foreign-toplevel-management: report parent toplevel

Based on the wlr-protocols PR:
https://github.com/swaywm/wlr-protocols/pull/52

examples/foreign-toplevel.c

@@ -7,7 +7,7 @@
 #include <wayland-client.h>
 #include "wlr-foreign-toplevel-management-unstable-v1-client-protocol.h"
 
-#define WLR_FOREIGN_TOPLEVEL_MANAGEMENT_VERSION 2
+#define WLR_FOREIGN_TOPLEVEL_MANAGEMENT_VERSION 3
 
 /**
  * Usage:
@@ -38,11 +38,14 @@ enum toplevel_state_field {
 	TOPLEVEL_STATE_INVALID = (1 << 4),
 };
 
+static const uint32_t no_parent = (uint32_t)-1;
+
 struct toplevel_state {
 	char *title;
 	char *app_id;
 
 	uint32_t state;
+	uint32_t parent_id;
 };
 
 static void copy_state(struct toplevel_state *current,
@@ -67,6 +70,8 @@ static void copy_state(struct toplevel_state *current,
 		current->state = pending->state;
 	}
 
+	current->parent_id = pending->parent_id;
+
 	pending->state = TOPLEVEL_STATE_INVALID;
 }
 
@@ -84,6 +89,12 @@ static void print_toplevel(struct toplevel_v1 *toplevel, bool print_endl) {
 			toplevel->current.title ?: "(nil)",
 			toplevel->current.app_id ?: "(nil)");
 
+	if (toplevel->current.parent_id != no_parent) {
+		printf(" parent=%u", toplevel->current.parent_id);
+	} else {
+		printf(" no parent");
+	}
+	
 	if (print_endl) {
 		printf("\n");
 	}
@@ -172,6 +183,28 @@ static void toplevel_handle_state(void *data,
 	toplevel->pending.state = array_to_state(state);
 }
 
+static struct zwlr_foreign_toplevel_manager_v1 *toplevel_manager = NULL;
+static struct wl_list toplevel_list;
+
+static void toplevel_handle_parent(void *data,
+		struct zwlr_foreign_toplevel_handle_v1 *zwlr_toplevel,
+		struct zwlr_foreign_toplevel_handle_v1 *zwlr_parent) {
+	struct toplevel_v1 *toplevel = data;
+	toplevel->pending.parent_id = no_parent;
+	if (zwlr_parent) {
+		struct toplevel_v1 *toplevel_tmp;
+		wl_list_for_each(toplevel_tmp, &toplevel_list, link) {
+			if (toplevel_tmp->zwlr_toplevel == zwlr_parent) {
+				toplevel->pending.parent_id = toplevel_tmp->id;
+				break;
+			}
+		}
+		if (toplevel->pending.parent_id == no_parent) {
+			fprintf(stderr, "Cannot find parent toplevel!\n");
+		}
+	}
+}
+
 static void toplevel_handle_done(void *data,
 		struct zwlr_foreign_toplevel_handle_v1 *zwlr_toplevel) {
 	struct toplevel_v1 *toplevel = data;
@@ -202,11 +235,9 @@ static const struct zwlr_foreign_toplevel_handle_v1_listener toplevel_impl = {
 	.state = toplevel_handle_state,
 	.done = toplevel_handle_done,
 	.closed = toplevel_handle_closed,
+	.parent = toplevel_handle_parent
 };
 
-static struct zwlr_foreign_toplevel_manager_v1 *toplevel_manager = NULL;
-static struct wl_list toplevel_list;
-
 static void toplevel_manager_handle_toplevel(void *data,
 		struct zwlr_foreign_toplevel_manager_v1 *toplevel_manager,
 		struct zwlr_foreign_toplevel_handle_v1 *zwlr_toplevel) {
@@ -218,6 +249,8 @@ static void toplevel_manager_handle_toplevel(void *data,
 
 	toplevel->id = global_id++;
 	toplevel->zwlr_toplevel = zwlr_toplevel;
+	toplevel->current.parent_id = no_parent;
+	toplevel->pending.parent_id = no_parent;
 	wl_list_insert(&toplevel_list, &toplevel->link);
 
 	zwlr_foreign_toplevel_handle_v1_add_listener(zwlr_toplevel, &toplevel_impl,

include/wlr/types/wlr_foreign_toplevel_management_v1.h

@@ -50,6 +50,7 @@ struct wlr_foreign_toplevel_handle_v1 {
 
 	char *title;
 	char *app_id;
+	struct wlr_foreign_toplevel_handle_v1 *parent;
 	struct wl_list outputs; // wlr_foreign_toplevel_v1_output
 	uint32_t state; // wlr_foreign_toplevel_v1_state
 
@@ -104,6 +105,12 @@ struct wlr_foreign_toplevel_manager_v1 *wlr_foreign_toplevel_manager_v1_create(
 
 struct wlr_foreign_toplevel_handle_v1 *wlr_foreign_toplevel_handle_v1_create(
 	struct wlr_foreign_toplevel_manager_v1 *manager);
+/* Destroy the given toplevel handle, sending the closed event to any
+ * client. Also, if the destroyed toplevel is set as a parent of any
+ * other valid toplevel, clients still holding a handle to both are
+ * sent a parent signal with NULL parent. If this is not desired, the
+ * caller should ensure that any child toplevels are destroyed before
+ * the parent. */
 void wlr_foreign_toplevel_handle_v1_destroy(
 	struct wlr_foreign_toplevel_handle_v1 *toplevel);
 
@@ -126,4 +133,14 @@ void wlr_foreign_toplevel_handle_v1_set_activated(
 void wlr_foreign_toplevel_handle_v1_set_fullscreen(
 	struct wlr_foreign_toplevel_handle_v1* toplevel, bool fullscreen);
 
+/* Set the parent of a toplevel. If the parent changed from its previous
+ * value, also sends a parent event to all clients that hold handles to
+ * both toplevel and parent (no message is sent to clients that have
+ * previously destroyed their parent handle). NULL is allowed as the
+ * parent, meaning no parent exists. */
+void wlr_foreign_toplevel_handle_v1_set_parent(
+	struct wlr_foreign_toplevel_handle_v1 *toplevel,
+	struct wlr_foreign_toplevel_handle_v1 *parent);
+
+
 #endif

protocol/wlr-foreign-toplevel-management-unstable-v1.xml

@@ -25,7 +25,7 @@
     THIS SOFTWARE.
   </copyright>
 
-  <interface name="zwlr_foreign_toplevel_manager_v1" version="2">
+  <interface name="zwlr_foreign_toplevel_manager_v1" version="3">
     <description summary="list and control opened apps">
       The purpose of this protocol is to enable the creation of taskbars
       and docks by providing them with a list of opened applications and
@@ -68,7 +68,7 @@
     </event>
   </interface>
 
-  <interface name="zwlr_foreign_toplevel_handle_v1" version="2">
+  <interface name="zwlr_foreign_toplevel_handle_v1" version="3">
     <description summary="an opened toplevel">
       A zwlr_foreign_toplevel_handle_v1 object represents an opened toplevel
       window. Each app may have multiple opened toplevels.
@@ -255,5 +255,16 @@
         actually changes, this will be indicated by the state event.
       </description>
     </request>
+
+    <!-- Version 3 additions -->
+
+    <event name="parent" since="3">
+      <description summary="parent change">
+        This event is emitted whenever the parent of the toplevel changes.
+        
+        No event is emitted when the parent handle is destroyed by the client.
+      </description>
+      <arg name="parent" type="object" interface="zwlr_foreign_toplevel_handle_v1" allow-null="true"/>
+    </event>
   </interface>
 </protocol>

types/wlr_foreign_toplevel_management_v1.c

@@ -9,7 +9,7 @@
 #include "util/signal.h"
 #include "wlr-foreign-toplevel-management-unstable-v1-protocol.h"
 
-#define FOREIGN_TOPLEVEL_MANAGEMENT_V1_VERSION 2
+#define FOREIGN_TOPLEVEL_MANAGEMENT_V1_VERSION 3
 
 static const struct zwlr_foreign_toplevel_handle_v1_interface toplevel_handle_impl;
 
@@ -405,6 +405,37 @@ void wlr_foreign_toplevel_handle_v1_set_fullscreen(
 	toplevel_send_state(toplevel);
 }
 
+static void toplevel_resource_send_parent(
+		struct wl_resource *toplevel_resource,
+		struct wlr_foreign_toplevel_handle_v1 *parent) {
+	struct wl_client *client = wl_resource_get_client(toplevel_resource);
+	struct wl_resource *parent_resource = NULL;
+	if (parent) {
+		parent_resource = wl_resource_find_for_client(&parent->resources, client);
+		if (!parent_resource) {
+			/* don't send an event if this client destroyed the parent handle */
+			return;
+		}
+	}
+	zwlr_foreign_toplevel_handle_v1_send_parent(toplevel_resource,
+		parent_resource);
+}
+
+void wlr_foreign_toplevel_handle_v1_set_parent(
+		struct wlr_foreign_toplevel_handle_v1 *toplevel,
+		struct wlr_foreign_toplevel_handle_v1 *parent) {
+	if (parent == toplevel->parent) {
+		/* only send parent event to the clients if there was a change */
+		return;
+	}
+	struct wl_resource *toplevel_resource, *tmp;
+	wl_resource_for_each_safe(toplevel_resource, tmp, &toplevel->resources) {
+		toplevel_resource_send_parent(toplevel_resource, parent);
+	}
+	toplevel->parent = parent;
+	toplevel_update_idle_source(toplevel);
+}
+
 void wlr_foreign_toplevel_handle_v1_destroy(
 		struct wlr_foreign_toplevel_handle_v1 *toplevel) {
 	if (!toplevel) {
@@ -432,6 +463,19 @@ void wlr_foreign_toplevel_handle_v1_destroy(
 
 	wl_list_remove(&toplevel->link);
 
+	/* need to ensure no other toplevels hold a pointer to this one as
+	 * a parent, so that a later call to foreign_toplevel_manager_bind()
+	 * will not result in a segfault */
+	struct wlr_foreign_toplevel_handle_v1 *tl, *tmp3;
+	wl_list_for_each_safe(tl, tmp3, &toplevel->manager->toplevels, link) {
+		if (tl->parent == toplevel) {
+			/* Note: we send a parent signal to all clients in this case;
+			 * the caller should first destroy the child handles if it
+			 * wishes to avoid this behavior. */
+			wlr_foreign_toplevel_handle_v1_set_parent(tl, NULL);
+		}
+	}
+
 	free(toplevel->title);
 	free(toplevel->app_id);
 	free(toplevel);
@@ -542,6 +586,8 @@ static void toplevel_send_details_to_toplevel_resource(
 	zwlr_foreign_toplevel_handle_v1_send_state(resource, &states);
 	wl_array_release(&states);
 
+	toplevel_resource_send_parent(resource, toplevel->parent);
+
 	zwlr_foreign_toplevel_handle_v1_send_done(resource);
 }
 
@@ -560,9 +606,17 @@ static void foreign_toplevel_manager_bind(struct wl_client *client, void *data,
 	wl_list_insert(&manager->resources, wl_resource_get_link(resource));
 
 	struct wlr_foreign_toplevel_handle_v1 *toplevel, *tmp;
+	/* First loop: create a handle for all toplevels for all clients.
+	 * Separation into two loops avoid the case where a child handle
+	 * is created before a parent handle, so the parent relationship
+	 * could not be sent to a client. */
 	wl_list_for_each_safe(toplevel, tmp, &manager->toplevels, link) {
-		struct wl_resource *toplevel_resource =
 		create_toplevel_resource_for_resource(toplevel, resource);
+	}
+	/* Second loop: send details about each toplevel. */
+	wl_list_for_each_safe(toplevel, tmp, &manager->toplevels, link) {
+		struct wl_resource *toplevel_resource =
+			wl_resource_find_for_client(&toplevel->resources, client);
 		toplevel_send_details_to_toplevel_resource(toplevel,
 			toplevel_resource);
 	}