config: change macos-background-style to be enums on background-blur

macos/Sources/Ghostty/Ghostty.Config.swift

@@ -413,12 +413,12 @@ extension Ghostty {
             return v;
         }
 
-        var backgroundBlurRadius: Int {
-            guard let config = self.config else { return 1 }
-            var v: Int = 0
+        var backgroundBlur: BackgroundBlur {
+            guard let config = self.config else { return .disabled }
+            var v: Int16 = 0
             let key = "background-blur"
             _ = ghostty_config_get(config, &v, key, UInt(key.lengthOfBytes(using: .utf8)))
-            return v;
+            return BackgroundBlur(fromCValue: v)
         }
 
         var unfocusedSplitOpacity: Double {
@@ -637,6 +637,50 @@ extension Ghostty.Config {
         case download
     }
 
+    /// Background blur configuration that maps from the C API values.
+    /// Positive values represent blur radius, special negative values
+    /// represent macOS-specific glass effects.
+    enum BackgroundBlur: Equatable {
+        case disabled
+        case radius(Int)
+        case macosGlassRegular
+        case macosGlassClear
+
+        init(fromCValue value: Int16) {
+            switch value {
+            case 0:
+                self = .disabled
+            case -1:
+                self = .macosGlassRegular
+            case -2:
+                self = .macosGlassClear
+            default:
+                self = .radius(Int(value))
+            }
+        }
+
+        var isEnabled: Bool {
+            switch self {
+            case .disabled:
+                return false
+            default:
+                return true
+            }
+        }
+
+        /// Returns the blur radius if applicable, nil for glass effects.
+        var radius: Int? {
+            switch self {
+            case .disabled:
+                return nil
+            case .radius(let r):
+                return r
+            case .macosGlassRegular, .macosGlassClear:
+                return nil
+            }
+        }
+    }
+
     struct BellFeatures: OptionSet {
         let rawValue: CUnsignedInt
 

src/config/Config.zig

@@ -8338,6 +8338,8 @@ pub const AutoUpdate = enum {
 pub const BackgroundBlur = union(enum) {
     false,
     true,
+    @"macos-glass-regular",
+    @"macos-glass-clear",
     radius: u8,
 
     pub fn parseCLI(self: *BackgroundBlur, input: ?[]const u8) !void {
@@ -8347,10 +8349,31 @@ pub const BackgroundBlur = union(enum) {
             return;
         };
 
-        self.* = if (cli.args.parseBool(input_)) |b|
-            if (b) .true else .false
-        else |_|
-            .{ .radius = std.fmt.parseInt(
+        // Try to parse normal bools
+        if (cli.args.parseBool(input_)) |b| {
+            self.* = if (b) .true else .false;
+            return;
+        } else |_| {}
+
+        // Try to parse enums
+        if (std.meta.stringToEnum(
+            std.meta.Tag(BackgroundBlur),
+            input_,
+        )) |v| switch (v) {
+            inline else => |tag| tag: {
+                // We can only parse void types
+                const info = std.meta.fieldInfo(BackgroundBlur, tag);
+                if (info.type != void) break :tag;
+                self.* = @unionInit(
+                    BackgroundBlur,
+                    @tagName(tag),
+                    {},
+                );
+                return;
+            },
+        };
+
+        self.* = .{ .radius = std.fmt.parseInt(
             u8,
             input_,
             0,
@@ -8365,11 +8388,16 @@ pub const BackgroundBlur = union(enum) {
         };
     }
 
-    pub fn cval(self: BackgroundBlur) u8 {
+    pub fn cval(self: BackgroundBlur) i16 {
         return switch (self) {
             .false => 0,
             .true => 20,
             .radius => |v| v,
+            // I hate sentinel values like this but this is only for
+            // our macOS application currently. We can switch to a proper
+            // tagged union if we ever need to.
+            .@"macos-glass-regular" => -1,
+            .@"macos-glass-clear" => -2,
         };
     }
 
@@ -8381,6 +8409,8 @@ pub const BackgroundBlur = union(enum) {
             .false => try formatter.formatEntry(bool, false),
             .true => try formatter.formatEntry(bool, true),
             .radius => |v| try formatter.formatEntry(u8, v),
+            .@"macos-glass-regular" => try formatter.formatEntry([]const u8, "macos-glass-regular"),
+            .@"macos-glass-clear" => try formatter.formatEntry([]const u8, "macos-glass-clear"),
         }
     }
 
@@ -8400,6 +8430,12 @@ pub const BackgroundBlur = union(enum) {
         try v.parseCLI("42");
         try testing.expectEqual(42, v.radius);
 
+        try v.parseCLI("macos-glass-regular");
+        try testing.expectEqual(.@"macos-glass-regular", v);
+
+        try v.parseCLI("macos-glass-clear");
+        try testing.expectEqual(.@"macos-glass-clear", v);
+
         try testing.expectError(error.InvalidValue, v.parseCLI(""));
         try testing.expectError(error.InvalidValue, v.parseCLI("aaaa"));
         try testing.expectError(error.InvalidValue, v.parseCLI("420"));

src/config/c_get.zig

@@ -193,20 +193,32 @@ test "c_get: background-blur" {
 
     {
         c.@"background-blur" = .false;
-        var cval: u8 = undefined;
+        var cval: i16 = undefined;
         try testing.expect(get(&c, .@"background-blur", @ptrCast(&cval)));
         try testing.expectEqual(0, cval);
     }
     {
         c.@"background-blur" = .true;
-        var cval: u8 = undefined;
+        var cval: i16 = undefined;
         try testing.expect(get(&c, .@"background-blur", @ptrCast(&cval)));
         try testing.expectEqual(20, cval);
     }
     {
         c.@"background-blur" = .{ .radius = 42 };
-        var cval: u8 = undefined;
+        var cval: i16 = undefined;
         try testing.expect(get(&c, .@"background-blur", @ptrCast(&cval)));
         try testing.expectEqual(42, cval);
     }
+    {
+        c.@"background-blur" = .@"macos-glass-regular";
+        var cval: i16 = undefined;
+        try testing.expect(get(&c, .@"background-blur", @ptrCast(&cval)));
+        try testing.expectEqual(-1, cval);
+    }
+    {
+        c.@"background-blur" = .@"macos-glass-clear";
+        var cval: i16 = undefined;
+        try testing.expect(get(&c, .@"background-blur", @ptrCast(&cval)));
+        try testing.expectEqual(-2, cval);
+    }
 }

src/renderer/generic.zig

@@ -728,9 +728,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                         options.config.background.r,
                         options.config.background.g,
                         options.config.background.b,
-                        if (shouldDisableBackground(options.config))
-                            0
-                        else
                         @intFromFloat(@round(options.config.background_opacity * 255.0)),
                     },
                     .bools = .{