Making backend::Backend into a std::Boxable trait (#229)

* Making Backend into a Boxable Trait

* Fixed up some typos in the previous and modified some of the docs so they still compile.

* Minor Changes requested by @gyscos

* Whoops

src/backend/blt.rs

@@ -145,7 +145,7 @@ impl Concrete {
 }
 
 impl backend::Backend for Concrete {
-    fn init() -> Self {
+    fn init() -> Box<Self> {
         terminal::open("Cursive", 80, 24);
         terminal::set(terminal::config::Window::empty().resizeable(true));
         terminal::set(vec![
@@ -159,37 +159,59 @@ impl backend::Backend for Concrete {
             },
         ]);
 
-        Concrete {
+        let c = Concrete {
             mouse_position: Vec2::zero(),
             buttons_pressed: HashSet::new(),
-        }
+        };
+
+        Box::new(c)
     }
 
     fn finish(&mut self) {
         terminal::close();
     }
 
-    fn with_color<F: FnOnce()>(&self, color: ColorPair, f: F) {
+    fn set_color(&self, color: ColorPair) -> ColorPair {
+        let current = ColorPair {
+            front: blt_colour_to_colour(state::foreground()),
+            back:  blt_colour_to_colour(state::background())
+        };
+        
         let fg = colour_to_blt_colour(color.front, ColorRole::Foreground);
         let bg = colour_to_blt_colour(color.back, ColorRole::Background);
-        terminal::with_colors(fg, bg, f);
+        
+        terminal::set_colors(fg, bg);
+
+        current
     }
 
-    fn with_effect<F: FnOnce()>(&self, effect: Effect, f: F) {
+    fn set_effect(&self, effect: Effect) {
         match effect {
             // TODO: does BLT support bold/italic/underline?
             Effect::Bold
             | Effect::Italic
             | Effect::Underline
-            | Effect::Simple => f(),
+            | Effect::Simple => {},
             // TODO: how to do this correctly?`
             //       BLT itself doesn't do this kind of thing,
             //       we'd need the colours in our position,
             //       but `f()` can do whatever
-            Effect::Reverse => terminal::with_colors(
-                BltColor::from_rgb(0, 0, 0),
-                BltColor::from_rgb(255, 255, 255),
-                f,
+            Effect::Reverse => terminal::set_colors(
+                state::background(), state::foreground()
+            ),
+        }
+    }
+
+    fn unset_effect(&self, effect: Effect) {
+        match effect {
+            // TODO: does BLT support bold/italic/underline?
+            Effect::Bold
+            | Effect::Italic
+            | Effect::Underline
+            | Effect::Simple => {},
+            // The process of reversing is the same as unreversing
+            Effect::Reverse => terminal::set_colors(
+                state::background(), state::foreground()
             ),
         }
     }
@@ -282,6 +304,10 @@ impl backend::Backend for Concrete {
     }
 }
 
+fn blt_colour_to_colour(c: BltColor) -> Color {
+    Color::Rgb(c.red, c.green, c.blue)
+}
+
 fn colour_to_blt_colour(clr: Color, role: ColorRole) -> BltColor {
     let (r, g, b) = match clr {
         Color::TerminalDefault => {

src/backend/curses/n.rs

@@ -150,7 +150,7 @@ impl Concrete {
 }
 
 impl backend::Backend for Concrete {
-    fn init() -> Self {
+    fn init() -> Box<Self> {
         // Change the locale.
         // For some reasons it's mandatory to get some UTF-8 support.
         ncurses::setlocale(ncurses::LcCategory::all, "");
@@ -186,7 +186,7 @@ impl backend::Backend for Concrete {
         print!("\x1B[?1002h");
         stdout().flush().expect("could not flush stdout");
 
-        Concrete {
+        let c = Concrete {
             current_style: Cell::new(ColorPair::from_256colors(0, 0)),
             pairs: RefCell::new(HashMap::new()),
 
@@ -194,7 +194,9 @@ impl backend::Backend for Concrete {
             event_queue: Vec::new(),
 
             key_codes: initialize_keymap(),
-        }
+        };
+
+        Box::new(c)
     }
 
     fn screen_size(&self) -> (usize, usize) {
@@ -214,21 +216,16 @@ impl backend::Backend for Concrete {
         ncurses::endwin();
     }
 
-    fn with_color<F: FnOnce()>(&self, colors: ColorPair, f: F) {
+    fn set_color(&self, colors: ColorPair) -> ColorPair {
         // eprintln!("Color used: {:?}", colors);
         let current = self.current_style.get();
         if current != colors {
             self.set_colors(colors);
         }
-
-        f();
-
-        if current != colors {
-            self.set_colors(current);
-        }
+        return current;
     }
 
-    fn with_effect<F: FnOnce()>(&self, effect: Effect, f: F) {
+    fn set_effect(&self, effect: Effect) {
         let style = match effect {
             Effect::Reverse => ncurses::A_REVERSE(),
             Effect::Simple => ncurses::A_NORMAL(),
@@ -237,7 +234,16 @@ impl backend::Backend for Concrete {
             Effect::Underline => ncurses::A_UNDERLINE(),
         };
         ncurses::attron(style);
-        f();
+    }
+
+    fn unset_effect(&self, effect: Effect) {
+        let style = match effect {
+            Effect::Reverse => ncurses::A_REVERSE(),
+            Effect::Simple => ncurses::A_NORMAL(),
+            Effect::Bold => ncurses::A_BOLD(),
+            Effect::Italic => ncurses::A_ITALIC(),
+            Effect::Underline => ncurses::A_UNDERLINE(),
+        };
         ncurses::attroff(style);
     }
 

src/backend/curses/pan.rs

@@ -133,7 +133,7 @@ impl Concrete {
 }
 
 impl backend::Backend for Concrete {
-    fn init() -> Self {
+    fn init() -> Box<Self> {
         ::std::env::set_var("ESCDELAY", "25");
 
         let window = pancurses::initscr();
@@ -155,14 +155,16 @@ impl backend::Backend for Concrete {
         print!("\x1B[?1002h");
         stdout().flush().expect("could not flush stdout");
 
-        Concrete {
+        let c = Concrete {
             current_style: Cell::new(ColorPair::from_256colors(0, 0)),
             pairs: RefCell::new(HashMap::new()),
             window: window,
             last_mouse_button: None,
             event_queue: Vec::new(),
             key_codes: initialize_keymap(),
-        }
+        };
+
+        Box::new(c)
     }
 
     fn screen_size(&self) -> (usize, usize) {
@@ -180,21 +182,17 @@ impl backend::Backend for Concrete {
         pancurses::endwin();
     }
 
-    fn with_color<F: FnOnce()>(&self, colors: ColorPair, f: F) {
+    fn set_color(&self, colors: ColorPair) -> ColorPair {
         let current = self.current_style.get();
 
         if current != colors {
             self.set_colors(colors);
         }
 
-        f();
-
-        if current != colors {
-            self.set_colors(current);
-        }
+        current
     }
 
-    fn with_effect<F: FnOnce()>(&self, effect: Effect, f: F) {
+    fn set_effect(&self, effect: Effect) {
         let style = match effect {
             Effect::Simple => pancurses::Attribute::Normal,
             Effect::Reverse => pancurses::Attribute::Reverse,
@@ -203,7 +201,16 @@ impl backend::Backend for Concrete {
             Effect::Underline => pancurses::Attribute::Underline,
         };
         self.window.attron(style);
-        f();
+    }
+
+    fn unset_effect(&self, effect: Effect) {
+        let style = match effect {
+            Effect::Simple => pancurses::Attribute::Normal,
+            Effect::Reverse => pancurses::Attribute::Reverse,
+            Effect::Bold => pancurses::Attribute::Bold,
+            Effect::Italic => pancurses::Attribute::Italic,
+            Effect::Underline => pancurses::Attribute::Underline,
+        };
         self.window.attroff(style);
     }
 

src/backend/mod.rs

@@ -16,7 +16,7 @@ pub use self::curses::*;
 pub use self::termion::*;
 
 pub trait Backend {
-    fn init() -> Self;
+    fn init() -> Box<Self> where Self: Sized;
     // TODO: take `self` by value?
     // Or implement Drop?
     fn finish(&mut self);
@@ -34,7 +34,11 @@ pub trait Backend {
     fn clear(&self, color: theme::Color);
 
     fn set_refresh_rate(&mut self, fps: u32);
-    // TODO: unify those into a single method?
-    fn with_color<F: FnOnce()>(&self, colors: theme::ColorPair, f: F);
-    fn with_effect<F: FnOnce()>(&self, effect: theme::Effect, f: F);
+
+    // This sets the Colours and returns the previous colours
+    // to allow you to set them back when you're done.
+    fn set_color(&self, colors: theme::ColorPair) -> theme::ColorPair;
+
+    fn set_effect(&self, effect: theme::Effect);
+    fn unset_effect(&self, effect: theme::Effect);
 }

src/backend/termion.rs

@@ -137,7 +137,7 @@ impl Concrete {
 }
 
 impl backend::Backend for Concrete {
-    fn init() -> Self {
+    fn init() -> Box<Self> {
         print!("{}", termion::cursor::Hide);
 
         let resize = chan_signal::notify(&[chan_signal::Signal::WINCH]);
@@ -157,14 +157,16 @@ impl backend::Backend for Concrete {
             }
         });
 
-        Concrete {
+        let c = Concrete {
             terminal: terminal,
             current_style: Cell::new(theme::ColorPair::from_256colors(0, 0)),
             input: receiver,
             resize: resize,
             timeout: None,
             last_button: None,
-        }
+        };
+
+        Box::new(c)
     }
 
     fn finish(&mut self) {
@@ -177,7 +179,7 @@ impl backend::Backend for Concrete {
         );
     }
 
-    fn with_color<F: FnOnce()>(&self, color: theme::ColorPair, f: F) {
+    fn set_color(&self, color: theme::ColorPair) -> theme::ColorPair {
         let current_style = self.current_style.get();
 
         if current_style != color {
@@ -185,17 +187,14 @@ impl backend::Backend for Concrete {
             self.current_style.set(color);
         }
 
-        f();
-
-        if current_style != color {
-            self.current_style.set(current_style);
-            self.apply_colors(current_style);
-        }
+        return current_style;
     }
 
-    fn with_effect<F: FnOnce()>(&self, effect: theme::Effect, f: F) {
+    fn set_effect(&self, effect: theme::Effect) {
         effect.on();
-        f();
+    }
+
+    fn unset_effect(&self, effect: theme::Effect) {
         effect.off();
     }
 

src/cursive.rs

@@ -54,7 +54,7 @@ pub struct Cursive {
 
     running: bool,
 
-    backend: backend::Concrete,
+    backend: Box<backend::Backend>,
 
     cb_source: mpsc::Receiver<Box<CbFunc>>,
     cb_sink: mpsc::Sender<Box<CbFunc>>,

src/printer.rs

@@ -1,6 +1,6 @@
 //! Makes drawing on ncurses windows easier.
 
-use backend::{self, Backend};
+use backend::Backend;
 use enumset::EnumSet;
 use std::cell::Cell;
 use std::cmp::min;
@@ -24,7 +24,7 @@ pub struct Printer<'a> {
     /// `true` if nothing has been drawn yet.
     new: Rc<Cell<bool>>,
     /// Backend used to actually draw things
-    backend: &'a backend::Concrete,
+    backend: &'a Box<Backend>,
 }
 
 impl<'a> Printer<'a> {
@@ -33,7 +33,7 @@ impl<'a> Printer<'a> {
     /// But nobody needs to know that.
     #[doc(hidden)]
     pub fn new<T: Into<Vec2>>(
-        size: T, theme: &'a Theme, backend: &'a backend::Concrete
+        size: T, theme: &'a Theme, backend: &'a Box<Backend>
     ) -> Self {
         Printer {
             offset: Vec2::zero(),
@@ -121,7 +121,7 @@ impl<'a> Printer<'a> {
     /// # use cursive::Printer;
     /// # use cursive::theme;
     /// # use cursive::backend::{self, Backend};
-    /// # let b = backend::Concrete::init();
+    /// # let b: Box<Backend> = backend::Concrete::init();
     /// # let t = theme::load_default();
     /// # let printer = Printer::new((6,4), &t, &b);
     /// printer.with_color(theme::ColorStyle::highlight(), |printer| {
@@ -132,8 +132,9 @@ impl<'a> Printer<'a> {
     where
         F: FnOnce(&Printer),
     {
-        self.backend
-            .with_color(c.resolve(&self.theme.palette), || f(self));
+        let old = self.backend.set_color(c.resolve(&self.theme.palette));
+        f(self);
+        self.backend.set_color(old);
     }
 
     /// Call the given closure with a styled printer,
@@ -165,7 +166,9 @@ impl<'a> Printer<'a> {
     where
         F: FnOnce(&Printer),
     {
-        self.backend.with_effect(effect, || f(self));
+        self.backend.set_effect(effect);
+        f(self);
+        self.backend.unset_effect(effect);
     }
 
     /// Call the given closure with a modified printer
@@ -196,7 +199,7 @@ impl<'a> Printer<'a> {
     /// # use cursive::Printer;
     /// # use cursive::theme;
     /// # use cursive::backend::{self, Backend};
-    /// # let b = backend::Concrete::init();
+    /// # let b: Box<Backend> = backend::Concrete::init();
     /// # let t = theme::load_default();
     /// # let printer = Printer::new((6,4), &t, &b);
     /// printer.print_box((0,0), (6,4), false);

src/view/scroll.rs

@@ -232,7 +232,7 @@ impl ScrollBase {
     /// # use cursive::theme;
     /// # use cursive::backend::{self, Backend};
     /// # let scrollbase = ScrollBase::new();
-    /// # let b = backend::Concrete::init();
+    /// # let b: Box<Backend> = backend::Concrete::init();
     /// # let t = theme::load_default();
     /// # let printer = Printer::new((5,1), &t, &b);
     /// # let printer = &printer;