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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
commit 91925db9ca
Notes: github-actions[bot] 2025-10-20 10:29:40 +00:00
5 changed files with 67 additions and 67 deletions
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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);
}