Qt实现不同Treewidget之间拖拽

拖拽是编程中经常要用到的，我这里主要是实习了Treewidget之间直接拖拽Item，按下Ctrl键的话是copy，不按Ctrl则是Move。以下是实现代码

1. class TreeItemMimeData:public QMimeData
2. {
3. Q_OBJECT
4. public:
5. TreeItemMimeData():QMimeData()
6. {
7. m_pDragItem = NULL;
8. }
9. ~TreeItemMimeData()
10. {
11. }
12. void SetDragData(QString mimeType , QTreeWidgetItem *pItem)
13. {
14. m_format<<mimeType;
15. m_pDragItem = pItem;
16. }
17. QStringList formats() const
18. {
19. return m_format;
20. }
21. const QTreeWidgetItem* DragItemData() const
22. {
23. return m_pDragItem;
24. }
25. protected:
26. QVariant retrieveData(const QString &mimetype, QVariant::Type preferredType) const
27. {
28. if (mimetype == "ItemMimeData")
29. {
30. return m_pDragItem;
31. }
32. else
33. {
34. return QMimeData::retrieveData(mimetype, preferredType);
35. }
36. }
37. private:
38. const QTreeWidgetItem   *m_pDragItem;
39. QStringList              m_format;
40. };
41. class MyTreeWidget:public QTreeWidget
42. {
43. Q_OBJECT
44. public:
45. MyTreeWidget(QWidget *parent = NULL);
46. ~MyTreeWidget();
47. protected:
48. void mouseMoveEvent(QMouseEvent *event);
49. void mousePressEvent(QMouseEvent *event);
50. void mouseReleaseEvent(QMouseEvent *event);
51. void dragEnterEvent(QDragEnterEvent *event);
52. void dragMoveEvent(QDragMoveEvent *event);
53. void dropEvent(QDropEvent *event);
54. void keyPressEvent(QKeyEvent *event);
55. void keyReleaseEvent(QKeyEvent *event);
56. private:
57. QPoint     m_startDragPoint;
58. void       performDrag();
59. bool       m_CtrlPressed;
60. };

1. MyTreeWidget::MyTreeWidget(QWidget *parent /*= NULL*/):QTreeWidget(parent)
2. {
3. m_CtrlPressed = false;
4. this->setSelectionMode(QAbstractItemView::ExtendedSelection);
5. this->setAcceptDrops(true);
6. this->setDragEnabled(true);
7. this->setStyleSheet("QTreeWidget::item:selected{ background-color: rgb(150, 0, 0)}");
8. }
9. MyTreeWidget::~MyTreeWidget()
10. {
11. }
12. void MyTreeWidget::keyPressEvent(QKeyEvent *event)
13. {
14. if (event->key() == Qt::Key_Control)
15. {
16. m_CtrlPressed = true;
17. }
18. }
19. void MyTreeWidget::keyReleaseEvent(QKeyEvent *event)
20. {
21. if (event->key() == Qt::Key_Control)
22. {
23. m_CtrlPressed = false;
24. }
25. }
26. void MyTreeWidget::mousePressEvent(QMouseEvent *event)
27. {
28. if (event->button() == Qt::LeftButton)
29. {
30. m_startDragPoint = event->pos();
31. }
32. QTreeWidget::mousePressEvent(event);
33. }
34. void MyTreeWidget::mouseMoveEvent(QMouseEvent *event)
35. {
36. if (event->buttons() & Qt::LeftButton)
37. {
38. int dragDistance = (event->pos() - m_startDragPoint).manhattanLength();
39. if (dragDistance > QApplication::startDragDistance())
40. {
41. performDrag();
42. }
43. }
44. QTreeWidget::mouseMoveEvent(event);
45. }
46. void MyTreeWidget::mouseReleaseEvent(QMouseEvent *event)
47. {
48. QTreeWidget::mouseReleaseEvent(event);
49. }
50. void MyTreeWidget::dragEnterEvent(QDragEnterEvent *event)
51. {
52. QWidget *source =  qobject_cast<MyTreeWidget *>(event->source());
53. if (source /*&& source != this*/)
54. {
55. if (m_CtrlPressed)
56. {
57. event->setDropAction(Qt::CopyAction);
58. }
59. else
60. {
61. event->setDropAction(Qt::MoveAction);
62. }
63. /*event->setDropAction(Qt::MoveAction);  */
64. event->accept();
65. }
66. }
67. void MyTreeWidget::dragMoveEvent(QDragMoveEvent *event)
68. {
69. QWidget *source =  qobject_cast<MyTreeWidget *>(event->source());
70. if (source /*&& source != this*/)
71. {
72. const TreeItemMimeData *pMimeData = (const TreeItemMimeData *)(event->mimeData());
73. const QTreeWidgetItem *item = pMimeData->DragItemData();
74. QTreeWidgetItem *currentItem = this->itemAt(event->pos());
75. if (currentItem == item)           //不允许拖回到原来的item
76. {
77. event->ignore();
78. }
79. else
80. {
81. setCurrentItem(currentItem);
82. if (m_CtrlPressed)
83. {
84. event->setDropAction(Qt::CopyAction);
85. }
86. else
87. {
88. event->setDropAction(Qt::MoveAction);
89. }
90. //event->setDropAction(Qt::MoveAction);
91. event->accept();
92. }
93. }
94. }
95. void MyTreeWidget::dropEvent(QDropEvent *event)
96. {
97. QWidget *source =  qobject_cast<MyTreeWidget *>(event->source());
98. const TreeItemMimeData *pMimeData = (const TreeItemMimeData *)(event->mimeData());
99. if (source /*&& source != this*/)
100. {
101. const QTreeWidgetItem *item = pMimeData->DragItemData();
102. QTreeWidgetItem *pItem = item->clone();
103. QTreeWidgetItem *currentItem = this->itemAt(event->pos());
104. if (currentItem && (currentItem != item))
105. {
106. currentItem->addChild(pItem);
107. }
108. else
109. {
110. this->addTopLevelItem(pItem);
111. }
112. if (m_CtrlPressed)
113. {
114. event->setDropAction(Qt::CopyAction);
115. }
116. else
117. {
118. event->setDropAction(Qt::MoveAction);
119. }
120. //event->setDropAction(Qt::MoveAction);
121. event->accept();
122. }
123. }
124. void MyTreeWidget::performDrag()
125. {
126. QTreeWidgetItem *item = currentItem();
127. if (item)
128. {
129. TreeItemMimeData *mimeData = new TreeItemMimeData;
130. mimeData->SetDragData("ItemMimeData",item);
131. QDrag *drag = new QDrag(this);
132. drag->setMimeData(mimeData);
133. drag->setPixmap(QPixmap(":/DragDropDemo/Resources/Mail.png"));
134. if (m_CtrlPressed)
135. {
136. drag->exec(Qt::CopyAction);
137. }
138. else
139. {
140. drag->exec(Qt::MoveAction);
141. delete item;
142. }
143. }
144. }

以下是我演示的截图

http://blog.csdn.net/hai200501019/article/details/9322329