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Qt实现不同Treewidget之间拖拽

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12/01
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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

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