Deduplicate code for rendering titlebar texts

The title itself and marks were being rendered by two very-similar yet
different functions, and any changes made to one had to be reflected on
the other.

This mostly prevents such oversights from happening, and keeps makes
sure we keep both consistent.

sway/tree/container.c

@@ -493,20 +493,9 @@ struct sway_output *container_get_effective_output(struct sway_container *con) {
 	return con->outputs->items[con->outputs->length - 1];
 }
 
-static void update_title_texture(struct sway_container *con,
-		struct wlr_texture **texture, struct border_colors *class) {
-	struct sway_output *output = container_get_effective_output(con);
-	if (!output) {
-		return;
-	}
-	if (*texture) {
-		wlr_texture_destroy(*texture);
-		*texture = NULL;
-	}
-	if (!con->formatted_title) {
-		return;
-	}
-
+static void render_titlebar_text_texture(struct sway_output *output,
+		struct sway_container *con, struct wlr_texture **texture,
+		struct border_colors *class, bool pango_markup, char *text) {
 	double scale = output->wlr_output->scale;
 	int width = 0;
 	int height = config->font_height * scale;
@@ -555,8 +544,7 @@ static void update_title_texture(struct sway_container *con,
 			class->text[2], class->text[3]);
 	cairo_move_to(cairo, 0, config->font_baseline * scale - baseline);
 
-	pango_printf(cairo, config->font, scale, config->pango_markup,
-			"%s", con->formatted_title);
+	pango_printf(cairo, config->font, scale, pango_markup, "%s", text);
 
 	cairo_surface_flush(surface);
 	unsigned char *data = cairo_image_surface_get_data(surface);
@@ -570,6 +558,24 @@ static void update_title_texture(struct sway_container *con,
 	cairo_destroy(cairo);
 }
 
+static void update_title_texture(struct sway_container *con,
+		struct wlr_texture **texture, struct border_colors *class) {
+	struct sway_output *output = container_get_effective_output(con);
+	if (!output) {
+		return;
+	}
+	if (*texture) {
+		wlr_texture_destroy(*texture);
+		*texture = NULL;
+	}
+	if (!con->formatted_title) {
+		return;
+	}
+
+	render_titlebar_text_texture(output, con, texture, class,
+		config->pango_markup, con->formatted_title);
+}
+
 void container_update_title_textures(struct sway_container *container) {
 	update_title_texture(container, &container->title_focused,
 			&config->border_colors.focused);
@@ -1615,48 +1621,8 @@ static void update_marks_texture(struct sway_container *con,
 	}
 	free(part);
 
-	double scale = output->wlr_output->scale;
-	int width = 0;
-	int height = config->font_height * scale;
-	int baseline;
-
-	cairo_t *c = cairo_create(NULL);
-	get_text_size(c, config->font, &width, NULL, &baseline, scale, false,
-			"%s", buffer);
-	cairo_destroy(c);
-
-	if (width == 0 || height == 0) {
-		return;
-	}
-
-	if (height > config->font_height) {
-		height = config->font_height;
-	}
-
-	cairo_surface_t *surface = cairo_image_surface_create(
-			CAIRO_FORMAT_ARGB32, width, height);
-	cairo_t *cairo = cairo_create(surface);
-	cairo_set_source_rgba(cairo, class->background[0], class->background[1],
-			class->background[2], class->background[3]);
-	cairo_paint(cairo);
-	PangoContext *pango = pango_cairo_create_context(cairo);
-	cairo_set_antialias(cairo, CAIRO_ANTIALIAS_BEST);
-	cairo_set_source_rgba(cairo, class->text[0], class->text[1],
-			class->text[2], class->text[3]);
-	cairo_move_to(cairo, 0, config->font_baseline * scale - baseline);
-
-	pango_printf(cairo, config->font, scale, false, "%s", buffer);
+	render_titlebar_text_texture(output, con, texture, class, false, buffer);
 
-	cairo_surface_flush(surface);
-	unsigned char *data = cairo_image_surface_get_data(surface);
-	int stride = cairo_image_surface_get_stride(surface);
-	struct wlr_renderer *renderer = wlr_backend_get_renderer(
-			output->wlr_output->backend);
-	*texture = wlr_texture_from_pixels(
-			renderer, DRM_FORMAT_ARGB8888, stride, width, height, data);
-	cairo_surface_destroy(surface);
-	g_object_unref(pango);
-	cairo_destroy(cairo);
 	free(buffer);
 }