vaxis: add support for color scheme updates

README.md

@@ -30,7 +30,7 @@ Vaxis uses zig `0.12.0`.
 | System Notifications (OSC 777) |  ✅   |    ✅    |    ❌     |
 | Synchronized Output (DEC 2026) |  ✅   |    ✅    |    ✅     |
 | Unicode Core (DEC 2027)        |  ✅   |    ✅    |    ❌     |
-| Color Mode Updates (DEC 2031)  |  ✅   | planned  |    ❌     |
+| Color Mode Updates (DEC 2031)  |  ✅   |    ✅    |    ❌     |
 | Images (full/space)            |  ✅   | planned  |    ✅     |
 | Images (half block)            |  ✅   | planned  |    ✅     |
 | Images (quadrant)              |  ✅   | planned  |    ✅     |

src/Cell.zig

@@ -118,6 +118,11 @@ pub const Color = union(enum) {
         value: [3]u8,
     };
 
+    pub const Scheme = enum {
+        dark,
+        light,
+    };
+
     pub fn eql(a: Color, b: Color) bool {
         switch (a) {
             .default => return b == .default,

src/Parser.zig

@@ -341,6 +341,47 @@ pub fn parse(self: *Parser, input: []const u8, paste_allocator: ?std.mem.Allocat
                                     },
                                 }
                             },
+                            'n' => {
+                                switch (seq.params[0]) {
+                                    5 => {
+                                        // "Ok" response
+                                        return .{
+                                            .event = null,
+                                            .n = i + 1,
+                                        };
+                                    },
+                                    997 => {
+                                        switch (seq.params[1]) {
+                                            1 => {
+                                                return .{
+                                                    .event = .{ .color_scheme = .dark },
+                                                    .n = i + 1,
+                                                };
+                                            },
+                                            2 => {
+                                                return .{
+                                                    .event = .{ .color_scheme = .dark },
+                                                    .n = i + 1,
+                                                };
+                                            },
+                                            else => {
+                                                log.warn("unhandled csi: CSI {s}", .{input[start + 1 .. i + 1]});
+                                                return .{
+                                                    .event = null,
+                                                    .n = i + 1,
+                                                };
+                                            },
+                                        }
+                                    },
+                                    else => {
+                                        log.warn("unhandled csi: CSI {s}", .{input[start + 1 .. i + 1]});
+                                        return .{
+                                            .event = null,
+                                            .n = i + 1,
+                                        };
+                                    },
+                                }
+                            },
                             'u' => blk: {
                                 if (seq.private_indicator) |priv| {
                                     // response to our kitty query
@@ -417,7 +458,12 @@ pub fn parse(self: *Parser, input: []const u8, paste_allocator: ?std.mem.Allocat
                                             else => return .{ .event = .cap_unicode, .n = i + 1 },
                                         }
                                     },
-                                    2031 => {},
+                                    2031 => {
+                                        switch (seq.params[1]) {
+                                            0, 4 => return .{ .event = null, .n = i + 1 },
+                                            else => return .{ .event = .cap_color_scheme_updates, .n = i + 1 },
+                                        }
+                                    },
                                     else => {
                                         log.warn("unhandled DECRPM: CSI {s}", .{input[start + 1 .. i + 1]});
                                         return .{ .event = null, .n = i + 1 };

src/Tty.zig

@@ -32,6 +32,7 @@ state: struct {
     bracketed_paste: bool = false,
     mouse: bool = false,
     pixel_mouse: bool = false,
+    color_scheme_updates: bool = false,
     cursor: struct {
         row: usize = 0,
         col: usize = 0,
@@ -67,6 +68,9 @@ pub fn deinit(self: *Tty) void {
     if (self.state.alt_screen) {
         _ = self.write(ctlseqs.rmcup) catch {};
     }
+    if (self.state.color_scheme_updates) {
+        _ = self.write(ctlseqs.color_scheme_reset) catch {};
+    }
     // always show the cursor on exit
     _ = self.write(ctlseqs.show_cursor) catch {};
     self.flush() catch {};
@@ -224,6 +228,11 @@ pub fn run(
                         loop.postEvent(.{ .color_report = report });
                     }
                 },
+                .color_scheme => |scheme| {
+                    if (@hasField(Event, "color_scheme")) {
+                        loop.postEvent(.{ .color_scheme = scheme });
+                    }
+                },
                 .cap_kitty_keyboard => {
                     log.info("kitty keyboard capability detected", .{});
                     loop.vaxis.caps.kitty_keyboard = true;
@@ -247,6 +256,10 @@ pub fn run(
                     log.info("pixel mouse capability detected", .{});
                     loop.vaxis.caps.sgr_pixels = true;
                 },
+                .cap_color_scheme_updates => {
+                    log.info("color_scheme_updates capability detected", .{});
+                    loop.vaxis.caps.color_scheme_updates = true;
+                },
                 .cap_da1 => {
                     std.Thread.Futex.wake(&loop.vaxis.query_futex, 10);
                 },

src/Vaxis.zig

@@ -32,6 +32,7 @@ pub const Capabilities = struct {
     rgb: bool = false,
     unicode: gwidth.Method = .wcwidth,
     sgr_pixels: bool = false,
+    color_scheme_updates: bool = false,
 };
 
 pub const Options = struct {
@@ -202,7 +203,7 @@ pub fn queryTerminalSend(self: *Vaxis) !void {
     // _ = try tty.write(ctlseqs.decrqm_sync);
     _ = try tty.write(ctlseqs.decrqm_sgr_pixels);
     _ = try tty.write(ctlseqs.decrqm_unicode);
-    _ = try tty.write(ctlseqs.decrqm_color_theme);
+    _ = try tty.write(ctlseqs.decrqm_color_scheme);
     // TODO: XTVERSION has a DCS response. uncomment when we can parse
     // that
     // _ = try tty.write(ctlseqs.xtversion);
@@ -872,3 +873,16 @@ pub fn queryColor(self: Vaxis, kind: Cell.Color.Kind) !void {
     }
     try tty.flush();
 }
+
+/// Subscribe to color theme updates. A `color_scheme: Color.Scheme` tag must
+/// exist on your Event type to receive the response. This is a queried
+/// capability. Support can be detected by checking the value of
+/// vaxis.caps.color_scheme_updates. The initial scheme will be reported when
+/// subscribing.
+pub fn subscribeToColorSchemeUpdates(self: Vaxis) !void {
+    var tty = self.tty orelse return;
+    _ = try tty.write(ctlseqs.color_scheme_request);
+    _ = try tty.write(ctlseqs.color_scheme_set);
+    try tty.flush();
+    tty.state.color_scheme_updates = true;
+}

src/ctlseqs.zig

@@ -7,7 +7,7 @@ pub const decrqm_focus = "\x1b[?1004$p";
 pub const decrqm_sgr_pixels = "\x1b[?1016$p";
 pub const decrqm_sync = "\x1b[?2026$p";
 pub const decrqm_unicode = "\x1b[?2027$p";
-pub const decrqm_color_theme = "\x1b[?2031$p";
+pub const decrqm_color_scheme = "\x1b[?2031$p";
 pub const csi_u_query = "\x1b[?u";
 pub const kitty_graphics_query = "\x1b_Gi=1,a=q\x1b\\";
 pub const sixel_geometry_query = "\x1b[?2;1;0S";
@@ -29,6 +29,11 @@ pub const unicode_reset = "\x1b[?2027l";
 pub const bp_set = "\x1b[?2004h";
 pub const bp_reset = "\x1b[?2004l";
 
+// color scheme updates
+pub const color_scheme_request = "\x1b[?996n";
+pub const color_scheme_set = "\x1b[?2031h";
+pub const color_scheme_reset = "\x1b[?2031l";
+
 // Key encoding
 pub const csi_u_push = "\x1b[>{d}u";
 pub const csi_u_pop = "\x1b[<u";

src/event.zig

@@ -13,6 +13,7 @@ pub const Event = union(enum) {
     paste_end, // bracketed paste end
     paste: []const u8, // osc 52 paste, caller must free
     color_report: Color.Report, // osc 4, 10, 11, 12 response
+    color_scheme: Color.Scheme,
 
     // these are delivered as discovered terminal capabilities
     cap_kitty_keyboard,
@@ -21,4 +22,5 @@ pub const Event = union(enum) {
     cap_sgr_pixels,
     cap_unicode,
     cap_da1,
+    cap_color_scheme_updates,
 };