1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtGui module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
39
40#include "qdnd_p.h"
41
42#include "qguiapplication.h"
43#include <ctype.h>
44#include <qpa/qplatformdrag.h>
45#include <qpa/qplatformintegration.h>
46#include <private/qguiapplication_p.h>
47
48QT_BEGIN_NAMESPACE
49
50// the universe's only drag manager
51QDragManager *QDragManager::m_instance = nullptr;
52
53QDragManager::QDragManager()
54 : QObject(qApp), m_currentDropTarget(nullptr),
55 m_platformDrag(QGuiApplicationPrivate::platformIntegration()->drag()),
56 m_object(nullptr)
57{
58 Q_ASSERT(!m_instance);
59}
60
61QDragManager::~QDragManager()
62{
63 m_instance = nullptr;
64}
65
66QDragManager *QDragManager::self()
67{
68 if (!m_instance && !QGuiApplication::closingDown())
69 m_instance = new QDragManager;
70 return m_instance;
71}
72
73QObject *QDragManager::source() const
74{
75 if (m_object)
76 return m_object->source();
77 return nullptr;
78}
79
80void QDragManager::setCurrentTarget(QObject *target, bool dropped)
81{
82 if (m_currentDropTarget == target)
83 return;
84
85 m_currentDropTarget = target;
86 if (!dropped && m_object) {
87 m_object->d_func()->target = target;
88 emit m_object->targetChanged(newTarget: target);
89 }
90}
91
92QObject *QDragManager::currentTarget() const
93{
94 return m_currentDropTarget;
95}
96
97Qt::DropAction QDragManager::drag(QDrag *o)
98{
99 if (!o || m_object == o)
100 return Qt::IgnoreAction;
101
102 if (!m_platformDrag || !o->source()) {
103 o->deleteLater();
104 return Qt::IgnoreAction;
105 }
106
107 if (m_object) {
108 qWarning(msg: "QDragManager::drag in possibly invalid state");
109 return Qt::IgnoreAction;
110 }
111
112 m_object = o;
113
114 m_object->d_func()->target = nullptr;
115
116 QGuiApplicationPrivate::instance()->notifyDragStarted(m_object.data());
117 const Qt::DropAction result = m_platformDrag->drag(m_drag: m_object);
118 if (!m_object.isNull() && !m_platformDrag->ownsDragObject())
119 m_object->deleteLater();
120
121 m_object.clear();
122 return result;
123}
124
125QT_END_NAMESPACE
126

source code of qtbase/src/gui/kernel/qdnd.cpp