scaled-buffer: introduce scaled_font_buffer_update_markup()

This function behaves identically to `scaled_font_buffer_update()`
but allows setting the text as pango markup, supporting further
customization like underscores.

include/common/font.h

@@ -4,6 +4,7 @@
 
 #include <cairo.h>
 #include <pango/pango-font.h>
+#include <stdbool.h>
 
 struct lab_data_buffer;
 
@@ -43,10 +44,11 @@ void font_get_buffer_size(int max_width, const char *text, struct font *font,
  * @font: font description
  * @color: foreground color in rgba format
  * @bg_pattern: background pattern
+ * @use_markup: flag to render pango markup
  */
 void font_buffer_create(struct lab_data_buffer **buffer, int max_width,
 	int height, const char *text, struct font *font, const float *color,
-	cairo_pattern_t *bg_pattern, double scale);
+	cairo_pattern_t *bg_pattern, double scale, bool use_markup);
 
 /**
  * font_finish - free some font related resources

include/scaled-buffer/scaled-font-buffer.h

@@ -15,6 +15,7 @@ struct scaled_font_buffer {
 
 	/* Private */
 	char *text;
+	bool use_markup;
 	int max_width;
 	float color[4];
 	float bg_color[4];
@@ -69,8 +70,18 @@ scaled_font_buffer_create_for_titlebar(struct wlr_scene_tree *parent,
  * bg_color is ignored for font buffers created with
  * scaled_font_buffer_create_for_titlebar().
  */
-void scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
+void scaled_font_buffer_update(struct scaled_font_buffer *self,
-	int max_width, struct font *font, const float *color,
+	const char *text, int max_width, struct font *font, const float *color,
 	const float *bg_color);
 
+/**
+ * Update an existing auto scaling font buffer allowing the use of pango markup.
+ *
+ * Behaves identically to scaled_font_buffer_update(), but allows customization
+ * of the `use_markup` field of the @self struct via @use_markup.
+ */
+void scaled_font_buffer_update_markup(struct scaled_font_buffer *self,
+	const char *text, int max_width, struct font *font, const float *color,
+	const float *bg_color, bool use_markup);
+
 #endif /* LABWC_SCALED_FONT_BUFFER_H */

src/common/font.c

@@ -79,7 +79,7 @@ font_get_buffer_size(int max_width, const char *text, struct font *font,
 void
 font_buffer_create(struct lab_data_buffer **buffer, int max_width,
 	int height, const char *text, struct font *font, const float *color,
-	cairo_pattern_t *bg_pattern, double scale)
+	cairo_pattern_t *bg_pattern, double scale, bool use_markup)
 {
 	if (string_null_or_empty(text)) {
 		return;
@@ -123,7 +123,13 @@ font_buffer_create(struct lab_data_buffer **buffer, int max_width,
 	PangoLayout *layout = pango_cairo_create_layout(cairo);
 	pango_context_set_round_glyph_positions(pango_layout_get_context(layout), false);
 	pango_layout_set_width(layout, width * PANGO_SCALE);
-	pango_layout_set_text(layout, text, -1);
+
+	if (use_markup) {
+		pango_layout_set_markup(layout, text, -1);
+	} else {
+		pango_layout_set_text(layout, text, -1);
+	}
+
 	pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
 
 	if (!opaque_bg) {

src/scaled-buffer/scaled-font-buffer.c

@@ -26,7 +26,7 @@ _create_buffer(struct scaled_buffer *scaled_buffer, double scale)
 
 	/* Buffer gets free'd automatically along the backing wlr_buffer */
 	font_buffer_create(&buffer, self->max_width, self->height, self->text,
-		&self->font, self->color, bg_pattern, scale);
+		&self->font, self->color, bg_pattern, scale, self->use_markup);
 
 	if (!buffer) {
 		wlr_log(WLR_ERROR, "font_buffer_create() failed");
@@ -56,6 +56,7 @@ _equal(struct scaled_buffer *scaled_buffer_a,
 	struct scaled_font_buffer *b = scaled_buffer_b->data;
 
 	return str_equal(a->text, b->text)
+		&& a->use_markup == b->use_markup
 		&& a->max_width == b->max_width
 		&& str_equal(a->font.name, b->font.name)
 		&& a->font.size == b->font.size
@@ -104,10 +105,10 @@ scaled_font_buffer_create_for_titlebar(struct wlr_scene_tree *parent,
 	return self;
 }
 
-void
+static void
-scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
+_scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
 		int max_width, struct font *font, const float *color,
-		const float *bg_color)
+		const float *bg_color, bool use_markup)
 {
 	assert(self);
 	assert(text);
@@ -120,6 +121,7 @@ scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
 
 	/* Update internal state */
 	self->text = xstrdup(text);
+	self->use_markup = use_markup;
 	self->max_width = max_width;
 	if (font->name) {
 		self->font.name = xstrdup(font->name);
@@ -139,3 +141,19 @@ scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
 	scaled_buffer_request_update(self->scaled_buffer,
 		self->width, self->height);
 }
+
+void
+scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
+		int max_width, struct font *font, const float *color,
+		const float *bg_color)
+{
+	_scaled_font_buffer_update(self, text, max_width, font, color, bg_color, false);
+}
+
+void
+scaled_font_buffer_update_markup(struct scaled_font_buffer *self, const char *text,
+		int max_width, struct font *font, const float *color,
+		const float *bg_color, bool use_markup)
+{
+	_scaled_font_buffer_update(self, text, max_width, font, color, bg_color, use_markup);
+}