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// Copyright 2018 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/accessibility/magnifier/magnifier_utils.h"
#include <algorithm>
#include <cmath>
#include "ash/accessibility/magnifier/docked_magnifier_controller.h"
#include "ash/accessibility/magnifier/fullscreen_magnifier_controller.h"
#include "ash/shell.h"
#include "base/check_op.h"
#include "ui/aura/window.h"
#include "ui/aura/window_tree_host.h"
#include "ui/base/ime/ash/ime_bridge.h"
namespace ash {
namespace magnifier_utils {
namespace {
// Converts the given |scale| to an index such that
// `kMagnificationScaleFactor ^ index = scale`.
int IndexFromScale(float scale) {
// Remember from the Logarithm rules:
// logBar(Foo) = log2(Foo) / log2(Bar).
return std::round(std::log(scale) / std::log(kMagnificationScaleFactor));
}
} // namespace
float GetScaleFromScroll(float linear_offset,
float current_scale,
float min_scale,
float max_scale) {
DCHECK_GE(current_scale, min_scale);
DCHECK_LE(current_scale, max_scale);
// Convert the current scale back to its corresponding linear scale according
// to the formula `scale = (max - min) * offset ^ 2 + min`.
const float scale_range = max_scale - min_scale;
float linear_adjustment =
std::sqrt((current_scale - min_scale) / scale_range);
// Add the new linear offset.
linear_adjustment += linear_offset;
// Convert back to the exponential scale.
return scale_range * linear_adjustment * linear_adjustment + min_scale;
}
float GetNextMagnifierScaleValue(int delta_index,
float current_scale,
float min_scale,
float max_scale) {
const int current_index = IndexFromScale(current_scale);
const int new_scale_index = current_index + delta_index;
const float new_scale = std::pow(kMagnificationScaleFactor, new_scale_index);
return std::clamp(new_scale, min_scale, max_scale);
}
gfx::Rect GetViewportWidgetBoundsInRoot(aura::Window* root,
float screen_height_divisor) {
DCHECK(root);
DCHECK(root->IsRootWindow());
auto root_bounds = root->GetBoundsInRootWindow();
root_bounds.set_height(root_bounds.height() / screen_height_divisor);
return root_bounds;
}
void MaybeUpdateActiveMagnifierFocus(const gfx::Point& point_in_screen) {
DockedMagnifierController* docked_magnifier =
Shell::Get()->docked_magnifier_controller();
FullscreenMagnifierController* fullscreen_magnifier =
Shell::Get()->fullscreen_magnifier_controller();
if (docked_magnifier->GetEnabled())
docked_magnifier->CenterOnPoint(point_in_screen);
else if (fullscreen_magnifier->IsEnabled())
fullscreen_magnifier->CenterOnPoint(point_in_screen);
}
} // namespace magnifier_utils
} // namespace ash
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