From c217057cfd32ef2acc7811651f48c5b0cb44827d Mon Sep 17 00:00:00 2001
From: Tim Ledbetter <tim.ledbetter@ladybird.org>
Date: Tue, 18 Feb 2025 07:25:09 +0000
Subject: [PATCH] LibWeb: Apply presentational hints for the HTMLHRElement
 color attribute

---
 Libraries/LibWeb/HTML/HTMLHRElement.cpp       | 21 +++++++++++++++++-
 .../the-hr-element-0/color-ref.html           | 22 +++++++++++++++++++
 .../the-hr-element-0/color.html               |  7 ++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 Tests/LibWeb/Ref/expected/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color-ref.html
 create mode 100644 Tests/LibWeb/Ref/input/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color.html

diff --git a/Libraries/LibWeb/HTML/HTMLHRElement.cpp b/Libraries/LibWeb/HTML/HTMLHRElement.cpp
index bf1ddc6cd7d..ef433a613fc 100644
--- a/Libraries/LibWeb/HTML/HTMLHRElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLHRElement.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2025, Tim Ledbetter <tim.ledbetter@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -7,6 +8,8 @@
 #include <LibWeb/Bindings/HTMLHRElementPrototype.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/CSS/ComputedProperties.h>
+#include <LibWeb/CSS/StyleValues/CSSColorValue.h>
+#include <LibWeb/CSS/StyleValues/CSSKeywordValue.h>
 #include <LibWeb/CSS/StyleValues/LengthStyleValue.h>
 #include <LibWeb/HTML/HTMLHRElement.h>
 #include <LibWeb/HTML/Parser/HTMLParser.h>
@@ -33,12 +36,28 @@ bool HTMLHRElement::is_presentational_hint(FlyString const& name) const
     if (Base::is_presentational_hint(name))
         return true;
 
-    return first_is_one_of(name, HTML::AttributeNames::width);
+    return first_is_one_of(name, HTML::AttributeNames::color, HTML::AttributeNames::noshade, HTML::AttributeNames::width);
 }
 
 void HTMLHRElement::apply_presentational_hints(GC::Ref<CSS::CascadedProperties> cascaded_properties) const
 {
     for_each_attribute([&](auto& name, auto& value) {
+        // https://html.spec.whatwg.org/multipage/rendering.html#the-hr-element-2
+        if (name == HTML::AttributeNames::color || name == HTML::AttributeNames::noshade) {
+            cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BorderTopStyle, CSS::CSSKeywordValue::create(CSS::Keyword::Solid));
+            cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BorderRightStyle, CSS::CSSKeywordValue::create(CSS::Keyword::Solid));
+            cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BorderBottomStyle, CSS::CSSKeywordValue::create(CSS::Keyword::Solid));
+            cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::BorderLeftStyle, CSS::CSSKeywordValue::create(CSS::Keyword::Solid));
+        }
+
+        // https://html.spec.whatwg.org/multipage/rendering.html#the-hr-element-2:attr-hr-color-3
+        // When an hr element has a color attribute, its value is expected to be parsed using the rules for parsing a legacy color value, and if that does not return failure,
+        // the user agent is expected to treat the attribute as a presentational hint setting the element's 'color' property to the resulting color.
+        if (name == HTML::AttributeNames::color) {
+            if (auto parsed_value = parse_legacy_color_value(value); parsed_value.has_value()) {
+                cascaded_properties->set_property_from_presentational_hint(CSS::PropertyID::Color, CSS::CSSColorValue::create_from_color(*parsed_value));
+            }
+        }
         // https://html.spec.whatwg.org/multipage/rendering.html#the-hr-element-2:maps-to-the-dimension-property
         if (name == HTML::AttributeNames::width) {
             if (auto parsed_value = parse_dimension_value(value)) {
diff --git a/Tests/LibWeb/Ref/expected/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color-ref.html b/Tests/LibWeb/Ref/expected/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color-ref.html
new file mode 100644
index 00000000000..5cd35c83ada
--- /dev/null
+++ b/Tests/LibWeb/Ref/expected/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color-ref.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<meta charset=utf-8>
+<style>
+.hr {
+  color: gray;
+  border-style: inset;
+  border-width: 1px;
+  margin: 0.5em auto;
+}
+
+.green {
+  color: green;
+}
+
+.no-inset {
+  border-style: solid;
+}
+</style>
+<div class='hr'></div>
+<div class='hr no-inset'></div>
+<div class='hr no-inset'></div>
+<div class='hr green no-inset'></div>
diff --git a/Tests/LibWeb/Ref/input/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color.html b/Tests/LibWeb/Ref/input/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color.html
new file mode 100644
index 00000000000..3050c58aecb
--- /dev/null
+++ b/Tests/LibWeb/Ref/input/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<meta charset=utf-8>
+<link rel=match href="../../../../../../expected/wpt-import/html/rendering/non-replaced-elements/the-hr-element-0/color-ref.html">
+<hr>
+<hr color="">
+<hr color=transparent>
+<hr color=green>