LibWeb: Parse ascent-, descent-, and line-gap-override descriptors

Author: https://github.com/AtkinsSJ Commit: 2f7d18865d Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1554
2025-08-07 16:49:54 +00:00 · 2024-09-26 12:51:41 +01:00 · 2024-09-26 12:51:41 +01:00 · 2f7d18865d · 2024-09-28 12:44:05 +00:00
commit 2f7d18865d
parent 3a5e78780e
5 changed files with 100 additions and 16 deletions
--- a/Userland/Libraries/LibWeb/CSS/FontFace.cpp
+++ b/Userland/Libraries/LibWeb/CSS/FontFace.cpp
@ -388,7 +388,7 @@ void FontFace::load_font_source()
            auto& style_computer = const_cast<StyleComputer&>(window.document()->style_computer());

            // FIXME: The ParsedFontFace is kind of expensive to create. We should be using a shared sub-object for the data
-            ParsedFontFace parsed_font_face { font->m_family, font->m_weight.to_number<int>(), 0 /* FIXME: slope */, font->m_urls, font->m_unicode_ranges };
+            ParsedFontFace parsed_font_face { font->m_family, font->m_weight.to_number<int>(), 0 /* FIXME: slope */, font->m_urls, font->m_unicode_ranges, /* FIXME: ascent_override */ {}, /* FIXME: descent_override */ {}, /* FIXME: line_gap_override */ {} };
            if (auto loader = style_computer.load_font_face(parsed_font_face, move(on_load), move(on_error)); loader.has_value())
                loader->start_loading_next_url();
        } else {
--- a/Userland/Libraries/LibWeb/CSS/ParsedFontFace.cpp
+++ b/Userland/Libraries/LibWeb/CSS/ParsedFontFace.cpp
@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2022-2024, Sam Atkins <sam@ladybird.org>
 * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
@ -9,12 +9,15 @@

 namespace Web::CSS {

-ParsedFontFace::ParsedFontFace(FlyString font_family, Optional<int> weight, Optional<int> slope, Vector<Source> sources, Vector<Gfx::UnicodeRange> unicode_ranges)
+ParsedFontFace::ParsedFontFace(FlyString font_family, Optional<int> weight, Optional<int> slope, Vector<Source> sources, Vector<Gfx::UnicodeRange> unicode_ranges, Optional<Percentage> ascent_override, Optional<Percentage> descent_override, Optional<Percentage> line_gap_override)
    : m_font_family(move(font_family))
    , m_weight(weight)
    , m_slope(slope)
    , m_sources(move(sources))
    , m_unicode_ranges(move(unicode_ranges))
+    , m_ascent_override(move(ascent_override))
+    , m_descent_override(move(descent_override))
+    , m_line_gap_override(move(line_gap_override))
 {
 }

--- a/Userland/Libraries/LibWeb/CSS/ParsedFontFace.h
+++ b/Userland/Libraries/LibWeb/CSS/ParsedFontFace.h
@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2022-2024, Sam Atkins <sam@ladybird.org>
 * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
@ -10,6 +10,7 @@
 #include <AK/FlyString.h>
 #include <LibGfx/Font/UnicodeRange.h>
 #include <LibURL/URL.h>
+#include <LibWeb/CSS/Percentage.h>

 namespace Web::CSS {

@ -21,15 +22,17 @@ public:
        Optional<FlyString> format;
    };

-    ParsedFontFace(FlyString font_family, Optional<int> weight, Optional<int> slope, Vector<Source> sources, Vector<Gfx::UnicodeRange> unicode_ranges);
+    ParsedFontFace(FlyString font_family, Optional<int> weight, Optional<int> slope, Vector<Source> sources, Vector<Gfx::UnicodeRange> unicode_ranges, Optional<Percentage> ascent_override, Optional<Percentage> descent_override, Optional<Percentage> line_gap_override);
    ~ParsedFontFace() = default;

+    Optional<Percentage> ascent_override() const { return m_ascent_override; }
+    Optional<Percentage> descent_override() const { return m_descent_override; }
    FlyString font_family() const { return m_font_family; }
-    Optional<int> weight() const { return m_weight; }
    Optional<int> slope() const { return m_slope; }
+    Optional<int> weight() const { return m_weight; }
+    Optional<Percentage> line_gap_override() const { return m_line_gap_override; }
    Vector<Source> const& sources() const { return m_sources; }
    Vector<Gfx::UnicodeRange> const& unicode_ranges() const { return m_unicode_ranges; }
-    // FIXME: font-stretch, font-feature-settings

 private:
    FlyString m_font_family;
@ -37,6 +40,9 @@ private:
    Optional<int> m_slope { 0 };
    Vector<Source> m_sources;
    Vector<Gfx::UnicodeRange> m_unicode_ranges;
+    Optional<Percentage> m_ascent_override;
+    Optional<Percentage> m_descent_override;
+    Optional<Percentage> m_line_gap_override;
 };

 }
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@ -5455,6 +5455,41 @@ JS::GCPtr<CSSFontFaceRule> Parser::parse_font_face_rule(TokenStream<ComponentVal
    Vector<Gfx::UnicodeRange> unicode_range;
    Optional<int> weight;
    Optional<int> slope;
+    Optional<Percentage> ascent_override;
+    Optional<Percentage> descent_override;
+    Optional<Percentage> line_gap_override;
+
+    // "normal" is returned as nullptr
+    auto parse_as_percentage_or_normal = [&](Vector<ComponentValue> const& values) -> ErrorOr<Optional<Percentage>> {
+        // normal | <percentage [0,∞]>
+        TokenStream tokens { values };
+        if (auto percentage_value = parse_percentage_value(tokens)) {
+            tokens.skip_whitespace();
+            if (tokens.has_next_token())
+                return Error::from_string_literal("Unexpected trailing tokens");
+
+            if (percentage_value->is_percentage() && percentage_value->as_percentage().percentage().value() >= 0)
+                return percentage_value->as_percentage().percentage();
+
+            // TODO: Once we implement calc-simplification in the parser, we should no longer see math values here,
+            //       unless they're impossible to resolve and thus invalid.
+            if (percentage_value->is_math()) {
+                if (auto result = percentage_value->as_math().resolve_percentage(); result.has_value())
+                    return result.value();
+            }
+
+            return Error::from_string_literal("Invalid percentage");
+        }
+
+        tokens.skip_whitespace();
+        if (!tokens.next_token().is_ident("normal"sv))
+            return Error::from_string_literal("Expected `normal | <percentage [0,∞]>`");
+        tokens.skip_whitespace();
+        if (tokens.has_next_token())
+            return Error::from_string_literal("Unexpected trailing tokens");
+
+        return OptionalNone {};
+    };

    for (auto& declaration_or_at_rule : declarations_and_at_rules) {
        if (declaration_or_at_rule.is_at_rule()) {
@ -5463,17 +5498,21 @@ JS::GCPtr<CSSFontFaceRule> Parser::parse_font_face_rule(TokenStream<ComponentVal
        }

        auto const& declaration = declaration_or_at_rule.declaration();
-        if (declaration.name().equals_ignoring_ascii_case("font-weight"sv)) {
-            TokenStream token_stream { declaration.values() };
-            if (auto value = parse_css_value(CSS::PropertyID::FontWeight, token_stream); !value.is_error()) {
-                weight = value.value()->to_font_weight();
+        if (declaration.name().equals_ignoring_ascii_case("ascent-override"sv)) {
+            auto value = parse_as_percentage_or_normal(declaration.values());
+            if (value.is_error()) {
+                dbgln_if(CSS_PARSER_DEBUG, "CSSParser: Failed to parse @font-face ascent-override: {}", value.error());
+            } else {
+                ascent_override = value.release_value();
            }
            continue;
        }
-        if (declaration.name().equals_ignoring_ascii_case("font-style"sv)) {
-            TokenStream token_stream { declaration.values() };
-            if (auto value = parse_css_value(CSS::PropertyID::FontStyle, token_stream); !value.is_error()) {
-                slope = value.value()->to_font_slope();
+        if (declaration.name().equals_ignoring_ascii_case("descent-override"sv)) {
+            auto value = parse_as_percentage_or_normal(declaration.values());
+            if (value.is_error()) {
+                dbgln_if(CSS_PARSER_DEBUG, "CSSParser: Failed to parse @font-face descent-override: {}", value.error());
+            } else {
+                descent_override = value.release_value();
            }
            continue;
        }
@ -5521,6 +5560,29 @@ JS::GCPtr<CSSFontFaceRule> Parser::parse_font_face_rule(TokenStream<ComponentVal
            font_family = String::join(' ', font_family_parts).release_value_but_fixme_should_propagate_errors();
            continue;
        }
+        if (declaration.name().equals_ignoring_ascii_case("font-style"sv)) {
+            TokenStream token_stream { declaration.values() };
+            if (auto value = parse_css_value(CSS::PropertyID::FontStyle, token_stream); !value.is_error()) {
+                slope = value.value()->to_font_slope();
+            }
+            continue;
+        }
+        if (declaration.name().equals_ignoring_ascii_case("font-weight"sv)) {
+            TokenStream token_stream { declaration.values() };
+            if (auto value = parse_css_value(CSS::PropertyID::FontWeight, token_stream); !value.is_error()) {
+                weight = value.value()->to_font_weight();
+            }
+            continue;
+        }
+        if (declaration.name().equals_ignoring_ascii_case("line-gap-override"sv)) {
+            auto value = parse_as_percentage_or_normal(declaration.values());
+            if (value.is_error()) {
+                dbgln_if(CSS_PARSER_DEBUG, "CSSParser: Failed to parse @font-face line-gap-override: {}", value.error());
+            } else {
+                line_gap_override = value.release_value();
+            }
+            continue;
+        }
        if (declaration.name().equals_ignoring_ascii_case("src"sv)) {
            TokenStream token_stream { declaration.values() };
            Vector<ParsedFontFace::Source> supported_sources = parse_font_face_src(token_stream);
@ -5550,7 +5612,7 @@ JS::GCPtr<CSSFontFaceRule> Parser::parse_font_face_rule(TokenStream<ComponentVal
        unicode_range.empend(0x0u, 0x10FFFFu);
    }

-    return CSSFontFaceRule::create(m_context.realm(), ParsedFontFace { font_family.release_value(), weight, slope, move(src), move(unicode_range) });
+    return CSSFontFaceRule::create(m_context.realm(), ParsedFontFace { font_family.release_value(), weight, slope, move(src), move(unicode_range), move(ascent_override), move(descent_override), move(line_gap_override) });
 }

 Vector<ParsedFontFace::Source> Parser::parse_as_font_face_src()
--- a/Userland/Libraries/LibWeb/Dump.cpp
+++ b/Userland/Libraries/LibWeb/Dump.cpp
@ -678,6 +678,19 @@ void dump_font_face_rule(StringBuilder& builder, CSS::CSSFontFaceRule const& rul
        indent(builder, indent_levels + 2);
        builder.appendff("{}\n", unicode_range.to_string());
    }
+
+    if (font_face.ascent_override().has_value()) {
+        indent(builder, indent_levels + 1);
+        builder.appendff("ascent-override: {}\n", font_face.ascent_override().value());
+    }
+    if (font_face.descent_override().has_value()) {
+        indent(builder, indent_levels + 1);
+        builder.appendff("descent-override: {}\n", font_face.descent_override().value());
+    }
+    if (font_face.line_gap_override().has_value()) {
+        indent(builder, indent_levels + 1);
+        builder.appendff("line-gap-override: {}\n", font_face.line_gap_override().value());
+    }
 }

 void dump_import_rule(StringBuilder& builder, CSS::CSSImportRule const& rule, int indent_levels)