qdnd.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qdnd_p.h"
 
#include "qguiapplication.h"
#include <ctype.h>
#include <qpa/qplatformdrag.h>
#include <qpa/qplatformintegration.h>
#include <private/qguiapplication_p.h>
 
QT_BEGIN_NAMESPACE
 
// the universe's only drag manager
QDragManager *QDragManager::m_instance = nullptr;
 
QDragManager::QDragManager()
    : QObject(qApp), m_currentDropTarget(nullptr),
      m_platformDrag(QGuiApplicationPrivate::platformIntegration()->drag()),
      m_object(nullptr)
{
    Q_ASSERT(!m_instance);
}
 
QDragManager::~QDragManager()
{
    m_instance = nullptr;
}
 
QDragManager *QDragManager::self()
{
    if (!m_instance && !QGuiApplication::closingDown())
        m_instance = new QDragManager;
    return m_instance;
}
 
QObject *QDragManager::source() const
{
    if (m_object)
        return m_object->source();
    return nullptr;
}
 
void QDragManager::setCurrentTarget(QObject *target, bool dropped)
{
    if (m_currentDropTarget == target)
        return;
 
    m_currentDropTarget = target;
    if (!dropped && m_object) {
        m_object->d_func()->target = target;
        emit m_object->targetChanged(target);
    }
}
 
QObject *QDragManager::currentTarget() const
{
    return m_currentDropTarget;
}
 
Qt::DropAction QDragManager::drag(QDrag *o)
{
    if (!o || m_object == o)
         return Qt::IgnoreAction;
 
    if (!m_platformDrag || !o->source()) {
        o->deleteLater();
        return Qt::IgnoreAction;
    }
 
    if (m_object) {
        qWarning("QDragManager::drag in possibly invalid state");
        return Qt::IgnoreAction;
    }
 
    m_object = o;
 
    m_object->d_func()->target = nullptr;
 
    QGuiApplicationPrivate::instance()->notifyDragStarted(m_object.data());
    const Qt::DropAction result = m_platformDrag->drag(m_object);
    if (!m_object.isNull() && !m_platformDrag->ownsDragObject())
        m_object->deleteLater();
 
    m_object.clear();
    return result;
}
 
QT_END_NAMESPACE
 
#include "moc_qdnd_p.cpp"