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LibWeb: Add a class to represent the "source set" concept from HTML

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Also comes with a little extra CSS parser helper for parsing "sizes"
attributes in images.
This commit is contained in:
Andreas Kling 2023-05-11 16:56:01 +02:00
parent 9281bf7a01
commit 6fe4fcb74b
5 changed files with 500 additions and 0 deletions
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47
Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
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@ -7820,4 +7820,51 @@ Optional<CSS::StyleProperty> parse_css_supports_condition(CSS::Parser::ParsingCo
return parser.parse_as_supports_condition();
}
// https://html.spec.whatwg.org/multipage/images.html#parse-a-srcset-attribute
CSS::Length CSS::Parser::Parser::parse_as_sizes_attribute()
{
Optional<CSS::Length> size;
// When asked to parse a sizes attribute from an element,
// parse a comma-separated list of component values from the value of the element's sizes attribute
// (or the empty string, if the attribute is absent), and let unparsed sizes list be the result.
auto unparsed_sizes_list = parse_a_comma_separated_list_of_component_values(m_token_stream);
// For each unparsed size in unparsed sizes list:
for (auto& unparsed_size : unparsed_sizes_list) {
// 1. Remove all consecutive <whitespace-token>s from the end of unparsed size.
// If unparsed size is now empty, that is a parse error; continue.
while (!unparsed_size.is_empty() && unparsed_size.last().is_token() && unparsed_size.last().token().is(Token::Type::Whitespace))
unparsed_size.take_last();
if (unparsed_size.is_empty())
continue;
// 2. If the last component value in unparsed size is a valid non-negative <source-size-value>,
// let size be its value and remove the component value from unparsed size.
// FIXME: Any CSS function other than the math functions is invalid.
// Otherwise, there is a parse error; continue.
auto length = parse_length(unparsed_size.last());
if (length.has_value() && length.value().raw_value() >= 0) {
size = length.value();
unparsed_size.take_last();
} else {
continue;
}
// 3. Remove all consecutive <whitespace-token>s from the end of unparsed size.
// If unparsed size is now empty, return size and exit this algorithm.
// If this was not the last item in unparsed sizes list, that is a parse error.
while (!unparsed_size.is_empty() && unparsed_size.last().is_token() && unparsed_size.last().token().is(Token::Type::Whitespace))
unparsed_size.take_last();
if (unparsed_size.is_empty())
return size.value();
// FIXME: 4. Parse the remaining component values in unparsed size as a <media-condition>.
// If it does not parse correctly, or it does parse correctly but the <media-condition> evaluates to false, continue. [MQ]
dbgln("FIXME: Implement parsing of media conditions in sizes attribute");
}
return CSS::Length(100, CSS::Length::Type::Vw);
}
}