chromium/ui/events/gesture_detection/snap_scroll_controller.cc

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/events/gesture_detection/snap_scroll_controller.h"

#include <algorithm>
#include <cmath>

#include "ui/events/velocity_tracker/motion_event.h"

namespace ui {
namespace {

// Minimum ratio between initial X and Y motion to allow snapping.
const float kMinSnapRatio = …;

// Size of the snap rail relative to the initial snap bound threshold.
const float kSnapBoundToChannelMultiplier = …;

float CalculateChannelDistance(float snap_bound,
                               const gfx::SizeF& display_size) { … }

}  // namespace

SnapScrollController::SnapScrollController(const gfx::SizeF& display_size)
    : … { … }

void SnapScrollController::SetSnapScrollMode(
    const MotionEvent& event,
    bool is_scale_gesture_detection_in_progress,
    float slop_distance) { … }

void SnapScrollController::UpdateSnapScrollMode(float distance_x,
                                                float distance_y,
                                                float slop_distance) { … }

bool SnapScrollController::IsSnapVertical() const { … }

bool SnapScrollController::IsSnapHorizontal() const { … }

bool SnapScrollController::IsSnappingScrolls() const { … }

}  // namespace ui