Backend::poll_event now takes &mut self

To manage an internal buffer, in case backend events and cursive events
don't match 1-for-1.

Planned uses: mouse support (translate click into Press+Release).

src/backend/blt.rs

@@ -79,7 +79,7 @@ impl backend::Backend for Concrete {
         // TODO: unsupported
     }
 
-    fn poll_event(&self) -> Event {
+    fn poll_event(&mut self) -> Event {
         // TODO: we could add backend-specific controls here.
         // Ex: ctrl+mouse wheel cause window cellsize to change
         if let Some(ev) = terminal::wait_event() {

src/backend/curses/n.rs

@@ -139,7 +139,7 @@ impl backend::Backend for Concrete {
         ncurses::mvaddstr(y as i32, x as i32, text);
     }
 
-    fn poll_event(&self) -> Event {
+    fn poll_event(&mut self) -> Event {
         let ch: i32 = ncurses::getch();
 
         // Is it a UTF-8 starting point?

src/backend/curses/pan.rs

@@ -136,7 +136,7 @@ impl backend::Backend for Concrete {
         self.window.mvaddstr(y as i32, x as i32, text);
     }
 
-    fn poll_event(&self) -> Event {
+    fn poll_event(&mut self) -> Event {
         // TODO: there seems to not be any indication
         // of Ctrl/Alt/Shift in these :v
         if let Some(ev) = self.window.getch() {

src/backend/mod.rs

@@ -27,7 +27,7 @@ pub trait Backend {
     fn screen_size(&self) -> (usize, usize);
 
     /// Main input method
-    fn poll_event(&self) -> event::Event;
+    fn poll_event(&mut self) -> event::Event;
 
     /// Main method used for printing
     fn print_at(&self, (usize, usize), &str);

src/backend/termion.rs

@@ -144,7 +144,7 @@ impl backend::Backend for Concrete {
         self.timeout = Some(1000 / fps as u32);
     }
 
-    fn poll_event(&self) -> Event {
+    fn poll_event(&mut self) -> Event {
         let input = &self.input;
         let resize = &self.resize;