::Effect::Italic => self.write(Attribute::Italic),
+            theme::Effect::Underline => self.write(Attribute::Underlined),
+        }
+    }
+
+    fn unset_effect(&self, effect: theme::Effect) {
+        match effect {
+            theme::Effect::Simple => (),
+            theme::Effect::Reverse => self.write(Attribute::Reverse),
+            theme::Effect::Bold => self.write(Attribute::NoBold),
+            theme::Effect::Italic => self.write(Attribute::NoItalic),
+            theme::Effect::Underline => self.write(Attribute::Underlined),
+        }
+    }
+}
+
+fn with_color<F, R>(clr: &theme::Color, f: F) -> R
+where
+    F: FnOnce(&Color) -> R,
+{
+    match *clr {
+        theme::Color::Dark(theme::BaseColor::Black) => f(&Color::Black),
+        theme::Color::Dark(theme::BaseColor::Red) => f(&Color::DarkRed),
+        theme::Color::Dark(theme::BaseColor::Green) => f(&Color::DarkGreen),
+        theme::Color::Dark(theme::BaseColor::Yellow) => f(&Color::DarkYellow),
+        theme::Color::Dark(theme::BaseColor::Blue) => f(&Color::DarkBlue),
+        theme::Color::Dark(theme::BaseColor::Magenta) => {
+            f(&Color::DarkMagenta)
+        }
+        theme::Color::Dark(theme::BaseColor::Cyan) => f(&Color::DarkCyan),
+        theme::Color::Dark(theme::BaseColor::White) => f(&Color::Grey),
+
+        theme::Color::Light(theme::BaseColor::Black) => f(&Color::Grey),
+        theme::Color::Light(theme::BaseColor::Red) => f(&Color::Red),
+        theme::Color::Light(theme::BaseColor::Green) => f(&Color::Green),
+        theme::Color::Light(theme::BaseColor::Yellow) => f(&Color::Yellow),
+        theme::Color::Light(theme::BaseColor::Blue) => f(&Color::Blue),
+        theme::Color::Light(theme::BaseColor::Magenta) => f(&Color::Magenta),
+        theme::Color::Light(theme::BaseColor::Cyan) => f(&Color::Cyan),
+        theme::Color::Light(theme::BaseColor::White) => f(&Color::White),
+
+        theme::Color::Rgb(r, g, b) => f(&Color::Rgb { r, g, b }),
+        theme::Color::RgbLowRes(r, g, b) => {
+            debug_assert!(r <= 5,
+                          "Red color fragment (r = {}) is out of bound. Make sure r ≤ 5.",
+                          r);
+            debug_assert!(g <= 5,
+                          "Green color fragment (g = {}) is out of bound. Make sure g ≤ 5.",
+                          g);
+            debug_assert!(b <= 5,
+                          "Blue color fragment (b = {}) is out of bound. Make sure b ≤ 5.",
+                          b);
+
+            f(&Color::AnsiValue(16 + 36 * r + 6 * g + b))
+        }
+
+        theme::Color::TerminalDefault => {
+            unimplemented!(
+                "I have to take a look at how reset has to work out"
+            );
+        }
+    }
+}

src/backend/mod.rs

@@ -18,6 +18,7 @@ mod resize;
 pub mod dummy;
 
 pub mod blt;
+pub mod crossterm;
 pub mod curses;
 pub mod termion;
 

src/cursive.rs

@@ -90,7 +90,14 @@ cfg_if::cfg_if! {
                 Self::termion().unwrap()
             }
         }
-    } else if #[cfg(feature = "pancurses-backend")] {
+    }else if #[cfg(feature = "crossterm-backend")] {
+        impl Default for Cursive {
+            fn default() -> Self {
+                Self::crossterm().unwrap()
+            }
+       }
+    }
+    else if #[cfg(feature = "pancurses-backend")] {
         impl Default for Cursive {
             fn default() -> Self {
                 Self::pancurses().unwrap()
@@ -103,7 +110,6 @@ cfg_if::cfg_if! {
             }
         }
     }
-    // No Default implementation otherwise.
 }
 
 impl Cursive {
@@ -126,6 +132,7 @@ impl Cursive {
     ///   * `Cursive::ncurses()` if the `ncurses-backend` feature is enabled (it is by default).
     ///   * `Cursive::pancurses()` if the `pancurses-backend` feature is enabled.
     ///   * `Cursive::termion()` if the `termion-backend` feature is enabled.
+    ///   * `Cursive::crossterm()` if the `crossterm-backend` feature is enabled.
     ///   * `Cursive::blt()` if the `blt-backend` feature is enabled.
     ///   * `Cursive::dummy()` for a dummy backend, mostly useful for tests.
     /// * If you want to use a third-party backend, then `Cursive::new` is indeed the way to go:
@@ -180,6 +187,12 @@ impl Cursive {
         Self::try_new(backend::termion::Backend::init)
     }
 
+    /// Creates a new Cursive root using a crossterm backend.
+    #[cfg(feature = "crossterm-backend")]
+    pub fn crossterm() -> std::io::Result<Self> {
+        Self::try_new(backend::crossterm::Backend::init)
+    }
+
     /// Creates a new Cursive root using a bear-lib-terminal backend.
     #[cfg(feature = "blt-backend")]
     pub fn blt() -> Self {