IP Editor popuppad Delete not clearing LineEdit



  • Hi everyone,

    I apologize for making the bajillion topic posts about my IP Editor. Every time I think I'm done with it, something else needs to be added/modified. Anyhoo! I made an IP Editor plugin that uses 4 lineedits, similar to this:

    ___.___.___.___
    

    A numberpad intended for touchscreen use, pops up when the LineEdits have focus. For each button on the numberpad, I am sending a QEvent::KeyPress. When implementing the "Delete" key, I made sure it was set to autorepeat. For the Delete key, I am sending a KeyEvent that Backspace was pressed.

    The problem I am having is that, if the complete IP Address is entered, for example 123.123.123.123, and the user presses and holds down the Delete key, it deletes 123 then moves to the previous LineEdit, but stops. I have to press Delete again in order to delete the next three numbers, and so on, until the IP Editor is empty again. When I use the Backspace key on the keyboard, it works fine. Does aynone have an idea of what's going on?

    Thanks


  • Moderators

    @Sh1gs

    You are trying to get people to crystal ball reading. You need to post a code snippet showing the problem.



  • My lineedits are receiving data in a function called "receiveData". In this function, for the delete key, I have the following:

    QKeyevent *event = new QKeyEvent(QEvent::keyPress, Qt::Key_Backspace, Qt::NoModifier, text, true);
    QApplication::sendEvent(this, event);
    QApplication::postEvent(curEdit, event);
    curEdit->installEventFilter(this);
    

    So when delete is pressed, it goes to my event filter which has:

    case Qt::Key_Backspace:
    if(input->text.isEmpty)
      movPrevLE(i);
    break;
    

    and then finally in movPrevLE, I have:

    if(i!=0)
      leList[i-1]->setFocus();
      leList[i-1]->setCursorPos(leList[i-1]->text.size());
    

    It works with the Backspace on the keyboard, but when I press and hold my delete key, it only deletes the current line edit text, moves to the previous line edit, and then stops. I'm assuming it's a signal/event issue that it needs to keep being triggered, but I'm not sure how to go about it.



  • I have seen these two Bug reports and am wondering if that is why I'm having difficult. Could someone shed some light on this?

    QTBUG-19060

    QTBUG-20444

    Thanks.


  • Moderators

    @Sh1gs said in IP Editor popuppad Delete not clearing LineEdit:

    I have seen these two Bug reports and am wondering if that is why I'm having difficult. Could someone shed some light on this?

    QTBUG-19060

    QTBUG-20444

    Thanks.

    Both bug reports are referring to 4.7.4 and are closed. One is done and the other was a duplicate. All this is 6 years old.
    In case you are still using Qt4 this would be a good information to supply as well. Probably more than 95% of users here are definitely on Qt 5. As noted above crystal ball reading is not a common gift for those people trying to help.

    Certainly there is always a chance that bugs are slipping back. However, chances are typically in the low percentage.



  • @koahnig

    The snide comment is unnecessary. This is why people get frustrated when posting on forums. As I've stated above, I provided as much code as I can, unfortunately I cannot provide everything because of the nature of my job and the hoops I have to jump through to post what I have already.

    I simply came on here to ask for help regarding a KeyPressEvent for a delete key to act as the Backspace key on the keyboard, and why it only deletes the the current LineEdit, moves to the previous LineEdit, and stops.


  • Qt Champions 2016

    @Sh1gs
    Hi
    When you say delete key , you refer to Qt::Key_Backspace: ?

    So as i understand it, this goes to prev edit if its empty
    case Qt::Key_Backspace:
    if(input->text.isEmpty)
    movPrevLE(i);
    break;

    So i wonder why it can one back and then stop. Did you try with debugger and
    see if movPrevLE(i); does as expected? and than i is also expected index.

    Since it works for first two, i wonder if it seems it as not empty.

    You can insert qDebug statements to see what differs when in second edit and
    if the delete key is still being sent.



  • @mrjj

    I apologize for not being more clear. I have a numberpad that pops up on screen whenever one of the LineEdits has focus, essentially my version of a "virtual keyboard". I have made sure that all of the PushButtons don't have focus. I have a "Delete" PushButton within that numberpad, that I want to act as the "Backspace" key on the keyboard. So when "Delete" is clicked, I have:

    QKeyevent *event = new QKeyEvent(QEvent::keyPress, Qt::Key_Backspace, Qt::NoModifier, text, true);
    QApplication::sendEvent(this, event);
    QApplication::postEvent(curEdit, event);
    QKeyevent *rE = new QKeyEvent(QEvent::keyRelease, Qt::Key_Backspace, Qt::NoModifier, text, true);
    QApplication::sendEvent(this, rE);
    QApplication::postEvent(curEdit, rE);
    curEdit->installEventFilter(this);
    

    Then when it goes to the eventFilter, it has as you wrote:

    case Qt::Key_Backspace:
    if(input->text.isempty())
    movPrevLE(i);
    break;
    

    It works with the backspace key on the keyboard, but for the life of me, I cannot figure out why the Delete PushButton I created doesn't act the same way. The Delete button moves fine and deletes if I keep pressing it. But if I press and hold, it only deletes the current LineEdit it is in, moves to the previous LineEdit, and then doesn't delete until it's pressed again.

    I have added qDebug() statements to see if the Press and Release events are occuring, and they are. I have also seen that it is indeed moving to the previous LineEdit.


  • Qt Champions 2016

    @Sh1gs
    Hi
    it might be related to how auto repeat is working.
    I assume you have
    button->setAutoRepeat(true);
    and tweaked setAutoRepeatInterval and setAutoRepeatDelay to your like.

    If you (for test) use a timer and call the same code, does it then work?



  • @mrjj

    Yes, I have delete->setAutoRepeat(true); as well as the parameter AutoRep in my keyPress is set to True. I did not change the autorepeatinterval or delay.

    I am not as familiar with QTimer, so how would I go about implementing that? Would it be something like...

    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(what slot to use?));
    timer->start(some amount of time);
    

    Where would this section of code go?



  • @mrjj

    Ok, this may not be correct, but I put the following within my eventFilter under Qt::Key_Backspace:

    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout(), this, SLOT(update()));
    timer->start(100);
    

    Then in my update() slot, I am emitting that "delete" was pressed.

    Doing this, deletes all of the LineEdit texts. Now I am having an issue that the signal keeps being sent as if the "Delete" key is being pressed/released for eternity, then it crashes. I've tried disconnecting the timer, and I've tried timer->stop() but that doesn't seem to fix the issue either. At least I'm getting closer :)


  • Qt Champions 2016

    @Sh1gs
    Super.
    It was not meant as a solution.
    I just wondered if the function would indeed work if something other than a repeating button was used.

    So it's fair to say the logic works (it will go through all 4) and it will clean all edits
    and it does send pressed/released as expected.

    Unless i missed something, it seems its the autorepeat feature that does something unexpected.

    Also i wonder other thing.

    in receiveData
    you call curEdit->installEventFilter(this);
    and as far as i understand it means it will be called multiple times.
    Normally you call it once, when you create the curEdit.
    Not sure if it will only be added once and others calls are just ignored. ( there can be mutiple)
    Would it be possible to move this line to where you create curEdit so its for sure only installed once?

    I think i understand the design now and i see no reason to differently with a button but im sure we can find it.



  • @mrjj

    I've changed it to check if it's in the first edit, to stop the timer so it'd look like

    123.___.___.___
    

    And then the user will have to manually hit "Delete" repeatedly to delete the characters. This way, the program doesn't crash. It's not exactly elegant, but it's close enough to the requirements I was given.

    I have also changed that curEdit->installEventFilter(this) is only called once.

    Thank you very much for your help, I will go ahead and mark this as solved.



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