river: make CSD-filters apply to existing views

doc/riverctl.1.scd

@@ -23,12 +23,12 @@ over the Wayland protocol.
 *csd-filter-add* _app-id_
 	Add _app-id_ to the CSD filter list. Views with this _app-id_ are
 	told to use client side decoration instead of the default server
-	side decoration. Note that this affects only new views, not already
+	side decoration. Note that this affects both new views, as well as already
 	existing ones.
 
 *csd-filter-remove* _app-id_
-	Remove an _app-id_ from the CSD filter list. Note that this affects only new
+	Remove an _app-id_ from the CSD filter list. Note that this affects both new
-	views, not already existing ones.
+	views, as well as already existing ones.
 
 *exit*
 	Exit the compositor, terminating the Wayland session.

river/Decoration.zig

@@ -49,7 +49,10 @@ fn handleDestroy(
     const self = @fieldParentPtr(Self, "destroy", listener);
     self.destroy.link.remove();
     self.request_mode.link.remove();
-    util.gpa.destroy(self);
+
+    const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);
+    server.decoration_manager.decorations.remove(node);
+    util.gpa.destroy(node);
 }
 
 fn handleRequestMode(

river/DecorationManager.zig

@@ -27,6 +27,10 @@ const util = @import("util.zig");
 const Decoration = @import("Decoration.zig");
 const Server = @import("Server.zig");
 
+/// List of all Decoration objects. This will clean itself up on exit through
+/// the wlr.XdgToplevelDecorationV1.events.destroy event.
+decorations: std.TailQueue(Decoration) = .{},
+
 xdg_decoration_manager: *wlr.XdgDecorationManagerV1,
 
 new_toplevel_decoration: wl.Listener(*wlr.XdgToplevelDecorationV1) =
@@ -45,9 +49,10 @@ fn handleNewToplevelDecoration(
     xdg_toplevel_decoration: *wlr.XdgToplevelDecorationV1,
 ) void {
     const self = @fieldParentPtr(Self, "new_toplevel_decoration", listener);
-    const decoration = util.gpa.create(Decoration) catch {
+    const decoration_node = util.gpa.create(std.TailQueue(Decoration).Node) catch {
         xdg_toplevel_decoration.resource.postNoMemory();
         return;
     };
-    decoration.init(xdg_toplevel_decoration);
+    decoration_node.data.init(xdg_toplevel_decoration);
+    self.decorations.append(decoration_node);
 }

river/command/filter.zig

@@ -20,6 +20,8 @@ const std = @import("std");
 const server = &@import("../main.zig").server;
 const util = @import("../util.zig");
 
+const View = @import("View.zig");
+const ViewStack = @import("view_stack.zig").ViewStack;
 const Error = @import("../command.zig").Error;
 const Seat = @import("../Seat.zig");
 
@@ -48,6 +50,7 @@ pub fn csdFilterAdd(
     out: *?[]const u8,
 ) Error!void {
     try modifyFilter(allocator, &server.config.csd_filter, args, .add);
+    csdFilterUpdateViews(args[1], .add);
 }
 
 pub fn csdFilterRemove(
@@ -57,6 +60,7 @@ pub fn csdFilterRemove(
     out: *?[]const u8,
 ) Error!void {
     try modifyFilter(allocator, &server.config.csd_filter, args, .remove);
+    csdFilterUpdateViews(args[1], .remove);
 }
 
 fn modifyFilter(
@@ -80,3 +84,47 @@ fn modifyFilter(
         list.appendAssumeCapacity(try std.mem.dupe(allocator, u8, args[1]));
     }
 }
+
+fn csdFilterUpdateViews(app_id: []const u8, operation: enum { add, remove }) void {
+    // There is no link between Decoration and View, so we need to iterate over
+    // both separately. Note that we do not need to arrange the outputs here; If
+    // the clients decoration mode changes, it will receive a configure event.
+    var decoration_it = server.decoration_manager.decorations.first;
+    while (decoration_it) |decoration_node| : (decoration_it = decoration_node.next) {
+        const xdg_toplevel_decoration = decoration_node.data.xdg_toplevel_decoration;
+        if (std.mem.eql(
+            u8,
+            std.mem.span(xdg_toplevel_decoration.surface.role_data.toplevel.app_id orelse return),
+            app_id,
+        )) {
+            _ = xdg_toplevel_decoration.setMode(switch (operation) {
+                .add => .client_side,
+                .remove => .server_side,
+            });
+        }
+    }
+
+    var output_it = server.root.outputs.first;
+    while (output_it) |output_node| : (output_it = output_node.next) {
+        var view_it = output_node.data.views.first;
+        while (view_it) |view_node| : (view_it = view_node.next) {
+            // CSD mode is not supported for XWayland views.
+            if (view_node.view.impl == .xwayland_view) continue;
+
+            const view_app_id = std.mem.span(view_node.view.getAppId() orelse continue);
+            if (std.mem.eql(u8, app_id, view_app_id)) {
+                const toplevel = view_node.view.impl.xdg_toplevel.xdg_surface.role_data.toplevel;
+                switch (operation) {
+                    .add => {
+                        view_node.view.draw_borders = false;
+                        _ = toplevel.setTiled(.{ .top = false, .bottom = false, .left = false, .right = false });
+                    },
+                    .remove => {
+                        view_node.view.draw_borders = true;
+                        _ = toplevel.setTiled(.{ .top = true, .bottom = true, .left = true, .right = true });
+                    },
+                }
+            }
+        }
+    }
+}