Add blinking cursor support

This adds support for blinking the terminal cursor. This can be
controlled either using the configuration file, or using escape
sequences.

The supported control sequences for changing the blinking state are
`CSI Ps SP q` and private mode 12.

1 files changed, 29 insertions, 16 deletions

diff --git a/alacritty_terminal/src/ansi.rs b/alacritty_terminal/src/ansi.rs
index 877fd65f..7567eba2 100644
--- a/alacritty_terminal/src/ansi.rs
+++ b/alacritty_terminal/src/ansi.rs
@@ -141,6 +141,9 @@ pub trait Handler {
     /// Set the cursor style.
     fn set_cursor_style(&mut self, _: Option<CursorStyle>) {}
 
+    /// Set the cursor shape.
+    fn set_cursor_shape(&mut self, _shape: CursorShape) {}
+
     /// A character to be displayed.
     fn input(&mut self, _c: char) {}
 
@@ -324,9 +327,16 @@ pub trait Handler {
     fn text_area_size_chars<W: io::Write>(&mut self, _: &mut W) {}
 }
 
-/// Describes shape of cursor.
-#[derive(Debug, Eq, PartialEq, Copy, Clone, Hash, Deserialize)]
-pub enum CursorStyle {
+/// Terminal cursor configuration.
+#[derive(Deserialize, Default, Debug, Eq, PartialEq, Copy, Clone, Hash)]
+pub struct CursorStyle {
+    pub shape: CursorShape,
+    pub blinking: bool,
+}
+
+/// Terminal cursor shape.
+#[derive(Deserialize, Debug, Eq, PartialEq, Copy, Clone, Hash)]
+pub enum CursorShape {
     /// Cursor is a block like `▒`.
     Block,
 
@@ -345,9 +355,9 @@ pub enum CursorStyle {
     Hidden,
 }
 
-impl Default for CursorStyle {
-    fn default() -> CursorStyle {
-        CursorStyle::Block
+impl Default for CursorShape {
+    fn default() -> CursorShape {
+        CursorShape::Block
     }
 }
 
@@ -874,13 +884,13 @@ where
                     && params[1].len() >= 13
                     && params[1][0..12] == *b"CursorShape="
                 {
-                    let style = match params[1][12] as char {
-                        '0' => CursorStyle::Block,
-                        '1' => CursorStyle::Beam,
-                        '2' => CursorStyle::Underline,
+                    let shape = match params[1][12] as char {
+                        '0' => CursorShape::Block,
+                        '1' => CursorShape::Beam,
+                        '2' => CursorShape::Underline,
                         _ => return unhandled(params),
                     };
-                    self.handler.set_cursor_style(Some(style));
+                    self.handler.set_cursor_shape(shape);
                     return;
                 }
                 unhandled(params);
@@ -1065,18 +1075,21 @@ where
             ('P', None) => handler.delete_chars(Column(next_param_or(1) as usize)),
             ('q', Some(b' ')) => {
                 // DECSCUSR (CSI Ps SP q) -- Set Cursor Style.
-                let style = match next_param_or(0) {
+                let cursor_style_id = next_param_or(0);
+                let shape = match cursor_style_id {
                     0 => None,
-                    1 | 2 => Some(CursorStyle::Block),
-                    3 | 4 => Some(CursorStyle::Underline),
-                    5 | 6 => Some(CursorStyle::Beam),
+                    1 | 2 => Some(CursorShape::Block),
+                    3 | 4 => Some(CursorShape::Underline),
+                    5 | 6 => Some(CursorShape::Beam),
                     _ => {
                         unhandled!();
                         return;
                     },
                 };
+                let cursor_style =
+                    shape.map(|shape| CursorStyle { shape, blinking: cursor_style_id % 2 == 1 });
 
-                handler.set_cursor_style(style);
+                handler.set_cursor_style(cursor_style);
             },
             ('r', None) => {
                 let top = next_param_or(1) as usize;