From 129e1a9b8e23007026d19c970941ccbc8ee2f0ca Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Fri, 6 May 2022 20:05:04 +0200
Subject: [PATCH] Add support for xdg_toplevel.wm_capabilities

See https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/122
---
 CHANGELOG.md |  3 +++
 render.c     |  6 ++++--
 wayland.c    | 46 +++++++++++++++++++++++++++++++++++++++++++---
 wayland.h    |  5 +++++
 4 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6823e16b..b82cfa00 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,12 +56,15 @@
   `key-bindings.unicode-input` and `search-bindings.unicode-input` key
   bindings. Note that there is no visual feedback, as the preferred
   way of entering Unicode characters is with an IME ([#1116][1116]).
+* Support for `xdg_toplevel.wm_capabilities`, to adapt the client-side
+  decoration buttons to the compositor capabilities ([#1061][1061]).
 
 [1058]: https://codeberg.org/dnkl/foot/issues/1058
 [1070]: https://codeberg.org/dnkl/foot/issues/1070
 [30]: https://codeberg.org/dnkl/foot/issues/30
 [1112]: https://codeberg.org/dnkl/foot/issues/1112
 [1116]: https://codeberg.org/dnkl/foot/issues/1116
+[1061]: https://codeberg.org/dnkl/foot/pulls/1061
 
 
 ### Changed
diff --git a/render.c b/render.c
index 9333deb7..ff82802e 100644
--- a/render.c
+++ b/render.c
@@ -1726,10 +1726,12 @@ get_csd_data(const struct terminal *term, enum csd_surface surf_idx)
     const int button_close_width = term->width >= 1 * button_width
         ? button_width : 0;
 
-    const int button_maximize_width = term->width >= 2 * button_width
+    const int button_maximize_width =
+        term->width >= 2 * button_width && term->window->wm_capabilities.maximize
         ? button_width : 0;
 
-    const int button_minimize_width = term->width >= 3 * button_width
+    const int button_minimize_width =
+        term->width >= 3 * button_width && term->window->wm_capabilities.minimize
         ? button_width : 0;
 
     switch (surf_idx) {
diff --git a/wayland.c b/wayland.c
index 2d7c303f..fb41cf7d 100644
--- a/wayland.c
+++ b/wayland.c
@@ -714,10 +714,38 @@ xdg_toplevel_configure_bounds(void *data,
     /* TODO: ensure we don't pick a bigger size */
 }
 
+#if defined(XDG_TOPLEVEL_WM_CAPABILITIES_SINCE_VERSION)
+static void
+xdg_toplevel_wm_capabilities(void *data,
+                             struct xdg_toplevel *xdg_toplevel,
+                             struct wl_array *caps)
+{
+    struct wl_window *win = data;
+
+    win->wm_capabilities.maximize = false;
+    win->wm_capabilities.minimize = false;
+
+    uint32_t *cap_ptr;
+    wl_array_for_each(cap_ptr, caps) {
+        switch (*cap_ptr) {
+        case XDG_TOPLEVEL_WM_CAPABILITIES_MAXIMIZE:
+            win->wm_capabilities.maximize = true;
+            break;
+        case XDG_TOPLEVEL_WM_CAPABILITIES_MINIMIZE:
+            win->wm_capabilities.minimize = true;
+            break;
+        }
+    }
+}
+#endif
+
 static const struct xdg_toplevel_listener xdg_toplevel_listener = {
     .configure = &xdg_toplevel_configure,
     /*.close = */&xdg_toplevel_close,  /* epoll-shim defines a macro ‘close’... */
     .configure_bounds = &xdg_toplevel_configure_bounds,
+#if defined(XDG_TOPLEVEL_WM_CAPABILITIES_SINCE_VERSION)
+    .wm_capabilities = xdg_toplevel_wm_capabilities,
+#endif
 };
 
 static void
@@ -905,13 +933,22 @@ handle_global(void *data, struct wl_registry *registry,
             return;
 
         /*
-         * We *require* version 1, but _can_ use version 2. Version 2
+         * We *require* version 1, but _can_ use version 5. Version 2
          * adds 'tiled' window states. We use that information to
-         * restore the window size when window is un-tiled.
+         * restore the window size when window is un-tiled. Version 5
+         * adds 'wm_capabilities'. We use that information to draw
+         * window decorations.
          */
+#if defined(XDG_TOPLEVEL_WM_CAPABILITIES_SINCE_VERSION)
+        const uint32_t preferred = XDG_TOPLEVEL_WM_CAPABILITIES_SINCE_VERSION;
+#elif defined(XDG_TOPLEVEL_STATE_TILED_LEFT_SINCE_VERSION)
+        const uint32_t preferred = XDG_TOPLEVEL_STATE_TILED_LEFT_SINCE_VERSION;
+#else
+        const uint32_t preferred = required;
+#endif
 
         wayl->shell = wl_registry_bind(
-            wayl->registry, name, &xdg_wm_base_interface, min(version, 4));
+            wayl->registry, name, &xdg_wm_base_interface, min(version, preferred));
         xdg_wm_base_add_listener(wayl->shell, &xdg_wm_base_listener, wayl);
     }
 
@@ -1427,6 +1464,9 @@ wayl_win_init(struct terminal *term, const char *token)
     win->csd.move_timeout_fd = -1;
     win->resize_timeout_fd = -1;
 
+    win->wm_capabilities.maximize = true;
+    win->wm_capabilities.minimize = true;
+
     win->surface = wl_compositor_create_surface(wayl->compositor);
     if (win->surface == NULL) {
         LOG_ERR("failed to create wayland surface");
diff --git a/wayland.h b/wayland.h
index 803fe390..e86c6a3d 100644
--- a/wayland.h
+++ b/wayland.h
@@ -339,6 +339,11 @@ struct wl_window {
         uint32_t serial;
     } csd;
 
+    struct {
+        bool maximize:1;
+        bool minimize:1;
+    } wm_capabilities;
+
     struct wl_surf_subsurf search;
     struct wl_surf_subsurf scrollback_indicator;
     struct wl_surf_subsurf render_timer;