自定义QGraphicsItem 

 1 #include <QtWidgets>
 2 //自定义item需要重写的两个函数boudingRect()和paint()
 3 class CheckBoxItem : public QGraphicsObject
 4 {
 5     Q_OBJECT
 6 public:
 7     CheckBoxItem(int w, int h, const QString &text, const QString &checkedIcon, const QString &emptyIcon, QGraphicsObject *parent = 0);
 8     QRectF boundingRect()const override; //用来设置该item的大小 必须
 9     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;//用来绘制该item的东西 必须
10     bool isChecked();
11     void setChecked(bool checked);
12 signals:
13     void stateChanged(bool checked);
14 protected:
15     void keyPressEvent(QKeyEvent * event) override;
16     void mousePressEvent(QGraphicsSceneMouseEvent *event) override;
17     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event) override;
18 private:
19     QString m_text;
20     int m_width;
21     int m_height;
22     bool m_checked;
23     QPixmap m_checkedIcon;
24     QPixmap m_emptyIcon;
25     bool m_leftButtonDown;
26 };
27 
28 CheckBoxItem::CheckBoxItem(int w, int h, const QString &text, const QString &checkedIcon, const QString &emptyIcon, QGraphicsObject *parent) :
29     m_width(w),
30     m_height(h),
31     m_text(text),
32     m_checkedIcon(checkedIcon),
33     m_emptyIcon(emptyIcon),
34     QGraphicsObject(parent), m_leftButtonDown(false)
35 {
36     setFlag(QGraphicsItem::ItemIsFocusable, true); //用来设置这个item可以获取焦点
37 }
38 QRectF CheckBoxItem::boundingRect() const
39 {
40     return QRectF(0,0, m_width, m_height);
41 }
42 //调用这里面的painter画家进行绘制图形
43 void CheckBoxItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
44 {
45     Q_UNUSED(option)
46     Q_UNUSED(widget)//这个宏是用来把不用到的参数注掉的功能
47     int x = 2;
48     int y = (m_height - m_checkedIcon.height()) / 2;
49     painter->drawPixmap(x, y, m_checked ? m_checkedIcon : m_emptyIcon);
50     if(!m_text.isEmpty())
51     {
52         x = x + m_checkedIcon.width() + 4;
53         QRect rc(x, 0, m_width - x - 2, m_height);
54         painter->drawText(rc, Qt::AlignVCenter | Qt::AlignLeft, m_text);
55     }
56 }
57 void CheckBoxItem::keyPressEvent(QKeyEvent *event)
58 {
59     if(event->key() == Qt::Key_Space)
60     {
61         event->accept();
62         m_checked = !m_checked;
63         update();
64     }
65 }
66 void CheckBoxItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
67 {
68     if(event->button() == Qt::LeftButton)
69     {
70         m_leftButtonDown = true;
71         event->accept();
72     }
73 }
74 void CheckBoxItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
75 {
76     if(event->button() == Qt::LeftButton)
77     {
78         m_leftButtonDown = false;
79         m_checked = !m_checked;
80         event->accept();
81         update();
82         emit stateChanged(m_checked);
83     }
84 }

 

posted @ 2017-03-10 15:59  Dayu0501  阅读(3382)  评论(0)    收藏  举报