ladybird/Userland/Libraries/LibWeb/SVG/AttributeParser.cpp
MacDue 650180811e LibWeb: Flesh out SVGMaskElement a bit
- Add method to resolve the masking area (based on the target element
  size)
- Parse the maskUnits and maskContentUnits attributes
2023-09-19 10:46:05 +02:00

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/*
* Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
* Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2023, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "AttributeParser.h"
#include <AK/FloatingPointStringConversions.h>
#include <AK/GenericShorthands.h>
#include <AK/StringBuilder.h>
#include <ctype.h>
namespace Web::SVG {
AttributeParser::AttributeParser(StringView source)
: m_lexer(source)
{
}
Optional<Vector<Transform>> AttributeParser::parse_transform(StringView input)
{
AttributeParser parser { input };
return parser.parse_transform();
}
Vector<PathInstruction> AttributeParser::parse_path_data(StringView input)
{
AttributeParser parser { input };
parser.parse_whitespace();
while (!parser.done())
parser.parse_drawto();
if (!parser.m_instructions.is_empty() && parser.m_instructions[0].type != PathInstructionType::Move) {
// Invalid. "A path data segment (if there is one) must begin with a "moveto" command."
return {};
}
return parser.m_instructions;
}
Optional<float> AttributeParser::parse_coordinate(StringView input)
{
AttributeParser parser { input };
parser.parse_whitespace();
if (parser.match_coordinate()) {
float result = parser.parse_coordinate();
parser.parse_whitespace();
if (parser.done())
return result;
}
return {};
}
Optional<float> AttributeParser::parse_length(StringView input)
{
AttributeParser parser { input };
parser.parse_whitespace();
if (parser.match_coordinate()) {
float result = parser.parse_length();
parser.parse_whitespace();
if (parser.done())
return result;
}
return {};
}
float NumberPercentage::resolve_relative_to(float length) const
{
if (!m_is_percentage)
return m_value;
return m_value * length;
}
Optional<NumberPercentage> AttributeParser::parse_number_percentage(StringView input)
{
AttributeParser parser { input };
parser.parse_whitespace();
if (parser.match_number()) {
float number = parser.parse_number();
bool is_percentage = parser.match('%');
if (is_percentage)
parser.consume();
parser.parse_whitespace();
if (parser.done())
return NumberPercentage(number, is_percentage);
}
return {};
}
Optional<float> AttributeParser::parse_positive_length(StringView input)
{
// FIXME: Where this is used, the spec usually (always?) says "A negative value is an error (see Error processing)."
// So, implement error processing! Maybe this should return ErrorOr.
auto result = parse_length(input);
if (result.has_value() && result.value() < 0)
result.clear();
return result;
}
Vector<Gfx::FloatPoint> AttributeParser::parse_points(StringView input)
{
AttributeParser parser { input };
parser.parse_whitespace();
// FIXME: "If an odd number of coordinates is provided, then the element is in error, with the same user agent behavior
// as occurs with an incorrectly specified path element. In such error cases the user agent will drop the last,
// odd coordinate and otherwise render the shape."
// The parser currently doesn't notice that there is a missing coordinate, so make it notice!
auto coordinate_pair_sequence = parser.parse_coordinate_pair_sequence();
parser.parse_whitespace();
if (!parser.done())
return {};
// FIXME: This is awkward. Can we return Gfx::FloatPoints from some of these parsing methods instead of Vector<float>?
Vector<Gfx::FloatPoint> points;
points.ensure_capacity(coordinate_pair_sequence.size());
for (auto const& pair : coordinate_pair_sequence)
points.empend(pair[0], pair[1]);
return points;
}
void AttributeParser::parse_drawto()
{
if (match('M') || match('m')) {
parse_moveto();
} else if (match('Z') || match('z')) {
parse_closepath();
} else if (match('L') || match('l')) {
parse_lineto();
} else if (match('H') || match('h')) {
parse_horizontal_lineto();
} else if (match('V') || match('v')) {
parse_vertical_lineto();
} else if (match('C') || match('c')) {
parse_curveto();
} else if (match('S') || match('s')) {
parse_smooth_curveto();
} else if (match('Q') || match('q')) {
parse_quadratic_bezier_curveto();
} else if (match('T') || match('t')) {
parse_smooth_quadratic_bezier_curveto();
} else if (match('A') || match('a')) {
parse_elliptical_arc();
} else {
dbgln("AttributeParser::parse_drawto failed to match: '{}'", ch());
TODO();
}
}
// https://www.w3.org/TR/SVG2/paths.html#PathDataMovetoCommands
void AttributeParser::parse_moveto()
{
bool absolute = consume() == 'M';
parse_whitespace();
bool is_first = true;
for (auto& pair : parse_coordinate_pair_sequence()) {
// NOTE: "M 1 2 3 4" is equivalent to "M 1 2 L 3 4".
auto type = is_first ? PathInstructionType::Move : PathInstructionType::Line;
m_instructions.append({ type, absolute, pair });
is_first = false;
}
}
void AttributeParser::parse_closepath()
{
bool absolute = consume() == 'Z';
parse_whitespace();
m_instructions.append({ PathInstructionType::ClosePath, absolute, {} });
}
void AttributeParser::parse_lineto()
{
bool absolute = consume() == 'L';
parse_whitespace();
for (auto& pair : parse_coordinate_pair_sequence())
m_instructions.append({ PathInstructionType::Line, absolute, pair });
}
void AttributeParser::parse_horizontal_lineto()
{
bool absolute = consume() == 'H';
parse_whitespace();
for (auto coordinate : parse_coordinate_sequence())
m_instructions.append({ PathInstructionType::HorizontalLine, absolute, { coordinate } });
}
void AttributeParser::parse_vertical_lineto()
{
bool absolute = consume() == 'V';
parse_whitespace();
for (auto coordinate : parse_coordinate_sequence())
m_instructions.append({ PathInstructionType::VerticalLine, absolute, { coordinate } });
}
void AttributeParser::parse_curveto()
{
bool absolute = consume() == 'C';
parse_whitespace();
while (true) {
m_instructions.append({ PathInstructionType::Curve, absolute, parse_coordinate_pair_triplet() });
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_coordinate())
break;
}
}
void AttributeParser::parse_smooth_curveto()
{
bool absolute = consume() == 'S';
parse_whitespace();
while (true) {
m_instructions.append({ PathInstructionType::SmoothCurve, absolute, parse_coordinate_pair_double() });
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_coordinate())
break;
}
}
void AttributeParser::parse_quadratic_bezier_curveto()
{
bool absolute = consume() == 'Q';
parse_whitespace();
while (true) {
m_instructions.append({ PathInstructionType::QuadraticBezierCurve, absolute, parse_coordinate_pair_double() });
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_coordinate())
break;
}
}
void AttributeParser::parse_smooth_quadratic_bezier_curveto()
{
bool absolute = consume() == 'T';
parse_whitespace();
while (true) {
m_instructions.append({ PathInstructionType::SmoothQuadraticBezierCurve, absolute, parse_coordinate_pair() });
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_coordinate())
break;
}
}
void AttributeParser::parse_elliptical_arc()
{
bool absolute = consume() == 'A';
parse_whitespace();
while (true) {
m_instructions.append({ PathInstructionType::EllipticalArc, absolute, parse_elliptical_arg_argument() });
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_coordinate())
break;
}
}
float AttributeParser::parse_length()
{
// https://www.w3.org/TR/SVG11/types.html#DataTypeLength
return parse_number();
}
float AttributeParser::parse_coordinate()
{
// https://www.w3.org/TR/SVG11/types.html#DataTypeCoordinate
// coordinate ::= length
return parse_length();
}
Vector<float> AttributeParser::parse_coordinate_pair()
{
Vector<float> coordinates;
coordinates.append(parse_coordinate());
if (match_comma_whitespace())
parse_comma_whitespace();
coordinates.append(parse_coordinate());
return coordinates;
}
Vector<float> AttributeParser::parse_coordinate_sequence()
{
Vector<float> sequence;
while (true) {
sequence.append(parse_coordinate());
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_comma_whitespace() && !match_coordinate())
break;
}
return sequence;
}
Vector<Vector<float>> AttributeParser::parse_coordinate_pair_sequence()
{
Vector<Vector<float>> sequence;
while (true) {
sequence.append(parse_coordinate_pair());
if (match_comma_whitespace())
parse_comma_whitespace();
if (!match_comma_whitespace() && !match_coordinate())
break;
}
return sequence;
}
Vector<float> AttributeParser::parse_coordinate_pair_double()
{
Vector<float> coordinates;
coordinates.extend(parse_coordinate_pair());
if (match_comma_whitespace())
parse_comma_whitespace();
coordinates.extend(parse_coordinate_pair());
return coordinates;
}
Vector<float> AttributeParser::parse_coordinate_pair_triplet()
{
Vector<float> coordinates;
coordinates.extend(parse_coordinate_pair());
if (match_comma_whitespace())
parse_comma_whitespace();
coordinates.extend(parse_coordinate_pair());
if (match_comma_whitespace())
parse_comma_whitespace();
coordinates.extend(parse_coordinate_pair());
return coordinates;
}
Vector<float> AttributeParser::parse_elliptical_arg_argument()
{
Vector<float> numbers;
numbers.append(parse_number());
if (match_comma_whitespace())
parse_comma_whitespace();
numbers.append(parse_number());
if (match_comma_whitespace())
parse_comma_whitespace();
numbers.append(parse_number());
parse_comma_whitespace();
numbers.append(parse_flag());
if (match_comma_whitespace())
parse_comma_whitespace();
numbers.append(parse_flag());
if (match_comma_whitespace())
parse_comma_whitespace();
numbers.extend(parse_coordinate_pair());
return numbers;
}
void AttributeParser::parse_whitespace(bool must_match_once)
{
bool matched = false;
while (!done() && match_whitespace()) {
consume();
matched = true;
}
VERIFY(!must_match_once || matched);
}
void AttributeParser::parse_comma_whitespace()
{
if (match(',')) {
consume();
parse_whitespace();
} else {
parse_whitespace(1);
if (match(','))
consume();
parse_whitespace();
}
}
// https://www.w3.org/TR/SVG11/types.html#DataTypeNumber
float AttributeParser::parse_number()
{
auto sign = parse_sign();
return sign * parse_nonnegative_number();
}
// https://www.w3.org/TR/SVG11/paths.html#PathDataBNF
float AttributeParser::parse_nonnegative_number()
{
// NOTE: The grammar is almost a floating point except we cannot have a sign
// at the start. That condition should have been checked by the caller.
VERIFY(!match('+') && !match('-'));
auto remaining_source_text = m_lexer.remaining();
char const* start = remaining_source_text.characters_without_null_termination();
auto maybe_float = parse_first_floating_point<float>(start, start + remaining_source_text.length());
VERIFY(maybe_float.parsed_value());
m_lexer.ignore(maybe_float.end_ptr - start);
return maybe_float.value;
}
float AttributeParser::parse_flag()
{
if (!match('0') && !match('1'))
VERIFY_NOT_REACHED();
return consume() - '0';
}
int AttributeParser::parse_sign()
{
if (match('-')) {
consume();
return -1;
}
if (match('+'))
consume();
return 1;
}
static bool whitespace(char c)
{
// wsp:
// Either a U+000A LINE FEED, U+000D CARRIAGE RETURN, U+0009 CHARACTER TABULATION, or U+0020 SPACE.
return AK::first_is_one_of(c, '\n', '\r', '\t', '\f', ' ');
}
// https://svgwg.org/svg2-draft/coords.html#PreserveAspectRatioAttribute
Optional<PreserveAspectRatio> AttributeParser::parse_preserve_aspect_ratio(StringView input)
{
// <align> <meetOrSlice>?
GenericLexer lexer { input };
lexer.ignore_while(whitespace);
auto align_string = lexer.consume_until(whitespace);
if (align_string.is_empty())
return {};
lexer.ignore_while(whitespace);
auto meet_or_slice_string = lexer.consume_until(whitespace);
// <align> =
// none
// | xMinYMin | xMidYMin | xMaxYMin
// | xMinYMid | xMidYMid | xMaxYMid
// | xMinYMax | xMidYMax | xMaxYMax
auto align = [&]() -> Optional<PreserveAspectRatio::Align> {
if (align_string == "none"sv)
return PreserveAspectRatio::Align::None;
if (align_string == "xMinYMin"sv)
return PreserveAspectRatio::Align::xMinYMin;
if (align_string == "xMidYMin"sv)
return PreserveAspectRatio::Align::xMidYMin;
if (align_string == "xMaxYMin"sv)
return PreserveAspectRatio::Align::xMaxYMin;
if (align_string == "xMinYMid"sv)
return PreserveAspectRatio::Align::xMinYMid;
if (align_string == "xMidYMid"sv)
return PreserveAspectRatio::Align::xMidYMid;
if (align_string == "xMaxYMid"sv)
return PreserveAspectRatio::Align::xMaxYMid;
if (align_string == "xMinYMax"sv)
return PreserveAspectRatio::Align::xMinYMax;
if (align_string == "xMidYMax"sv)
return PreserveAspectRatio::Align::xMidYMax;
if (align_string == "xMaxYMax"sv)
return PreserveAspectRatio::Align::xMaxYMax;
return {};
}();
if (!align.has_value())
return {};
// <meetOrSlice> = meet | slice
auto meet_or_slice = [&]() -> Optional<PreserveAspectRatio::MeetOrSlice> {
if (meet_or_slice_string.is_empty() || meet_or_slice_string == "meet"sv)
return PreserveAspectRatio::MeetOrSlice::Meet;
if (meet_or_slice_string == "slice"sv)
return PreserveAspectRatio::MeetOrSlice::Slice;
return {};
}();
if (!meet_or_slice.has_value())
return {};
return PreserveAspectRatio { *align, *meet_or_slice };
}
// https://svgwg.org/svg2-draft/pservers.html#LinearGradientElementGradientUnitsAttribute
// https://drafts.fxtf.org/css-masking/#element-attrdef-mask-maskunits
// https://drafts.fxtf.org/css-masking/#element-attrdef-mask-maskcontentunits
Optional<SVGUnits> AttributeParser::parse_units(StringView input)
{
GenericLexer lexer { input };
lexer.ignore_while(whitespace);
auto gradient_units_string = lexer.consume_until(whitespace);
if (gradient_units_string == "userSpaceOnUse"sv)
return SVGUnits::UserSpaceOnUse;
if (gradient_units_string == "objectBoundingBox"sv)
return SVGUnits::ObjectBoundingBox;
return {};
}
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementSpreadMethodAttribute
Optional<SpreadMethod> AttributeParser::parse_spread_method(StringView input)
{
GenericLexer lexer { input };
lexer.ignore_while(whitespace);
auto spread_method_string = lexer.consume_until(whitespace);
if (spread_method_string == "pad"sv)
return SpreadMethod::Pad;
if (spread_method_string == "repeat"sv)
return SpreadMethod::Repeat;
if (spread_method_string == "reflect"sv)
return SpreadMethod::Reflect;
return {};
}
// https://drafts.csswg.org/css-transforms/#svg-syntax
Optional<Vector<Transform>> AttributeParser::parse_transform()
{
auto consume_whitespace = [&] {
m_lexer.ignore_while(whitespace);
};
auto consume_comma_whitespace = [&] {
consume_whitespace();
m_lexer.consume_specific(',');
consume_whitespace();
};
// FIXME: This parsing is quite lenient, so will accept (with default values) some transforms that should be rejected.
auto parse_optional_number = [&](float default_value = 0.0f) {
consume_comma_whitespace();
if (match_number())
return parse_number();
return default_value;
};
auto try_parse_number = [&]() -> Optional<float> {
if (match_number())
return parse_number();
return {};
};
auto parse_function = [&](auto body) -> Optional<Transform> {
consume_whitespace();
if (!m_lexer.consume_specific('('))
return {};
consume_whitespace();
auto maybe_operation = body();
if (!maybe_operation.has_value())
return {};
Transform transform { .operation = Transform::Operation { *maybe_operation } };
consume_whitespace();
if (m_lexer.consume_specific(')'))
return transform;
return {};
};
// NOTE: This looks very similar to the CSS transform but the syntax is not compatible.
Vector<Transform> transform_list;
consume_whitespace();
while (!done()) {
Optional<Transform> maybe_transform;
if (m_lexer.consume_specific("translate"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::Translate> {
Transform::Translate translate {};
auto maybe_x = try_parse_number();
if (!maybe_x.has_value())
return {};
translate.x = *maybe_x;
translate.y = parse_optional_number();
return translate;
});
} else if (m_lexer.consume_specific("scale"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::Scale> {
Transform::Scale scale {};
auto maybe_x = try_parse_number();
if (!maybe_x.has_value())
return {};
scale.x = *maybe_x;
scale.y = parse_optional_number(scale.x);
return scale;
});
} else if (m_lexer.consume_specific("rotate"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::Rotate> {
Transform::Rotate rotate {};
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
rotate.a = *maybe_a;
rotate.x = parse_optional_number();
rotate.y = parse_optional_number();
return rotate;
});
} else if (m_lexer.consume_specific("skewX"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::SkewX> {
Transform::SkewX skew_x {};
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
skew_x.a = *maybe_a;
return skew_x;
});
} else if (m_lexer.consume_specific("skewY"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::SkewY> {
Transform::SkewY skew_y {};
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
skew_y.a = *maybe_a;
return skew_y;
});
} else if (m_lexer.consume_specific("matrix"sv)) {
maybe_transform = parse_function([&]() -> Optional<Transform::Matrix> {
Transform::Matrix matrix;
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
matrix.a = *maybe_a;
consume_comma_whitespace();
auto maybe_b = try_parse_number();
if (!maybe_b.has_value())
return {};
matrix.b = *maybe_b;
consume_comma_whitespace();
auto maybe_c = try_parse_number();
if (!maybe_c.has_value())
return {};
matrix.c = *maybe_c;
consume_comma_whitespace();
auto maybe_d = try_parse_number();
if (!maybe_d.has_value())
return {};
matrix.d = *maybe_d;
consume_comma_whitespace();
auto maybe_e = try_parse_number();
if (!maybe_e.has_value())
return {};
matrix.e = *maybe_e;
consume_comma_whitespace();
auto maybe_f = try_parse_number();
if (!maybe_f.has_value())
return {};
matrix.f = *maybe_f;
return matrix;
});
}
if (maybe_transform.has_value())
transform_list.append(*maybe_transform);
else
return {};
consume_comma_whitespace();
}
return transform_list;
}
bool AttributeParser::match_whitespace() const
{
if (done())
return false;
char c = ch();
return c == 0x9 || c == 0x20 || c == 0xa || c == 0xc || c == 0xd;
}
bool AttributeParser::match_comma_whitespace() const
{
return match_whitespace() || match(',');
}
bool AttributeParser::match_coordinate() const
{
return match_length();
}
bool AttributeParser::match_number() const
{
return match_length();
}
bool AttributeParser::match_length() const
{
return !done() && (isdigit(ch()) || ch() == '-' || ch() == '+' || ch() == '.');
}
}