Return Redraw enum instead of bool

Boolean values were too easy to accidentally interpret the wrong way.

examples/hello_world.rs

@@ -1,8 +1,7 @@
-use std::io;
+use crossterm::event::Event;
-
 use crossterm::style::{ContentStyle, Stylize};
 use toss::frame::{Frame, Pos};
-use toss::terminal::Terminal;
+use toss::terminal::{Redraw, Terminal};
 
 fn draw(f: &mut Frame) {
     f.write(
@@ -18,24 +17,32 @@ fn draw(f: &mut Frame) {
     f.show_cursor(Pos::new(16, 0));
 }
 
-fn main() -> io::Result<()> {
+fn render_frame(term: &mut Terminal) {
-    // Automatically enters alternate screen and enables raw mode
-    let mut term = Terminal::new()?;
-
     loop {
         // Must be called before rendering, otherwise the terminal has out-of-date
         // size information and will present garbage.
-        term.autoresize()?;
+        term.autoresize().unwrap();
 
         draw(term.frame());
 
-        if !term.present()? {
+        if term.present().unwrap() == Redraw::NotRequired {
+            break;
+        }
+    }
+}
+
+fn main() {
+    // Automatically enters alternate screen and enables raw mode
+    let mut term = Terminal::new().unwrap();
+
+    loop {
+        // Render and display a frame. A full frame is displayed on the terminal
+        // once this function exits.
+        render_frame(&mut term);
+
+        // Exit if the user presses any buttons
+        if !matches!(crossterm::event::read().unwrap(), Event::Resize(_, _)) {
             break;
         }
     }
-
-    // Wait for input before exiting
-    let _ = crossterm::event::read();
-
-    Ok(())
 }

examples/overlapping_graphemes.rs

@@ -1,8 +1,7 @@
-use std::io;
+use crossterm::event::Event;
-
 use crossterm::style::{ContentStyle, Stylize};
 use toss::frame::{Frame, Pos};
-use toss::terminal::Terminal;
+use toss::terminal::{Redraw, Terminal};
 
 fn draw(f: &mut Frame) {
     f.write(
@@ -58,24 +57,32 @@ fn draw(f: &mut Frame) {
     }
 }
 
-fn main() -> io::Result<()> {
+fn render_frame(term: &mut Terminal) {
-    // Automatically enters alternate screen and enables raw mode
-    let mut term = Terminal::new()?;
-
     loop {
         // Must be called before rendering, otherwise the terminal has out-of-date
         // size information and will present garbage.
-        term.autoresize()?;
+        term.autoresize().unwrap();
 
         draw(term.frame());
 
-        if !term.present()? {
+        if term.present().unwrap() == Redraw::NotRequired {
+            break;
+        }
+    }
+}
+
+fn main() {
+    // Automatically enters alternate screen and enables raw mode
+    let mut term = Terminal::new().unwrap();
+
+    loop {
+        // Render and display a frame. A full frame is displayed on the terminal
+        // once this function exits.
+        render_frame(&mut term);
+
+        // Exit if the user presses any buttons
+        if !matches!(crossterm::event::read().unwrap(), Event::Resize(_, _)) {
             break;
         }
     }
-
-    // Wait for input before exiting
-    let _ = crossterm::event::read();
-
-    Ok(())
 }

src/terminal.rs

@@ -11,6 +11,12 @@ use crossterm::{ExecutableCommand, QueueableCommand};
 use crate::buffer::{Buffer, Size};
 use crate::frame::Frame;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Redraw {
+    Required,
+    NotRequired,
+}
+
 pub struct Terminal {
     /// Render target.
     out: Box<dyn Write>,
@@ -71,7 +77,7 @@ impl Terminal {
     ///
     /// After calling this function, the frame returned by [`Self::frame`] will
     /// be empty again and have no cursor position.
-    pub fn present(&mut self) -> io::Result<bool> {
+    pub fn present(&mut self) -> io::Result<Redraw> {
         if self.frame.widthdb.measuring_required() {
             self.frame.widthdb.measure_widths(&mut self.out)?;
             // Since we messed up the screen by measuring widths, we'll need to
@@ -81,7 +87,7 @@ impl Terminal {
             // with unconfirmed width data. Also, this function guarantees that
             // after it is called, the frame is empty.
             self.frame.reset();
-            return Ok(true);
+            return Ok(Redraw::Required);
         }
 
         if self.full_redraw {
@@ -97,7 +103,7 @@ impl Terminal {
         mem::swap(&mut self.prev_frame_buffer, &mut self.frame.buffer);
         self.frame.reset();
 
-        Ok(false)
+        Ok(Redraw::NotRequired)
     }
 
     fn draw_differences(&mut self) -> io::Result<()> {