From 8c39fee34d6ac6395dd28dbf2cffad42046915f3 Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@gmail.com>
Date: Thu, 12 Aug 2021 16:41:09 +0100
Subject: [PATCH] LibWeb: Handle non-px font sizes

The previous code assumed all font sizes were in px, but now we perform
the conversion. There is an existing bug with em sizes returning 0,
which seems to affect other places too - see
`NodeWithStyle::apply_style()`.

This also implements 'larger', 'smaller' and calc() font-sizes.
---
 .../Libraries/LibWeb/CSS/StyleProperties.cpp  | 34 +++++++++++++------
 .../Libraries/LibWeb/CSS/StyleProperties.h    |  6 ++--
 Userland/Libraries/LibWeb/Layout/Node.cpp     |  2 +-
 3 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
index b066a96e8b..e02eb24e77 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
@@ -9,6 +9,8 @@
 #include <LibGfx/FontDatabase.h>
 #include <LibWeb/CSS/StyleProperties.h>
 #include <LibWeb/FontCache.h>
+#include <LibWeb/Layout/BlockBox.h>
+#include <LibWeb/Layout/Node.h>
 
 namespace Web::CSS {
 
@@ -90,7 +92,7 @@ Color StyleProperties::color_or_fallback(CSS::PropertyID id, const DOM::Document
     return value.value()->to_color(document);
 }
 
-void StyleProperties::load_font() const
+void StyleProperties::load_font(Layout::Node const& node) const
 {
     auto family_value = string_or_fallback(CSS::PropertyID::FontFamily, "Katica");
     auto font_size = property(CSS::PropertyID::FontSize).value_or(IdentifierStyleValue::create(CSS::ValueID::Medium));
@@ -142,6 +144,9 @@ void StyleProperties::load_font() const
     bold = weight > 400;
 
     int size = 10;
+    auto parent_font_size = node.parent() == nullptr ? size : node.parent()->font_size();
+    constexpr float font_size_ratio = 1.2f;
+
     if (font_size->is_identifier()) {
         switch (static_cast<const IdentifierStyleValue&>(*font_size).id()) {
         case CSS::ValueID::XxSmall:
@@ -159,21 +164,30 @@ void StyleProperties::load_font() const
             size = 12;
             break;
         case CSS::ValueID::Smaller:
-            // FIXME: This should be relative to the parent.
-            size = 10;
+            size = roundf(parent_font_size / font_size_ratio);
             break;
         case CSS::ValueID::Larger:
-            // FIXME: This should be relative to the parent.
-            size = 12;
+            size = roundf(parent_font_size * font_size_ratio);
             break;
 
         default:
             break;
         }
-    } else if (font_size->is_length()) {
-        // FIXME: This isn't really a length, it's a numeric value..
-        int font_size_integer = font_size->to_length().raw_value();
-        size = font_size_integer;
+    } else {
+        Optional<Length> maybe_length;
+        if (font_size->is_length()) {
+            maybe_length = font_size->to_length();
+        } else if (font_size->is_calculated()) {
+            Length length = Length(0, Length::Type::Calculated);
+            length.set_calculated_style(verify_cast<CalculatedStyleValue>(font_size.ptr()));
+            maybe_length = length;
+        }
+        if (maybe_length.has_value()) {
+            // FIXME: em sizes return 0 here, for some reason
+            auto calculated_size = maybe_length.value().resolved_or_zero(node, parent_font_size).to_px(node);
+            if (calculated_size != 0)
+                size = calculated_size;
+        }
     }
 
     FontSelector font_selector { family, size, weight };
@@ -217,7 +231,7 @@ float StyleProperties::line_height(const Layout::Node& layout_node) const
     auto line_height_length = length_or_fallback(CSS::PropertyID::LineHeight, Length::make_auto());
     if (line_height_length.is_absolute())
         return (float)line_height_length.to_px(layout_node);
-    return (float)font().glyph_height() * 1.4f;
+    return (float)font(layout_node).glyph_height() * 1.4f;
 }
 
 Optional<int> StyleProperties::z_index() const
diff --git a/Userland/Libraries/LibWeb/CSS/StyleProperties.h b/Userland/Libraries/LibWeb/CSS/StyleProperties.h
index 40da2b77dc..23049e4271 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleProperties.h
+++ b/Userland/Libraries/LibWeb/CSS/StyleProperties.h
@@ -64,10 +64,10 @@ public:
     Optional<CSS::Repeat> background_repeat_y() const;
     Optional<CSS::BoxShadowData> box_shadow() const;
 
-    const Gfx::Font& font() const
+    const Gfx::Font& font(Layout::Node const& node) const
     {
         if (!m_font)
-            load_font();
+            load_font(node);
         return *m_font;
     }
 
@@ -83,7 +83,7 @@ private:
     HashMap<unsigned, NonnullRefPtr<StyleValue>> m_property_values;
     Optional<CSS::Overflow> overflow(CSS::PropertyID) const;
 
-    void load_font() const;
+    void load_font(Layout::Node const&) const;
     RefPtr<Gfx::Font> font_fallback(bool monospace, bool bold) const;
 
     mutable RefPtr<Gfx::Font> m_font;
diff --git a/Userland/Libraries/LibWeb/Layout/Node.cpp b/Userland/Libraries/LibWeb/Layout/Node.cpp
index 982d969258..83d8719495 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.cpp
+++ b/Userland/Libraries/LibWeb/Layout/Node.cpp
@@ -219,7 +219,7 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& specified_style)
 {
     auto& computed_values = static_cast<CSS::MutableComputedValues&>(m_computed_values);
 
-    m_font = specified_style.font();
+    m_font = specified_style.font(*this);
     m_line_height = specified_style.line_height(*this);
 
     {