config: add cursor-invert-fg-bg option

When set, the cursor-invert-fg-bg option uses the inverted foreground
and background colors of the cursor's current cell to color the cursor,
rather than using a fixed color. This option has higher precedence than
the cursor-color and cursor-text options, but has lower precedence than
an OSC 12 command to change the cursor color.

src/config/Config.zig

@@ -289,6 +289,12 @@ palette: Palette = .{},
 /// The color of the cursor. If this is not set, a default will be chosen.
 @"cursor-color": ?Color = null,
 
+/// Swap the foreground and background colors of the cell under the cursor. This
+/// option overrides the `cursor-color` and `cursor-text` options.
+///
+/// This is currently only supported on macOS.
+@"cursor-invert-fg-bg": bool = false,
+
 /// The opacity level (opposite of transparency) of the cursor. A value of 1
 /// is fully opaque and a value of 0 is fully transparent. A value less than 0
 /// or greater than 1 will be clamped to the nearest valid value. Note that a

src/renderer/Metal.zig

@@ -91,6 +91,11 @@ background_color: terminal.color.RGB,
 /// by a terminal application
 cursor_color: ?terminal.color.RGB,
 
+/// When `cursor_color` is null, swap the foreground and background colors of
+/// the cell under the cursor for the cursor color. Otherwise, use the default
+/// foreground color as the cursor color.
+cursor_invert: bool,
+
 /// The current frame background color. This is only updated during
 /// the updateFrame method.
 current_background_color: terminal.color.RGB,
@@ -317,6 +322,7 @@ pub const DerivedConfig = struct {
     font_features: std.ArrayListUnmanaged([:0]const u8),
     font_styles: font.CodepointResolver.StyleStatus,
     cursor_color: ?terminal.color.RGB,
+    cursor_invert: bool,
     cursor_opacity: f64,
     cursor_text: ?terminal.color.RGB,
     background: terminal.color.RGB,
@@ -357,17 +363,21 @@ pub const DerivedConfig = struct {
             config.link.links.items,
         );
 
+        const cursor_invert = config.@"cursor-invert-fg-bg";
+
         return .{
             .background_opacity = @max(0, @min(1, config.@"background-opacity")),
             .font_thicken = config.@"font-thicken",
             .font_features = font_features,
             .font_styles = font_styles,
 
-            .cursor_color = if (config.@"cursor-color") |col|
+            .cursor_color = if (!cursor_invert and config.@"cursor-color" != null)
-                col.toTerminalRGB()
+                config.@"cursor-color".?.toTerminalRGB()
             else
                 null,
 
+            .cursor_invert = cursor_invert,
+
             .cursor_text = if (config.@"cursor-text") |txt|
                 txt.toTerminalRGB()
             else
@@ -590,6 +600,7 @@ pub fn init(alloc: Allocator, options: renderer.Options) !Metal {
         .foreground_color = options.config.foreground,
         .background_color = options.config.background,
         .cursor_color = options.config.cursor_color,
+        .cursor_invert = options.config.cursor_invert,
         .current_background_color = options.config.background,
 
         // Render state
@@ -1753,7 +1764,8 @@ pub fn changeConfig(self: *Metal, config: *DerivedConfig) !void {
     // Set our new colors
     self.background_color = config.background;
     self.foreground_color = config.foreground;
-    self.cursor_color = config.cursor_color;
+    self.cursor_invert = config.cursor_invert;
+    self.cursor_color = if (!config.cursor_invert) config.cursor_color else null;
 
     self.config.deinit();
     self.config = config.*;
@@ -2040,7 +2052,16 @@ fn rebuildCells(
 
         // Prepare the cursor cell contents.
         const style = cursor_style_ orelse break :cursor;
-        self.addCursor(screen, style);
+        const cursor_color = self.cursor_color orelse color: {
+            if (self.cursor_invert) {
+                const sty = screen.cursor.page_pin.style(screen.cursor.page_cell);
+                break :color sty.fg(color_palette, self.config.bold_is_bright) orelse self.foreground_color;
+            } else {
+                break :color self.foreground_color;
+            }
+        };
+
+        self.addCursor(screen, style, cursor_color);
 
         // If the cursor is visible then we set our uniforms.
         if (style == .block and screen.viewportIsBottom()) {
@@ -2048,15 +2069,19 @@ fn rebuildCells(
                 screen.cursor.x,
                 screen.cursor.y,
             };
-            self.uniforms.cursor_color = if (self.config.cursor_text) |txt| .{
+
-                txt.r,
+            const uniform_color = if (self.cursor_invert) blk: {
-                txt.g,
+                const sty = screen.cursor.page_pin.style(screen.cursor.page_cell);
-                txt.b,
+                break :blk sty.bg(screen.cursor.page_cell, color_palette) orelse self.background_color;
-                255,
+            } else if (self.config.cursor_text) |txt|
-            } else .{
+                txt
-                self.background_color.r,
+            else
-                self.background_color.g,
+                self.background_color;
-                self.background_color.b,
+
+            self.uniforms.cursor_color = .{
+                uniform_color.r,
+                uniform_color.g,
+                uniform_color.b,
                 255,
             };
         }
@@ -2317,6 +2342,7 @@ fn addCursor(
     self: *Metal,
     screen: *terminal.Screen,
     cursor_style: renderer.CursorStyle,
+    cursor_color: terminal.color.RGB,
 ) void {
     // Add the cursor. We render the cursor over the wide character if
     // we're on the wide characer tail.
@@ -2332,7 +2358,6 @@ fn addCursor(
         break :cell .{ prev_cell.wide == .wide, screen.cursor.x - 1 };
     };
 
-    const color = self.cursor_color orelse self.foreground_color;
     const alpha: u8 = if (!self.focused) 255 else alpha: {
         const alpha = 255 * self.config.cursor_opacity;
         break :alpha @intFromFloat(@ceil(alpha));
@@ -2362,7 +2387,7 @@ fn addCursor(
         .mode = .cursor,
         .grid_pos = .{ x, screen.cursor.y },
         .cell_width = if (wide) 2 else 1,
-        .color = .{ color.r, color.g, color.b, alpha },
+        .color = .{ cursor_color.r, cursor_color.g, cursor_color.b, alpha },
         .bg_color = .{ 0, 0, 0, 0 },
         .glyph_pos = .{ render.glyph.atlas_x, render.glyph.atlas_y },
         .glyph_size = .{ render.glyph.width, render.glyph.height },

src/termio/Termio.zig

@@ -82,6 +82,7 @@ pub const DerivedConfig = struct {
     cursor_style: terminal.CursorStyle,
     cursor_blink: ?bool,
     cursor_color: ?configpkg.Config.Color,
+    cursor_invert: bool,
     foreground: configpkg.Config.Color,
     background: configpkg.Config.Color,
     osc_color_report_format: configpkg.Config.OSCColorReportFormat,
@@ -103,6 +104,7 @@ pub const DerivedConfig = struct {
             .cursor_style = config.@"cursor-style",
             .cursor_blink = config.@"cursor-style-blink",
             .cursor_color = config.@"cursor-color",
+            .cursor_invert = config.@"cursor-invert-fg-bg",
             .foreground = config.foreground,
             .background = config.background,
             .osc_color_report_format = config.@"osc-color-report-format",
@@ -176,8 +178,8 @@ pub fn init(self: *Termio, alloc: Allocator, opts: termio.Options) !void {
     // Create our stream handler. This points to memory in self so it
     // isn't safe to use until self.* is set.
     const handler: StreamHandler = handler: {
-        const default_cursor_color = if (opts.config.cursor_color) |col|
+        const default_cursor_color = if (!opts.config.cursor_invert and opts.config.cursor_color != null)
-            col.toTerminalRGB()
+            opts.config.cursor_color.?.toTerminalRGB()
         else
             null;
 

src/termio/stream_handler.zig

@@ -115,8 +115,8 @@ pub const StreamHandler = struct {
         self.default_background_color = config.background.toTerminalRGB();
         self.default_cursor_style = config.cursor_style;
         self.default_cursor_blink = config.cursor_blink;
-        self.default_cursor_color = if (config.cursor_color) |col|
+        self.default_cursor_color = if (!config.cursor_invert and config.cursor_color != null)
-            col.toTerminalRGB()
+            config.cursor_color.?.toTerminalRGB()
         else
             null;