8c9d3b30cf
Apple Clang doesn't like this, rather than waiting for their version of random-clang-commit-to-call-a-release to catch up with llvm trunk, just work around the issue. Fixes #186.
275 lines
11 KiB
C++
275 lines
11 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.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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namespace Web::CSS {
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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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double EasingStyleValue::Function::evaluate_at(double input_progress, bool before_flag) 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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return visit(
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[&](Linear const&) { return input_progress; },
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[&](CubicBezier const& bezier) {
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auto const& [x1, y1, x2, y2, cached_x_samples] = bezier;
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// https://www.w3.org/TR/css-easing-1/#cubic-bezier-algo
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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 (x1 > 0.0)
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return y1 / 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 (x2 > 0.0)
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return y2 / 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 (x2 < 1.0)
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return (1.0 - y2) / (1.0 - 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 (x1 < 1.0)
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return (1.0 - y1) / (1.0 - 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(bezier.x1, bezier.x2, t);
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auto y = cubic_bezier_at(bezier.y1, bezier.y2, t);
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return CubicBezier::CachedSample { x, y, t };
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};
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if (cached_x_samples.is_empty())
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cached_x_samples.append(solve(0.));
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size_t nearby_index = 0;
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if (auto found = binary_search(cached_x_samples, x, &nearby_index, [](auto x, auto& sample) {
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if (x > sample.x)
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return 1;
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if (x < sample.x)
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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 == cached_x_samples.size() || nearby_index + 1 == cached_x_samples.size()) {
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// Produce more samples until we have enough.
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auto last_t = cached_x_samples.last().t;
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auto last_x = 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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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(cached_x_samples, x, &nearby_index, [](auto x, auto& sample) {
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if (x > sample.x)
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return 1;
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if (x < sample.x)
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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 = cached_x_samples[nearby_index];
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auto& sample2 = 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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[&](Steps const& steps) {
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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 [number_of_steps, position] = steps;
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auto current_step = floor(input_progress * number_of_steps);
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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::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 * number_of_steps;
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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 = steps.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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}
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String EasingStyleValue::Function::to_string() const
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{
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StringBuilder builder;
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visit(
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[&](Linear const& linear) {
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builder.append("linear"sv);
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if (!linear.stops.is_empty()) {
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builder.append('(');
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bool first = true;
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for (auto const& stop : linear.stops) {
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if (!first)
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builder.append(", "sv);
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first = false;
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builder.appendff("{}"sv, stop.offset);
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if (stop.position.has_value())
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builder.appendff(" {}"sv, stop.position.value());
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}
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builder.append(')');
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}
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},
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[&](CubicBezier const& bezier) {
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if (bezier == CubicBezier::ease()) {
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builder.append("ease"sv);
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} else if (bezier == CubicBezier::ease_in()) {
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builder.append("ease-in"sv);
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} else if (bezier == CubicBezier::ease_out()) {
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builder.append("ease-out"sv);
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} else if (bezier == CubicBezier::ease_in_out()) {
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builder.append("ease-in-out"sv);
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} else {
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builder.appendff("cubic-bezier({}, {}, {}, {})", bezier.x1, bezier.y1, bezier.x2, bezier.y2);
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}
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},
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[&](Steps const& steps) {
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if (steps == Steps::step_start()) {
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builder.append("step-start"sv);
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} else if (steps == Steps::step_end()) {
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builder.append("step-end"sv);
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} else {
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auto position = [&] -> Optional<StringView> {
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switch (steps.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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if (position.has_value()) {
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builder.appendff("steps({}, {})", steps.number_of_intervals, position.value());
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} else {
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builder.appendff("steps({})", steps.number_of_intervals);
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}
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}
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});
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return MUST(builder.to_string());
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}
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}
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