Support window-rules

Two types of window rules are supported, actions and properties. They are
defined as shown below.

    <windowRules>

      <!-- Action -->
      <windowRule identifier="some-application">
        <action name="Maximize"/>
      </windowRule>

      <!-- Property -->
      <windowRule identifier="foo*" serverDecoration="yes|no"/>

    </windowRules>

Rules are applied if windows match the criteria defined by the
'identifier' attribute which relates to app_id for native Wayland windows
and WM_CLASS for XWayland clients.

Matching against patterns with '*' (wildcard) and '?' (joker) is
supported.

Add 'serverDecoration' property.

docs/labwc-config.5.scd

@@ -330,6 +330,48 @@ The rest of this man page describes configuration options.
 	any motion events while a keyboard is typing, and for a short while
 	after as well.
 
+## WINDOW RULES
+
+Two types of window rules are supported, actions and properties. They are
+defined as shown below.
+
+```
+<windowRules>
+
+  <!-- Action -->
+  <windowRule identifier="">
+    <action name=""/>
+  </windowRule>
+
+  <!-- Property -->
+  <windowRule identifier="" serverDecoration="" />
+
+</windowRules>
+```
+
+*Actions*
+
+*<windowRules><windowRule identifier="">*
+	Define a window rule for any window which matches the criteria defined
+	by the attribute *identifier*. Matching against patterns with '\*'
+	(wildcard) and '?' (joker) is supported. Pattern matching is
+	case-insensitive.
+
+	*identifier* relates to app_id for native Wayland windows and WM_CLASS
+	for XWayland clients.
+
+*Properties*
+
+Property values can be *yes*, *no* or *default*.
+
+If a window matches criteria for multiple rules which set the same property,
+later config entries have higher priority. *default* can be useful in this
+situation.
+
+*<windowRules><windowRule serverDecoration="">* [yes|no|default]
+	*serverDecoration* over-rules any other setting for server-side window
+	decoration on first map.
+
 ## ENVIRONMENT VARIABLES
 
 *XCURSOR_THEME* and *XCURSOR_SIZE* are supported to set cursor theme

docs/rc.xml.all

@@ -374,4 +374,13 @@
     </device>
   </libinput>
 
+  <!--
+  <windowRules>
+    <windowRule identifier="*">
+      <action name="Maximize" />
+    </windowRule>
+    <windowRule identifier="some-application" serverDecoration="yes" />
+  </windowRules>
+  -->
+
 </labwc_config>

include/config/rcxml.h

@@ -80,6 +80,8 @@ struct rcxml {
 		bool outlines;
 		struct wl_list fields;  /* struct window_switcher_field.link */
 	} window_switcher;
+
+	struct wl_list window_rules; /* struct window_rule.link */
 };
 
 extern struct rcxml rc;

include/window-rules.h

@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __WINDOW_RULES_H
+#define __WINDOW_RULES_H
+
+enum window_rule_event {
+	LAB_WINDOW_RULE_EVENT_ON_FIRST_MAP = 0,
+};
+
+enum property {
+	LAB_PROP_UNSPECIFIED = 0,
+	LAB_PROP_UNSET,
+	LAB_PROP_FALSE,
+	LAB_PROP_TRUE,
+};
+
+/*
+ * 'identifier' represents:
+ *   - 'app_id' for native Wayland windows
+ *   - 'WM_CLASS' for XWayland clients
+ */
+struct window_rule {
+	char *identifier;
+
+	enum window_rule_event event;
+	struct wl_list actions;
+
+	enum property server_decoration;
+
+	struct wl_list link; /* struct rcxml.window_rules */
+};
+
+struct view;
+
+void window_rules_apply(struct view *view, enum window_rule_event event);
+enum property window_rules_get_property(struct view *view, const char *property);
+
+#endif /* __WINDOW_RULES_H */

src/common/match.c

@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #define _POSIX_C_SOURCE 200809L
-#include <glib.h>
 #include <stdbool.h>
 #include "common/match.h"
 

src/config/rcxml.c

@@ -25,6 +25,7 @@
 #include "config/mousebind.h"
 #include "config/rcxml.h"
 #include "regions.h"
+#include "window-rules.h"
 #include "workspaces.h"
 
 static bool in_regions;
@@ -32,6 +33,7 @@ static bool in_keybind;
 static bool in_mousebind;
 static bool in_libinput_category;
 static bool in_window_switcher_field;
+static bool in_window_rules;
 
 static struct keybind *current_keybind;
 static struct mousebind *current_mousebind;
@@ -41,6 +43,8 @@ static struct action *current_keybind_action;
 static struct action *current_mousebind_action;
 static struct region *current_region;
 static struct window_switcher_field *current_field;
+static struct window_rule *current_window_rule;
+static struct action *current_window_rule_action;
 
 enum font_place {
 	FONT_PLACE_NONE = 0,
@@ -54,6 +58,63 @@ enum font_place {
 static void load_default_key_bindings(void);
 static void load_default_mouse_bindings(void);
 
+/* Does a boolean-parse but also allows 'default' */
+static void
+set_property(const char *str, enum property *variable)
+{
+	if (!str || !strcasecmp(str, "default")) {
+		*variable = LAB_PROP_UNSET;
+		return;
+	}
+	int ret = parse_bool(str, -1);
+	if (ret < 0) {
+		return;
+	}
+	*variable = ret ? LAB_PROP_TRUE : LAB_PROP_FALSE;
+}
+
+static void
+fill_window_rule(char *nodename, char *content)
+{
+	if (!strcasecmp(nodename, "windowRule.windowRules")) {
+		current_window_rule = znew(*current_window_rule);
+		wl_list_append(&rc.window_rules, &current_window_rule->link);
+		wl_list_init(&current_window_rule->actions);
+		return;
+	}
+
+	string_truncate_at_pattern(nodename, ".windowrule.windowrules");
+	if (!content) {
+		/* nop */
+	} else if (!current_window_rule) {
+		wlr_log(WLR_ERROR, "no window-rule");
+	} else if (!strcmp(nodename, "identifier")) {
+		free(current_window_rule->identifier);
+		current_window_rule->identifier = xstrdup(content);
+	} else if (!strcmp(nodename, "event")) {
+		/*
+		 * This is just in readiness for adding any other types of
+		 * events in the future. We default to onFirstMap anyway.
+		 */
+		if (!strcasecmp(content, "onFirstMap")) {
+			current_window_rule->event = LAB_WINDOW_RULE_EVENT_ON_FIRST_MAP;
+		}
+	} else if (!strcasecmp(nodename, "serverDecoration")) {
+		set_property(content, &current_window_rule->server_decoration);
+	} else if (!strcmp(nodename, "name.action")) {
+		current_window_rule_action = action_create(content);
+		if (current_window_rule_action) {
+			wl_list_append(&current_window_rule->actions,
+				&current_window_rule_action->link);
+		}
+	} else if (!current_window_rule_action) {
+		wlr_log(WLR_ERROR, "expect <action name=\"\"> element first. "
+			"nodename: '%s' content: '%s'", nodename, content);
+	} else {
+		action_arg_from_xml_node(current_window_rule_action, nodename, content);
+	}
+}
+
 static void
 fill_window_switcher_field(char *nodename, char *content)
 {
@@ -417,6 +478,10 @@ entry(xmlNode *node, char *nodename, char *content)
 		fill_window_switcher_field(nodename, content);
 		return;
 	}
+	if (in_window_rules) {
+		fill_window_rule(nodename, content);
+		return;
+	}
 
 	/* handle nodes without content, e.g. <keyboard><default /> */
 	if (!strcmp(nodename, "default.keyboard")) {
@@ -600,6 +665,12 @@ xml_tree_walk(xmlNode *node)
 			in_window_switcher_field = false;
 			continue;
 		}
+		if (!strcasecmp((char *)n->name, "windowRules")) {
+			in_window_rules = true;
+			traverse(n);
+			in_window_rules = false;
+			continue;
+		}
 		traverse(n);
 	}
 }
@@ -638,6 +709,7 @@ rcxml_init(void)
 		wl_list_init(&rc.workspace_config.workspaces);
 		wl_list_init(&rc.regions);
 		wl_list_init(&rc.window_switcher.fields);
+		wl_list_init(&rc.window_rules);
 	}
 	has_run = true;
 
@@ -1059,6 +1131,14 @@ rcxml_finish(void)
 		zfree(field);
 	}
 
+	struct window_rule *rule, *rule_tmp;
+	wl_list_for_each_safe(rule, rule_tmp, &rc.window_rules, link) {
+		wl_list_remove(&rule->link);
+		zfree(rule->identifier);
+		action_list_free(&rule->actions);
+		zfree(rule);
+	}
+
 	/* Reset state vars for starting fresh when Reload is triggered */
 	current_keybind = NULL;
 	current_mousebind = NULL;
@@ -1068,4 +1148,6 @@ rcxml_finish(void)
 	current_mousebind_action = NULL;
 	current_region = NULL;
 	current_field = NULL;
+	current_window_rule = NULL;
+	current_window_rule_action = NULL;
 }

src/meson.build

@@ -23,6 +23,7 @@ labwc_sources = files(
   'theme.c',
   'view.c',
   'view-impl-common.c',
+  'window-rules.c',
   'workspaces.c',
   'xdg.c',
   'xdg-popup.c',

src/view-impl-common.c

@@ -6,6 +6,7 @@
 #include "labwc.h"
 #include "view.h"
 #include "view-impl-common.h"
+#include "window-rules.h"
 
 void
 view_impl_move_to_front(struct view *view)
@@ -26,6 +27,9 @@ view_impl_move_to_back(struct view *view)
 void
 view_impl_map(struct view *view)
 {
+	if (!view->been_mapped) {
+		window_rules_apply(view, LAB_WINDOW_RULE_EVENT_ON_FIRST_MAP);
+	}
 	desktop_focus_and_activate_view(&view->server->seat, view);
 	view_move_to_front(view);
 	view_update_title(view);

src/view.c

@@ -9,6 +9,7 @@
 #include "regions.h"
 #include "ssd.h"
 #include "view.h"
+#include "window-rules.h"
 #include "workspaces.h"
 #include "xwayland.h"
 
@@ -658,6 +659,7 @@ void
 view_set_decorations(struct view *view, bool decorations)
 {
 	assert(view);
+
 	if (view->ssd_enabled != decorations && !view->fullscreen) {
 		/*
 		 * Set view->ssd_enabled first since it is referenced

src/window-rules.c

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _POSIX_C_SOURCE 200809L
+#include "config.h"
+#include <assert.h>
+#include <cairo.h>
+#include <glib.h>
+#include <strings.h>
+#include <wlr/util/log.h>
+#include "action.h"
+#include "common/match.h"
+#include "config/rcxml.h"
+#include "labwc.h"
+#include "view.h"
+#include "window-rules.h"
+
+void
+window_rules_apply(struct view *view, enum window_rule_event event)
+{
+	const char *identifier = view_get_string_prop(view, "app_id");
+	if (!identifier) {
+		return;
+	}
+
+	struct window_rule *rule;
+	wl_list_for_each(rule, &rc.window_rules, link) {
+		if (!rule->identifier || rule->event != event) {
+			continue;
+		}
+		if (match_glob(rule->identifier, identifier)) {
+			actions_run(view, view->server, &rule->actions, 0);
+		}
+	}
+}
+
+enum property
+window_rules_get_property(struct view *view, const char *property)
+{
+	assert(property);
+
+	const char *identifier = view_get_string_prop(view, "app_id");
+	if (!identifier) {
+		goto out;
+	}
+
+	/*
+	 * We iterate in reverse here because later items in list have higher
+	 * priority. For example, in the config below we want the return value
+	 * for foot's "serverDecoration" property to be "default".
+	 *
+	 *     <windowRules>
+	 *       <windowRule identifier="*" serverDecoration="no"/>
+	 *       <windowRule identifier="foot" serverDecoration="default"/>
+	 *     </windowRules>
+	 */
+	struct window_rule *rule;
+	wl_list_for_each_reverse(rule, &rc.window_rules, link) {
+		if (!rule->identifier) {
+			continue;
+		}
+		/*
+		 * Only return if property != LAB_PROP_UNSPECIFIED otherwise a
+		 * <windowRule> which does not set a particular property
+		 * attribute would still return here if that property was asked
+		 * for.
+		 */
+		if (match_glob(rule->identifier, identifier)) {
+			if (!strcasecmp(property, "serverDecoration")) {
+				if (rule->server_decoration) {
+					return rule->server_decoration;
+				}
+			}
+		}
+	}
+out:
+	return LAB_PROP_UNSPECIFIED;
+}

src/xdg.c

@@ -6,6 +6,7 @@
 #include "node.h"
 #include "view.h"
 #include "view-impl-common.h"
+#include "window-rules.h"
 #include "workspaces.h"
 
 #define CONFIGURE_TIMEOUT_MS 100
@@ -49,6 +50,16 @@ handle_new_xdg_popup(struct wl_listener *listener, void *data)
 static bool
 has_ssd(struct view *view)
 {
+	/* Window-rules take priority if they exist for this view */
+	switch (window_rules_get_property(view, "serverDecoration")) {
+	case LAB_PROP_TRUE:
+		return true;
+	case LAB_PROP_FALSE:
+		return false;
+	default:
+		break;
+	}
+
 	/*
 	 * view->ssd_preference may be set by the decoration implementation
 	 * e.g. src/decorations/xdg-deco.c or src/decorations/kde-deco.c.
@@ -425,13 +436,13 @@ xdg_toplevel_view_map(struct view *view)
 		view->current.y = view->pending.y;
 
 		view_moved(view);
-		view->been_mapped = true;
 	}
 
 	view->commit.notify = handle_commit;
 	wl_signal_add(&xdg_surface->surface->events.commit, &view->commit);
 
 	view_impl_map(view);
+	view->been_mapped = true;
 }
 
 static void

src/xwayland.c

@@ -9,6 +9,7 @@
 #include "ssd.h"
 #include "view.h"
 #include "view-impl-common.h"
+#include "window-rules.h"
 #include "workspaces.h"
 #include "xwayland.h"
 
@@ -103,6 +104,18 @@ ensure_initial_geometry_and_output(struct view *view)
 static bool
 want_deco(struct wlr_xwayland_surface *xwayland_surface)
 {
+	struct view *view = (struct view *)xwayland_surface->data;
+
+	/* Window-rules take priority if they exist for this view */
+	switch (window_rules_get_property(view, "serverDecoration")) {
+	case LAB_PROP_TRUE:
+		return true;
+	case LAB_PROP_FALSE:
+		return false;
+	default:
+		break;
+	}
+
 	return xwayland_surface->decorations ==
 		WLR_XWAYLAND_SURFACE_DECORATIONS_ALL;
 }
@@ -464,7 +477,6 @@ xwayland_view_map(struct view *view)
 		 */
 		view->current = view->pending;
 		view_moved(view);
-		view->been_mapped = true;
 	}
 
 	if (view->ssd_enabled && view_is_floating(view)) {
@@ -476,6 +488,7 @@ xwayland_view_map(struct view *view)
 	view->commit.notify = handle_commit;
 
 	view_impl_map(view);
+	view->been_mapped = true;
 }
 
 static void