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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ash/ambient/ui/jitter_calculator.h"
#include <utility>
#include "base/check.h"
#include "base/check_op.h"
#include "base/rand_util.h"
namespace ash {
JitterCalculator::JitterCalculator(AmbientJitterConfig config)
: JitterCalculator(std::move(config),
base::BindRepeating(&base::RandInt, 0, 1)) {}
JitterCalculator::JitterCalculator(
AmbientJitterConfig config,
RandomBinaryGenerator random_binary_generator)
: config_(std::move(config)),
random_binary_generator_(std::move(random_binary_generator)) {
DCHECK_GE(config_.step_size, 0);
DCHECK_LE(config_.x_min_translation, 0);
DCHECK_GE(config_.x_max_translation, 0);
DCHECK_LE(config_.y_min_translation, 0);
DCHECK_GE(config_.y_max_translation, 0);
DCHECK(random_binary_generator_);
}
JitterCalculator::~JitterCalculator() = default;
gfx::Vector2d JitterCalculator::Calculate() {
AssertCurrentTranslationWithinBounds();
// Move the translation point randomly one step on each x/y direction.
int x_increment = config_.step_size * random_binary_generator_.Run();
int y_increment = x_increment == 0
? config_.step_size
: config_.step_size * random_binary_generator_.Run();
current_translation_.Add(gfx::Vector2d(translate_x_direction * x_increment,
translate_y_direction * y_increment));
// If the translation point is out of bounds, reset it within bounds and
// reverse the direction.
if (current_translation_.x() < config_.x_min_translation) {
translate_x_direction = 1;
current_translation_.set_x(config_.x_min_translation);
} else if (current_translation_.x() > config_.x_max_translation) {
translate_x_direction = -1;
current_translation_.set_x(config_.x_max_translation);
}
if (current_translation_.y() > config_.y_max_translation) {
translate_y_direction = -1;
current_translation_.set_y(config_.y_max_translation);
} else if (current_translation_.y() < config_.y_min_translation) {
translate_y_direction = 1;
current_translation_.set_y(config_.y_min_translation);
}
AssertCurrentTranslationWithinBounds();
return current_translation_;
}
void JitterCalculator::AssertCurrentTranslationWithinBounds() const {
DCHECK_LE(current_translation_.x(), config_.x_max_translation);
DCHECK_GE(current_translation_.x(), config_.x_min_translation);
DCHECK_LE(current_translation_.y(), config_.y_max_translation);
DCHECK_GE(current_translation_.y(), config_.y_min_translation);
}
} // namespace ash
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