Move apply_alpha functionality into rgba

include/components/renderer.hpp

@@ -129,10 +129,10 @@ class renderer
   alignment m_align;
   std::bitset<3> m_attr;
   int m_font{0};
-  rgba m_bg{0U};
-  rgba m_fg{0U};
-  rgba m_ol{0U};
-  rgba m_ul{0U};
+  rgba m_bg{};
+  rgba m_fg{};
+  rgba m_ol{};
+  rgba m_ul{};
   vector<action_block> m_actions;
 
   bool m_fixedcenter;

include/utils/color.hpp

@@ -12,6 +12,14 @@ struct rgba {
    */
   uint32_t m_value;
 
+  /**
+   * NONE marks this instance as invalid. If such a color is encountered, it
+   * should be treated as if no color was set.
+   *
+   * ALPHA_ONLY is used for color strings that only have an alpha channel (#AA)
+   * these kinds should be combined with another color that has RGB channels
+   * before they are used to render anything.
+   */
   enum color_type { NONE, ARGB, ALPHA_ONLY } m_type{NONE};
 
   explicit rgba();
@@ -33,6 +41,7 @@ struct rgba {
   uint8_t b_int() const;
 
   bool has_color() const;
+  void apply_alpha(rgba other);
 };
 
 namespace color_util {

src/components/builder.cpp

@@ -261,7 +261,8 @@ void builder::font_close() {
 void builder::background(rgba color) {
   if (color.m_type == color.ALPHA_ONLY) {
     rgba bg = m_bar.background;
-    color.m_value |= bg;
+    bg.apply_alpha(color);
+    color = bg;
   }
 
   auto hex = color_util::simplify_hex(color);
@@ -282,8 +283,9 @@ void builder::background_close() {
  */
 void builder::color(rgba color) {
   if (color.m_type == color.ALPHA_ONLY) {
-    rgba bg = m_bar.foreground;
-    color.m_value |= bg;
+    rgba fg = m_bar.foreground;
+    fg.apply_alpha(color);
+    color = fg;
   }
 
   auto hex = color_util::simplify_hex(color);

src/utils/color.cpp

@@ -30,7 +30,7 @@ static string normalize_hex(string hex) {
   }
 
   if (hex.length() == 3) {
-    // RGB -> ARGB
+    // RGB -> FRGB
     hex.insert(0, 1, 'f');
   }
 
@@ -134,6 +134,15 @@ bool rgba::has_color() const {
   return m_type != NONE;
 }
 
+/**
+ * Replaces the current alpha channel with the alpha channel of the other color
+ *
+ * Useful for ALPHA_ONLY colors
+ */
+void rgba::apply_alpha(rgba other) {
+  m_value = (m_value & 0x00FFFFFF) | (other.a_int() << 24);
+}
+
 string color_util::simplify_hex(string hex) {
   // convert #ffrrggbb to #rrggbb
   if (hex.length() == 9 && std::toupper(hex[1]) == 'F' && std::toupper(hex[2]) == 'F') {