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

[cpp] view plain copy

class TreeItemMimeData:public QMimeData

{

Q_OBJECT

public:

TreeItemMimeData():QMimeData()

{

m_pDragItem = NULL;

}

~TreeItemMimeData()

{

}

void SetDragData(QString mimeType , QTreeWidgetItem *pItem)

{

m_format<<mimeType;

m_pDragItem = pItem;

}

QStringList formats() const

{

return m_format;

}

const QTreeWidgetItem* DragItemData() const

{

return m_pDragItem;

}

protected:

QVariant retrieveData(const QString &mimetype, QVariant::Type preferredType) const

{

if (mimetype == "ItemMimeData")

{

return m_pDragItem;

}

else

{

return QMimeData::retrieveData(mimetype, preferredType);

}

}

private:

const QTreeWidgetItem *m_pDragItem;

QStringList m_format;

};

class MyTreeWidget:public QTreeWidget

{

Q_OBJECT

public:

MyTreeWidget(QWidget *parent = NULL);

~MyTreeWidget();

protected:

void mouseMoveEvent(QMouseEvent *event);

void mousePressEvent(QMouseEvent *event);

void mouseReleaseEvent(QMouseEvent *event);

void dragEnterEvent(QDragEnterEvent *event);

void dragMoveEvent(QDragMoveEvent *event);

void dropEvent(QDropEvent *event);

void keyPressEvent(QKeyEvent *event);

void keyReleaseEvent(QKeyEvent *event);

private:

QPoint m_startDragPoint;

void performDrag();

bool m_CtrlPressed;

};

[cpp] view plain copy

MyTreeWidget::MyTreeWidget(QWidget *parent /*= NULL*/):QTreeWidget(parent)

{

m_CtrlPressed = false;

this->setSelectionMode(QAbstractItemView::ExtendedSelection);

this->setAcceptDrops(true);

this->setDragEnabled(true);

this->setStyleSheet("QTreeWidget::item:selected{ background-color: rgb(150, 0, 0)}");

}

MyTreeWidget::~MyTreeWidget()

{

}

void MyTreeWidget::keyPressEvent(QKeyEvent *event)

{

if (event->key() == Qt::Key_Control)

{

m_CtrlPressed = true;

}

}

void MyTreeWidget::keyReleaseEvent(QKeyEvent *event)

{

if (event->key() == Qt::Key_Control)

{

m_CtrlPressed = false;

}

}

void MyTreeWidget::mousePressEvent(QMouseEvent *event)

{

if (event->button() == Qt::LeftButton)

{

m_startDragPoint = event->pos();

}

QTreeWidget::mousePressEvent(event);

}

void MyTreeWidget::mouseMoveEvent(QMouseEvent *event)

{

if (event->buttons() & Qt::LeftButton)

{

int dragDistance = (event->pos() - m_startDragPoint).manhattanLength();

if (dragDistance > QApplication::startDragDistance())

{

performDrag();

}

}

QTreeWidget::mouseMoveEvent(event);

}

void MyTreeWidget::mouseReleaseEvent(QMouseEvent *event)

{

QTreeWidget::mouseReleaseEvent(event);

}

void MyTreeWidget::dragEnterEvent(QDragEnterEvent *event)

{

QWidget *source = qobject_cast<MyTreeWidget *>(event->source());

if (source /*&& source != this*/)

{

if (m_CtrlPressed)

{

event->setDropAction(Qt::CopyAction);

}

else

{

event->setDropAction(Qt::MoveAction);

}

/*event->setDropAction(Qt::MoveAction); */

event->accept();

}

}

void MyTreeWidget::dragMoveEvent(QDragMoveEvent *event)

{

QWidget *source = qobject_cast<MyTreeWidget *>(event->source());

if (source /*&& source != this*/)

{

const TreeItemMimeData *pMimeData = (const TreeItemMimeData *)(event->mimeData());

const QTreeWidgetItem *item = pMimeData->DragItemData();

QTreeWidgetItem *currentItem = this->itemAt(event->pos());

if (currentItem == item) //不允许拖回到原来的item

{

event->ignore();

}

else

{

setCurrentItem(currentItem);

if (m_CtrlPressed)

{

event->setDropAction(Qt::CopyAction);

}

else

{

event->setDropAction(Qt::MoveAction);

}

//event->setDropAction(Qt::MoveAction);

event->accept();

}

}

}

void MyTreeWidget::dropEvent(QDropEvent *event)

{

QWidget *source = qobject_cast<MyTreeWidget *>(event->source());

const TreeItemMimeData *pMimeData = (const TreeItemMimeData *)(event->mimeData());

if (source /*&& source != this*/)

{

const QTreeWidgetItem *item = pMimeData->DragItemData();

QTreeWidgetItem *pItem = item->clone();

QTreeWidgetItem *currentItem = this->itemAt(event->pos());

if (currentItem && (currentItem != item))

{

currentItem->addChild(pItem);

}

else

{

this->addTopLevelItem(pItem);

}

if (m_CtrlPressed)

{

event->setDropAction(Qt::CopyAction);

}

else

{

event->setDropAction(Qt::MoveAction);

}

//event->setDropAction(Qt::MoveAction);

event->accept();

}

}

void MyTreeWidget::performDrag()

{

QTreeWidgetItem *item = currentItem();

if (item)

{

TreeItemMimeData *mimeData = new TreeItemMimeData;

mimeData->SetDragData("ItemMimeData",item);

QDrag *drag = new QDrag(this);

drag->setMimeData(mimeData);

drag->setPixmap(QPixmap(":/DragDropDemo/Resources/Mail.png"));

if (m_CtrlPressed)

{

drag->exec(Qt::CopyAction);

}

else

{

drag->exec(Qt::MoveAction);

delete item;

}

}

}

以下是我演示的截图


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