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49 ****************************************************************************/
50
51 //! [0]
52 class SimpleItem : public QGraphicsItem
53 {
54 public:
boundingRect() const55 QRectF boundingRect() const override
56 {
57 qreal penWidth = 1;
58 return QRectF(-10 - penWidth / 2, -10 - penWidth / 2,
59 20 + penWidth, 20 + penWidth);
60 }
61
paint(QPainter * painter,const QStyleOptionGraphicsItem * option,QWidget * widget)62 void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
63 QWidget *widget) override
64 {
65 painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
66 }
67 };
68 //! [0]
69
70
71 //! [1]
72 class CustomItem : public QGraphicsItem
73 {
74 public:
75 enum { Type = UserType + 1 };
76
type() const77 int type() const override
78 {
79 // Enable the use of qgraphicsitem_cast with this item.
80 return Type;
81 }
82 ...
83 };
84 //! [1]
85
86
87 //! [2]
88 item->setCursor(Qt::IBeamCursor);
89 //! [2]
90
91
92 //! [3]
93 item->setCursor(Qt::IBeamCursor);
94 //! [3]
95
96
97 //! [4]
98 QGraphicsRectItem rect;
99 rect.setPos(100, 100);
100
101 rect.sceneTransform().map(QPointF(0, 0));
102 // returns QPointF(100, 100);
103
104 rect.sceneTransform().inverted().map(QPointF(100, 100));
105 // returns QPointF(0, 0);
106 //! [4]
107
108
109 //! [5]
110 QGraphicsRectItem rect;
111 rect.setPos(100, 100);
112
113 rect.deviceTransform(view->viewportTransform()).map(QPointF(0, 0));
114 // returns the item's (0, 0) point in view's viewport coordinates
115
116 rect.deviceTransform(view->viewportTransform()).inverted().map(QPointF(100, 100));
117 // returns view's viewport's (100, 100) coordinate in item coordinates
118 //! [5]
119
120
121 //! [6]
122 // Rotate an item 45 degrees around (0, 0).
123 item->rotate(45);
124
125 // Rotate an item 45 degrees around (x, y).
126 item->setTransform(QTransform().translate(x, y).rotate(45).translate(-x, -y));
127 //! [6]
128
129
130 //! [7]
131 // Scale an item by 3x2 from its origin
132 item->scale(3, 2);
133
134 // Scale an item by 3x2 from (x, y)
135 item->setTransform(QTransform().translate(x, y).scale(3, 2).translate(-x, -y));
136 //! [7]
137
138
139 //! [8]
boundingRect() const140 QRectF CircleItem::boundingRect() const
141 {
142 qreal penWidth = 1;
143 return QRectF(-radius - penWidth / 2, -radius - penWidth / 2,
144 diameter + penWidth, diameter + penWidth);
145 }
146 //! [8]
147
148
149 //! [9]
shape() const150 QPainterPath RoundItem::shape() const
151 {
152 QPainterPath path;
153 path.addEllipse(boundingRect());
154 return path;
155 }
156 //! [9]
157
158
159 //! [10]
paint(QPainter * painter,const QStyleOptionGraphicsItem * option,QWidget * widget)160 void RoundRectItem::paint(QPainter *painter,
161 const QStyleOptionGraphicsItem *option,
162 QWidget *widget)
163 {
164 painter->drawRoundedRect(-10, -10, 20, 20, 5, 5);
165 }
166 //! [10]
167
168
169 //! [11]
170 static const int ObjectName = 0;
171
172 QGraphicsItem *item = scene.itemAt(100, 50);
173 if (item->data(ObjectName).toString().isEmpty()) {
174 if (qgraphicsitem_cast<ButtonItem *>(item))
175 item->setData(ObjectName, "Button");
176 }
177 //! [11]
178
179
180 //! [12]
181 QGraphicsScene scene;
182 QGraphicsEllipseItem *ellipse = scene.addEllipse(QRectF(-10, -10, 20, 20));
183 QGraphicsLineItem *line = scene.addLine(QLineF(-10, -10, 20, 20));
184
185 line->installSceneEventFilter(ellipse);
186 // line's events are filtered by ellipse's sceneEventFilter() function.
187
188 ellipse->installSceneEventFilter(line);
189 // ellipse's events are filtered by line's sceneEventFilter() function.
190 //! [12]
191
192
193 //! [13]
contextMenuEvent(QGraphicsSceneContextMenuEvent * event)194 void CustomItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
195 {
196 QMenu menu;
197 QAction *removeAction = menu.addAction("Remove");
198 QAction *markAction = menu.addAction("Mark");
199 QAction *selectedAction = menu.exec(event->screenPos());
200 // ...
201 }
202 //! [13]
203
204
205 //! [14]
CustomItem()206 CustomItem::CustomItem()
207 {
208 setAcceptDrops(true);
209 ...
210 }
211
dragEnterEvent(QGraphicsSceneDragDropEvent * event)212 void CustomItem::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
213 {
214 event->setAccepted(event->mimeData()->hasFormat("text/plain"));
215 }
216 //! [14]
217
218
219 //! [15]
itemChange(GraphicsItemChange change,const QVariant & value)220 QVariant Component::itemChange(GraphicsItemChange change, const QVariant &value)
221 {
222 if (change == ItemPositionChange && scene()) {
223 // value is the new position.
224 QPointF newPos = value.toPointF();
225 QRectF rect = scene()->sceneRect();
226 if (!rect.contains(newPos)) {
227 // Keep the item inside the scene rect.
228 newPos.setX(qMin(rect.right(), qMax(newPos.x(), rect.left())));
229 newPos.setY(qMin(rect.bottom(), qMax(newPos.y(), rect.top())));
230 return newPos;
231 }
232 }
233 return QGraphicsItem::itemChange(change, value);
234 }
235 //! [15]
236
237
238 //! [16]
setRadius(qreal newRadius)239 void CircleItem::setRadius(qreal newRadius)
240 {
241 if (radius != newRadius) {
242 prepareGeometryChange();
243 radius = newRadius;
244 }
245 }
246 //! [16]
247
248
249 //! [17]
250 // Group all selected items together
251 QGraphicsItemGroup *group = scene->createItemGroup(scene->selecteditems());
252
253 // Destroy the group, and delete the group item
254 scene->destroyItemGroup(group);
255 //! [17]
256
257
258 //! [18]
259 class QGraphicsPathItem : public QAbstractGraphicsShapeItem
260 {
261 public:
262 enum { Type = 2 };
type() const263 int type() const override { return Type; }
264 ...
265 };
266 //! [18]
267
268 //! [19]
269 QTransform xform = item->deviceTransform(view->viewportTransform());
270 QRect deviceRect = xform.mapRect(rect).toAlignedRect();
271 view->viewport()->scroll(dx, dy, deviceRect);
272 //! [19]
273
274 //! [20]
275 item->setTransform(QTransform().rotate(angle), true);
276 //! [20]
277
278 //! [21]
279 setTransform(QTransform::fromScale(sx, sy), true);
280 //! [21]
281
282 //! [22]
283 setTransform(QTransform().shear(sh, sv), true);
284 //! [22]
285
286 //! [23]
287 setTransform(QTransform::fromTranslate(dx, dy), true);
288 //! [23]
289