Qt: TextEdit created by QStyledItemDelegate can't receive Escape key press event? - qt

Question

I have a QTableView to display a bunch of data, which is stored in a QAbstractTableModel. I also want to edit the data sometime, so I use a QStyledItemDelegate to create an editor (of QTextEdit type) when I double click on the cell. However, I want to handle the key Press event myself, but I never catch Key_Escape pressing in the Text Edit editor (Other keys such as Enter and Ascii can be captured). I checked the code, and found that Escape is directly connected to QTableView's closeEditor() function, which is a virtual method and is automatically invoked. As far as I know, key press event is the bottom layer of event handling, but it is not true with such case.
I do need to capture the Escape key press event so that I can handle it myself, can anyone tell me how to do this? Thanks!

Answer 1

I got the answer, and I think would help others:
Override QStyledItemDelegate::eventFilter() method:
MyItemDelegate::eventFilter(QObject* editor, QEvent* event)
{
if(event->type()==QEvent::KeyPress)
return false;
return QStyledItemDelegate::eventFilter(editor, event);
}
According to Qt's documentation, QStyledItemDelegate::eventFilter() returns true if the given editor is a valid QWidget and the given event is handled; otherwise returns false. Tab, Backtab, Enter, Return and Ecs are handled by default. So, if you want to handle the key press event yourself, you must let eventFilter return false when KeyPress event occurs. So that the editor's keyPressEvent() method will be invoked instead.

Answer 2

QStyledItemDelegate::eventFilter is not a possibility beacuse is virtual protected
In order to get the events you should subclass your own QEditLine and override ::keyPressEvent there. Take notice of the code. I pass actual row and colum of my QTableWidget cell in order to know what we are editing in the overrided QLineEditor.
//.h
class MyStyledItemDelegate : public QStyledItemDelegate
{
public:
MyStyledItemDelegate(QObject *parent = 0);
QWidget* createEditor(QWidget* parent,const QStyleOptionViewItem &option,const QModelIndex &index) const;
};
//.cpp
#include "mylineedit.h"
MyStyledItemDelegate::MyStyledItemDelegate(QObject *parent)
:QStyledItemDelegate(parent)
{
}
QWidget* MyStyledItemDelegate::createEditor(QWidget* parent,const QStyleOptionViewItem &option,const QModelIndex &index) const
{
MyLineEdit* editor = new MyLineEdit(parent,index.row(),index.column());
return editor;
}
/////////////////////////////////////////////////////////////
//My own QLineEdit
/////////////////////////////////////////////////////////////
//.h
class MyLineEdit : public QLineEdit
{
Q_OBJECT
public:
int _nRow;
int _nCol;
public:
MyLineEdit(QWidget *parent = 0,int nRow=-1, int nCol=-1);
virtual void keyPressEvent(QKeyEvent* event);
signals:
void mySignal(const QVector<QVariant> &);
public slots:
};
//.cpp
MyLineEdit::MyLineEdit(QWidget *parent, int nRow,int nCol):
QLineEdit(parent)
{
_nRow=nRow;
_nCol=nCol;
}
/////////////////////////////////////////////////////////////////////////
void MyLineEdit::keyPressEvent(QKeyEvent* event)
{
qDebug() << "MyLineEdit::OnKeyPressEvent:"<<event->text()<< " row="<<_nRow<<" col=" <<_nCol;
///SET YOUR CODE HERE
QLineEdit::keyPressEvent(event);
}