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456 lines
18 KiB
C++
456 lines
18 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
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* Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
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* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
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* Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
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* Copyright (c) 2023, Ali Mohammad Pur <mpfard@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "EasingStyleValue.h"
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#include <AK/BinarySearch.h>
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#include <AK/StringBuilder.h>
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#include <LibWeb/CSS/StyleValues/IntegerStyleValue.h>
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namespace Web::CSS {
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// https://drafts.csswg.org/css-easing-1/#valdef-easing-function-linear
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EasingStyleValue::Linear EasingStyleValue::Linear::identity()
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{
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static Linear linear { { { 0, {}, false }, { 1, {}, false } } };
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return linear;
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}
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// NOTE: Magic cubic bezier values from https://www.w3.org/TR/css-easing-1/#valdef-cubic-bezier-easing-function-ease
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EasingStyleValue::CubicBezier EasingStyleValue::CubicBezier::ease()
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{
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static CubicBezier bezier { 0.25, 0.1, 0.25, 1.0 };
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return bezier;
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}
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EasingStyleValue::CubicBezier EasingStyleValue::CubicBezier::ease_in()
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{
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static CubicBezier bezier { 0.42, 0.0, 1.0, 1.0 };
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return bezier;
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}
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EasingStyleValue::CubicBezier EasingStyleValue::CubicBezier::ease_out()
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{
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static CubicBezier bezier { 0.0, 0.0, 0.58, 1.0 };
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return bezier;
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}
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EasingStyleValue::CubicBezier EasingStyleValue::CubicBezier::ease_in_out()
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{
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static CubicBezier bezier { 0.42, 0.0, 0.58, 1.0 };
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return bezier;
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}
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EasingStyleValue::Steps EasingStyleValue::Steps::step_start()
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{
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static Steps steps { 1, Steps::Position::Start };
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return steps;
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}
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EasingStyleValue::Steps EasingStyleValue::Steps::step_end()
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{
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static Steps steps { 1, Steps::Position::End };
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return steps;
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}
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bool EasingStyleValue::CubicBezier::operator==(Web::CSS::EasingStyleValue::CubicBezier const& other) const
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{
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return x1 == other.x1 && y1 == other.y1 && x2 == other.x2 && y2 == other.y2;
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}
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// https://drafts.csswg.org/css-easing/#linear-canonicalization
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EasingStyleValue::Linear::Linear(Vector<EasingStyleValue::Linear::Stop> stops)
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{
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// To canonicalize a linear() function’s control points, perform the following:
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// 1. If the first control point lacks an input progress value, set its input progress value to 0.
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if (!stops.first().input.has_value())
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stops.first().input = 0;
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// 2. If the last control point lacks an input progress value, set its input progress value to 1.
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if (!stops.last().input.has_value())
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stops.last().input = 1;
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// 3. If any control point has an input progress value that is less than
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// the input progress value of any preceding control point,
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// set its input progress value to the largest input progress value of any preceding control point.
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double largest_input = 0;
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for (auto& stop : stops) {
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if (stop.input.has_value()) {
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if (stop.input.value() < largest_input) {
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stop.input = largest_input;
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} else {
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largest_input = stop.input.value();
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}
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}
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}
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// 4. If any control point still lacks an input progress value,
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// then for each contiguous run of such control points,
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// set their input progress values so that they are evenly spaced
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// between the preceding and following control points with input progress values.
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Optional<size_t> run_start_idx;
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for (size_t idx = 0; idx < stops.size(); idx++) {
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auto& stop = stops[idx];
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if (stop.input.has_value() && run_start_idx.has_value()) {
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// Note: this stop is immediately after a run
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// set inputs of [start, idx-1] stops to be evenly spaced between start-1 and idx
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auto start_input = stops[run_start_idx.value() - 1].input.value();
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auto end_input = stops[idx].input.value();
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auto run_stop_count = idx - run_start_idx.value() + 1;
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auto delta = (end_input - start_input) / run_stop_count;
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for (size_t run_idx = 0; run_idx < run_stop_count; run_idx++) {
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stops[run_idx + run_start_idx.value() - 1].input = start_input + delta * run_idx;
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}
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run_start_idx = {};
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} else if (!stop.input.has_value() && !run_start_idx.has_value()) {
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// Note: this stop is the start of a run
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run_start_idx = idx;
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}
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}
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this->stops = move(stops);
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}
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// https://drafts.csswg.org/css-easing/#linear-easing-function-output
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double EasingStyleValue::Linear::evaluate_at(double input_progress, bool before_flag) const
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{
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// To calculate linear easing output progress for a given linear easing function func,
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// an input progress value inputProgress, and an optional before flag (defaulting to false),
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// perform the following:
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// 1. Let points be func’s control points.
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// 2. If points holds only a single item, return the output progress value of that item.
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if (stops.size() == 1)
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return stops[0].output;
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// 3. If inputProgress matches the input progress value of the first point in points,
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// and the before flag is true, return the first point’s output progress value.
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if (input_progress == stops[0].input.value() && before_flag)
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return stops[0].output;
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// 4. If inputProgress matches the input progress value of at least one point in points,
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// return the output progress value of the last such point.
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auto maybe_match = stops.last_matching([&](auto& stop) { return input_progress == stop.input.value(); });
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if (maybe_match.has_value())
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return maybe_match->output;
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// 5. Otherwise, find two control points in points, A and B, which will be used for interpolation:
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Stop A;
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Stop B;
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if (input_progress < stops[0].input.value()) {
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// 1. If inputProgress is smaller than any input progress value in points,
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// let A and B be the first two items in points.
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// If A and B have the same input progress value, return A’s output progress value.
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A = stops[0];
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B = stops[1];
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if (A.input == B.input)
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return A.output;
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} else if (input_progress > stops.last().input.value()) {
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// 2. If inputProgress is larger than any input progress value in points,
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// let A and B be the last two items in points.
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// If A and B have the same input progress value, return B’s output progress value.
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A = stops[stops.size() - 2];
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B = stops[stops.size() - 1];
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if (A.input == B.input)
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return B.output;
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} else {
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// 3. Otherwise, let A be the last control point whose input progress value is smaller than inputProgress,
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// and let B be the first control point whose input progress value is larger than inputProgress.
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A = stops.last_matching([&](auto& stop) { return stop.input.value() < input_progress; }).value();
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B = stops.first_matching([&](auto& stop) { return stop.input.value() > input_progress; }).value();
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}
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// 6. Linearly interpolate (or extrapolate) inputProgress along the line defined by A and B, and return the result.
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auto factor = (input_progress - A.input.value()) / (B.input.value() - A.input.value());
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return A.output + factor * (B.output - A.output);
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}
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// https://drafts.csswg.org/css-easing/#linear-easing-function-serializing
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String EasingStyleValue::Linear::to_string(SerializationMode) const
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{
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// The linear keyword is serialized as itself.
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if (*this == identity())
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return "linear"_string;
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// To serialize a linear() function:
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// 1. Let s be the string "linear(".
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StringBuilder builder;
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builder.append("linear("sv);
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// 2. Serialize each control point of the function,
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// concatenate the results using the separator ", ",
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// and append the result to s.
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bool first = true;
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for (auto stop : stops) {
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if (first) {
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first = false;
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} else {
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builder.append(", "sv);
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}
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// To serialize a linear() control point:
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// 1. Let s be the serialization, as a <number>, of the control point’s output progress value.
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builder.appendff("{}", stop.output);
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// 2. If the control point originally lacked an input progress value, return s.
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// 3. Otherwise, append " " (U+0020 SPACE) to s,
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// then serialize the control point’s input progress value as a <percentage> and append it to s.
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if (stop.had_explicit_input) {
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builder.appendff(" {}%", stop.input.value() * 100);
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}
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// 4. Return s.
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}
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// 4. Append ")" to s, and return it.
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builder.append(')');
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return MUST(builder.to_string());
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}
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double EasingStyleValue::CubicBezier::evaluate_at(double input_progress, bool) const
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{
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constexpr static auto cubic_bezier_at = [](double x1, double x2, double t) {
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auto a = 1.0 - 3.0 * x2 + 3.0 * x1;
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auto b = 3.0 * x2 - 6.0 * x1;
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auto c = 3.0 * x1;
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auto t2 = t * t;
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auto t3 = t2 * t;
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return (a * t3) + (b * t2) + (c * t);
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};
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// https://www.w3.org/TR/css-easing-1/#cubic-bezier-algo
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auto resolved_x1 = clamp(x1.resolved({}).value_or(0.0), 0.0, 1.0);
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auto resolved_y1 = y1.resolved({}).value_or(0.0);
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auto resolved_x2 = clamp(x2.resolved({}).value_or(0.0), 0.0, 1.0);
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auto resolved_y2 = y2.resolved({}).value_or(0.0);
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// For input progress values outside the range [0, 1], the curve is extended infinitely using tangent of the curve
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// at the closest endpoint as follows:
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// - For input progress values less than zero,
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if (input_progress < 0.0) {
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// 1. If the x value of P1 is greater than zero, use a straight line that passes through P1 and P0 as the
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// tangent.
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if (resolved_x1 > 0.0)
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return resolved_y1 / resolved_x1 * input_progress;
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// 2. Otherwise, if the x value of P2 is greater than zero, use a straight line that passes through P2 and P0 as
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// the tangent.
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if (resolved_x2 > 0.0)
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return resolved_y2 / resolved_x2 * input_progress;
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// 3. Otherwise, let the output progress value be zero for all input progress values in the range [-∞, 0).
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return 0.0;
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}
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// - For input progress values greater than one,
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if (input_progress > 1.0) {
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// 1. If the x value of P2 is less than one, use a straight line that passes through P2 and P3 as the tangent.
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if (resolved_x2 < 1.0)
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return (1.0 - resolved_y2) / (1.0 - resolved_x2) * (input_progress - 1.0) + 1.0;
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// 2. Otherwise, if the x value of P1 is less than one, use a straight line that passes through P1 and P3 as the
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// tangent.
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if (resolved_x1 < 1.0)
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return (1.0 - resolved_y1) / (1.0 - resolved_x1) * (input_progress - 1.0) + 1.0;
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// 3. Otherwise, let the output progress value be one for all input progress values in the range (1, ∞].
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return 1.0;
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}
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// Note: The spec does not specify the precise algorithm for calculating values in the range [0, 1]:
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// "The evaluation of this curve is covered in many sources such as [FUND-COMP-GRAPHICS]."
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auto x = input_progress;
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auto solve = [&](auto t) {
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auto x = cubic_bezier_at(resolved_x1, resolved_x2, t);
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auto y = cubic_bezier_at(resolved_y1, resolved_y2, t);
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return CubicBezier::CachedSample { x, y, t };
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};
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if (m_cached_x_samples.is_empty())
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m_cached_x_samples.append(solve(0.));
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size_t nearby_index = 0;
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if (auto found = binary_search(m_cached_x_samples, x, &nearby_index, [](auto x, auto& sample) {
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if (x - sample.x >= NumericLimits<double>::epsilon())
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return 1;
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if (x - sample.x <= NumericLimits<double>::epsilon())
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return -1;
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return 0;
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}))
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return found->y;
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if (nearby_index == m_cached_x_samples.size() || nearby_index + 1 == m_cached_x_samples.size()) {
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// Produce more samples until we have enough.
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auto last_t = m_cached_x_samples.last().t;
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auto last_x = m_cached_x_samples.last().x;
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while (last_x <= x && last_t < 1.0) {
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last_t += 1. / 60.;
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auto solution = solve(last_t);
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m_cached_x_samples.append(solution);
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last_x = solution.x;
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}
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if (auto found = binary_search(m_cached_x_samples, x, &nearby_index, [](auto x, auto& sample) {
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if (x - sample.x >= NumericLimits<double>::epsilon())
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return 1;
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if (x - sample.x <= NumericLimits<double>::epsilon())
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return -1;
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return 0;
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}))
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return found->y;
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}
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// We have two samples on either side of the x value we want, so we can linearly interpolate between them.
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auto& sample1 = m_cached_x_samples[nearby_index];
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auto& sample2 = m_cached_x_samples[nearby_index + 1];
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auto factor = (x - sample1.x) / (sample2.x - sample1.x);
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return sample1.y + factor * (sample2.y - sample1.y);
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}
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// https://drafts.csswg.org/css-easing/#bezier-serialization
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String EasingStyleValue::CubicBezier::to_string(SerializationMode mode) const
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{
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StringBuilder builder;
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if (*this == CubicBezier::ease()) {
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builder.append("ease"sv);
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} else if (*this == CubicBezier::ease_in()) {
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builder.append("ease-in"sv);
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} else if (*this == CubicBezier::ease_out()) {
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builder.append("ease-out"sv);
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} else if (*this == CubicBezier::ease_in_out()) {
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builder.append("ease-in-out"sv);
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} else {
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auto x1_value = x1;
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auto y1_value = y1;
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auto x2_value = x2;
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auto y2_value = y2;
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if (mode == SerializationMode::ResolvedValue) {
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x1_value = clamp(x1_value.resolved({}).value_or(0.0), 0.0, 1.0);
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x2_value = clamp(x2_value.resolved({}).value_or(0.0), 0.0, 1.0);
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y1_value = y1_value.resolved({}).value_or(0.0);
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y2_value = y2_value.resolved({}).value_or(0.0);
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}
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builder.appendff("cubic-bezier({}, {}, {}, {})",
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x1_value.to_string(mode), y1_value.to_string(mode), x2_value.to_string(mode), y2_value.to_string(mode));
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}
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return MUST(builder.to_string());
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}
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double EasingStyleValue::Steps::evaluate_at(double input_progress, bool before_flag) const
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{
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// https://www.w3.org/TR/css-easing-1/#step-easing-algo
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// 1. Calculate the current step as floor(input progress value × steps).
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auto resolved_number_of_intervals = number_of_intervals.resolved({}).value_or(1);
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resolved_number_of_intervals = max(resolved_number_of_intervals, position == Steps::Position::JumpNone ? 2 : 1);
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auto current_step = floor(input_progress * resolved_number_of_intervals);
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// 2. If the step position property is one of:
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// - jump-start,
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// - jump-both,
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// increment current step by one.
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if (position == Steps::Position::JumpStart || position == Steps::Position::Start || position == Steps::Position::JumpBoth)
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current_step += 1;
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// 3. If both of the following conditions are true:
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// - the before flag is set, and
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// - input progress value × steps mod 1 equals zero (that is, if input progress value × steps is integral), then
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// decrement current step by one.
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auto step_progress = input_progress * resolved_number_of_intervals;
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if (before_flag && trunc(step_progress) == step_progress)
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current_step -= 1;
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// 4. If input progress value ≥ 0 and current step < 0, let current step be zero.
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if (input_progress >= 0.0 && current_step < 0.0)
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current_step = 0.0;
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// 5. Calculate jumps based on the step position as follows:
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// jump-start or jump-end -> steps
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// jump-none -> steps - 1
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// jump-both -> steps + 1
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auto jumps = resolved_number_of_intervals;
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if (position == Steps::Position::JumpNone) {
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jumps--;
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} else if (position == Steps::Position::JumpBoth) {
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jumps++;
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}
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// 6. If input progress value ≤ 1 and current step > jumps, let current step be jumps.
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if (input_progress <= 1.0 && current_step > jumps)
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current_step = jumps;
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// 7. The output progress value is current step / jumps.
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return current_step / jumps;
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}
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// https://drafts.csswg.org/css-easing/#steps-serialization
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String EasingStyleValue::Steps::to_string(SerializationMode mode) const
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{
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StringBuilder builder;
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// Unlike the other easing function keywords, step-start and step-end do not serialize as themselves.
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// Instead, they serialize as "steps(1, start)" and "steps(1)", respectively.
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if (*this == Steps::step_start()) {
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builder.append("steps(1, start)"sv);
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} else if (*this == Steps::step_end()) {
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builder.append("steps(1)"sv);
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} else {
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auto position = [&] -> Optional<StringView> {
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switch (this->position) {
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case Steps::Position::JumpStart:
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return "jump-start"sv;
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case Steps::Position::JumpNone:
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return "jump-none"sv;
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case Steps::Position::JumpBoth:
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return "jump-both"sv;
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case Steps::Position::Start:
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return "start"sv;
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default:
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return {};
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}
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}();
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auto intervals = number_of_intervals;
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if (mode == SerializationMode::ResolvedValue) {
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auto resolved_value = number_of_intervals.resolved({}).value_or(1);
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intervals = max(resolved_value, this->position == Steps::Position::JumpNone ? 2 : 1);
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}
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if (position.has_value()) {
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builder.appendff("steps({}, {})", intervals.to_string(mode), position.value());
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} else {
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builder.appendff("steps({})", intervals.to_string(mode));
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}
|
||
}
|
||
return MUST(builder.to_string());
|
||
}
|
||
|
||
double EasingStyleValue::Function::evaluate_at(double input_progress, bool before_flag) const
|
||
{
|
||
return visit(
|
||
[&](auto const& curve) {
|
||
return curve.evaluate_at(input_progress, before_flag);
|
||
});
|
||
}
|
||
|
||
String EasingStyleValue::Function::to_string(SerializationMode mode) const
|
||
{
|
||
return visit(
|
||
[&](auto const& curve) {
|
||
return curve.to_string(mode);
|
||
});
|
||
}
|
||
|
||
}
|