blob: b0bf7e5043f391e992db8fa3e1b529e0f07f9129 [file] [log] [blame]
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ash/highlighter/highlighter_gesture_util.h"
#include <cmath>
#include "ash/components/fast_ink/fast_ink_points.h"
#include "base/numerics/math_constants.h"
namespace ash {
namespace {
constexpr float kHorizontalStrokeLengthThreshold = 20;
constexpr float kHorizontalStrokeThicknessThreshold = 2;
constexpr float kHorizontalStrokeFlatnessThreshold = 0.1;
constexpr double kClosedShapeSweepThreshold = base::kPiDouble * 2 * 0.8;
constexpr double kClosedShapeJiggleThreshold = 0.1;
bool DetectHorizontalStroke(const gfx::RectF& box,
const gfx::SizeF& pen_tip_size) {
return box.width() > kHorizontalStrokeLengthThreshold &&
box.height() <
pen_tip_size.height() * kHorizontalStrokeThicknessThreshold &&
box.height() < box.width() * kHorizontalStrokeFlatnessThreshold;
}
bool DetectClosedShape(const gfx::RectF& box,
const fast_ink::FastInkPoints& points) {
if (points.GetNumberOfPoints() < 3)
return false;
const gfx::PointF center = box.CenterPoint();
// Analyze vectors pointing from the center to each point.
// Compute the cumulative swept angle and count positive
// and negative angles separately.
double swept_angle = 0.0;
int positive = 0;
int negative = 0;
double prev_angle = 0.0;
bool has_prev_angle = false;
for (const auto& point : points.points()) {
const double angle =
atan2(point.location.y() - center.y(), point.location.x() - center.x());
if (has_prev_angle) {
double diff_angle = angle - prev_angle;
if (diff_angle > base::kPiDouble) {
diff_angle -= base::kPiDouble * 2;
} else if (diff_angle < -base::kPiDouble) {
diff_angle += base::kPiDouble * 2;
}
swept_angle += diff_angle;
if (diff_angle > 0)
positive++;
if (diff_angle < 0)
negative++;
} else {
has_prev_angle = true;
}
prev_angle = angle;
}
if (std::abs(swept_angle) < kClosedShapeSweepThreshold) {
// Has not swept enough of the full circle.
return false;
}
if (swept_angle > 0 && (static_cast<double>(negative) / positive) >
kClosedShapeJiggleThreshold) {
// Main direction is positive, but went too often in the negative direction.
return false;
}
if (swept_angle < 0 && (static_cast<double>(positive) / negative) >
kClosedShapeJiggleThreshold) {
// Main direction is negative, but went too often in the positive direction.
return false;
}
return true;
}
} // namespace
HighlighterGestureType DetectHighlighterGesture(
const gfx::RectF& box,
const gfx::SizeF& pen_tip_size,
const fast_ink::FastInkPoints& points) {
if (DetectHorizontalStroke(box, pen_tip_size))
return HighlighterGestureType::kHorizontalStroke;
if (DetectClosedShape(box, points))
return HighlighterGestureType::kClosedShape;
return HighlighterGestureType::kNotRecognized;
}
} // namespace ash