Add `cursor.blink_timeout` config option

This option should prevent extensive power usage due to cursor blinking
when there's no user activity being performed.

Fixes #5992.

6 files changed, 75 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8591416e..6c8816d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,12 +21,14 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Escape sequence to reset underline color (`CSI 59 m`)
 - Vi mode keybinding (z) to center view around vi mode cursor
 - Accept hexadecimal values starting with `0x` for `--embed`
+- Config option `cursor.blink_timeout` to timeout cursor blinking after inactivity
 
 ### Changed
 
 - The `--help` output was reworked with a new colorful syntax
 - OSC 52 is now disabled on unfocused windows
 - `SpawnNewInstance` no longer inherits initial `--command`
+- Blinking cursor will timeout after `5` seconds by default
 
 ### Fixed
 
diff --git a/alacritty.yml b/alacritty.yml
index 3ba6a7f5..511a10d6 100644
--- a/alacritty.yml
+++ b/alacritty.yml
@@ -412,6 +412,11 @@
   # Cursor blinking interval in milliseconds.
   #blink_interval: 750
 
+  # Time after which cursor stops blinking, in seconds.
+  #
+  # Specifying '0' will disable timeout for blinking.
+  #blink_timeout: 5
+
   # If this is `true`, the cursor will be rendered as a hollow box when the
   # window is not focused.
   #unfocused_hollow: true
diff --git a/alacritty/src/event.rs b/alacritty/src/event.rs
index 2955ab8c..f91ef962 100644
--- a/alacritty/src/event.rs
+++ b/alacritty/src/event.rs
@@ -90,6 +90,7 @@ pub enum EventType {
     Scroll(Scroll),
     CreateWindow(WindowOptions),
     BlinkCursor,
+    BlinkCursorTimeout,
     SearchNext,
 }
 
@@ -180,6 +181,7 @@ pub struct ActionContext<'a, N, T> {
     pub display: &'a mut Display,
     pub message_buffer: &'a mut MessageBuffer,
     pub config: &'a mut UiConfig,
+    pub cursor_blink_timed_out: &'a mut bool,
     pub event_loop: &'a EventLoopWindowTarget<Event>,
     pub event_proxy: &'a EventLoopProxy<Event>,
     pub scheduler: &'a mut Scheduler,
@@ -647,14 +649,15 @@ impl<'a, N: Notify + 'a, T: EventListener> input::ActionContext<T> for ActionCon
     fn on_typing_start(&mut self) {
         // Disable cursor blinking.
         let timer_id = TimerId::new(Topic::BlinkCursor, self.display.window.id());
-        if let Some(timer) = self.scheduler.unschedule(timer_id) {
-            let interval =
-                Duration::from_millis(self.config.terminal_config.cursor.blink_interval());
-            self.scheduler.schedule(timer.event, interval, true, timer.id);
+        if self.scheduler.unschedule(timer_id).is_some() {
+            self.schedule_blinking();
             self.display.cursor_hidden = false;
-            *self.dirty = true;
+        } else if *self.cursor_blink_timed_out {
+            self.update_cursor_blinking();
         }
 
+        *self.dirty = true;
+
         // Hide mouse cursor.
         if self.config.mouse.hide_when_typing {
             self.display.window.set_mouse_visible(false);
@@ -945,18 +948,44 @@ impl<'a, N: Notify + 'a, T: EventListener> ActionContext<'a, N, T> {
         blinking &= vi_mode || self.terminal().mode().contains(TermMode::SHOW_CURSOR);
 
         // Update cursor blinking state.
-        let timer_id = TimerId::new(Topic::BlinkCursor, self.display.window.id());
-        self.scheduler.unschedule(timer_id);
+        let window_id = self.display.window.id();
+        self.scheduler.unschedule(TimerId::new(Topic::BlinkCursor, window_id));
+        self.scheduler.unschedule(TimerId::new(Topic::BlinkTimeout, window_id));
+
+        // Reset blinkinig timeout.
+        *self.cursor_blink_timed_out = false;
+
         if blinking && self.terminal.is_focused {
-            let event = Event::new(EventType::BlinkCursor, self.display.window.id());
-            let interval =
-                Duration::from_millis(self.config.terminal_config.cursor.blink_interval());
-            self.scheduler.schedule(event, interval, true, timer_id);
+            self.schedule_blinking();
+            self.schedule_blinking_timeout();
         } else {
             self.display.cursor_hidden = false;
             *self.dirty = true;
         }
     }
+
+    fn schedule_blinking(&mut self) {
+        let window_id = self.display.window.id();
+        let timer_id = TimerId::new(Topic::BlinkCursor, window_id);
+        let event = Event::new(EventType::BlinkCursor, window_id);
+        let blinking_interval =
+            Duration::from_millis(self.config.terminal_config.cursor.blink_interval());
+        self.scheduler.schedule(event, blinking_interval, true, timer_id);
+    }
+
+    fn schedule_blinking_timeout(&mut self) {
+        let blinking_timeout = self.config.terminal_config.cursor.blink_timeout();
+        if blinking_timeout == 0 {
+            return;
+        }
+
+        let window_id = self.display.window.id();
+        let blinking_timeout_interval = Duration::from_secs(blinking_timeout);
+        let event = Event::new(EventType::BlinkCursorTimeout, window_id);
+        let timer_id = TimerId::new(Topic::BlinkTimeout, window_id);
+
+        self.scheduler.schedule(event, blinking_timeout_interval, false, timer_id);
+    }
 }
 
 #[derive(Debug, Eq, PartialEq)]
@@ -1048,6 +1077,14 @@ impl input::Processor<EventProxy, ActionContext<'_, Notifier, EventProxy>> {
                     self.ctx.display.cursor_hidden ^= true;
                     *self.ctx.dirty = true;
                 },
+                EventType::BlinkCursorTimeout => {
+                    // Disable blinking after timeout reached.
+                    let timer_id = TimerId::new(Topic::BlinkCursor, self.ctx.display.window.id());
+                    self.ctx.scheduler.unschedule(timer_id);
+                    self.ctx.display.cursor_hidden = false;
+                    *self.ctx.cursor_blink_timed_out = true;
+                    *self.ctx.dirty = true;
+                },
                 EventType::Message(message) => {
                     self.ctx.message_buffer.push(message);
                     self.ctx.display.pending_update.dirty = true;
diff --git a/alacritty/src/scheduler.rs b/alacritty/src/scheduler.rs
index 924f5904..08388b94 100644
--- a/alacritty/src/scheduler.rs
+++ b/alacritty/src/scheduler.rs
@@ -27,6 +27,7 @@ pub enum Topic {
     SelectionScrolling,
     DelayedSearch,
     BlinkCursor,
+    BlinkTimeout,
 }
 
 /// Event scheduled to be emitted at a specific time.
diff --git a/alacritty/src/window_context.rs b/alacritty/src/window_context.rs
index f04a8e04..a45b9404 100644
--- a/alacritty/src/window_context.rs
+++ b/alacritty/src/window_context.rs
@@ -43,6 +43,7 @@ pub struct WindowContext {
     pub display: Display,
     event_queue: Vec<GlutinEvent<'static, Event>>,
     terminal: Arc<FairMutex<Term<EventProxy>>>,
+    cursor_blink_timed_out: bool,
     modifiers: ModifiersState,
     search_state: SearchState,
     received_count: usize,
@@ -151,6 +152,7 @@ impl WindowContext {
             master_fd,
             #[cfg(not(windows))]
             shell_pid,
+            cursor_blink_timed_out: Default::default(),
             suppress_chars: Default::default(),
             message_buffer: Default::default(),
             received_count: Default::default(),
@@ -267,6 +269,7 @@ impl WindowContext {
         let old_is_searching = self.search_state.history_index.is_some();
 
         let context = ActionContext {
+            cursor_blink_timed_out: &mut self.cursor_blink_timed_out,
             message_buffer: &mut self.message_buffer,
             received_count: &mut self.received_count,
             suppress_chars: &mut self.suppress_chars,
diff --git a/alacritty_terminal/src/config/mod.rs b/alacritty_terminal/src/config/mod.rs
index 40c42d4f..5822d591 100644
--- a/alacritty_terminal/src/config/mod.rs
+++ b/alacritty_terminal/src/config/mod.rs
@@ -1,4 +1,4 @@
-use std::cmp::max;
+use std::cmp;
 use std::collections::HashMap;
 use std::path::PathBuf;
 
@@ -13,6 +13,7 @@ use crate::ansi::{CursorShape, CursorStyle};
 pub use crate::config::scrolling::{Scrolling, MAX_SCROLLBACK_LINES};
 
 pub const LOG_TARGET_CONFIG: &str = "alacritty_config_derive";
+
 const MIN_BLINK_INTERVAL: u64 = 10;
 
 /// Top-level config type.
@@ -75,6 +76,7 @@ pub struct Cursor {
 
     thickness: Percentage,
     blink_interval: u64,
+    blink_timeout: u8,
 }
 
 impl Default for Cursor {
@@ -83,6 +85,7 @@ impl Default for Cursor {
             thickness: Percentage(0.15),
             unfocused_hollow: true,
             blink_interval: 750,
+            blink_timeout: 5,
             style: Default::default(),
             vi_mode_style: Default::default(),
         }
@@ -107,7 +110,18 @@ impl Cursor {
 
     #[inline]
     pub fn blink_interval(self) -> u64 {
-        max(self.blink_interval, MIN_BLINK_INTERVAL)
+        cmp::max(self.blink_interval, MIN_BLINK_INTERVAL)
+    }
+
+    #[inline]
+    pub fn blink_timeout(self) -> u64 {
+        const MILLIS_IN_SECOND: u64 = 1000;
+        match self.blink_timeout {
+            0 => 0,
+            blink_timeout => {
+                cmp::max(self.blink_interval * 5 / MILLIS_IN_SECOND, blink_timeout as u64)
+            },
+        }
     }
 }