Merge pull request #4896 from nickjj/feature-clock-calendar-css-classes

feat (clock): Add support for optional CSS classes to the clock module's calendar tooltip

src/modules/clock.cpp

@@ -187,6 +187,45 @@ auto waybar::modules::Clock::update() -> void {
     }
 
     m_tlpText_ = fmt_lib::vformat(m_locale_, m_tlpText_, fmt_lib::make_format_args(now));
+
+    // Pango doesn't support CSS classes but to continue using it while staying
+    // backwards compatible this approach uses post-posting to replace fake
+    // classes with attributes Pango does understand.
+    //
+    // The benefit of this approach is anyone using the original styling choices
+    // can continue doing that and folks can optionally opt into using classes.
+    //
+    // It's also forwards compatible to where if this implemention ever changes
+    // to support proper classes anyone using them will continue to work.
+    auto context = label_.get_style_context();
+
+    static const std::vector<std::pair<std::string, std::string>> calendar_class_map = {
+        {"calendar-today", "class='today'"},
+        {"calendar-days", "class='days'"},
+        {"calendar-weeks", "class='weeks'"},
+        {"calendar-weekdays", "class='weekdays'"},
+        {"calendar-months", "class='months'"}};
+
+    for (const auto& [css_class, search_str] : calendar_class_map) {
+      try {
+        context->add_class(css_class);
+        const Gdk::RGBA color = context->get_color();
+        context->remove_class(css_class);
+
+        const std::string replace_str = fmt::format(
+            "color='#{:02x}{:02x}{:02x}'", static_cast<int>(color.get_red() * 255),
+            static_cast<int>(color.get_green() * 255), static_cast<int>(color.get_blue() * 255));
+
+        m_tlpText_ = std::regex_replace(m_tlpText_, std::regex(search_str), replace_str);
+      } catch (const Glib::Error& e) {
+        spdlog::warn("Clock: Failed to fetch CSS color for {}: {}", css_class, e.what().raw());
+        continue;
+      } catch (...) {
+        // Catch-all for any other weirdness.
+        continue;
+      }
+    }
+
     m_tooltip_->set_markup(m_tlpText_);
     label_.trigger_tooltip_query();
   }