QTableWidget KeyPress filtering

[grantbj74]

Hi,

I have a QTableWidget with one column that can have 0 to 255 entered (all other characters should be ignored). All other columns are read only.

I setup the table to pass events to the main window eventFilter, unfortunately keyPress doesn't make it there keyRelease does.

So I guess I need to catch them from QTableWidgetItem. I tried the following, this was in the program body, maybe I should try similar in constructor? Also I think the item in the connect function probably needs to be *item or &item or something ?

QTableWidgetItem *item;
 
if((item = new QTableWidgetItem("0")) != NULL) {
 
    table->setItem(row, col, item);
    connect(item, SIGNAL(keyPressEvent(QKeyEvent *)), this, SLOT(onKeyPressEvent(QKeyEvent *)));
}

QTableWidgetItem *item;

if((item = new QTableWidgetItem("0")) != NULL) {

    table->setItem(row, col, item);
    connect(item, SIGNAL(keyPressEvent(QKeyEvent *)), this, SLOT(onKeyPressEvent(QKeyEvent *)));
}

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[wysota]

Why are you using event filters? Use an item delegate.

[grantbj74]

Thanks, Could you give a little more information or point me to an example?

[wysota]

QAbstractItemDelegate

[grantbj74]

Thanks I got the basic key filtering working with the following code.

bool StringDelegate::eventFilter(QObject *obj, QEvent *event)
{
    if(event->type() == QEvent::KeyPress) {
 
        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
 
        return (keyEvent->key() < '0' || keyEvent->key() > '9');
    }
         // standard event processing
    return QObject::eventFilter(obj, event);
}

bool StringDelegate::eventFilter(QObject *obj, QEvent *event)
{
    if(event->type() == QEvent::KeyPress) {

        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

        return (keyEvent->key() < '0' || keyEvent->key() > '9');
    }
         // standard event processing
    return QObject::eventFilter(obj, event);
}

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Now I am trying to enforce the range when the user exits editing: I tried to add the following to the eventFilter, it compiles but doesn't work.

} else if(event->type() == QEvent::Leave) {
 
         QLineEdit *lineEdit = static_cast<QLineEdit*>(obj);
         QString text = lineEdit->text();
 
        if(text.toInt() > 255)
             text = "255";
        else if(text.toInt() < 1)
             text = "0";
 
        lineEdit->setText(text);
    }

} else if(event->type() == QEvent::Leave) {

         QLineEdit *lineEdit = static_cast<QLineEdit*>(obj);
         QString text = lineEdit->text();

        if(text.toInt() > 255)
             text = "255";
        else if(text.toInt() < 1)
             text = "0";

        lineEdit->setText(text);
    }

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The following code checks range when editing starts, but i'm just interested in when editing ends:

void StringDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString value = index.model()->data(index, Qt::EditRole).toString();
    QLineEdit *lineEdit = static_cast<QLineEdit*>(editor);
 
    if(value.toInt() > 255)
        value = "255";
    else if(value.toInt() < 1)
        value = "0";
 
    lineEdit->setText(value);
}

void StringDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString value = index.model()->data(index, Qt::EditRole).toString();
    QLineEdit *lineEdit = static_cast<QLineEdit*>(editor);

    if(value.toInt() > 255)
        value = "255";
    else if(value.toInt() < 1)
        value = "0";

    lineEdit->setText(value);
}

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Any ideas? Thanks in advance.

[wysota]

Why did you fix yourself on using an event filter????? All you need to do is to override QAbstractItemDelegate::createEditor().

[grantbj74]

Thanks,

So the following code sets the range (0 to 255), using a validator:

QWidget* StringDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &,const QModelIndex &) const
{
    QLineEdit *editor = new QLineEdit(parent);
    QIntValidator *val = new QIntValidator(editor);
 
    val->setRange(0, 255);
    editor->setValidator(val);
 
    return editor;
}

QWidget* StringDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &,const QModelIndex &) const
{
    QLineEdit *editor = new QLineEdit(parent);
    QIntValidator *val = new QIntValidator(editor);

    val->setRange(0, 255);
    editor->setValidator(val);

    return editor;
}

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Is there a way to say chop off leading zeros once editing is finished using delegates?

[wysota]

How about returning a spinbox from createEditor() with a range set to 0-255?

[grantbj74]

Yes that worked, Thanks

QWidget* StringDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &,const QModelIndex &) const
{
    QSpinBox *spin = new QSpinBox(parent);
 
    spin->setRange(0, 255);
    return spin;
}

QWidget* StringDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &,const QModelIndex &) const
{
    QSpinBox *spin = new QSpinBox(parent);

    spin->setRange(0, 255);
    return spin;
}

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