core: colorSchemeCallback on surface, can report

src/Surface.zig

@@ -90,6 +90,11 @@ mouse: Mouse,
 /// less important.
 pressed_key: ?input.KeyEvent = null,
 
+/// The current color scheme of the GUI element containing this surface.
+/// This will default to light until the apprt sends us the actual color
+/// scheme. This is used by mode 3031 and CSI 996 n.
+color_scheme: apprt.ColorScheme = .light,
+
 /// The hash value of the last keybinding trigger that we performed. This
 /// is only set if the last key input matched a keybinding, consumed it,
 /// and performed it. This is used to prevent sending release/repeat events
@@ -832,6 +837,16 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
         },
 
         .renderer_health => |health| self.updateRendererHealth(health),
+
+        .report_color_scheme => {
+            const output = switch (self.color_scheme) {
+                .light => "\x1B[?997;2n",
+                .dark => "\x1B[?997;1n",
+            };
+
+            _ = self.io_thread.mailbox.push(.{ .write_stable = output }, .{ .forever = {} });
+            try self.io_thread.wakeup.notify();
+        },
     }
 }
 
@@ -2786,6 +2801,12 @@ fn dragLeftClickBefore(
     return screen_point.before(click_point);
 }
 
+/// Call to notify Ghostty that the color scheme for the terminal has
+/// changed.
+pub fn colorSchemeCallback(self: *Surface, scheme: apprt.ColorScheme) void {
+    self.color_scheme = scheme;
+}
+
 fn posToViewport(self: Surface, xpos: f64, ypos: f64) terminal.point.Viewport {
     // xpos/ypos need to be adjusted for window padding
     // (i.e. "window-padding-*" settings.

src/apprt/structs.zig

@@ -61,3 +61,9 @@ pub const DesktopNotification = struct {
     /// The body of a notification. This will always be shown.
     body: []const u8,
 };
+
+/// The color scheme in use (light vs dark).
+pub const ColorScheme = enum(u2) {
+    light = 0,
+    dark = 1,
+};

src/apprt/surface.zig

@@ -57,6 +57,9 @@ pub const Message = union(enum) {
 
     /// Health status change for the renderer.
     renderer_health: renderer.Health,
+
+    /// Report the color scheme
+    report_color_scheme: void,
 };
 
 /// A surface mailbox.

src/terminal/device_status.zig

@@ -0,0 +1,67 @@
+const std = @import("std");
+
+/// An enum(u16) of the available device status requests.
+pub const Request = dsr_enum: {
+    const EnumField = std.builtin.Type.EnumField;
+    var fields: [entries.len]EnumField = undefined;
+    for (entries, 0..) |entry, i| {
+        fields[i] = .{
+            .name = entry.name,
+            .value = @as(Tag.Backing, @bitCast(Tag{
+                .value = entry.value,
+                .question = entry.question,
+            })),
+        };
+    }
+
+    break :dsr_enum @Type(.{ .Enum = .{
+        .tag_type = Tag.Backing,
+        .fields = &fields,
+        .decls = &.{},
+        .is_exhaustive = true,
+    } });
+};
+
+/// The tag type for our enum is a u16 but we use a packed struct
+/// in order to pack the question bit into the tag. The "u16" size is
+/// chosen somewhat arbitrarily to match the largest expected size
+/// we see as a multiple of 8 bits.
+pub const Tag = packed struct(u16) {
+    pub const Backing = @typeInfo(@This()).Struct.backing_integer.?;
+    value: u15,
+    question: bool = false,
+
+    test "order" {
+        const t: Tag = .{ .value = 1 };
+        const int: Backing = @bitCast(t);
+        try std.testing.expectEqual(@as(Backing, 1), int);
+    }
+};
+
+pub fn reqFromInt(v: u16, question: bool) ?Request {
+    inline for (entries) |entry| {
+        if (entry.value == v and entry.question == question) {
+            const tag: Tag = .{ .question = question, .value = entry.value };
+            const int: Tag.Backing = @bitCast(tag);
+            return @enumFromInt(int);
+        }
+    }
+
+    return null;
+}
+
+/// A single entry of a possible device status request we support. The
+/// "question" field determines if it is valid with or without the "?"
+/// prefix.
+const Entry = struct {
+    name: [:0]const u8,
+    value: comptime_int,
+    question: bool = false, // "?" request
+};
+
+/// The full list of device status request entries.
+const entries: []const Entry = &.{
+    .{ .name = "operating_status", .value = 5 },
+    .{ .name = "cursor_position", .value = 6 },
+    .{ .name = "theme", .value = 996, .question = true },
+};

src/termio/Exec.zig

@@ -2375,7 +2375,7 @@ const StreamHandler = struct {
                 self.messageWriter(msg);
             },
 
-            .theme => {},
+            .theme => self.surfaceMessageWriter(.{ .report_color_scheme = {} }),
         }
     }