Source/WebKit/UIProcess/API/wpe/TouchGestureController.cpp

/*
 * Copyright (C) 2017 Igalia S.L.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "TouchGestureController.h"

#include "WebKitSettings.h"
#include <WebCore/Scrollbar.h>

namespace WebKit {

// FIXME: These ought to be either configurable or derived from system
//        properties, such as screen size and pixel density.
static constexpr uint32_t scrollCaptureThreshold { 200 };
static constexpr uint32_t axisLockMovementThreshold { 8 };
static constexpr uint32_t axisLockActivationThreshold { 15 };
static constexpr uint32_t axisLockReleaseThreshold { 30 };

TouchGestureController::EventVariant TouchGestureController::handleEvent(const struct wpe_input_touch_event_raw* touchPoint)
{
    switch (touchPoint->type) {
    case wpe_input_touch_event_type_down:
        // Start of the touch interaction, first possible event is a mouse click.
        m_gesturedEvent = GesturedEvent::Click;
        m_start = { true, touchPoint->time, touchPoint->x, touchPoint->y };
        m_offset = { touchPoint->x, touchPoint->y };
        m_xAxisLockBroken = m_yAxisLockBroken = false;
        break;
    case wpe_input_touch_event_type_motion:
    {
        switch (m_gesturedEvent) {
        case GesturedEvent::None:
            break;
        case GesturedEvent::Click:
        {
            // If currently only gesturing a click, determine if the touch has progressed
            // so far that it should become a scrolling gesture.
            int32_t deltaX = touchPoint->x - m_start.x;
            int32_t deltaY = touchPoint->y - m_start.y;
            uint32_t deltaTime = touchPoint->time - m_start.time;

            int pixelsPerLineStep = WebCore::Scrollbar::pixelsPerLineStep();
            bool overThreshold = std::abs(deltaX) >= pixelsPerLineStep
                || std::abs(deltaY) >= pixelsPerLineStep
                || deltaTime >= scrollCaptureThreshold;
            if (!overThreshold)
                break;

            // Over threshold, bump the gestured event and directly fall through to handling it.
            m_gesturedEvent = GesturedEvent::Axis;
            FALLTHROUGH;
        }
        case GesturedEvent::Axis:
        {
            AxisEvent generatedEvent;
            generatedEvent.phase = WebWheelEvent::Phase::PhaseChanged;

#if WPE_CHECK_VERSION(1, 5, 0)
            generatedEvent.event.base = {
                static_cast<enum wpe_input_axis_event_type>(wpe_input_axis_event_type_mask_2d | wpe_input_axis_event_type_motion_smooth),
                touchPoint->time, m_start.x, m_start.y,
                0, 0, 0,
            };

            uint32_t xOffset = std::abs(touchPoint->x - m_start.x);
            uint32_t yOffset = std::abs(touchPoint->y - m_start.y);

            if (xOffset >= axisLockReleaseThreshold)
                m_xAxisLockBroken = true;
            if (yOffset >= axisLockReleaseThreshold)
                m_yAxisLockBroken = true;

            if (xOffset >= axisLockMovementThreshold && yOffset >= axisLockMovementThreshold && xOffset < axisLockActivationThreshold && yOffset < axisLockActivationThreshold) {
                m_xAxisLockBroken = true;
                m_yAxisLockBroken = true;
            }

            generatedEvent.event.x_axis = (m_xAxisLockBroken || yOffset < axisLockActivationThreshold) ?  -(m_offset.x - touchPoint->x) : 0;
            generatedEvent.event.y_axis = (m_yAxisLockBroken || xOffset < axisLockActivationThreshold) ?  -(m_offset.y - touchPoint->y) : 0;
#else
            generatedEvent.event = {
                wpe_input_axis_event_type_motion,
                touchPoint->time, m_start.x, m_start.y,
                2, (touchPoint->y - m_offset.y), 0
            };
#endif
            m_offset.x = touchPoint->x;
            m_offset.y = touchPoint->y;
            return generatedEvent;
        }
        }
        break;
    }
    case wpe_input_touch_event_type_up:
    {
        switch (m_gesturedEvent) {
        case GesturedEvent::None:
            break;
        case GesturedEvent::Click:
        {
            m_gesturedEvent = GesturedEvent::None;

            ClickEvent generatedEvent;
            generatedEvent.event = {
                wpe_input_pointer_event_type_null, touchPoint->time, touchPoint->x, touchPoint->y,
                0, 0, 0,
            };
            return generatedEvent;
        }
        case GesturedEvent::Axis:
        {
            m_gesturedEvent = GesturedEvent::None;

            AxisEvent generatedEvent;
            generatedEvent.phase = WebWheelEvent::Phase::PhaseEnded;

#if WPE_CHECK_VERSION(1, 5, 0)
            generatedEvent.event.base = {
                static_cast<enum wpe_input_axis_event_type>(wpe_input_axis_event_type_mask_2d | wpe_input_axis_event_type_motion_smooth),
                touchPoint->time, m_start.x, m_start.y,
                0, 0, 0
            };
            generatedEvent.event.x_axis = generatedEvent.event.y_axis = 0;
#else
            generatedEvent.event = {
                wpe_input_axis_event_type_motion,
                touchPoint->time, m_start.x, m_start.y,
                0, 0, 0
            };
#endif
            m_offset.x = m_offset.y = 0;
            return generatedEvent;
        }
        }
        break;
    }
    default:
        break;
    }

    return NoEvent { };
}

} // namespace WebKit