Add CSD to border modes

This replaces view.using_csd with a new border mode: B_CSD. This also
removes sway_xdg_shell{_v6}_view.deco_mode and
view->has_client_side_decorations as we can now get these from the
border.

You can use `border toggle` to cycle through the modes including CSD, or
use `border csd` to set it directly. The client must support the
xdg-decoration protocol, and the only client I know of that does is the
example in wlroots.

If the client switches from SSD to CSD without us expecting it (via the
server-decoration protocol), we stash the previous border type into
view.saved_border so we can restore it if the client returns to SSD. I
haven't found a way to test this though.

18 files changed, 250 insertions, 140 deletions

diff --git a/include/sway/server.h b/include/sway/server.h
index 5dabb61f..3e1cbb33 100644
--- a/include/sway/server.h
+++ b/include/sway/server.h
@@ -54,6 +54,10 @@ struct sway_server {
         struct wl_listener server_decoration;
         struct wl_list decorations; // sway_server_decoration::link
 
+        struct wlr_xdg_decoration_manager_v1 *xdg_decoration_manager;
+        struct wl_listener xdg_decoration;
+        struct wl_list xdg_decorations; // sway_xdg_decoration::link
+
         size_t txn_timeout_ms;
         list_t *transactions;
         list_t *dirty_nodes;
@@ -78,5 +82,6 @@ void handle_xdg_shell_surface(struct wl_listener *listener, void *data);
 void handle_xwayland_surface(struct wl_listener *listener, void *data);
 #endif
 void handle_server_decoration(struct wl_listener *listener, void *data);
+void handle_xdg_decoration(struct wl_listener *listener, void *data);
 
 #endif
diff --git a/include/sway/tree/container.h b/include/sway/tree/container.h
index 5e281a2f..6019602c 100644
--- a/include/sway/tree/container.h
+++ b/include/sway/tree/container.h
@@ -28,6 +28,7 @@ enum sway_container_border {
         B_NONE,
         B_PIXEL,
         B_NORMAL,
+        B_CSD,
 };
 
 struct sway_root;
@@ -63,7 +64,6 @@ struct sway_container_state {
         bool border_bottom;
         bool border_left;
         bool border_right;
-        bool using_csd;
 };
 
 struct sway_container {
diff --git a/include/sway/tree/view.h b/include/sway/tree/view.h
index d10251dd..49df7c88 100644
--- a/include/sway/tree/view.h
+++ b/include/sway/tree/view.h
@@ -11,6 +11,7 @@
 #include "sway/input/seat.h"
 
 struct sway_container;
+struct sway_xdg_decoration;
 
 enum sway_view_type {
         SWAY_VIEW_XDG_SHELL_V6,
@@ -44,7 +45,6 @@ struct sway_view_impl {
         void (*set_tiled)(struct sway_view *view, bool tiled);
         void (*set_fullscreen)(struct sway_view *view, bool fullscreen);
         bool (*wants_floating)(struct sway_view *view);
-        bool (*has_client_side_decorations)(struct sway_view *view);
         void (*for_each_surface)(struct sway_view *view,
                 wlr_surface_iterator_func_t iterator, void *user_data);
         void (*for_each_popup)(struct sway_view *view,
@@ -60,6 +60,7 @@ struct sway_view {
 
         struct sway_container *container; // NULL if unmapped and transactions finished
         struct wlr_surface *surface; // NULL for unmapped views
+        struct sway_xdg_decoration *xdg_decoration;
 
         pid_t pid;
 
@@ -76,12 +77,12 @@ struct sway_view {
 
         char *title_format;
         enum sway_container_border border;
+        enum sway_container_border saved_border;
         int border_thickness;
         bool border_top;
         bool border_bottom;
         bool border_left;
         bool border_right;
-        bool using_csd;
 
         struct timespec urgent;
         bool allow_request_urgent;
@@ -127,8 +128,6 @@ struct sway_view {
 struct sway_xdg_shell_v6_view {
         struct sway_view view;
 
-        enum wlr_server_decoration_manager_mode deco_mode;
-
         struct wl_listener commit;
         struct wl_listener request_move;
         struct wl_listener request_resize;
@@ -145,8 +144,6 @@ struct sway_xdg_shell_v6_view {
 struct sway_xdg_shell_view {
         struct sway_view view;
 
-        enum wlr_server_decoration_manager_mode deco_mode;
-
         struct wl_listener commit;
         struct wl_listener request_move;
         struct wl_listener request_resize;
@@ -175,6 +172,7 @@ struct sway_xwayland_view {
         struct wl_listener set_role;
         struct wl_listener set_window_type;
         struct wl_listener set_hints;
+        struct wl_listener set_decorations;
         struct wl_listener map;
         struct wl_listener unmap;
         struct wl_listener destroy;
@@ -268,6 +266,17 @@ void view_set_activated(struct sway_view *view, bool activated);
  */
 void view_request_activate(struct sway_view *view);
 
+/**
+ * If possible, instructs the client to change their decoration mode.
+ */
+void view_set_csd_from_server(struct sway_view *view, bool enabled);
+
+/**
+ * Updates the view's border setting when the client unexpectedly changes their
+ * decoration mode.
+ */
+void view_set_csd_from_client(struct sway_view *view, bool enabled);
+
 void view_set_tiled(struct sway_view *view, bool tiled);
 
 void view_close(struct sway_view *view);
diff --git a/include/sway/xdg_decoration.h b/include/sway/xdg_decoration.h
new file mode 100644
index 00000000..46fb8d34
--- /dev/null
+++ b/include/sway/xdg_decoration.h
@@ -0,0 +1,19 @@
+#ifndef _SWAY_XDG_DECORATION_H
+#define _SWAY_XDG_DECORATION_H
+
+#include <wlr/types/wlr_xdg_decoration_v1.h>
+
+struct sway_xdg_decoration {
+        struct wlr_xdg_toplevel_decoration_v1 *wlr_xdg_decoration;
+        struct wl_list link;
+
+        struct sway_view *view;
+
+        struct wl_listener destroy;
+        struct wl_listener surface_commit;
+};
+
+struct sway_xdg_decoration *xdg_decoration_from_surface(
+        struct wlr_surface *surface);
+
+#endif
diff --git a/sway/commands/border.c b/sway/commands/border.c
index 95498b2f..673fea08 100644
--- a/sway/commands/border.c
+++ b/sway/commands/border.c
@@ -7,6 +7,17 @@
 #include "sway/tree/container.h"
 #include "sway/tree/view.h"
 
+static void set_border(struct sway_view *view,
+                enum sway_container_border new_border) {
+        if (view->border == B_CSD && new_border != B_CSD) {
+                view_set_csd_from_server(view, false);
+        } else if (view->border != B_CSD && new_border == B_CSD) {
+                view_set_csd_from_server(view, true);
+        }
+        view->saved_border = view->border;
+        view->border = new_border;
+}
+
 struct cmd_results *cmd_border(int argc, char **argv) {
         struct cmd_results *error = NULL;
         if ((error = checkarg(argc, "border", EXPECTED_AT_LEAST, 1))) {
@@ -21,13 +32,15 @@ struct cmd_results *cmd_border(int argc, char **argv) {
         struct sway_view *view = container->view;
 
         if (strcmp(argv[0], "none") == 0) {
-                view->border = B_NONE;
+                set_border(view, B_NONE);
         } else if (strcmp(argv[0], "normal") == 0) {
-                view->border = B_NORMAL;
+                set_border(view, B_NORMAL);
         } else if (strcmp(argv[0], "pixel") == 0) {
-                view->border = B_PIXEL;
+                set_border(view, B_PIXEL);
+        } else if (strcmp(argv[0], "csd") == 0) {
+                set_border(view, B_CSD);
         } else if (strcmp(argv[0], "toggle") == 0) {
-                view->border = (view->border + 1) % 3;
+                set_border(view, (view->border + 1) % 4);
         } else {
                 return cmd_results_new(CMD_INVALID, "border",
                                 "Expected 'border <none|normal|pixel|toggle>' "
diff --git a/sway/decoration.c b/sway/decoration.c
index 0e3e67ac..fea6ed4c 100644
--- a/sway/decoration.c
+++ b/sway/decoration.c
@@ -1,6 +1,8 @@
 #include <stdlib.h>
 #include "sway/decoration.h"
+#include "sway/desktop/transaction.h"
 #include "sway/server.h"
+#include "sway/tree/arrange.h"
 #include "sway/tree/view.h"
 #include "log.h"
 
@@ -24,20 +26,12 @@ static void server_decoration_handle_mode(struct wl_listener *listener,
                 return;
         }
 
-        switch (view->type) {
-        case SWAY_VIEW_XDG_SHELL_V6:;
-                struct sway_xdg_shell_v6_view *xdg_shell_v6_view =
-                        (struct sway_xdg_shell_v6_view *)view;
-                xdg_shell_v6_view->deco_mode = deco->wlr_server_decoration->mode;
-                break;
-        case SWAY_VIEW_XDG_SHELL:;
-                struct sway_xdg_shell_view *xdg_shell_view =
-                        (struct sway_xdg_shell_view *)view;
-                xdg_shell_view->deco_mode = deco->wlr_server_decoration->mode;
-                break;
-        default:
-                break;
-        }
+        bool csd = deco->wlr_server_decoration->mode ==
+                        WLR_SERVER_DECORATION_MANAGER_MODE_CLIENT;
+        view_set_csd_from_client(view, csd);
+
+        arrange_container(view->container);
+        transaction_commit_dirty();
 }
 
 void handle_server_decoration(struct wl_listener *listener, void *data) {
diff --git a/sway/desktop/render.c b/sway/desktop/render.c
index af4e2905..c8b08a58 100644
--- a/sway/desktop/render.c
+++ b/sway/desktop/render.c
@@ -272,7 +272,7 @@ static void render_view(struct sway_output *output, pixman_region32_t *damage,
                 render_view_toplevels(view, output, damage, view->container->alpha);
         }
 
-        if (view->container->current.using_csd) {
+        if (con->current.border == B_NONE || con->current.border == B_CSD) {
                 return;
         }
 
@@ -281,51 +281,49 @@ static void render_view(struct sway_output *output, pixman_region32_t *damage,
         float color[4];
         struct sway_container_state *state = &con->current;
 
-        if (state->border != B_NONE) {
-                if (state->border_left) {
-                        memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        premultiply_alpha(color, con->alpha);
-                        box.x = state->con_x;
-                        box.y = state->view_y;
-                        box.width = state->border_thickness;
-                        box.height = state->view_height;
-                        scale_box(&box, output_scale);
-                        render_rect(output->wlr_output, damage, &box, color);
-                }
+        if (state->border_left) {
+                memcpy(&color, colors->child_border, sizeof(float) * 4);
+                premultiply_alpha(color, con->alpha);
+                box.x = state->con_x;
+                box.y = state->view_y;
+                box.width = state->border_thickness;
+                box.height = state->view_height;
+                scale_box(&box, output_scale);
+                render_rect(output->wlr_output, damage, &box, color);
+        }
 
-                list_t *siblings = container_get_current_siblings(con);
-                enum sway_container_layout layout =
-                        container_current_parent_layout(con);
+        list_t *siblings = container_get_current_siblings(con);
+        enum sway_container_layout layout =
+                container_current_parent_layout(con);
 
-                if (state->border_right) {
-                        if (siblings->length == 1 && layout == L_HORIZ) {
-                                memcpy(&color, colors->indicator, sizeof(float) * 4);
-                        } else {
-                                memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        }
-                        premultiply_alpha(color, con->alpha);
-                        box.x = state->view_x + state->view_width;
-                        box.y = state->view_y;
-                        box.width = state->border_thickness;
-                        box.height = state->view_height;
-                        scale_box(&box, output_scale);
-                        render_rect(output->wlr_output, damage, &box, color);
+        if (state->border_right) {
+                if (siblings->length == 1 && layout == L_HORIZ) {
+                        memcpy(&color, colors->indicator, sizeof(float) * 4);
+                } else {
+                        memcpy(&color, colors->child_border, sizeof(float) * 4);
                 }
+                premultiply_alpha(color, con->alpha);
+                box.x = state->view_x + state->view_width;
+                box.y = state->view_y;
+                box.width = state->border_thickness;
+                box.height = state->view_height;
+                scale_box(&box, output_scale);
+                render_rect(output->wlr_output, damage, &box, color);
+        }
 
-                if (state->border_bottom) {
-                        if (siblings->length == 1 && layout == L_VERT) {
-                                memcpy(&color, colors->indicator, sizeof(float) * 4);
-                        } else {
-                                memcpy(&color, colors->child_border, sizeof(float) * 4);
-                        }
-                        premultiply_alpha(color, con->alpha);
-                        box.x = state->con_x;
-                        box.y = state->view_y + state->view_height;
-                        box.width = state->con_width;
-                        box.height = state->border_thickness;
-                        scale_box(&box, output_scale);
-                        render_rect(output->wlr_output, damage, &box, color);
+        if (state->border_bottom) {
+                if (siblings->length == 1 && layout == L_VERT) {
+                        memcpy(&color, colors->indicator, sizeof(float) * 4);
+                } else {
+                        memcpy(&color, colors->child_border, sizeof(float) * 4);
                 }
+                premultiply_alpha(color, con->alpha);
+                box.x = state->con_x;
+                box.y = state->view_y + state->view_height;
+                box.width = state->con_width;
+                box.height = state->border_thickness;
+                scale_box(&box, output_scale);
+                render_rect(output->wlr_output, damage, &box, color);
         }
 }
 
@@ -645,14 +643,12 @@ static void render_containers_linear(struct sway_output *output,
                                 marks_texture = view->marks_unfocused;
                         }
 
-                        if (!view->container->current.using_csd) {
-                                if (state->border == B_NORMAL) {
-                                        render_titlebar(output, damage, child, state->con_x,
-                                                        state->con_y, state->con_width, colors,
-                                                        title_texture, marks_texture);
-                                } else {
-                                        render_top_border(output, damage, child, colors);
-                                }
+                        if (state->border == B_NORMAL) {
+                                render_titlebar(output, damage, child, state->con_x,
+                                                state->con_y, state->con_width, colors,
+                                                title_texture, marks_texture);
+                        } else if (state->border == B_PIXEL) {
+                                render_top_border(output, damage, child, colors);
                         }
                         render_view(output, damage, child, colors);
                 } else {
@@ -859,14 +855,12 @@ static void render_floating_container(struct sway_output *soutput,
                         marks_texture = view->marks_unfocused;
                 }
 
-                if (!view->container->current.using_csd) {
-                        if (con->current.border == B_NORMAL) {
-                                render_titlebar(soutput, damage, con, con->current.con_x,
-                                                con->current.con_y, con->current.con_width, colors,
-                                                title_texture, marks_texture);
-                        } else if (con->current.border != B_NONE) {
-                                render_top_border(soutput, damage, con, colors);
-                        }
+                if (con->current.border == B_NORMAL) {
+                        render_titlebar(soutput, damage, con, con->current.con_x,
+                                        con->current.con_y, con->current.con_width, colors,
+                                        title_texture, marks_texture);
+                } else if (con->current.border == B_PIXEL) {
+                        render_top_border(soutput, damage, con, colors);
                 }
                 render_view(soutput, damage, con, colors);
         } else {
diff --git a/sway/desktop/transaction.c b/sway/desktop/transaction.c
index 797f6b4c..4624d824 100644
--- a/sway/desktop/transaction.c
+++ b/sway/desktop/transaction.c
@@ -167,7 +167,6 @@ static void copy_container_state(struct sway_container *container,
                 state->border_left = view->border_left;
                 state->border_right = view->border_right;
                 state->border_bottom = view->border_bottom;
-                state->using_csd = view->using_csd;
         } else {
                 state->children = create_list();
                 list_cat(state->children, container->children);
diff --git a/sway/desktop/xdg_shell.c b/sway/desktop/xdg_shell.c
index 6d1ccdd7..d563edae 100644
--- a/sway/desktop/xdg_shell.c
+++ b/sway/desktop/xdg_shell.c
@@ -175,15 +175,6 @@ static bool wants_floating(struct sway_view *view) {
                 || toplevel->parent;
 }
 
-static bool has_client_side_decorations(struct sway_view *view) {
-        struct sway_xdg_shell_view *xdg_shell_view =
-                xdg_shell_view_from_view(view);
-        if (xdg_shell_view == NULL) {
-                return true;
-        }
-        return xdg_shell_view->deco_mode != WLR_SERVER_DECORATION_MANAGER_MODE_SERVER;
-}
-
 static void for_each_surface(struct sway_view *view,
                 wlr_surface_iterator_func_t iterator, void *user_data) {
         if (xdg_shell_view_from_view(view) == NULL) {
@@ -240,7 +231,6 @@ static const struct sway_view_impl view_impl = {
         .set_tiled = set_tiled,
         .set_fullscreen = set_fullscreen,
         .wants_floating = wants_floating,
-        .has_client_side_decorations = has_client_side_decorations,
         .for_each_surface = for_each_surface,
         .for_each_popup = for_each_popup,
         .close = _close,
@@ -385,15 +375,13 @@ static void handle_map(struct wl_listener *listener, void *data) {
                 view->natural_height = view->wlr_xdg_surface->surface->current.height;
         }
 
+        view_map(view, view->wlr_xdg_surface->surface);
+
         struct sway_server_decoration *deco =
                 decoration_from_surface(xdg_surface->surface);
-        if (deco != NULL) {
-                xdg_shell_view->deco_mode = deco->wlr_server_decoration->mode;
-        } else {
-                xdg_shell_view->deco_mode = WLR_SERVER_DECORATION_MANAGER_MODE_CLIENT;
-        }
-
-        view_map(view, view->wlr_xdg_surface->surface);
+        bool csd = !deco || deco->wlr_server_decoration->mode ==
+                WLR_SERVER_DECORATION_MANAGER_MODE_CLIENT;
+        view_set_csd_from_client(view, csd);
 
         if (xdg_surface->toplevel->client_pending.fullscreen) {
                 container_set_fullscreen(view->container, true);
diff --git a/sway/desktop/xdg_shell_v6.c b/sway/desktop/xdg_shell_v6.c
index 95ca396c..8c8085f7 100644
--- a/sway/desktop/xdg_shell_v6.c
+++ b/sway/desktop/xdg_shell_v6.c
@@ -171,15 +171,6 @@ static bool wants_floating(struct sway_view *view) {
                 || toplevel->parent;
 }
 
-static bool has_client_side_decorations(struct sway_view *view) {
-        struct sway_xdg_shell_v6_view *xdg_shell_v6_view =
-                xdg_shell_v6_view_from_view(view);
-        if (xdg_shell_v6_view == NULL) {
-                return true;
-        }
-        return xdg_shell_v6_view->deco_mode != WLR_SERVER_DECORATION_MANAGER_MODE_SERVER;
-}
-
 static void for_each_surface(struct sway_view *view,
                 wlr_surface_iterator_func_t iterator, void *user_data) {
         if (xdg_shell_v6_view_from_view(view) == NULL) {
@@ -237,7 +228,6 @@ static const struct sway_view_impl view_impl = {
         .set_tiled = set_tiled,
         .set_fullscreen = set_fullscreen,
         .wants_floating = wants_floating,
-        .has_client_side_decorations = has_client_side_decorations,
         .for_each_surface = for_each_surface,
         .for_each_popup = for_each_popup,
         .close = _close,
@@ -382,15 +372,13 @@ static void handle_map(struct wl_listener *listener, void *data) {
                 view->natural_height = view->wlr_xdg_surface_v6->surface->current.height;
         }
 
+        view_map(view, view->wlr_xdg_surface_v6->surface);
+
         struct sway_server_decoration *deco =
                 decoration_from_surface(xdg_surface->surface);
-        if (deco != NULL) {
-                xdg_shell_v6_view->deco_mode = deco->wlr_server_decoration->mode;
-        } else {
-                xdg_shell_v6_view->deco_mode = WLR_SERVER_DECORATION_MANAGER_MODE_CLIENT;
-        }
-
-        view_map(view, view->wlr_xdg_surface_v6->surface);
+        bool csd = !deco || deco->wlr_server_decoration->mode ==
+                        WLR_SERVER_DECORATION_MANAGER_MODE_CLIENT;
+        view_set_csd_from_client(view, csd);
 
         if (xdg_surface->toplevel->client_pending.fullscreen) {
                 container_set_fullscreen(view->container, true);
diff --git a/sway/desktop/xwayland.c b/sway/desktop/xwayland.c
index a12ac854..f1205518 100644
--- a/sway/desktop/xwayland.c
+++ b/sway/desktop/xwayland.c
@@ -243,12 +243,14 @@ static bool wants_floating(struct sway_view *view) {
         return false;
 }
 
-static bool has_client_side_decorations(struct sway_view *view) {
-        if (xwayland_view_from_view(view) == NULL) {
-                return false;
-        }
-        struct wlr_xwayland_surface *surface = view->wlr_xwayland_surface;
-        return surface->decorations != WLR_XWAYLAND_SURFACE_DECORATIONS_ALL;
+static void handle_set_decorations(struct wl_listener *listener, void *data) {
+        struct sway_xwayland_view *xwayland_view =
+                wl_container_of(listener, xwayland_view, set_decorations);
+        struct sway_view *view = &xwayland_view->view;
+        struct wlr_xwayland_surface *xsurface = view->wlr_xwayland_surface;
+
+        bool csd = xsurface->decorations != WLR_XWAYLAND_SURFACE_DECORATIONS_ALL;
+        view_set_csd_from_client(view, csd);
 }
 
 static void _close(struct sway_view *view) {
@@ -274,7 +276,6 @@ static const struct sway_view_impl view_impl = {
         .set_tiled = set_tiled,
         .set_fullscreen = set_fullscreen,
         .wants_floating = wants_floating,
-        .has_client_side_decorations = has_client_side_decorations,
         .close = _close,
         .destroy = destroy,
 };
@@ -343,6 +344,7 @@ static void handle_destroy(struct wl_listener *listener, void *data) {
         wl_list_remove(&xwayland_view->set_role.link);
         wl_list_remove(&xwayland_view->set_window_type.link);
         wl_list_remove(&xwayland_view->set_hints.link);
+        wl_list_remove(&xwayland_view->set_decorations.link);
         wl_list_remove(&xwayland_view->map.link);
         wl_list_remove(&xwayland_view->unmap.link);
         view_begin_destroy(&xwayland_view->view);
@@ -613,6 +615,10 @@ void handle_xwayland_surface(struct wl_listener *listener, void *data) {
         wl_signal_add(&xsurface->events.set_hints, &xwayland_view->set_hints);
         xwayland_view->set_hints.notify = handle_set_hints;
 
+        wl_signal_add(&xsurface->events.set_decorations,
+                        &xwayland_view->set_decorations);
+        xwayland_view->set_decorations.notify = handle_set_decorations;
+
         wl_signal_add(&xsurface->events.unmap, &xwayland_view->unmap);
         xwayland_view->unmap.notify = handle_unmap;
 
diff --git a/sway/input/cursor.c b/sway/input/cursor.c
index aa0e07f5..eab102fd 100644
--- a/sway/input/cursor.c
+++ b/sway/input/cursor.c
@@ -175,7 +175,8 @@ static enum wlr_edges find_edge(struct sway_container *cont,
                 return WLR_EDGE_NONE;
         }
         struct sway_view *view = cont->view;
-        if (view->border == B_NONE || !view->border_thickness || view->using_csd) {
+        if (view->border == B_NONE || !view->border_thickness ||
+                        view->border == B_CSD) {
                 return WLR_EDGE_NONE;
         }
 
diff --git a/sway/ipc-json.c b/sway/ipc-json.c
index f054ac9f..df24b812 100644
--- a/sway/ipc-json.c
+++ b/sway/ipc-json.c
@@ -216,6 +216,8 @@ static const char *describe_container_border(enum sway_container_border border)
                 return "pixel";
         case B_NORMAL:
                 return "normal";
+        case B_CSD:
+                return "csd";
         }
         return "unknown";
 }
diff --git a/sway/meson.build b/sway/meson.build
index d67a4c64..2a3c5b5e 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -10,6 +10,7 @@ sway_sources = files(
         'security.c',
         'server.c',
         'swaynag.c',
+        'xdg_decoration.c',
 
         'desktop/desktop.c',
         'desktop/idle_inhibit_v1.c',
diff --git a/sway/server.c b/sway/server.c
index bed5aed1..63bfa7e1 100644
--- a/sway/server.c
+++ b/sway/server.c
@@ -16,6 +16,7 @@
 #include <wlr/types/wlr_screencopy_v1.h>
 #include <wlr/types/wlr_server_decoration.h>
 #include <wlr/types/wlr_xcursor_manager.h>
+#include <wlr/types/wlr_xdg_decoration_v1.h>
 #include <wlr/types/wlr_xdg_output_v1.h>
 #include <wlr/util/log.h>
 #include "list.h"
@@ -115,6 +116,14 @@ bool server_init(struct sway_server *server) {
         server->server_decoration.notify = handle_server_decoration;
         wl_list_init(&server->decorations);
 
+        server->xdg_decoration_manager =
+                wlr_xdg_decoration_manager_v1_create(server->wl_display);
+        wl_signal_add(
+                        &server->xdg_decoration_manager->events.new_toplevel_decoration,
+                        &server->xdg_decoration);
+        server->xdg_decoration.notify = handle_xdg_decoration;
+        wl_list_init(&server->xdg_decorations);
+
         wlr_export_dmabuf_manager_v1_create(server->wl_display);
         wlr_screencopy_manager_v1_create(server->wl_display);
 
diff --git a/sway/tree/container.c b/sway/tree/container.c
index baaa82fd..d75e34a5 100644
--- a/sway/tree/container.c
+++ b/sway/tree/container.c
@@ -715,7 +715,7 @@ void container_set_geometry_from_floating_view(struct sway_container *con) {
         size_t border_width = 0;
         size_t top = 0;
 
-        if (!view->using_csd) {
+        if (view->border != B_CSD) {
                 border_width = view->border_thickness * (view->border != B_NONE);
                 top = view->border == B_NORMAL ?
                         container_titlebar_height() : border_width;
diff --git a/sway/tree/view.c b/sway/tree/view.c
index e370443c..c370de2d 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -5,6 +5,8 @@
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_buffer.h>
 #include <wlr/types/wlr_output_layout.h>
+#include <wlr/types/wlr_server_decoration.h>
+#include <wlr/types/wlr_xdg_decoration_v1.h>
 #include "config.h"
 #ifdef HAVE_XWAYLAND
 #include <wlr/xwayland.h>
@@ -23,6 +25,7 @@
 #include "sway/tree/view.h"
 #include "sway/tree/workspace.h"
 #include "sway/config.h"
+#include "sway/xdg_decoration.h"
 #include "pango.h"
 #include "stringop.h"
 
@@ -231,12 +234,8 @@ void view_autoconfigure(struct sway_view *view) {
                 view->border_top = false;
         }
 
-        enum sway_container_border border = view->border;
-        if (view->using_csd) {
-                border = B_NONE;
-        }
-
-        switch (border) {
+        switch (view->border) {
+        case B_CSD:
         case B_NONE:
                 x = con->x;
                 y = con->y + y_offset;
@@ -309,16 +308,26 @@ void view_request_activate(struct sway_view *view) {
         }
 }
 
-void view_set_tiled(struct sway_view *view, bool tiled) {
-        if (!tiled) {
-                view->using_csd = true;
-                if (view->impl->has_client_side_decorations) {
-                        view->using_csd = view->impl->has_client_side_decorations(view);
-                }
-        } else {
-                view->using_csd = false;
+void view_set_csd_from_server(struct sway_view *view, bool enabled) {
+        if (view->xdg_decoration) {
+                uint32_t mode = enabled ?
+                        WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE :
+                        WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_SERVER_SIDE;
+                wlr_xdg_toplevel_decoration_v1_set_mode(
+                                view->xdg_decoration->wlr_xdg_decoration, mode);
         }
+}
 
+void view_set_csd_from_client(struct sway_view *view, bool enabled) {
+        if (enabled && view->border != B_CSD) {
+                view->saved_border = view->border;
+                view->border = B_CSD;
+        } else if (!enabled && view->border == B_CSD) {
+                view->border = view->saved_border;
+        }
+}
+
+void view_set_tiled(struct sway_view *view, bool tiled) {
         if (view->impl->set_tiled) {
                 view->impl->set_tiled(view, tiled);
         }
diff --git a/sway/xdg_decoration.c b/sway/xdg_decoration.c
new file mode 100644
index 00000000..2e7e4bd0
--- /dev/null
+++ b/sway/xdg_decoration.c
@@ -0,0 +1,73 @@
+#include <stdlib.h>
+#include "sway/desktop/transaction.h"
+#include "sway/server.h"
+#include "sway/tree/arrange.h"
+#include "sway/tree/view.h"
+#include "sway/xdg_decoration.h"
+#include "log.h"
+
+static void xdg_decoration_handle_destroy(struct wl_listener *listener,
+                void *data) {
+        struct sway_xdg_decoration *deco =
+                wl_container_of(listener, deco, destroy);
+        deco->view->xdg_decoration = NULL;
+        wl_list_remove(&deco->destroy.link);
+        wl_list_remove(&deco->surface_commit.link);
+        wl_list_remove(&deco->link);
+        free(deco);
+}
+
+static void xdg_decoration_handle_surface_commit(struct wl_listener *listener,
+                void *data) {
+        struct sway_xdg_decoration *decoration =
+                wl_container_of(listener, decoration, surface_commit);
+
+        bool csd = decoration->wlr_xdg_decoration->current_mode ==
+                WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE;
+        struct sway_view *view = decoration->view;
+
+        view_set_csd_from_client(view, csd);
+
+        arrange_container(view->container);
+        transaction_commit_dirty();
+}
+
+void handle_xdg_decoration(struct wl_listener *listener, void *data) {
+        struct wlr_xdg_toplevel_decoration_v1 *wlr_deco = data;
+        struct sway_xdg_shell_view *xdg_shell_view = wlr_deco->surface->data;
+        struct wlr_xdg_surface *wlr_xdg_surface =
+                xdg_shell_view->view.wlr_xdg_surface;
+
+        struct sway_xdg_decoration *deco = calloc(1, sizeof(*deco));
+        if (deco == NULL) {
+                return;
+        }
+
+        deco->view = &xdg_shell_view->view;
+        deco->view->xdg_decoration = deco;
+        deco->wlr_xdg_decoration = wlr_deco;
+
+        wl_signal_add(&wlr_deco->events.destroy, &deco->destroy);
+        deco->destroy.notify = xdg_decoration_handle_destroy;
+
+        // Note: We don't listen to the request_mode signal here, effectively
+        // ignoring any modes the client asks to set. The client can still force a
+        // mode upon us, in which case we get upset but live with it.
+
+        deco->surface_commit.notify = xdg_decoration_handle_surface_commit;
+        wl_signal_add(&wlr_xdg_surface->surface->events.commit,
+                &deco->surface_commit);
+
+        wl_list_insert(&server.xdg_decorations, &deco->link);
+}
+
+struct sway_xdg_decoration *xdg_decoration_from_surface(
+                struct wlr_surface *surface) {
+        struct sway_xdg_decoration *deco;
+        wl_list_for_each(deco, &server.xdg_decorations, link) {
+                if (deco->wlr_xdg_decoration->surface->surface == surface) {
+                        return deco;
+                }
+        }
+        return NULL;
+}