config: allow booleans for background-blur-radius

src/apprt/embedded.zig

@@ -1953,7 +1953,7 @@ pub const CAPI = struct {
         _ = CGSSetWindowBackgroundBlurRadius(
             CGSDefaultConnectionForThread(),
             nswindow.msgSend(usize, objc.sel("windowNumber"), .{}),
-            @intCast(config.@"background-blur-radius"),
+            @intCast(config.@"background-blur-radius".cval()),
         );
     }
 

src/apprt/gtk/Window.zig

@@ -400,7 +400,12 @@ pub fn syncAppearance(self: *Window, config: *const configpkg.Config) !void {
     }
 
     if (self.wayland) |*wl| {
-        try wl.setBlur(config.@"background-blur-radius" > 0);
+        const blurred = switch (config.@"background-blur-radius") {
+            .false => false,
+            .true => true,
+            .value => |v| v > 0,
+        };
+        try wl.setBlur(blurred);
     }
 }
 

src/cli/args.zig

@@ -533,7 +533,7 @@ fn parsePackedStruct(comptime T: type, v: []const u8) !T {
     return result;
 }
 
-fn parseBool(v: []const u8) !bool {
+pub fn parseBool(v: []const u8) !bool {
     const t = &[_][]const u8{ "1", "t", "T", "true" };
     const f = &[_][]const u8{ "0", "f", "F", "false" };
 

src/config/Config.zig

@@ -582,29 +582,38 @@ palette: Palette = .{},
 /// On macOS, changing this configuration requires restarting Ghostty completely.
 @"background-opacity": f64 = 1.0,
 
-/// A positive value enables blurring of the background when background-opacity
-/// is less than 1.
+/// Whether to blur the background when `background-opacity` is less than 1.
 ///
-/// On macOS, the value is the blur radius to apply. A value of 20
-/// is reasonable for a good looking blur. Higher values will cause strange
-/// rendering issues as well as performance issues.
+/// Valid values are:
 ///
-/// On KDE Plasma under Wayland, the exact value is _ignored_ —  the reason is
-/// that KWin, the window compositor powering Plasma, only has one global blur
-/// setting and does not allow applications to have individual blur settings.
+///   * a nonnegative integer specifying the *blur intensity*
+///   * `false`, equivalent to a blur intensity of 0
+///   * `true`, equivalent to the default blur intensity of 20, which is
+///     reasonable for a good looking blur. Higher blur intensities may
+///     cause strange rendering and performance issues.
+///
+/// Supported on macOS and on some Linux desktop environments, including:
+///
+///   * KDE Plasma (Wayland only)
+///
+/// Warning: the exact blur intensity is _ignored_ under KDE Plasma, and setting
+/// this setting to either `true` or any positive blur intensity value would
+/// achieve the same effect. The reason is that KWin, the window compositor
+/// powering Plasma, only has one global blur setting and does not allow
+/// applications to specify individual blur settings.
 ///
 /// To configure KWin's global blur setting, open System Settings and go to
 /// "Apps & Windows" > "Window Management" > "Desktop Effects" and select the
 /// "Blur" plugin. If disabled, enable it by ticking the checkbox to the left.
 /// Then click on the "Configure" button and there will be two sliders that
-/// allow you to set background blur and noise strengths for all apps,
+/// allow you to set background blur and noise intensities for all apps,
 /// including Ghostty.
 ///
 /// All other Linux desktop environments are as of now unsupported. Users may
 /// need to set environment-specific settings and/or install third-party plugins
 /// in order to support background blur, as there isn't a unified interface for
 /// doing so.
-@"background-blur-radius": u8 = 0,
+@"background-blur-radius": BackgroundBlur = .false,
 
 /// The opacity level (opposite of transparency) of an unfocused split.
 /// Unfocused splits by default are slightly faded out to make it easier to see
@@ -5653,6 +5662,68 @@ pub const AutoUpdate = enum {
     download,
 };
 
+/// See background-blur-radius
+pub const BackgroundBlur = union(enum) {
+    false,
+    true,
+    value: u8,
+
+    pub fn parseCLI(self: *BackgroundBlur, input: ?[]const u8) !void {
+        const input_ = input orelse {
+            // Emulate behavior for bools
+            self.* = .true;
+            return;
+        };
+
+        if (cli.args.parseBool(input_)) |b| {
+            self.* = if (b) .true else .false;
+        } else |_| {
+            const value = std.fmt.parseInt(u8, input_, 0) catch return error.InvalidValue;
+            self.* = .{ .value = value };
+        }
+    }
+
+    pub fn cval(self: BackgroundBlur) u8 {
+        return switch (self) {
+            .false => 0,
+            .true => 20,
+            .value => |v| v,
+        };
+    }
+
+    pub fn formatEntry(
+        self: BackgroundBlur,
+        formatter: anytype,
+    ) !void {
+        switch (self) {
+            .false => try formatter.formatEntry(bool, false),
+            .true => try formatter.formatEntry(bool, true),
+            .value => |v| try formatter.formatEntry(u8, v),
+        }
+    }
+
+    test "parse BackgroundBlur" {
+        const testing = std.testing;
+        var v: BackgroundBlur = undefined;
+
+        try v.parseCLI(null);
+        try testing.expectEqual(.true, v);
+
+        try v.parseCLI("true");
+        try testing.expectEqual(.true, v);
+
+        try v.parseCLI("false");
+        try testing.expectEqual(.false, v);
+
+        try v.parseCLI("42");
+        try testing.expectEqual(42, v.value);
+
+        try testing.expectError(error.InvalidValue, v.parseCLI(""));
+        try testing.expectError(error.InvalidValue, v.parseCLI("aaaa"));
+        try testing.expectError(error.InvalidValue, v.parseCLI("420"));
+    }
+};
+
 /// See theme
 pub const Theme = struct {
     light: []const u8,

src/config/c_get.zig

@@ -84,6 +84,17 @@ fn getValue(ptr_raw: *anyopaque, value: anytype) bool {
                 ptr.* = @intCast(@as(Backing, @bitCast(value)));
             },
 
+            .Union => |_| {
+                if (@hasDecl(T, "cval")) {
+                    const PtrT = @typeInfo(@TypeOf(T.cval)).Fn.return_type.?;
+                    const ptr: *PtrT = @ptrCast(@alignCast(ptr_raw));
+                    ptr.* = value.cval();
+                    return true;
+                }
+
+                return false;
+            },
+
             else => return false,
         },
     }
@@ -172,3 +183,30 @@ test "c_get: optional" {
         try testing.expectEqual(0, cval.b);
     }
 }
+
+test "c_get: background-blur" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var c = try Config.default(alloc);
+    defer c.deinit();
+
+    {
+        c.@"background-blur-radius" = .false;
+        var cval: u8 = undefined;
+        try testing.expect(get(&c, .@"background-blur-radius", @ptrCast(&cval)));
+        try testing.expectEqual(0, cval);
+    }
+    {
+        c.@"background-blur-radius" = .true;
+        var cval: u8 = undefined;
+        try testing.expect(get(&c, .@"background-blur-radius", @ptrCast(&cval)));
+        try testing.expectEqual(20, cval);
+    }
+    {
+        c.@"background-blur-radius" = .{ .value = 42 };
+        var cval: u8 = undefined;
+        try testing.expect(get(&c, .@"background-blur-radius", @ptrCast(&cval)));
+        try testing.expectEqual(42, cval);
+    }
+}