I#1898 - Better handle Dark Style GNOME 42 setting

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/1898

src/e-util/CMakeLists.txt

@@ -100,6 +100,7 @@ set(SOURCES
 	e-collection-account-wizard.c
 	e-color-chooser-widget.c
 	e-color-combo.c
+	e-color-scheme-watcher.c
 	e-config.c
 	e-config-lookup.c
 	e-config-lookup-result.c
@@ -381,6 +382,7 @@ set(HEADERS
 	e-collection-account-wizard.h
 	e-color-chooser-widget.h
 	e-color-combo.h
+	e-color-scheme-watcher.h
 	e-config.h
 	e-config-lookup.h
 	e-config-lookup-result.h

src/e-util/e-color-scheme-watcher.c

@@ -0,0 +1,490 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+/*
+ * SPDX-FileCopyrightText: (C) 2022 Red Hat (www.redhat.com)
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include "evolution-config.h"
+
+/* This is partly based on:
+ * https://gitlab.gnome.org/GNOME/Initiatives/-/wikis/Dark-Style-Preference
+ * and partly on the libhandy code.
+ */
+
+#include <gio/gio.h>
+#include <gtk/gtk.h>
+
+#include "e-color-scheme-watcher.h"
+
+typedef enum {
+	E_COLOR_SCHEME_UNKNOWN = -1,
+	E_COLOR_SCHEME_DEFAULT = 0,
+	E_COLOR_SCHEME_PREFER_DARK,
+	E_COLOR_SCHEME_PREFER_LIGHT
+} EColorScheme;
+
+struct _EColorSchemeWatcher
+{
+	GObject parent_instance;
+
+	GCancellable *cancellable;
+	GDBusProxy *settings_portal;
+	gchar *last_theme_name;
+	EColorScheme color_scheme;
+	gboolean use_fdo_setting;
+};
+
+G_DEFINE_TYPE (EColorSchemeWatcher, e_color_scheme_watcher, G_TYPE_OBJECT);
+
+#if (GTK_MINOR_VERSION % 2)
+#define MINOR (GTK_MINOR_VERSION + 1)
+#else
+#define MINOR GTK_MINOR_VERSION
+#endif
+
+static gboolean
+e_color_scheme_watcher_theme_dir_exists (const gchar *dir,
+					 const gchar *subdir,
+					 const gchar *name,
+					 const gchar *variant)
+{
+	gchar *file;
+	gchar *base;
+	gboolean exists = FALSE;
+	gint ii;
+
+	if (variant)
+		file = g_strconcat ("gtk-", variant, ".css", NULL);
+	else
+		file = g_strdup ("gtk.css");
+
+	if (subdir)
+		base = g_build_filename (dir, subdir, name, NULL);
+	else
+		base = g_build_filename (dir, name, NULL);
+
+	for (ii = MINOR; ii >= 0 && !exists; ii = ii - 2) {
+		gchar *subsubdir = NULL;
+		gchar *path = NULL;
+
+		if (ii < 14)
+			ii = 0;
+
+		subsubdir = g_strdup_printf ("gtk-3.%d", ii);
+		path = g_build_filename (base, subsubdir, file, NULL);
+
+		exists = g_file_test (path, G_FILE_TEST_EXISTS);
+
+		g_clear_pointer (&path, g_free);
+		g_clear_pointer (&subsubdir, g_free);
+	}
+
+	g_clear_pointer (&file, g_free);
+	g_clear_pointer (&base, g_free);
+
+	return exists;
+}
+
+#undef MINOR
+
+static gboolean
+e_color_scheme_watcher_theme_exists (const gchar *name,
+				     const gchar *variant)
+{
+	gchar *dir = NULL;
+	const gchar *const *dirs;
+	const gchar *var;
+	gint ii;
+
+	/* First look in the user's data directory */
+	if (e_color_scheme_watcher_theme_dir_exists (g_get_user_data_dir (), "themes", name, variant))
+		return TRUE;
+
+	/* Next look in the user's home directory */
+	if (e_color_scheme_watcher_theme_dir_exists (g_get_home_dir (), ".themes", name, variant))
+		return TRUE;
+
+	/* Look in system data directories */
+	dirs = g_get_system_data_dirs ();
+	for (ii = 0; dirs[ii]; ii++) {
+		if (e_color_scheme_watcher_theme_dir_exists (dirs[ii], "themes", name, variant))
+			return TRUE;
+	}
+
+	/* Finally, try in the default theme directory */
+
+	var = g_getenv ("GTK_DATA_PREFIX");
+	if (var)
+		dir = g_build_filename (var, "share", "themes", NULL);
+	else
+		dir = g_build_filename (EVOLUTION_DATADIR, "themes", NULL);
+
+	if (e_color_scheme_watcher_theme_dir_exists (dir, NULL, name, variant)) {
+		g_free (dir);
+		return TRUE;
+	}
+
+	g_free (dir);
+
+	return FALSE;
+}
+
+static gboolean
+e_color_scheme_watcher_check_theme_exists (const gchar *name,
+					   const gchar *variant)
+{
+	gchar *resource_path = NULL;
+
+	/* try loading the resource for the theme. This is mostly meant for built-in themes. */
+	if (variant)
+		resource_path = g_strdup_printf ("/org/gtk/libgtk/theme/%s/gtk-%s.css", name, variant);
+	else
+		resource_path = g_strdup_printf ("/org/gtk/libgtk/theme/%s/gtk.css", name);
+
+	if (g_resources_get_info (resource_path, 0, NULL, NULL, NULL)) {
+		g_free (resource_path);
+		return TRUE;
+	}
+
+	g_free (resource_path);
+
+	return e_color_scheme_watcher_theme_exists (name, variant);
+}
+
+static void
+e_color_scheme_watcher_sync_theme (EColorSchemeWatcher *self)
+{
+	GtkSettings *gtk_settings = gtk_settings_get_default ();
+	gchar *theme_name = NULL;
+
+	g_object_get (gtk_settings,
+		"gtk-theme-name", &theme_name,
+		NULL);
+
+	if (theme_name) {
+		gboolean update_theme = FALSE;
+
+		if (self->color_scheme == E_COLOR_SCHEME_PREFER_DARK) {
+			g_object_set (gtk_settings,
+				"gtk-application-prefer-dark-theme", TRUE,
+				NULL);
+
+			if (g_strcmp0 (theme_name, "HighContrast") == 0) {
+				g_object_set (gtk_settings,
+					"gtk-theme-name", "HighContrastInverse",
+					NULL);
+			} else if (g_strcmp0 (theme_name, "Breeze") == 0) {
+				g_object_set (gtk_settings,
+					"gtk-theme-name", "Breeze-Dark",
+					NULL);
+			} else {
+				update_theme = g_strcmp0 (theme_name, "HighContrastInverse") != 0 &&
+					       g_strcmp0 (theme_name, "Breeze-Dark") != 0;
+			}
+		} else if (self->color_scheme == E_COLOR_SCHEME_PREFER_LIGHT) {
+			g_object_set (gtk_settings,
+				"gtk-application-prefer-dark-theme", FALSE,
+				NULL);
+
+			if (g_strcmp0 (theme_name, "HighContrastInverse") == 0) {
+				g_object_set (gtk_settings,
+					"gtk-theme-name", "HighContrast",
+					NULL);
+			} else if (g_strcmp0 (theme_name, "Breeze-Dark") == 0) {
+				g_object_set (gtk_settings,
+					"gtk-theme-name", "Breeze",
+					NULL);
+			} else {
+				update_theme = g_strcmp0 (theme_name, "HighContrast") != 0 &&
+					       g_strcmp0 (theme_name, "Breeze") != 0;
+			}
+		} else {
+			gtk_settings_reset_property (gtk_settings, "gtk-theme-name");
+			gtk_settings_reset_property (gtk_settings, "gtk-application-prefer-dark-theme");
+		}
+
+		if (update_theme) {
+			gchar *new_theme_name = NULL;
+			gboolean suffix_cut = FALSE;
+
+			if (g_str_has_suffix (theme_name, "-dark")) {
+				theme_name[strlen (theme_name) - 5] = '\0';
+				suffix_cut = TRUE;
+			}
+
+			if (self->color_scheme == E_COLOR_SCHEME_PREFER_DARK &&
+			    e_color_scheme_watcher_check_theme_exists (theme_name, "dark")) {
+				new_theme_name = g_strconcat (theme_name, "-dark", NULL);
+			} else if (suffix_cut && e_color_scheme_watcher_check_theme_exists (theme_name, NULL)) {
+				new_theme_name = theme_name;
+				theme_name = NULL;
+			}
+
+			if (new_theme_name) {
+				g_object_set (gtk_settings,
+					"gtk-theme-name", new_theme_name,
+					NULL);
+			}
+
+			g_free (new_theme_name);
+		}
+
+		g_free (theme_name);
+	}
+}
+
+static void
+e_color_scheme_watcher_set_color_scheme (EColorSchemeWatcher *self,
+					 EColorScheme color_scheme)
+{
+	if (color_scheme > E_COLOR_SCHEME_PREFER_LIGHT || color_scheme == E_COLOR_SCHEME_UNKNOWN)
+		color_scheme = E_COLOR_SCHEME_DEFAULT;
+
+	if (color_scheme != self->color_scheme) {
+		self->color_scheme = color_scheme;
+
+		e_color_scheme_watcher_sync_theme (self);
+	}
+}
+
+static EColorScheme
+e_color_scheme_watcher_read_dgo (GVariant *value)
+{
+	const gchar *str;
+
+	if (!value || !g_variant_is_of_type (value, G_VARIANT_TYPE_STRING))
+		return E_COLOR_SCHEME_UNKNOWN;
+
+	str = g_variant_get_string (value, NULL);
+
+	if (!g_strcmp0 (str, "default"))
+		return E_COLOR_SCHEME_DEFAULT;
+
+	if (!g_strcmp0 (str, "prefer-dark"))
+		return E_COLOR_SCHEME_PREFER_DARK;
+
+	if (!g_strcmp0 (str, "prefer-light"))
+		return E_COLOR_SCHEME_PREFER_LIGHT;
+
+	g_debug ("Invalid/unknown GNOME color scheme: '%s'", str);
+
+	return E_COLOR_SCHEME_UNKNOWN;
+}
+
+static void
+e_color_scheme_watcher_settings_portal_changed_cb (GDBusProxy *proxy,
+						   const gchar *sender_name,
+						   const gchar *signal_name,
+						   GVariant *parameters,
+						   EColorSchemeWatcher *self)
+{
+	const gchar *namespc;
+	const gchar *name;
+	GVariant *value = NULL;
+
+	if (g_strcmp0 (signal_name, "SettingChanged"))
+		return;
+
+	g_variant_get (parameters, "(&s&sv)", &namespc, &name, &value);
+
+	if (self->use_fdo_setting &&
+	    g_strcmp0 (namespc, "org.freedesktop.appearance") == 0 &&
+	    g_strcmp0 (name, "color-scheme") == 0) {
+		e_color_scheme_watcher_set_color_scheme (self, g_variant_get_uint32 (value));
+	} else if (g_strcmp0 (namespc, "org.gnome.desktop.interface") == 0) {
+		if (g_strcmp0 (name, "gtk-theme") == 0) {
+			const gchar *theme_name = g_variant_get_string (value, NULL);
+			if (g_strcmp0 (theme_name, self->last_theme_name) != 0) {
+				GtkSettings *gtk_settings = gtk_settings_get_default ();
+
+				g_clear_pointer (&self->last_theme_name, g_free);
+				self->last_theme_name = g_strdup (theme_name);
+
+				gtk_settings_reset_property (gtk_settings, "gtk-theme-name");
+				gtk_settings_reset_property (gtk_settings, "gtk-application-prefer-dark-theme");
+				e_color_scheme_watcher_sync_theme (self);
+			}
+		} else if (!self->use_fdo_setting && g_strcmp0 (name, "color-scheme") == 0) {
+			EColorScheme color_scheme = e_color_scheme_watcher_read_dgo (value);
+
+			if (color_scheme != E_COLOR_SCHEME_UNKNOWN)
+				e_color_scheme_watcher_set_color_scheme (self, color_scheme);
+		}
+	}
+
+	g_clear_pointer (&value, g_variant_unref);
+}
+
+static void
+e_color_scheme_watcher_read_dgo_cb (GObject *source_object,
+				    GAsyncResult *async_result,
+				    gpointer user_data)
+{
+	EColorSchemeWatcher *self = user_data;
+	GVariant *result;
+	GVariant *child = NULL;
+	GVariant *value = NULL;
+	GError *error = NULL;
+
+	result = g_dbus_proxy_call_finish (G_DBUS_PROXY (source_object), async_result, &error);
+
+	if (result) {
+		g_variant_get (result, "(v)", &child);
+
+		if (child) {
+			g_variant_get (child, "v", &value);
+
+			if (value) {
+				EColorScheme color_scheme = e_color_scheme_watcher_read_dgo (value);
+
+				if (color_scheme != E_COLOR_SCHEME_UNKNOWN) {
+					e_color_scheme_watcher_set_color_scheme (self, color_scheme);
+
+					g_signal_connect_object (self->settings_portal, "g-signal",
+						G_CALLBACK (e_color_scheme_watcher_settings_portal_changed_cb), self, 0);
+				}
+			}
+		}
+	} else {
+		g_debug ("Failed to read color scheme from GNOME: %s", error ? error->message : "Unknown error");
+		g_clear_error (&error);
+	}
+
+	g_clear_pointer (&result, g_variant_unref);
+	g_clear_pointer (&child, g_variant_unref);
+	g_clear_pointer (&value, g_variant_unref);
+}
+
+static void
+e_color_scheme_watcher_read_fdo_cb (GObject *source_object,
+				    GAsyncResult *async_result,
+				    gpointer user_data)
+{
+	EColorSchemeWatcher *self = user_data;
+	GVariant *result;
+	GVariant *child = NULL;
+	GVariant *value = NULL;
+	GError *error = NULL;
+
+	result = g_dbus_proxy_call_finish (G_DBUS_PROXY (source_object), async_result, &error);
+
+	if (result) {
+		g_variant_get (result, "(v)", &child);
+
+		if (child) {
+			g_variant_get (child, "v", &value);
+
+			if (value) {
+				EColorScheme color_scheme = g_variant_get_uint32 (value);
+
+				self->use_fdo_setting = TRUE;
+
+				e_color_scheme_watcher_set_color_scheme (self, color_scheme);
+
+				g_signal_connect_object (self->settings_portal, "g-signal",
+					G_CALLBACK (e_color_scheme_watcher_settings_portal_changed_cb), self, 0);
+			}
+		}
+	} else {
+		g_debug ("Failed to read color scheme from freedesktop.org: %s", error ? error->message : "Unknown error");
+		g_clear_error (&error);
+	}
+
+	g_clear_pointer (&result, g_variant_unref);
+	g_clear_pointer (&child, g_variant_unref);
+	g_clear_pointer (&value, g_variant_unref);
+
+	if (!self->use_fdo_setting) {
+		g_dbus_proxy_call (self->settings_portal,
+				   "Read",
+				   g_variant_new ("(ss)",
+						  "org.gnome.desktop.interface",
+						  "color-scheme"),
+				   G_DBUS_CALL_FLAGS_NONE,
+				   5000,
+				   self->cancellable,
+				   e_color_scheme_watcher_read_dgo_cb,
+				   self);
+	}
+}
+
+static void
+e_color_scheme_watcher_got_proxy_cb (GObject *source_object,
+				     GAsyncResult *result,
+				     gpointer user_data)
+{
+	EColorSchemeWatcher *self = user_data;
+	GDBusProxy *proxy;
+	GError *error = NULL;
+
+	proxy = g_dbus_proxy_new_for_bus_finish (result, &error);
+
+	if (!proxy) {
+		g_debug ("Failed to get color scheme proxy: %s\n", error ? error->message : "Unknown error");
+		g_clear_error (&error);
+		return;
+	}
+
+	g_return_if_fail (E_IS_COLOR_SCHEME_WATCHER (self));
+
+	self->settings_portal = proxy;
+
+	g_dbus_proxy_call (self->settings_portal,
+			   "Read",
+			   g_variant_new ("(ss)",
+					  "org.freedesktop.appearance",
+					  "color-scheme"),
+			   G_DBUS_CALL_FLAGS_NONE,
+			   5000,
+			   self->cancellable,
+			   e_color_scheme_watcher_read_fdo_cb,
+			   self);
+}
+
+static void
+e_color_scheme_watcher_dispose (GObject *object)
+{
+	EColorSchemeWatcher *self = E_COLOR_SCHEME_WATCHER (object);
+
+	if (self->cancellable) {
+		g_cancellable_cancel (self->cancellable);
+		g_clear_object (&self->cancellable);
+	}
+
+	g_clear_object (&self->settings_portal);
+	g_clear_pointer (&self->last_theme_name, g_free);
+
+	G_OBJECT_CLASS (e_color_scheme_watcher_parent_class)->dispose (object);
+}
+
+static void
+e_color_scheme_watcher_class_init (EColorSchemeWatcherClass *klass)
+{
+	GObjectClass *object_class;
+
+	object_class = G_OBJECT_CLASS (klass);
+	object_class->dispose = e_color_scheme_watcher_dispose;
+}
+
+static void
+e_color_scheme_watcher_init (EColorSchemeWatcher *self)
+{
+	self->color_scheme = E_COLOR_SCHEME_UNKNOWN;
+	self->cancellable = g_cancellable_new ();
+
+	g_dbus_proxy_new_for_bus (G_BUS_TYPE_SESSION,
+				  G_DBUS_PROXY_FLAGS_NONE,
+				  NULL,
+				  "org.freedesktop.portal.Desktop",
+				  "/org/freedesktop/portal/desktop",
+				  "org.freedesktop.portal.Settings",
+				  self->cancellable,
+				  e_color_scheme_watcher_got_proxy_cb,
+				  self);
+}
+
+EColorSchemeWatcher *
+e_color_scheme_watcher_new (void)
+{
+	return g_object_new (E_TYPE_COLOR_SCHEME_WATCHER, NULL);
+}

src/e-util/e-color-scheme-watcher.h

@@ -0,0 +1,27 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+/*
+ * SPDX-FileCopyrightText: (C) 2022 Red Hat (www.redhat.com)
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#if !defined (__E_UTIL_H_INSIDE__) && !defined (LIBEUTIL_COMPILATION)
+#error "Only <e-util/e-util.h> should be included directly."
+#endif
+
+#ifndef E_COLOR_SCHEME_WATCHER_H
+#define E_COLOR_SCHEME_WATCHER_H
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+#define E_TYPE_COLOR_SCHEME_WATCHER e_color_scheme_watcher_get_type ()
+
+G_DECLARE_FINAL_TYPE (EColorSchemeWatcher, e_color_scheme_watcher, E, COLOR_SCHEME_WATCHER, GObject)
+
+EColorSchemeWatcher *
+		e_color_scheme_watcher_new	(void);
+
+G_END_DECLS
+
+#endif /* E_COLOR_SCHEME_WATCHER_H */

src/e-util/e-util.h

@@ -83,6 +83,7 @@
 #include <e-util/e-collection-account-wizard.h>
 #include <e-util/e-color-chooser-widget.h>
 #include <e-util/e-color-combo.h>
+#include <e-util/e-color-scheme-watcher.h>
 #include <e-util/e-config.h>
 #include <e-util/e-config-lookup.h>
 #include <e-util/e-config-lookup-result.h>

src/shell/e-shell.c

@@ -54,6 +54,7 @@ struct _EShellPrivate {
 	EClientCache *client_cache;
 	GtkWidget *preferences_window;
 	GCancellable *cancellable;
+	EColorSchemeWatcher *color_scheme_watcher;
 
 	/* Shell Backends */
 	GList *loaded_backends;              /* not referenced */
@@ -1655,6 +1656,7 @@ shell_dispose (GObject *object)
 	g_clear_object (&priv->registry);
 	g_clear_object (&priv->credentials_prompter);
 	g_clear_object (&priv->client_cache);
+	g_clear_object (&priv->color_scheme_watcher);
 
 	g_clear_pointer (&priv->preferences_window, gtk_widget_destroy);
 
@@ -2205,6 +2207,7 @@ e_shell_init (EShell *shell)
 	shell->priv->auth_prompt_parents = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 	shell->priv->safe_mode = e_file_lock_exists ();
 	shell->priv->requires_shutdown = FALSE;
+	shell->priv->color_scheme_watcher = e_color_scheme_watcher_new ();
 
 	/* Add our icon directory to the theme's search path
 	 * here instead of in main() so Anjal picks it up. */