From 14b0d9067e2ccb47fb84459d0d4ec0fb6bcc493a Mon Sep 17 00:00:00 2001
From: Ayose <ayosec@gmail.com>
Date: Fri, 2 Apr 2021 00:54:28 +0100
Subject: Implementation of the XTSMGRAPHICS sequence.

---
 alacritty_terminal/src/ansi.rs           |  3 +++
 alacritty_terminal/src/graphics/sixel.rs |  2 +-
 alacritty_terminal/src/term/mod.rs       | 31 +++++++++++++++++++++++++++++++
 docs/escape_support.md                   |  1 +
 4 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/alacritty_terminal/src/ansi.rs b/alacritty_terminal/src/ansi.rs
index 7eb87910..7a89ad23 100644
--- a/alacritty_terminal/src/ansi.rs
+++ b/alacritty_terminal/src/ansi.rs
@@ -462,6 +462,9 @@ pub trait Handler {
     /// Report text area size in characters.
     fn text_area_size_chars(&mut self) {}
 
+    /// Report a graphics attribute.
+    fn graphics_attribute<W: io::Write>(&mut self, _: &mut W, _: u16, _: u16) {}
+
     /// Create a parser for Sixel data.
     fn start_sixel_graphic(&mut self, _params: &Params) -> Option<Box<sixel::Parser>> {
         None
diff --git a/alacritty_terminal/src/graphics/sixel.rs b/alacritty_terminal/src/graphics/sixel.rs
index 476089cc..221fe7cd 100644
--- a/alacritty_terminal/src/graphics/sixel.rs
+++ b/alacritty_terminal/src/graphics/sixel.rs
@@ -33,7 +33,7 @@ use vte::Params;
 struct ColorRegister(u16);
 
 /// Number of color registers.
-const MAX_COLOR_REGISTERS: usize = 1024;
+pub const MAX_COLOR_REGISTERS: usize = 1024;
 
 /// Color register for transparent pixels.
 const REG_TRANSPARENT: ColorRegister = ColorRegister(u16::MAX);
diff --git a/alacritty_terminal/src/term/mod.rs b/alacritty_terminal/src/term/mod.rs
index 1e87ec8a..63a2e282 100644
--- a/alacritty_terminal/src/term/mod.rs
+++ b/alacritty_terminal/src/term/mod.rs
@@ -1771,6 +1771,37 @@ impl<T: EventListener> Handler for Term<T> {
         self.event_proxy.send_event(Event::PtyWrite(text));
     }
 
+    #[inline]
+    fn graphics_attribute<W: io::Write>(&mut self, writer: &mut W, pi: u16, pa: u16) {
+        // From Xterm documentation:
+        //
+        //   Pi = 1  -> item is number of color registers.
+        //   Pi = 2  -> item is Sixel graphics geometry (in pixels).
+        //
+        //   Pa = 1  -> read attribute.
+        //   Pa = 4  -> read the maximum allowed value.
+        //
+        // Any other request reports an error.
+
+        let (ps, pv) = if pa == 1 || pa == 4 {
+            match pi {
+                1 => (0, &[sixel::MAX_COLOR_REGISTERS][..]),
+                2 => (0, &[MAX_GRAPHIC_DIMENSIONS.0, MAX_GRAPHIC_DIMENSIONS.1][..]),
+                _ => (1, &[][..]), // Report error in Pi
+            }
+        } else {
+            (2, &[][..]) // Report error in Pa
+        };
+
+        let _ = write!(writer, "\x1b[?{};{}", pi, ps);
+
+        for item in pv {
+            let _ = write!(writer, ";{}", item);
+        }
+
+        let _ = write!(writer, "S");
+    }
+
     fn start_sixel_graphic(&mut self, params: &Params) -> Option<Box<sixel::Parser>> {
         let palette = self.graphics.sixel_shared_palette.take();
         Some(Box::new(sixel::Parser::new(params, palette)))
diff --git a/docs/escape_support.md b/docs/escape_support.md
index 5008d6a6..bc951753 100644
--- a/docs/escape_support.md
+++ b/docs/escape_support.md
@@ -71,6 +71,7 @@ brevity.
 | `CSI SP q` | IMPLEMENTED |                                                   |
 | `CSI r`    | IMPLEMENTED |                                                   |
 | `CSI S`    | IMPLEMENTED |                                                   |
+| `CSI ? S`  | PARTIAL     | Only for reading attributes.                      |
 | `CSI s`    | IMPLEMENTED |                                                   |
 | `CSI T`    | IMPLEMENTED |                                                   |
 | `CSI t`    | PARTIAL     | Only parameters `22` and `23` are supported       |
-- 
cgit