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 examples of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:BSD$
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** BSD License Usage
18** Alternatively, you may use this file under the terms of the BSD license
19** as follows:
20**
21** "Redistribution and use in source and binary forms, with or without
22** modification, are permitted provided that the following conditions are
23** met:
24** * Redistributions of source code must retain the above copyright
25** notice, this list of conditions and the following disclaimer.
26** * Redistributions in binary form must reproduce the above copyright
27** notice, this list of conditions and the following disclaimer in
28** the documentation and/or other materials provided with the
29** distribution.
30** * Neither the name of The Qt Company Ltd nor the names of its
31** contributors may be used to endorse or promote products derived
32** from this software without specific prior written permission.
33**
34**
35** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
38** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
39** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
42** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
43** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
44** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
46**
47** $QT_END_LICENSE$
48**
49****************************************************************************/
50
51#include "pieceslist.h"
52
53#include <QDrag>
54#include <QDragEnterEvent>
55#include <QMimeData>
56
57PiecesList::PiecesList(int pieceSize, QWidget *parent)
58 : QListWidget(parent), m_PieceSize(pieceSize)
59{
60 setDragEnabled(true);
61 setViewMode(QListView::IconMode);
62 setIconSize(QSize(m_PieceSize, m_PieceSize));
63 setSpacing(10);
64 setAcceptDrops(true);
65 setDropIndicatorShown(true);
66}
67
68void PiecesList::dragEnterEvent(QDragEnterEvent *event)
69{
70 if (event->mimeData()->hasFormat(mimetype: PiecesList::puzzleMimeType()))
71 event->accept();
72 else
73 event->ignore();
74}
75
76void PiecesList::dragMoveEvent(QDragMoveEvent *event)
77{
78 if (event->mimeData()->hasFormat(mimetype: PiecesList::puzzleMimeType())) {
79 event->setDropAction(Qt::MoveAction);
80 event->accept();
81 } else {
82 event->ignore();
83 }
84}
85
86void PiecesList::dropEvent(QDropEvent *event)
87{
88 if (event->mimeData()->hasFormat(mimetype: PiecesList::puzzleMimeType())) {
89 QByteArray pieceData = event->mimeData()->data(mimetype: PiecesList::puzzleMimeType());
90 QDataStream dataStream(&pieceData, QIODevice::ReadOnly);
91 QPixmap pixmap;
92 QPoint location;
93 dataStream >> pixmap >> location;
94
95 addPiece(pixmap, location);
96
97 event->setDropAction(Qt::MoveAction);
98 event->accept();
99 } else {
100 event->ignore();
101 }
102}
103
104void PiecesList::addPiece(const QPixmap &pixmap, const QPoint &location)
105{
106 QListWidgetItem *pieceItem = new QListWidgetItem(this);
107 pieceItem->setIcon(QIcon(pixmap));
108 pieceItem->setData(role: Qt::UserRole, value: QVariant(pixmap));
109 pieceItem->setData(role: Qt::UserRole+1, value: location);
110 pieceItem->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDragEnabled);
111}
112
113void PiecesList::startDrag(Qt::DropActions /*supportedActions*/)
114{
115 QListWidgetItem *item = currentItem();
116
117 QByteArray itemData;
118 QDataStream dataStream(&itemData, QIODevice::WriteOnly);
119 QPixmap pixmap = qvariant_cast<QPixmap>(v: item->data(role: Qt::UserRole));
120 QPoint location = item->data(role: Qt::UserRole+1).toPoint();
121
122 dataStream << pixmap << location;
123
124 QMimeData *mimeData = new QMimeData;
125 mimeData->setData(mimetype: PiecesList::puzzleMimeType(), data: itemData);
126
127 QDrag *drag = new QDrag(this);
128 drag->setMimeData(mimeData);
129 drag->setHotSpot(QPoint(pixmap.width()/2, pixmap.height()/2));
130 drag->setPixmap(pixmap);
131
132 if (drag->exec(supportedActions: Qt::MoveAction) == Qt::MoveAction)
133 delete takeItem(row: row(item));
134}
135

source code of qtbase/examples/widgets/draganddrop/puzzle/pieceslist.cpp