Theme improvements (#1382)

* Improve GTK+3 theme loading

- Merge geany-3.0.css into geany.css
- Load geany-3.20.css to override if runtime version dictates
- Load geany.css from app->configdir if it exists.

* Add initial documentation for GTK+ CSS theming

* Add geany.css file to the `Tools->Configuration Files` menu

Also mark such config files as changed if they don't already exist to
force the user to save or discard any newly created config files.

* Allow customizing message window using GTK+ themes

* Improve GTK+3 CSS docs a bit

State which classes are meant to be overridden by themes.

* Go back to conditionally loading geany-3.0.css

It can't be merged into geany.css since GTK+ CSS parser doesn't ignore
invalid properties when prefixed with vendor extension (ie. -Gtk).

* Don't mark unedited config files as changed

They probably should be marked as changed since they don't exist on
disk yet, but for the time being leave it how it was.

* Fix misuse of CSS ID vs class in manual

* Minor colour value tweaks

Based on feedback from @b4n

data/geany-3.0.css

@@ -1,5 +1,3 @@
-@import "geany.css";
-
 /* make close button on the editor's tabs smaller */
 #geany-close-tab-button {
 	-GtkWidget-focus-padding: 0;

data/geany-3.20.css

@@ -1,5 +1,3 @@
-@import "geany.css";
-
 /* make close button on the editor's tabs smaller */
 #geany-close-tab-button {
 	outline-offset: 0;

data/geany.css

@@ -36,6 +36,17 @@
 	color: #007f00;
 }
 
+/* compiler message colors */
+#geany-compiler-error {
+    color: #ff0000;
+}
+#geany-compiler-context {
+    color: #7f0000;
+}
+#geany-compiler-message {
+    color: #0000D0;
+}
+
 /* red "Terminal" label when terminal dirty */
 #geany-terminal-dirty {
 	color: #ff0000;

data/geany.gtkrc

@@ -50,5 +50,22 @@ widget "*.geany-document-status-changed" style "geany-document-status-changed-st
 widget "*.geany-document-status-disk-changed" style "geany-document-status-disk-changed-style"
 widget "*.geany-document-status-readonly" style "geany-document-status-readonly-style"
 
+# compiler message colors
+style "geany-compiler-error-style" {
+    fg[NORMAL] = "#ffff00000000"
+    fg[ACTIVE] = "#ffff00000000"
+}
+style "geany-compiler-context-style" {
+    fg[NORMAL] = "#7f7f00000000"
+    fg[ACTIVE] = "#7f7f00000000"
+}
+style "geany-compiler-message-style" {
+    fg[NORMAL] = "#00000000D000"
+    fg[ACTIVE] = "#00000000D000"
+}
+widget "*.geany-compiler-error" style "geany-compiler-error-style"
+widget "*.geany-compiler-context" style "geany-compiler-context-style"
+widget "*.geany-compiler-message" style "geany-compiler-message-style"
+
 # red "Terminal" label when terminal dirty
 widget "*.geany-terminal-dirty" style "geany-document-status-changed-style"

doc/geany.txt

@@ -494,6 +494,27 @@ An example of a simple ``.gtkrc-2.0``::
     widget "GeanyPrefsDialog" style "geanyStyle"
 
 
+Customizing Geany's appearance using GTK+ 3 CSS
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+To override GTK+ CSS styles, you can use traditional mechanisms or you
+can create a file named ``geany.css`` in the user configuration directory
+(usually ``~/.config/geany``) which will be loaded after other CSS styles
+are applied to allow overriding the default styles.
+
+Geany offers a number of CSS IDs which can be used to taylor its
+appearence. Among the more interesting include:
+
+* ``geany-compiler-context`` - the style used for build command output surrounding errors
+* ``geany-compiler-error`` - the style used for build command errors
+* ``geany-compiler-message`` - the style other output encountered while running build command
+* ``geany-document-status-changed`` - the style for document tab labels when the document is changed
+* ``geany-document-status-disk-changed`` - the style for document tab labels when the file on disk has changed
+* ``geany-document-status-readyonly``` - the style for document tab labels when the document is read-only
+* ``geany-search-entry-no-match`` - the style of find/replace diaog entries when no match is found
+* ``geany-terminal-dirty`` - the style for the message window Terminal tab label when the terminal output has changed.
+
+
 Documents
 ---------
 

src/msgwindow.c

@@ -83,6 +83,11 @@ enum
 };
 
 
+static GdkColor color_error = {0, 0xFFFF, 0, 0};
+static GdkColor color_context = {0, 0x7FFF, 0, 0};
+static GdkColor color_message = {0, 0, 0, 0xD000};
+
+
 static void prepare_msg_tree_view(void);
 static void prepare_status_tree_view(void);
 static void prepare_compiler_tree_view(void);
@@ -112,6 +117,40 @@ void msgwin_set_messages_dir(const gchar *messages_dir)
 }
 
 
+GdkColor load_color(gchar *color_name) {
+	GdkColor color;
+
+#if GTK_CHECK_VERSION(3, 0, 0)
+	GdkRGBA rgba_color;
+	GtkWidgetPath *path = gtk_widget_path_new();
+	GtkStyleContext *ctx = gtk_style_context_new();
+
+	gtk_widget_path_append_type(path, GTK_TYPE_WINDOW);
+	gtk_widget_path_iter_set_name(path, -1, color_name);
+	gtk_style_context_set_screen(ctx, gdk_screen_get_default());
+	gtk_style_context_set_path(ctx, path);
+	gtk_style_context_get_color(ctx, gtk_style_context_get_state(ctx), &rgba_color);
+
+	color.red   = 0xffff * rgba_color.red;
+	color.green = 0xffff * rgba_color.green;
+	color.blue  = 0xffff * rgba_color.blue;
+
+	gtk_widget_path_unref(path);
+	g_object_unref(ctx);
+#else
+	gchar *path = g_strconcat("*.", color_name, NULL);
+
+	GtkSettings *settings = gtk_settings_get_default();
+	GtkStyle *style = gtk_rc_get_style_by_paths(settings, path, NULL, GTK_TYPE_WIDGET);
+	color = style->fg[GTK_STATE_NORMAL];
+
+	g_free(path);
+#endif
+
+	return color;
+}
+
+
 void msgwin_init(void)
 {
 	msgwindow.notebook = ui_lookup_widget(main_widgets.window, "notebook_info");
@@ -130,6 +169,10 @@ void msgwin_init(void)
 
 	ui_widget_modify_font_from_string(msgwindow.scribble, interface_prefs.msgwin_font);
 	g_signal_connect(msgwindow.scribble, "populate-popup", G_CALLBACK(on_scribble_populate), NULL);
+
+	color_error = load_color("geany-compiler-error");
+	color_context = load_color("geany-compiler-context");
+	color_message = load_color("geany-compiler-message");
 }
 
 
@@ -262,19 +305,13 @@ static void prepare_compiler_tree_view(void)
 	/*g_signal_connect(selection, "changed", G_CALLBACK(on_msg_tree_selection_changed), NULL);*/
 }
 
-
-static const GdkColor color_error = {0, 65535, 0, 0};
-
 static const GdkColor *get_color(gint msg_color)
 {
-	static const GdkColor dark_red = {0, 65535 / 2, 0, 0};
-	static const GdkColor blue = {0, 0, 0, 0xD000};	/* not too bright ;-) */
-
 	switch (msg_color)
 	{
 		case COLOR_RED: return &color_error;
-		case COLOR_DARK_RED: return &dark_red;
-		case COLOR_BLUE: return &blue;
+		case COLOR_DARK_RED: return &color_context;
+		case COLOR_BLUE: return &color_message;
 		default: return NULL;
 	}
 }

src/ui_utils.c

@@ -2492,53 +2492,85 @@ void ui_init_builder(void)
 }
 
 
-static void init_custom_style(void)
-{
 #if GTK_CHECK_VERSION(3, 0, 0)
-	const struct {
-		guint version;
-		const gchar *file;
-	} css_files[] = {
-		/*
-		 * Keep these from newest to oldest,
-		 * and make sure 0 remains last
-		 */
-		{ 20, "geany-3.20.css" },
-		{ 0, "geany-3.0.css" },
-	};
-	guint gtk_version = gtk_get_minor_version();
-	gsize i = 0;
-	gchar *css_file;
-	GtkCssProvider *css = gtk_css_provider_new();
+static void load_css_theme(const gchar *fn, guint priority)
+{
+	GtkCssProvider *provider = gtk_css_provider_new();
 	GError *error = NULL;
 
-	/* gtk_version will never be smaller than 0 */
-	while (css_files[i].version > gtk_version)
-		++i;
-
-	css_file = g_build_filename(app->datadir, css_files[i].file, NULL);
-	if (! gtk_css_provider_load_from_path(css, css_file, &error))
+	if (! gtk_css_provider_load_from_path(provider, fn, &error))
 	{
 		g_warning("Failed to load custom CSS: %s", error->message);
 		g_error_free(error);
-	}
-	else
-	{
-		gtk_style_context_add_provider_for_screen(gdk_screen_get_default(),
-			GTK_STYLE_PROVIDER(css), GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+		return;
 	}
 
-	g_object_unref(css);
-	g_free(css_file);
-#else
-	/* see setup_gtk2_styles() in main.c */
-#endif
+	gtk_style_context_add_provider_for_screen(gdk_screen_get_default(),
+		GTK_STYLE_PROVIDER(provider), priority);
+	geany_debug("Loaded GTK+ CSS theme '%s'", fn);
+
+	g_object_unref(provider);
 }
 
 
+// see setup_gtk2_styles() in libmain.c for GTK+ 2-specific theme initialization
+static void init_css_styles(void)
+{
+	gchar *theme_fn;
+
+	// load the main geany.css file from system data dir
+	theme_fn = g_build_filename(app->datadir, "geany.css", NULL);
+	load_css_theme(theme_fn, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+	g_free(theme_fn);
+
+	// load themes to handle breakage between various GTK+ versions
+	const struct
+	{
+		guint min_version;
+		guint max_version;
+		const gchar *file;
+	}
+	css_files[] =
+	{
+		{ 20, G_MAXUINT, "geany-3.20.css" },
+		{ 0, 19, "geany-3.0.css" },
+	};
+
+	guint gtk_version = gtk_get_minor_version();
+	for (guint i = 0; i < G_N_ELEMENTS(css_files); i++)
+	{
+		if (gtk_version >= css_files[i].min_version &&
+			gtk_version <= css_files[i].max_version)
+		{
+			theme_fn = g_build_filename(app->datadir, css_files[i].file, NULL);
+			load_css_theme(theme_fn, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+			g_free(theme_fn);
+		}
+	}
+
+	// if the user provided a geany.css file in their config dir, try and load that
+	theme_fn = g_build_filename(app->configdir, "geany.css", NULL);
+	if (g_file_test(theme_fn, G_FILE_TEST_EXISTS))
+		load_css_theme(theme_fn, GTK_STYLE_PROVIDER_PRIORITY_USER);
+	g_free(theme_fn);
+}
+
+
+static void add_css_config_file_item(void)
+{
+	gchar *theme_fn;
+	theme_fn = g_build_filename(app->configdir, "geany.css", NULL);
+	ui_add_config_file_menu_item(theme_fn, NULL, NULL);
+	g_free(theme_fn);
+}
+#endif // GTK3
+
+
 void ui_init(void)
 {
-	init_custom_style();
+#if GTK_CHECK_VERSION(3, 0, 0)
+	init_css_styles();
+#endif
 
 	init_recent_files();
 
@@ -2585,7 +2617,11 @@ void ui_init(void)
 
 	ui_init_toolbar_widgets();
 	init_document_widgets();
+
 	create_config_files_menu();
+#if GTK_CHECK_VERSION(3, 0, 0)
+	add_css_config_file_item();
+#endif
 }