LibWeb: Add pc CSS unit

Author: https://github.com/Lubrsi
Commit: https://github.com/SerenityOS/serenity/commit/043b31ad9a9
Pull-request: https://github.com/SerenityOS/serenity/pull/3694

Libraries/LibWeb/CSS/Length.cpp

@@ -74,6 +74,8 @@ const char* Length::unit_name() const
         return "mm";
     case Type::Q:
         return "Q";
+    case Type::Pc:
+        return "pc";
     case Type::Ex:
         return "ex";
     case Type::Em:

Libraries/LibWeb/CSS/Length.h

@@ -43,6 +43,7 @@ public:
         Q,
         Px,
         Pt,
+        Pc,
         Ex,
         Em,
         Rem,
@@ -100,6 +101,7 @@ public:
             || m_type == Type::Mm
             || m_type == Type::Px
             || m_type == Type::Pt
+            || m_type == Type::Pc
             || m_type == Type::Q;
     }
 
@@ -119,21 +121,25 @@ public:
     {
         if (is_relative())
             return relative_length_to_px(layout_node);
+        constexpr float inch_pixels = 96.0f;
+        constexpr float centimeter_pixels = (inch_pixels / 2.54f);
         switch (m_type) {
         case Type::Auto:
             return 0;
         case Type::Cm:
-            return m_value * (96.0f / 2.54f); // 1cm = 96px/2.54
+            return m_value * centimeter_pixels; // 1cm = 96px/2.54
         case Type::In:
-            return m_value * 96.0f; // 1in = 2.54 cm = 96px
+            return m_value * inch_pixels; // 1in = 2.54 cm = 96px
         case Type::Px:
             return m_value; // 1px = 1/96th of 1in
         case Type::Pt:
-            return m_value * 1.33333333f; // 1pt = 1/72th of 1in
+            return m_value * ((1.0f / 72.0f) * inch_pixels); // 1pt = 1/72th of 1in
+        case Type::Pc:
+            return m_value * ((1.0f / 6.0f) * inch_pixels); // 1pc = 1/6th of 1in
         case Type::Mm:
-            return m_value * (0.1f * (96.0f / 2.54f)); // 1mm = 1/10th of 1cm
+            return m_value * ((1.0f / 10.0f) * centimeter_pixels); // 1mm = 1/10th of 1cm
         case Type::Q:
-            return m_value * (0.025f * (96.0f / 2.54f)); // 1Q = 1/40th of 1cm
+            return m_value * ((1.0f / 40.0f) * centimeter_pixels); // 1Q = 1/40th of 1cm
         case Type::Undefined:
         case Type::Percentage:
         default:

Libraries/LibWeb/CSS/Parser/CSSParser.cpp

@@ -284,6 +284,9 @@ static CSS::Length parse_length(const CSS::ParsingContext& context, const String
     } else if (view.ends_with("pt", CaseSensitivity::CaseInsensitive)) {
         type = CSS::Length::Type::Pt;
         value = try_parse_float(view.substring_view(0, view.length() - 2));
+    } else if (view.ends_with("pc", CaseSensitivity::CaseInsensitive)) {
+        type = CSS::Length::Type::Pc;
+        value = try_parse_float(view.substring_view(0, view.length() - 2));
     } else if (view.ends_with("mm", CaseSensitivity::CaseInsensitive)) {
         type = CSS::Length::Type::Mm;
         value = try_parse_float(view.substring_view(0, view.length() - 2));