[Solved] How to avoid Flickering in a QLineEdit Text.

[Macro]

tilsitt ....

This is my Code...

@if (keyEvent->key() == Qt::Key_Period)
{
QString tempString = q_LineEdit->text();
if(tempString.indexOf(".") != tempString.lastIndexOf("."))
{
int index = tempString.lastIndexOf(".");
tempString = tempString.mid(0, index);
q_LineEdit->setText(tempString);
}
}@

This is working fine. The Dot key Value doesn't gets appended when it is pressed continously. The only problem is, as i mentioned earlier, When the Dot Value is pressed for the second time the Value is shown in the QLineEdit until the Dot Key is Released. Once the Key is released it does not gets appended.. what i want is when i am pressing the Dot Key for the second time the value should not be shown in the QLineEdit...

[tilsitt]

and my question is: in your event filter, do you return true or not?

if not, after your event filter where you didn't append the dot, the event will still be computed by the QLineEdit, so the dot will be still added, before being removed by the QRegExp.

[Macro]

If i return true, Then the Dot value is not even getting appended when i press it for the first time... :-(

[tilsitt]

Could you please post the complete code of your event filter function? (version with and without returning true)

[Macro]

ok.... i will post the complete coding of my Event Filter Function...

[Macro]

[quote author="tilsitt" date="1358766947"]Could you please post the complete code of your event filter function? (version with and without returning true)[/quote]

Here's my complete code of my event filter function...

@bool MyWidget::eventFilter(QObject *target, QEvent *event)
{
if (target == q_LineEdit)
{
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

         if (keyEvent->key() == Qt::Key_Period)
         {
               QString tempString = q_LineEdit->text();
               if(tempString.indexOf(".") != tempString.lastIndexOf("."))
               {
                       int index = tempString.lastIndexOf(".");
                       tempString = tempString.mid(0, index);
                       q_LineEdit->setText(tempString);
               }
              
              else
              {
                     q_LineEdit->clear();
                     if(tempString == ".")
                     {
                              tempString.insert(0, "0");
                     }
                     q_LineEdit->setText(tempString);
             }
             return true;
  }

}@

[tilsitt]

Try this:
@
bool MyWidget::eventFilter(QObject *target, QEvent *event)
{
if (target == q_LineEdit)
{
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

    if (keyEvent->key() == Qt::Key_Period)
    {
        QString tempString = q_LineEdit->text();
        if(tempString.indexOf(".") != tempString.lastIndexOf("."))
        {
            int index = tempString.lastIndexOf(".");
            tempString = tempString.mid(0, index);
            q_LineEdit->setText(tempString);
            return true;
        }
        else
        {
            q_LineEdit->clear();
            if(tempString == ".")
            {
                tempString.insert(0, "0");
            }
            q_LineEdit->setText(tempString);
        }
    }
}
return MyWidget::eventFilter(target, event);

}
@

[Macro]

Oops... Sorry.. I already included that one & the result is the same.. Missed it while posting it... :-( Sorry for the Mistake...

[tilsitt]

To block the second dot using your event filter, the following works for me:

@
bool MyWidget::eventFilter(QObject *target, QEvent *event)
{
if (target == q_LineEdit)
{
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

    if (keyEvent->key() == Qt::Key_Period)
    {
        QString tempString = q_LineEdit->text();
        if(tempString.contains('.'))
        {
            return true; // QLineEdit::keyPressEvent will not be executed, the key press will just vanish
        }
    }
}
return MyWidget::eventFilter(target, event);

}
@

I don't understand why you're using this:

@
int index = tempString.lastIndexOf(".");
tempString = tempString.mid(0, index);
q_LineEdit->setText(tempString);
@

with this code, if you press some keys, a dot, some other keys and a second dot, the "some other keys" will be deleted. If that's what you want, why not.

one last thing: you don't check the type of your event, so if your QLineEdit send an event which is not a key press your program will crash. you should do something like that:

@
bool MyWidget::eventFilter(QObject *target, QEvent *event)
{
if (target == q_LineEdit && event->type()==QEvent::KeyPress)
{
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

    if (keyEvent->key() == Qt::Key_Period)
    {
        QString tempString = q_LineEdit->text();
        if(tempString.contains('.'))
        {
            return true;
        }
    }
}
return MyWidget::eventFilter(target, event);

}
@

so with your initial code:

@
bool MyWidget::eventFilter(QObject *target, QEvent *event)
{
if (target == q_LineEdit && event->type()==QEvent::KeyPress)
{
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

    if (keyEvent->key() == Qt::Key_Period)
    {
        QString tempString = q_LineEdit->text();
        if(tempString.contains('.'))
        {
            int index = tempString.lastIndexOf(".");
            tempString = tempString.mid(0, index);
            q_LineEdit->setText(tempString);
            return true;
        }
        else
        {
            q_LineEdit->clear();
            if(tempString == ".")
            {
                tempString.insert(0, "0");
            }
            q_LineEdit->setText(tempString);
        }
    }
}
return MyWidget::eventFilter(target, event);

}
@

[Macro]

Wooww.. It works Fine... Thanks a lot tilsitt... :-)