summaryrefslogtreecommitdiffstats
path: root/doc/src/snippets/code/src_gui_graphicsview_qgraphicsitem.cpp
blob: 6d4b0e2465ff9dac7740ea3110ac185b816df8b0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://qt.nokia.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/

//! [0]
class SimpleItem : public QGraphicsItem
{
public:
    QRectF boundingRect() const
    {
        qreal penWidth = 1;
        return QRectF(-10 - penWidth / 2, -10 - penWidth / 2,
                      20 + penWidth, 20 + penWidth);
    }

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
               QWidget *widget)
    {
        painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
    }
};
//! [0]


//! [1]
class CustomItem : public QGraphicsItem
{
   ...
   enum { Type = UserType + 1 };

   int type() const
   {
       // Enable the use of qgraphicsitem_cast with this item.
       return Type;
   }
   ...
};
//! [1]


//! [2]
item->setCursor(Qt::IBeamCursor);
//! [2]


//! [3]
item->setCursor(Qt::IBeamCursor);
//! [3]


//! [4]
QGraphicsRectItem rect;
rect.setPos(100, 100);

rect.sceneTransform().map(QPointF(0, 0));
// returns QPointF(100, 100);

rect.sceneTransform().inverted().map(QPointF(100, 100));
// returns QPointF(0, 0);
//! [4]


//! [5]
QGraphicsRectItem rect;
rect.setPos(100, 100);

rect.deviceTransform(view->viewportTransform()).map(QPointF(0, 0));
// returns the item's (0, 0) point in view's viewport coordinates

rect.deviceTransform(view->viewportTransform()).inverted().map(QPointF(100, 100));
// returns view's viewport's (100, 100) coordinate in item coordinates
//! [5]


//! [6]
// Rotate an item 45 degrees around (0, 0).
item->rotate(45);

// Rotate an item 45 degrees around (x, y).
item->setTransform(QTransform().translate(x, y).rotate(45).translate(-x, -y));
//! [6]


//! [7]
// Scale an item by 3x2 from its origin
item->scale(3, 2);

// Scale an item by 3x2 from (x, y)
item->setTransform(QTransform().translate(x, y).scale(3, 2).translate(-x, -y));
//! [7]


//! [8]
QRectF CircleItem::boundingRect() const
{
    qreal penWidth = 1;
    return QRectF(-radius - penWidth / 2, -radius - penWidth / 2,
                  diameter + penWidth, diameter + penWidth);
}
//! [8]


//! [9]
QPainterPath RoundItem::shape() const
{
    QPainterPath path;
    path.addEllipse(boundingRect());
    return path;
}
//! [9]


//! [10]
void RoundRectItem::paint(QPainter *painter,
                          const QStyleOptionGraphicsItem *option,
                          QWidget *widget)
{
    painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
}
//! [10]


//! [11]
static const int ObjectName = 0;

QGraphicsItem *item = scene.itemAt(100, 50);
if (item->data(ObjectName).toString().isEmpty()) {
    if (qgraphicsitem_cast<ButtonItem *>(item))
        item->setData(ObjectName, "Button");
}
//! [11]


//! [12]
QGraphicsScene scene;
QGraphicsEllipseItem *ellipse = scene.addEllipse(QRectF(-10, -10, 20, 20));
QGraphicsLineItem *line = scene.addLine(QLineF(-10, -10, 20, 20));

line->installSceneEventFilter(ellipse);
// line's events are filtered by ellipse's sceneEventFilter() function.

ellipse->installSceneEventFilter(line);
// ellipse's events are filtered by line's sceneEventFilter() function.
//! [12]


//! [13]
void CustomItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
    QMenu menu;
    QAction *removeAction = menu.addAction("Remove");
    QAction *markAction = menu.addAction("Mark");
    QAction *selectedAction = menu.exec(event->screenPos());
    // ...
}
//! [13]


//! [14]
CustomItem::CustomItem()
{
    setAcceptDrops(true);
    ...
}

void CustomItem::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
{
    event->setAccepted(event->mimeData()->hasFormat("text/plain"));
}
//! [14]


//! [15]
QVariant Component::itemChange(GraphicsItemChange change, const QVariant &value)
{
    if (change == ItemPositionChange && scene()) {
        // value is the new position.
        QPointF newPos = value.toPointF();
        QRectF rect = scene()->sceneRect();
        if (!rect.contains(newPos)) {
            // Keep the item inside the scene rect.
            newPos.setX(qMin(rect.right(), qMax(newPos.x(), rect.left())));
            newPos.setY(qMin(rect.bottom(), qMax(newPos.y(), rect.top())));
            return newPos;
        }
    }
    return QGraphicsItem::itemChange(change, value);
}
//! [15]


//! [16]
void CircleItem::setRadius(qreal newRadius)
{
    if (radius != newRadius) {
        prepareGeometryChange();
        radius = newRadius;
    }
}
//! [16]


//! [17]
// Group all selected items together
QGraphicsItemGroup *group = scene->createItemGroup(scene->selecteditems());

// Destroy the group, and delete the group item
scene->destroyItemGroup(group);
//! [17]


//! [QGraphicsItem type]
class CustomItem : public QGraphicsItem
{
   ...
   enum { Type = UserType + 1 };

   int type() const
   {
       // Enable the use of qgraphicsitem_cast with this item.
       return Type;
   }
   ...
};
//! [QGraphicsItem type]