Qt - QTableWidget不接受下降

Question

我正在制作一个使用QTableWidget的项目。当我试图让它接受滴滴时，我开始意识到它不像我想象的那样行事。事情是，如果我将QTableWidget改成QWidget，那么drop会被接受。所以，这个问题不在编码中。这里谈到的代码，并以此为，因为我关于这个问题是在“MyDropWidget”类

#include <QMouseEvent> 
#include <QWidget> 
#include <QMessageBox> 
#include <math.h> 
#include <QApplication> 
#include <QPainter> 
#include <sstream> 
#include <QDragEnterEvent> 
#include <QDropEvent> 
#include <QLabel> 
#include <QPaintEvent> 
#include <QTableWidget> 
#define RADIUS 2 
#define DISTANCE_BETWEEN_OBJECTS 2 
#define DASH_RECT_HALF_WIDTH 2 
#include <QHeaderView> 
#include <QPainter> 
#include <QHBoxLayout> 
#include <QWidget> 
#include <QApplication> 

class MyMessageBox:public QMessageBox 
{ 
public: 
    MyMessageBox(std::string message,QWidget *parent=0):QMessageBox(QMessageBox::NoIcon,QString("ErrorMessage"),QString(message.c_str()),QMessageBox::Ok,parent,Qt::Widget) 
    { 
    } 
}; 

class MyDragWidget:public QWidget 
{ 
private: 
    QPoint * start_Pos; 
    QPixmap drag_Pixmap; 
public: 
    MyDragWidget(QWidget * parent); 
private: 
    void mousePressEvent(QMouseEvent * event); 
    void mouseReleaseEvent(QMouseEvent * event); 
    void mouseMoveEvent(QMouseEvent * event); 
}; 

MyDragWidget::MyDragWidget(QWidget * parent):QWidget(parent) 
{ 
    setPalette(QPalette(QColor(0,0,0))); 
    setAutoFillBackground(true); 
    start_Pos = NULL; 

    drag_Pixmap = QPixmap(50,50); 
    QPainter painter(&drag_Pixmap); 
    painter.setPen(QColor(255,0,0)); 
    painter.drawText(0,0,50,50,Qt::AlignCenter,"drag Pic"); 
    painter.end(); 
    resize(100,200); 
} 

void MyDragWidget::mousePressEvent(QMouseEvent *event) 
{ 
    QWidget::mousePressEvent(event); 
    if(event->button() == Qt::LeftButton) 
    { 
     if(start_Pos) 
      delete start_Pos; 
     start_Pos = new QPoint(event->pos()); 
    } 
} 

void MyDragWidget::mouseReleaseEvent(QMouseEvent *event) 
{ 
    if(start_Pos) 
     delete start_Pos; 
    start_Pos = NULL; 
} 

void MyDragWidget::mouseMoveEvent(QMouseEvent *event) 
{ 
    if(!(event->buttons() & Qt::LeftButton)) 
    { 
     MyMessageBox mb("mouse move 0"); 
     mb.exec(); 
     return; 
    } 

    if(!start_Pos) 
     return; 
    QDrag * drag = new QDrag(this); 
    drag->setPixmap(drag_Pixmap); 
    QMimeData * mimeData = new QMimeData(); 
    mimeData->setText("name"); 
    drag->setMimeData(mimeData); 

    Qt::DropAction dropAction = drag->exec(Qt::CopyAction,Qt::MoveAction); 
} 

class MyDropWidget:public QTableWidget 
{ 
public: 
    MyDropWidget(QWidget * parent); 
private: 
    void dragEnterEvent(QDragEnterEvent * event); 
    void dropEvent(QDropEvent *event); 
}; 

MyDropWidget::MyDropWidget(QWidget * parent):QTableWidget(parent) 
{ 
    setColumnCount(6); 
    setRowCount(9); 
    setAcceptDrops(true); 
    setPalette(QPalette(QColor(250,150,210))); 
    setAutoFillBackground(true); 
} 

void MyDropWidget::dragEnterEvent(QDragEnterEvent * event) 
{ 
    if(event->mimeData()->hasFormat("text/plain")) 
     event->acceptProposedAction(); 

    QTableWidget::dragEnterEvent(event); 
} 

void MyDropWidget::dropEvent(QDropEvent * event) 
{ 
    QString shape = event->mimeData()->text(); 

    MyMessageBox mm("Drop "); 
    mm.exec(); 
    QTableWidget::dropEvent(event); 
} 

class Main_Widget:public QWidget 
{ 
    MyDragWidget * courses_DragWidget; 
    MyDragWidget * rooms_DragWidget; 
    MyDropWidget * timeTable_Widget; 
public: 
    Main_Widget(); 
}; 

Main_Widget::Main_Widget() 
{ 
    courses_DragWidget = new MyDragWidget(NULL); 
    timeTable_Widget = new MyDropWidget(NULL); 

    QHBoxLayout * hBoxLayout = new QHBoxLayout; 
    hBoxLayout->addWidget(courses_DragWidget,1); 
    hBoxLayout->addWidget(timeTable_Widget,2); 

    setLayout(hBoxLayout); 
} 

int main(int argc,char * argv[]) 
{ 
    QApplication app(argc,argv); 

    Main_Widget * main_Widget = new Main_Widget; 
    main_Widget->show(); 
    main_Widget->resize(100,200); 

    return app.exec(); 
} 

所以，如果QTableWidget的接受的下降，然后会有一个消息框将拿出一个消息“落”。但是，是不是未来=>下降不被接受。有人能帮我解决这个问题吗？

注：我使用Qt-4.7.2在windows平台

Answer 1

有你需要做两件事情：

1）实施dragMoveEvent。这是当拖动进入QWidget时。一个实现可能是这样的：

void MyDropWidget::dragMoveEvent(QDragMoveEvent *event) 
{ 
    event->accept(); 
} 

当你选中拖动MIME数据当它进入，无需再点击此处查看，但你可以做区域的检查，你希望能够在下降到。

2）不要致电父母dragEnterEvent处理程序。所以，你的dragEnterEvent功能会是这样的：

void MyDropWidget::dragEnterEvent(QDragEnterEvent * event) 
{ 
    if(event->mimeData()->hasFormat("text/plain")) 
     event->acceptProposedAction(); 

    /* Don't need this.. QTableWidget::dragEnterEvent(event); */ 
} 

原因是，QTableWidget的支持它的拖放操作的自己的形式，所以它设置事件回，即使你接受它被拒绝。