Added experimental support for DEC Sixel using sixel_bytes.

Cargo.toml

@@ -8,6 +8,8 @@ libc = "0.2"
 unicode-width = "0.1.10"
 unicode-segmentation = "1.10.0"
 chrono = "0.4.23"
+sixel-bytes = "0.2"
+fast_image_resize = { version = "5", features = ["rayon"] }
 
 [lib]
 name = "carbonyl"

build.rs

@@ -12,8 +12,14 @@ fn link_sysroot() {
             "cargo:rustc-link-arg=--sysroot=./chromium/src/build/linux/debian_bullseye_amd64-sysroot"
         );
     } else {
-        println!("cargo:warning={}", "x86_64 debian sysroot provided by chromium was not found!");
-        println!("cargo:warning={}", "carbonyl may fail to link against a proper libc!");
+        println!(
+            "cargo:warning={}",
+            "x86_64 debian sysroot provided by chromium was not found!"
+        );
+        println!(
+            "cargo:warning={}",
+            "carbonyl may fail to link against a proper libc!"
+        );
     }
 }
 
@@ -29,8 +35,14 @@ fn link_sysroot() {
             "cargo:rustc-link-arg=--sysroot=./chromium/src/build/linux/debian_bullseye_i386-sysroot"
         );
     } else {
-        println!("cargo:warning={}", "x86 debian sysroot provided by chromium was not found!");
-        println!("cargo:warning={}", "carbonyl may fail to link against a proper libc!");
+        println!(
+            "cargo:warning={}",
+            "x86 debian sysroot provided by chromium was not found!"
+        );
+        println!(
+            "cargo:warning={}",
+            "carbonyl may fail to link against a proper libc!"
+        );
     }
 }
 

readme.md

@@ -67,6 +67,10 @@ $ carbonyl https://github.com
   </tbody>
 </table>
 
+## Rendering
+
+Carbonyl now prefers Sixel graphics for page rendering whenever the terminal reports support. Legacy character-based rendering is automatically used as a fallback if Sixel frames cannot be sent. Sixel scrolling is enabled by default so web content can be browsed normally; set `CARBONYL_SIXEL_SCROLL=off` (or `0`) to opt back into the legacy non-scrolling behaviour.
+
 ## Known issues
 
 - Fullscreen mode not supported yet

src/browser/bridge.rs

@@ -187,12 +187,15 @@ pub extern "C" fn carbonyl_renderer_resize(bridge: RendererPtr) {
     let mut bridge = bridge.unwrap().lock().unwrap();
     let window = bridge.window.update();
     let cells = window.cells.clone();
+    // Use the full terminal pixel geometry for SIXEL frames.
+    let geometry = window.graphics_px;
 
     log::debug!("resizing renderer, terminal window: {:?}", window);
 
-    bridge
-        .renderer
-        .render(move |renderer| renderer.set_size(cells));
+    bridge.renderer.render(move |renderer| {
+        renderer.set_size(cells);
+        renderer.update_sixel_geometry(geometry);
+    });
 }
 
 #[no_mangle]
@@ -411,6 +414,11 @@ pub extern "C" fn carbonyl_renderer_listen(bridge: RendererPtr, delegate: *mut B
                         Terminal(terminal) => match terminal {
                             TerminalEvent::Name(name) => log::debug!("terminal name: {name}"),
                             TerminalEvent::TrueColorSupported => renderer.enable_true_color(),
+                            TerminalEvent::SixelSupported { .. } => {
+                                let geometry = bridge.lock().unwrap().window.graphics_px;
+
+                                renderer.enable_sixel(geometry)
+                            }
                         },
                     }
                 }

src/cli/cli.rs

@@ -9,13 +9,15 @@ pub struct CommandLine {
     pub zoom: f32,
     pub debug: bool,
     pub bitmap: bool,
+    pub sixel_only: bool,
     pub program: CommandLineProgram,
     pub shell_mode: bool,
 }
 
 pub enum EnvVar {
     Debug,
     Bitmap,
+    SixelOnly,
     ShellMode,
 }
 
@@ -24,6 +26,7 @@ impl EnvVar {
         match self {
             EnvVar::Debug => "CARBONYL_ENV_DEBUG",
             EnvVar::Bitmap => "CARBONYL_ENV_BITMAP",
+            EnvVar::SixelOnly => "CARBONYL_ENV_SIXEL_ONLY",
             EnvVar::ShellMode => "CARBONYL_ENV_SHELL_MODE",
         }
     }
@@ -41,6 +44,7 @@ impl CommandLine {
         let mut zoom = 1.0;
         let mut debug = false;
         let mut bitmap = false;
+        let mut sixel_only = true;
         let mut shell_mode = false;
         let mut program = CommandLineProgram::Main;
         let args = env::args().skip(1).collect::<Vec<String>>();
@@ -77,6 +81,12 @@ impl CommandLine {
                 "-z" | "--zoom" => set_f32!(zoom = zoom / 100.0),
                 "-d" | "--debug" => set!(debug, Debug),
                 "-b" | "--bitmap" => set!(bitmap, Bitmap),
+                "--sixel-only" => set!(sixel_only, SixelOnly),
+                "--legacy-text" => {
+                    sixel_only = false;
+
+                    env::set_var(EnvVar::SixelOnly, "0");
+                }
 
                 "-h" | "--help" => program = CommandLineProgram::Help,
                 "-v" | "--version" => program = CommandLineProgram::Version,
@@ -92,6 +102,14 @@ impl CommandLine {
             bitmap = true;
         }
 
+        if let Ok(value) = env::var(EnvVar::SixelOnly) {
+            let normalized = value.trim().to_ascii_lowercase();
+
+            sixel_only = !matches!(normalized.as_str(), "0" | "false" | "off" | "no");
+        }
+
+        env::set_var(EnvVar::SixelOnly, if sixel_only { "1" } else { "0" });
+
         if env::var(EnvVar::ShellMode).is_ok() {
             shell_mode = true;
         }
@@ -102,6 +120,7 @@ impl CommandLine {
             zoom,
             debug,
             bitmap,
+            sixel_only,
             program,
             shell_mode,
         }

src/cli/usage.txt

@@ -9,6 +9,7 @@ Usage: carbonyl [options] [url]
 Options:
     -f, --fps=<fps>            set the maximum number of frames per second (default: 60)
     -z, --zoom=<zoom>          set the zoom level in percent (default: 100)
+        --legacy-text          re-enable the legacy ANSI text renderer
     -b, --bitmap               render text as bitmaps
     -d, --debug                enable debug logs
     -h, --help                 display this help message

src/input.rs

@@ -1,4 +1,5 @@
 mod dcs;
+mod graphics;
 mod keyboard;
 mod listen;
 mod mouse;

src/input/graphics.rs

@@ -0,0 +1,72 @@
+use crate::control_flow;
+
+use super::{Event, ParseControlFlow, TerminalEvent};
+
+#[derive(Default, Clone, Debug)]
+pub struct Graphics {
+    params: Vec<u32>,
+    buffer: Vec<u8>,
+}
+
+impl Graphics {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn parse(&mut self, key: u8) -> ParseControlFlow {
+        match key {
+            b'0'..=b'9' => {
+                self.buffer.push(key);
+
+                control_flow!(continue)
+            }
+            b';' => {
+                self.push_param();
+
+                control_flow!(continue)
+            }
+            b'S' => {
+                self.push_param();
+
+                control_flow!(break self.event())?
+            }
+            _ => control_flow!(break)?,
+        }
+    }
+
+    fn push_param(&mut self) {
+        if self.buffer.is_empty() {
+            self.params.push(0);
+            return;
+        }
+
+        if let Ok(text) = std::str::from_utf8(&self.buffer) {
+            if let Ok(value) = text.parse::<u32>() {
+                self.params.push(value);
+            }
+        }
+
+        self.buffer.clear();
+    }
+
+    fn event(&mut self) -> Option<Event> {
+        let params = std::mem::take(&mut self.params);
+
+        if params.len() >= 2 {
+            let item = params[0];
+            let status = params[1];
+
+            if item == 2 && status == 0 {
+                let width = params.get(2).copied().unwrap_or_default();
+                let height = params.get(3).copied().unwrap_or_default();
+
+                return Some(Event::Terminal(TerminalEvent::SixelSupported {
+                    width,
+                    height,
+                }));
+            }
+        }
+
+        None
+    }
+}

src/input/parser.rs

@@ -1,5 +1,6 @@
 use std::ops::ControlFlow;
 
+use super::graphics::Graphics;
 use crate::input::*;
 
 #[derive(Default)]
@@ -17,12 +18,14 @@ enum Sequence {
     Mouse(Mouse),
     Keyboard(Keyboard),
     DeviceControl(DeviceControl),
+    Graphics(Graphics),
 }
 
 #[derive(Clone, Debug)]
 pub enum TerminalEvent {
     Name(String),
     TrueColorSupported,
+    SixelSupported { width: u32, height: u32 },
 }
 
 #[derive(Clone, Debug)]
@@ -91,12 +94,14 @@ impl Parser {
                 },
                 Sequence::Control => match key {
                     b'<' => Sequence::Mouse(Mouse::new()),
+                    b'?' => Sequence::Graphics(Graphics::new()),
                     b'1' => Sequence::Keyboard(Keyboard::new()),
                     key => emit!(Keyboard::key(key, 0)),
                 },
                 Sequence::Mouse(ref mut mouse) => parse!(mouse, key),
                 Sequence::Keyboard(ref mut keyboard) => parse!(keyboard, key),
                 Sequence::DeviceControl(ref mut dcs) => parse!(dcs, key),
+                Sequence::Graphics(ref mut graphics) => parse!(graphics, key),
             }
         }
 

src/input/tty.rs

@@ -87,12 +87,16 @@ impl TTY {
             write!(out, "\x1b[?{}{}", sequence, if enable { "h" } else { "l" })?;
         }
 
-        // Set the current foreground color to black
+        // Set the current background color to black
         write!(out, "\x1b[48;2;0;0;0m")?;
         // Query current foreground color to for true-color support detection
         write!(out, "\x1bP$qm\x1b\\")?;
         // Query current terminal name
         write!(out, "\x1bP+q544e\x1b\\")?;
+        // Query graphics capability (XTSMGRAPHICS). Some terminals expect DCS form;
+        // use it first and fall back to CSI if ignored.
+        write!(out, "\x1bP?2;1;0S\x1b\\")?;
+        write!(out, "\x1b[?2;1;0S")?;
 
         out.flush()
     }

src/output.rs

@@ -6,6 +6,7 @@ mod painter;
 mod quad;
 mod render_thread;
 mod renderer;
+mod sixel;
 mod window;
 mod xterm;
 

src/output/cell.rs

@@ -18,6 +18,7 @@ pub struct Cell {
     /// Text grapheme if any
     pub grapheme: Option<Rc<Grapheme>>,
     pub quadrant: (Color, Color, Color, Color),
+    pub image: bool,
 }
 
 impl Cell {
@@ -31,6 +32,7 @@ impl Cell {
                 Color::black(),
                 Color::black(),
             ),
+            image: false,
         }
     }
 }