Add foreground/background request escape codes

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Config group `debug` with the options `debug.log_level`, `debug.print_events`
     and `debug.ref_test`
 - Select until next matching bracket when double-clicking a bracket
+- Added foreground/background escape code request sequences
 
 ### Changed
 

alacritty_terminal/src/ansi.rs

@@ -332,6 +332,9 @@ pub trait Handler {
     /// Set an indexed color value
     fn set_color(&mut self, _: usize, _: Rgb) {}
 
+    /// Write a foreground/background color escape sequence with the current color
+    fn dynamic_color_sequence<W: io::Write>(&mut self, _: &mut W, _: u8, _: usize) {}
+
     /// Reset an indexed color to original value
     fn reset_color(&mut self, _: usize) {}
 
@@ -741,6 +744,8 @@ where
     // TODO replace OSC parsing with parser combinators
     #[inline]
     fn osc_dispatch(&mut self, params: &[&[u8]]) {
+        let writer = &mut self.writer;
+
         fn unhandled(params: &[&[u8]]) {
             let mut buf = String::new();
             for items in params {
@@ -788,23 +793,37 @@ where
                 unhandled(params);
             },
 
-            // Set foreground color
+            // Get/set foreground color
             b"10" => {
                 if params.len() >= 2 {
                     if let Some(color) = parse_rgb_color(params[1]) {
                         self.handler.set_color(NamedColor::Foreground as usize, color);
                         return;
+                    } else if params[1] == b"?" {
+                        self.handler.dynamic_color_sequence(
+                            writer,
+                            10,
+                            NamedColor::Foreground as usize,
+                        );
+                        return;
                     }
                 }
                 unhandled(params);
             },
 
-            // Set background color
+            // Get/set background color
             b"11" => {
                 if params.len() >= 2 {
                     if let Some(color) = parse_rgb_color(params[1]) {
                         self.handler.set_color(NamedColor::Background as usize, color);
                         return;
+                    } else if params[1] == b"?" {
+                        self.handler.dynamic_color_sequence(
+                            writer,
+                            11,
+                            NamedColor::Background as usize,
+                        );
+                        return;
                     }
                 }
                 unhandled(params);

alacritty_terminal/src/term/mod.rs

@@ -1870,6 +1870,14 @@ impl ansi::Handler for Term {
         self.color_modified[index] = true;
     }
 
+    /// Write a foreground/background color escape sequence with the current color
+    #[inline]
+    fn dynamic_color_sequence<W: io::Write>(&mut self, writer: &mut W, code: u8, index: usize) {
+        trace!("Writing escape sequence for dynamic color code {}: color[{}]", code, index);
+        let color = self.colors[index];
+        let _ = write!(writer, "\x1b]{};rgb:{:x}/{:x}/{:x}\x07", code, color.r, color.g, color.b);
+    }
+
     /// Reset the indexed color to original value
     #[inline]
     fn reset_color(&mut self, index: usize) {