control: implement swap

river/command/swap.zig

@@ -0,0 +1,83 @@
+// This file is part of river, a dynamic tiling wayland compositor.
+//
+// Copyright 2020 Marten Ringwelski
+//
+// 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 Direction = @import("../command.zig").Direction;
+const Seat = @import("../Seat.zig");
+const View = @import("../View.zig");
+const ViewStack = @import("../view_stack.zig").ViewStack;
+
+/// Swap the currently focused view with either the view higher or lower in the visible stack
+pub fn swap(
+    allocator: *std.mem.Allocator,
+    seat: *Seat,
+    args: []const []const u8,
+    out: *?[]const u8,
+) Error!void {
+    if (args.len < 2) return Error.NotEnoughArguments;
+    if (args.len > 2) return Error.TooManyArguments;
+
+    if (seat.focused != .view)
+        return;
+
+    // Filter out everything that is not part of the current layout
+    if (seat.focused.view.pending.float or seat.focused.view.pending.fullscreen) return;
+
+    const direction = std.meta.stringToEnum(Direction, args[1]) orelse return Error.InvalidDirection;
+
+    const focused_node = @fieldParentPtr(ViewStack(View).Node, "view", seat.focused.view);
+    const output = seat.focused_output;
+    var it = ViewStack(View).iter(
+        focused_node,
+        if (direction == .next) .forward else .reverse,
+        output.pending.tags,
+        filter,
+    );
+    var it_wrap = ViewStack(View).iter(
+        if (direction == .next) output.views.first else output.views.last,
+        .forward,
+        output.pending.tags,
+        filter,
+    );
+
+    // skip the first node which is focused_node
+    _ = it.next().?;
+
+    const to_swap = @fieldParentPtr(
+        ViewStack(View).Node,
+        "view",
+        // Wrap around if needed
+        if (it.next()) |next| next else it_wrap.next().?,
+    );
+
+    // Dont swap when only the focused view is part of the layout
+    if (focused_node == to_swap) {
+        return;
+    }
+
+    output.views.swap(focused_node, to_swap);
+
+    output.arrangeViews();
+    output.root.startTransaction();
+}
+
+fn filter(view: *View, filter_tags: u32) bool {
+    return !view.destroying and !view.pending.float and
+        !view.pending.fullscreen and view.pending.tags & filter_tags != 0;
+}