QWidget once lose focus, it cannt get the focus again

chris_rookie

I defined a Widget.
It is like this.

TopLevel::TopLevel(QWidget* parent) : QWidget(parent,
Qt::Tool | Qt::WindowStaysOnTopHint
| Qt::FramelessWindowHint | Qt::X11BypassWindowManagerHint)
{
setAttribute(Qt::WA_TranslucentBackground, true);
QVBoxLayout *lay = new QVBoxLayout(this);
lay->setMargin(0);
lay->setSpacing(0);
setLayout(lay);

setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);

}

void TopLevel::setCenterWidget(QWidget* widget)
{
if (m_widget) {
m_widget->removeEventFilter(this);
layout()->removeWidget(m_widget);
}
m_widget = widget;
widget->installEventFilter(this);
widget->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
layout()->addWidget(widget);
}

And I defined a QDeclarativeView.
Then a call the function setCenterWidget(QDeclarativeView).
after I open a application, the application full of the screen. The Widget that I defined can't get the focus.
There was no response to my dragging or clicking.

SGaist

Hi,

@chris_rookie said in QWidget once lose focus, it cannt get the focus again:

widget->installEventFilter(this);

Are you sure your event filter isn't breaking things ?
In any case, you should try first without it.

By the way, after your call to removeWidget, shouldn't you delete the widget pointed to by m_widget ? Because otherwise you are just going to use memory for nothing unless you manage that widget lifetime somewhere else.

chris_rookie

@SGaist
Hi.
I tried as this.

void TopLevel::setCenterWidget(QWidget* widget)
{
if (m_widget) {
m_widget->removeEventFilter(this);
layout()->removeWidget(m_widget);
delete m_widget;
m_widget = NULL;
}
m_widget = widget;
//widget->installEventFilter(this);
widget->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
layout()->addWidget(widget);
layout()->activate();//?
}

but The problem still there.

I put a QDeclarativeView in it, Does it matter?

SGaist

My main point was: what do you do in your event filter ?

chris_rookie

@SGaist
TopLevel::TopLevel(QWidget* parent) : QWidget(parent,
Qt::Tool | Qt::WindowStaysOnTopHint
| Qt::FramelessWindowHint | Qt::X11BypassWindowManagerHint)
{
setAttribute(Qt::WA_TranslucentBackground, true);
QVBoxLayout *lay = new QVBoxLayout(this);
lay->setMargin(0);
lay->setSpacing(0);
setLayout(lay);

setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);

}

void TopLevel::setCenterWidget(QWidget* widget)
{
if (m_widget) {
m_widget->removeEventFilter(this);
layout()->removeWidget(m_widget);
}
m_widget = widget;
widget->installEventFilter(this);
widget->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
layout()->addWidget(widget);
layout()->activate();//?
}

void TopLevel::showEvent(QShowEvent* event)
{
QWidget::showEvent(event);
setMask(rect());
updateLocation();
}

bool TopLevel::eventFilter(QObject object, QEvent event)
{
if (object == m_widget.data() &&
event->type() == QEvent::Resize) {
setMinimumSize(m_widget->sizeHint());
setMaximumSize(m_widget->sizeHint());
}
return QObject::eventFilter(object, event);
}**

void TopLevel::resizeEvent(QResizeEvent* resize)
{
QWidget::resizeEvent(resize);
setMask(rect());
updateLocation();
}

void TopLevel::setSpotRect(const QRect& rect)
{
m_spotRect = rect;
updateLocation();
}

void TopLevel::updateLocation()
{
if (this->isVisible() == false)
return;

QRect screenRect = QApplication::desktop()->screenGeometry(QPoint(m_spotRect.x(), m_spotRect.y()));
int x;
x = qMin(m_spotRect.x(), screenRect.x() + screenRect.width() - width());
x = qMax(x, screenRect.x());
int oy = m_spotRect.y() + m_spotRect.height();
int y = oy + 10;
if (y < screenRect.y()) {
    y = screenRect.y();
}

if (y > screenRect.y() + screenRect.height()) {
    y = screenRect.height();
}

if (y + height() > screenRect.y() + screenRect.height()) {
    /// minus 20 to make preedit bar never overlap the input context
    y = oy - (height() + ((m_spotRect.height() == 0)?20:(m_spotRect.height() + 10)));
}

QPoint p(x, y);
if (p != pos())
    move(p);

}

I put whole class here.
The eventFilter function didn't do much work. just filter QEvent::Resize.

SGaist

@chris_rookie said in QWidget once lose focus, it cannt get the focus again:

bool TopLevel::eventFilter(QObject object, QEvent event)
{
if (object == m_widget.data() &&
event->type() == QEvent::Resize) {
setMinimumSize(m_widget->sizeHint());
setMaximumSize(m_widget->sizeHint());
}
return QObject::eventFilter(object, event);
}

That last line has one issue: you are not calling the base class (which is QWidget in your case) implementation thus bypassing everything that it might be handling in there.

chris_rookie

@SGaist
Before I put my whole class here.
I also had try

return object->eventFilter(event);

or

return false;

I got the same result.
.....

It behaves like this.

This is my widget. when it on the desktop， I can drag it or click it.
After I open a folder, like this.

The folder below my widget. I cannt drag it or click it.

SGaist

That's not what I meant. You should call QWidget::eventFilter and not QObject::eventFilter.

In any case, why are you implementing it like that ? It seems you should rather call setFixedSize when you call setCenterWidget.

chris_rookie

@SGaist

if (object == m_widget.data() &&
event->type() == QEvent::Resize) {
setMinimumSize(m_widget->sizeHint());
setMaximumSize(m_widget->sizeHint());
}

Because I used it in other place.
In that case, I put a QDeclarativeView in it.
The QDeclarativeView's size would be changed.

As you said, I tried
return QWidget::eventFilter(object, event);

and

remove the function eventFilter and installEventFilter.

but it still does not work.
When I opened the folder, the folder under my widget. The folder get the focus.
Even I clicked my Widget, The focus still on the folder.
After I closed the folder or made the folder smaller(doesnt under my widget), my widget can get focus again.

SGaist

Sorry but your explanation are not really clear.

You should:

Provide a minimal compilable example that shows the issue
Explain your setup exactly (Qt version, Linux distribution, Desktop Environment, etc.)
Explain how you are using your application
Explain what you are doing to trigger the bug

You might think you did but with there's a lack of details that makes it so we don't know whether you are all doing that within your application or doing some other stuff with your file manager.

chris_rookie

@SGaist
Hi.
I execute my program on a little-known linux os.
Then I let my program executed on ubuntu 17.
The qt's version all 4.8.7.
On ubuntu 17 is ok.
I would find out the differnce of the two systems.
Thanks for your answer very much and Happy Chinese New Year.