Bump version to 0.3.4

I'm pretty sure it still breaks in lots of terminal emulators, but it
works far better than what recent versions of the unicode_width crate
were doing.

CHANGELOG.md

@@ -13,6 +13,27 @@ Procedure when bumping the version number:
 
 ## Unreleased
 
+## v0.3.4 - 2025-03-8
+
+### Added
+- `Frame::set_bell` to print a bell character when the frame is displayed
+- `widgets::bell`
+
+## v0.3.3 - 2025-02-28
+
+### Fixed
+- Rendering glitches in unicode-based with estimation
+
+## v0.3.2 - 2025-02-23
+
+### Added
+- Unicode-based grapheme width estimation method
+
+## v0.3.1 - 2025-02-21
+
+### Fixed
+- Rendering glitches, mainly related to emoji
+
 ## v0.3.0 - 2024-11-06
 
 ### Added

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "toss"
-version = "0.3.0"
+version = "0.3.4"
 edition = "2021"
 
 [dependencies]

src/frame.rs

@@ -8,6 +8,7 @@ pub struct Frame {
     pub(crate) widthdb: WidthDb,
     pub(crate) buffer: Buffer,
     pub(crate) title: Option<String>,
+    pub(crate) bell: bool,
 }
 
 impl Frame {
@@ -48,6 +49,10 @@ impl Frame {
         self.title = title;
     }
 
+    pub fn set_bell(&mut self, bell: bool) {
+        self.bell = bell;
+    }
+
     pub fn widthdb(&mut self) -> &mut WidthDb {
         &mut self.widthdb
     }

src/terminal.rs

@@ -8,7 +8,7 @@ use crossterm::event::{
     DisableBracketedPaste, EnableBracketedPaste, KeyboardEnhancementFlags,
     PopKeyboardEnhancementFlags, PushKeyboardEnhancementFlags,
 };
-use crossterm::style::{PrintStyledContent, StyledContent};
+use crossterm::style::{Print, PrintStyledContent, StyledContent};
 use crossterm::terminal::{
     BeginSynchronizedUpdate, Clear, ClearType, EndSynchronizedUpdate, EnterAlternateScreen,
     LeaveAlternateScreen, SetTitle,
@@ -16,7 +16,7 @@ use crossterm::terminal::{
 use crossterm::{ExecutableCommand, QueueableCommand};
 
 use crate::buffer::Buffer;
-use crate::{AsyncWidget, Frame, Size, Widget, WidthDb};
+use crate::{AsyncWidget, Frame, Size, Widget, WidthDb, WidthEstimationMethod};
 
 /// Wrapper that manages terminal output.
 ///
@@ -112,11 +112,25 @@ impl Terminal {
         self.frame.widthdb.tab_width
     }
 
+    /// Set the grapheme width estimation method.
+    ///
+    /// For more details, see [`WidthEstimationMethod`].
+    pub fn set_width_estimation_method(&mut self, method: WidthEstimationMethod) {
+        self.frame.widthdb.estimate = method;
+    }
+
+    /// The grapheme width estimation method.
+    ///
+    /// For more details, see [`WidthEstimationMethod`].
+    pub fn width_estimation_method(&mut self) -> WidthEstimationMethod {
+        self.frame.widthdb.estimate
+    }
+
     /// Enable or disable grapheme width measurements.
     ///
     /// For more details, see [`Self::measuring`].
     pub fn set_measuring(&mut self, active: bool) {
-        self.frame.widthdb.active = active;
+        self.frame.widthdb.measure = active;
     }
 
     /// Whether grapheme widths should be measured or estimated.
@@ -135,7 +149,7 @@ impl Terminal {
     /// Standard Annex #11. This usually works fine, but may break on some emoji
     /// or other less commonly used character sequences.
     pub fn measuring(&self) -> bool {
-        self.frame.widthdb.active
+        self.frame.widthdb.measure
     }
 
     /// Whether any unmeasured graphemes were seen since the last call to
@@ -260,6 +274,7 @@ impl Terminal {
         self.draw_differences()?;
         self.update_cursor()?;
         self.update_title()?;
+        self.ring_bell()?;
 
         Ok(())
     }
@@ -301,4 +316,12 @@ impl Terminal {
         }
         Ok(())
     }
+
+    fn ring_bell(&mut self) -> io::Result<()> {
+        if self.frame.bell {
+            self.out.queue(Print('\x07'))?;
+        }
+        self.frame.bell = false;
+        Ok(())
+    }
 }

src/widgets.rs

@@ -1,4 +1,5 @@
 pub mod background;
+pub mod bell;
 pub mod border;
 pub mod boxed;
 pub mod cursor;
@@ -16,6 +17,7 @@ pub mod text;
 pub mod title;
 
 pub use background::*;
+pub use bell::*;
 pub use border::*;
 pub use boxed::*;
 pub use cursor::*;

src/widgets/bell.rs

@@ -0,0 +1,55 @@
+use crate::{Frame, Size, Widget, WidthDb};
+
+///////////
+// State //
+///////////
+
+#[derive(Debug, Default, Clone)]
+pub struct BellState {
+    // Whether the bell should be rung the next time the widget is displayed.
+    pub ring: bool,
+}
+
+impl BellState {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn widget(&mut self) -> Bell<'_> {
+        Bell { state: self }
+    }
+}
+
+////////////
+// Widget //
+////////////
+
+#[derive(Debug)]
+pub struct Bell<'a> {
+    state: &'a mut BellState,
+}
+
+impl Bell<'_> {
+    pub fn state(&mut self) -> &mut BellState {
+        self.state
+    }
+}
+
+impl<E> Widget<E> for Bell<'_> {
+    fn size(
+        &self,
+        _widthdb: &mut WidthDb,
+        _max_width: Option<u16>,
+        _max_height: Option<u16>,
+    ) -> Result<Size, E> {
+        Ok(Size::ZERO)
+    }
+
+    fn draw(self, frame: &mut Frame) -> Result<(), E> {
+        if self.state.ring {
+            frame.set_bell(true);
+            self.state.ring = false
+        }
+        Ok(())
+    }
+}

src/widthdb.rs

@@ -6,14 +6,31 @@ use crossterm::style::Print;
 use crossterm::terminal::{Clear, ClearType};
 use crossterm::QueueableCommand;
 use unicode_segmentation::UnicodeSegmentation;
-use unicode_width::UnicodeWidthStr;
+use unicode_width::{UnicodeWidthChar, UnicodeWidthStr};
 
 use crate::wrap;
 
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub enum WidthEstimationMethod {
+    /// Estimate the width of a grapheme using legacy methods.
+    ///
+    /// Different terminal emulators all use different approaches to determine
+    /// grapheme widths, so this method will never be able to give a fully
+    /// correct solution. For that, the only possible approach is measuring the
+    /// actual grapheme width.
+    #[default]
+    Legacy,
+
+    /// Estimate the width of a grapheme using the unicode standard in a
+    /// best-effort manner.
+    Unicode,
+}
+
 /// Measures and stores the with (in terminal coordinates) of graphemes.
 #[derive(Debug)]
 pub struct WidthDb {
-    pub(crate) active: bool,
+    pub(crate) estimate: WidthEstimationMethod,
+    pub(crate) measure: bool,
     pub(crate) tab_width: u8,
     known: HashMap<String, u8>,
     requested: HashSet<String>,
@@ -22,7 +39,8 @@ pub struct WidthDb {
 impl Default for WidthDb {
     fn default() -> Self {
         Self {
-            active: false,
+            estimate: WidthEstimationMethod::default(),
+            measure: false,
             tab_width: 8,
             known: Default::default(),
             requested: Default::default(),
@@ -47,14 +65,37 @@ impl WidthDb {
         if grapheme == "\t" {
             return self.tab_width_at_column(col);
         }
-        if !self.active {
+
-            return grapheme.width() as u8;
+        if self.measure {
-        }
             if let Some(width) = self.known.get(grapheme) {
-            *width
+                return *width;
-        } else {
+            }
             self.requested.insert(grapheme.to_string());
-            grapheme.width() as u8
+        }
+
+        match self.estimate {
+            // A character-wise width calculation is a simple and obvious
+            // approach to compute character widths. The idea is that dumb
+            // terminal emulators tend to do something roughly like this, and
+            // smart terminal emulators try to emulate dumb ones for
+            // compatibility. In practice, this approach seems to be fairly
+            // robust.
+            WidthEstimationMethod::Legacy => grapheme
+                .chars()
+                .filter(|c| !c.is_ascii_control())
+                .flat_map(|c| c.width())
+                .sum::<usize>()
+                .try_into()
+                .unwrap_or(u8::MAX),
+
+            // The unicode width crate considers control chars to have a width
+            // of 1 even though they usually have a width of 0 when displayed.
+            WidthEstimationMethod::Unicode => grapheme
+                .split(|c: char| c.is_ascii_control())
+                .map(|s| s.width())
+                .sum::<usize>()
+                .try_into()
+                .unwrap_or(u8::MAX),
         }
     }
 
@@ -87,7 +128,7 @@ impl WidthDb {
     /// Whether any new graphemes have been seen since the last time
     /// [`Self::measure_widths`] was called.
     pub(crate) fn measuring_required(&self) -> bool {
-        self.active && !self.requested.is_empty()
+        self.measure && !self.requested.is_empty()
     }
 
     /// Measure the width of all new graphemes that have been seen since the
@@ -97,11 +138,11 @@ impl WidthDb {
     /// the terminal. After it finishes, the terminal's contents should be
     /// assumed to be garbage and a full redraw should be performed.
     pub(crate) fn measure_widths(&mut self, out: &mut impl Write) -> io::Result<()> {
-        if !self.active {
+        if !self.measure {
             return Ok(());
         }
         for grapheme in self.requested.drain() {
-            if grapheme.chars().any(|c|c.is_ascii_control()){
+            if grapheme.chars().any(|c| c.is_ascii_control()) {
                 // ASCII control characters like the escape character or the
                 // bell character tend to be interpreted specially by terminals.
                 // This may break width measurements. To avoid this, we just