command: implement set-option

Only border and padding options are currently available.

river/command/set_option.zig

@@ -0,0 +1,46 @@
+// This file is part of river, a dynamic tiling wayland compositor.
+//
+// Copyright 2020 Rishabh Das
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+
+const Error = @import("../command.zig").Error;
+const Option = @import("../command.zig").Option;
+const Seat = @import("../Seat.zig");
+
+/// Set option to a specified value.
+pub fn setOption(
+    allocator: *std.mem.Allocator,
+    seat: *Seat,
+    args: []const []const u8,
+    failure_message: *[]const u8,
+) Error!void {
+    if (args.len < 3) return Error.NotEnoughArguments;
+    if (args.len > 3) return Error.TooManyArguments;
+
+    // Parse option and value.
+    const option = try Option.parse(args[1]);
+    const value = try std.fmt.parseInt(u32, args[2], 10);
+
+    // Assign value to option.
+    switch (option) {
+        .BorderWidth => seat.focused_output.root.server.config.border_width = value,
+        .OuterPadding => seat.focused_output.root.server.config.outer_padding = value,
+    }
+
+    // 'Refresh' focused output to display the desired changes.
+    seat.focused_output.root.arrange();
+}