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LibWeb: Don't canonicalize linear easing function points until use time

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Canonicalization can require information that is only known after
compute time (i.e. resolved relative lengths within calcs).

This also allows us to get rid of the `had_explicit_input` flag and just
rely on whether Optional has a value
This commit is contained in:
Callum Law 2025-10-09 21:55:55 +13:00 committed by Sam Atkins
parent 95e26819d9
commit 91925db9ca
5 changed files with 67 additions and 67 deletions
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60
Libraries/LibWeb/CSS/EasingFunction.cpp
View File

@ -210,6 +210,61 @@ double StepsEasingFunction::evaluate_at(double input_progress, bool before_flag)
return current_step / jumps;
}
// https://drafts.csswg.org/css-easing/#linear-canonicalization
static Vector<LinearEasingFunction::ControlPoint> canonicalize_linear_easing_function_control_points(Vector<LinearEasingFunction::ControlPoint> control_points)
{
// To canonicalize a linear() function’s control points, perform the following:
Vector<LinearEasingFunction::ControlPoint> canonicalized_control_points = control_points;
// 1. If the first control point lacks an input progress value, set its input progress value to 0.
if (!canonicalized_control_points.first().input.has_value())
canonicalized_control_points.first().input = 0;
// 2. If the last control point lacks an input progress value, set its input progress value to 1.
if (!canonicalized_control_points.last().input.has_value())
canonicalized_control_points.last().input = 1;
// 3. If any control point has an input progress value that is less than
// the input progress value of any preceding control point,
// set its input progress value to the largest input progress value of any preceding control point.
double largest_input = 0;
for (auto& control_point : canonicalized_control_points) {
if (control_point.input.has_value()) {
if (control_point.input.value() < largest_input) {
control_point.input = largest_input;
} else {
largest_input = control_point.input.value();
}
}
}
// 4. If any control point still lacks an input progress value,
// then for each contiguous run of such control points,
// set their input progress values so that they are evenly spaced
// between the preceding and following control points with input progress values.
Optional<size_t> run_start_idx;
for (size_t idx = 0; idx < canonicalized_control_points.size(); idx++) {
auto& control_point = canonicalized_control_points[idx];
if (control_point.input.has_value() && run_start_idx.has_value()) {
// Note: this stop is immediately after a run
// set inputs of [start, idx-1] stops to be evenly spaced between start-1 and idx
auto start_input = canonicalized_control_points[run_start_idx.value() - 1].input.value();
auto end_input = canonicalized_control_points[idx].input.value();
auto run_stop_count = idx - run_start_idx.value() + 1;
auto delta = (end_input - start_input) / run_stop_count;
for (size_t run_idx = 0; run_idx < run_stop_count; run_idx++) {
canonicalized_control_points[run_idx + run_start_idx.value() - 1].input = start_input + delta * run_idx;
}
run_start_idx = {};
} else if (!control_point.input.has_value() && !run_start_idx.has_value()) {
// Note: this stop is the start of a run
run_start_idx = idx;
}
}
return canonicalized_control_points;
}
EasingFunction EasingFunction::from_style_value(StyleValue const& style_value)
{
if (style_value.is_easing()) {
@ -220,6 +275,11 @@ EasingFunction EasingFunction::from_style_value(StyleValue const& style_value)
for (auto const& control_point : linear.stops)
resolved_control_points.append({ control_point.input, control_point.output });
// https://drafts.csswg.org/css-easing-2/#funcdef-linear
// If an argument lacks a <percentage>, its input progress value is initially empty. This is corrected
// at used value time by linear() canonicalization.
resolved_control_points = canonicalize_linear_easing_function_control_points(resolved_control_points);
return LinearEasingFunction { resolved_control_points, linear.to_string(SerializationMode::ResolvedValue) };
},
[](EasingStyleValue::CubicBezier const& cubic_bezier) -> EasingFunction {

4
Libraries/LibWeb/CSS/Parser/ValueParsing.cpp
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@ -2931,9 +2931,9 @@ RefPtr<StyleValue const> Parser::parse_easing_value(TokenStream<ComponentValue>&
if (argument_tokens.has_next_token() || !output.has_value())
return nullptr;
stops.append({ output.value(), first_input, first_input.has_value() });
stops.append({ output.value(), first_input });
if (second_input.has_value())
stops.append({ output.value(), second_input, true });
stops.append({ output.value(), second_input });
}
if (stops.is_empty())

58
Libraries/LibWeb/CSS/StyleValues/EasingStyleValue.cpp
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@ -18,7 +18,7 @@ namespace Web::CSS {
// https://drafts.csswg.org/css-easing-1/#valdef-easing-function-linear
EasingStyleValue::Linear EasingStyleValue::Linear::identity()
{
static Linear linear { { { 0, {}, false }, { 1, {}, false } } };
static Linear linear { { { 0, {} }, { 1, {} } } };
return linear;
}
@ -60,60 +60,6 @@ EasingStyleValue::Steps EasingStyleValue::Steps::step_end()
return steps;
}
// https://drafts.csswg.org/css-easing/#linear-canonicalization
EasingStyleValue::Linear::Linear(Vector<EasingStyleValue::Linear::Stop> stops)
{
// To canonicalize a linear() function’s control points, perform the following:
// 1. If the first control point lacks an input progress value, set its input progress value to 0.
if (!stops.first().input.has_value())
stops.first().input = 0;
// 2. If the last control point lacks an input progress value, set its input progress value to 1.
if (!stops.last().input.has_value())
stops.last().input = 1;
// 3. If any control point has an input progress value that is less than
// the input progress value of any preceding control point,
// set its input progress value to the largest input progress value of any preceding control point.
double largest_input = 0;
for (auto& stop : stops) {
if (stop.input.has_value()) {
if (stop.input.value() < largest_input) {
stop.input = largest_input;
} else {
largest_input = stop.input.value();
}
}
}
// 4. If any control point still lacks an input progress value,
// then for each contiguous run of such control points,
// set their input progress values so that they are evenly spaced
// between the preceding and following control points with input progress values.
Optional<size_t> run_start_idx;
for (size_t idx = 0; idx < stops.size(); idx++) {
auto& stop = stops[idx];
if (stop.input.has_value() && run_start_idx.has_value()) {
// Note: this stop is immediately after a run
// set inputs of [start, idx-1] stops to be evenly spaced between start-1 and idx
auto start_input = stops[run_start_idx.value() - 1].input.value();
auto end_input = stops[idx].input.value();
auto run_stop_count = idx - run_start_idx.value() + 1;
auto delta = (end_input - start_input) / run_stop_count;
for (size_t run_idx = 0; run_idx < run_stop_count; run_idx++) {
stops[run_idx + run_start_idx.value() - 1].input = start_input + delta * run_idx;
}
run_start_idx = {};
} else if (!stop.input.has_value() && !run_start_idx.has_value()) {
// Note: this stop is the start of a run
run_start_idx = idx;
}
}
this->stops = move(stops);
}
// https://drafts.csswg.org/css-easing/#linear-easing-function-serializing
String EasingStyleValue::Linear::to_string(SerializationMode) const
{
@ -144,7 +90,7 @@ String EasingStyleValue::Linear::to_string(SerializationMode) const
// 2. If the control point originally lacked an input progress value, return s.
// 3. Otherwise, append " " (U+0020 SPACE) to s,
// then serialize the control point’s input progress value as a <percentage> and append it to s.
if (stop.had_explicit_input) {
if (stop.input.has_value()) {
builder.appendff(" {}%", stop.input.value() * 100);
}

6
Libraries/LibWeb/CSS/StyleValues/EasingStyleValue.h
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@ -25,10 +25,6 @@ public:
double output;
Optional<double> input;
// "NOTE: Serialization relies on whether or not an input progress value was originally supplied,
// so that information should be retained in the internal representation."
bool had_explicit_input;
bool operator==(Stop const&) const = default;
};
@ -37,8 +33,6 @@ public:
bool operator==(Linear const&) const = default;
String to_string(SerializationMode) const;
Linear(Vector<Stop> stops);
};
struct CubicBezier {

6
Tests/LibWeb/Text/expected/wpt-import/css/css-easing/linear-timing-functions-syntax.txt
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@ -2,13 +2,13 @@ Harness status: OK
Found 35 tests
12 Pass
23 Fail
13 Pass
22 Fail
Pass e.style['animation-timing-function'] = "linear(0 0%, 1 100%)" should set the property value
Pass e.style['animation-timing-function'] = "linear( 0 0%, 1 100% )" should set the property value
Fail e.style['animation-timing-function'] = "linear(0, 1)" should set the property value
Pass e.style['animation-timing-function'] = "linear(-10, -5, 0, 5, 10)" should set the property value
Fail e.style['animation-timing-function'] = "linear(-10 -10%, -5 -5%, 0, 5, 10)" should set the property value
Pass e.style['animation-timing-function'] = "linear(-10 -10%, -5 -5%, 0, 5, 10)" should set the property value
Fail e.style['animation-timing-function'] = "linear(0 calc(0%), 0 calc(100%))" should set the property value
Fail e.style['animation-timing-function'] = "linear(0 calc(50% - 50%), 0 calc(50% + 50%))" should set the property value
Fail e.style['animation-timing-function'] = "linear(0 calc(50%), 0 100%)" should set the property value