Somehow my QSlider is not sliding. I am only able to click on the slider and then the slider changes his position. I have checked with examples but everything seems to be the same.
Here is one of my QSliders:
QSlider *obj_scale_x= new QSlider(Qt::Horizontal);
obj_scale_x->setValue(10);
obj_scale_x->setToolTip(tr("Scale object"));
obj_scale_x->setRange(1,50);
obj_scale_x->setTickPosition(QSlider::TicksAbove);
connect(obj_scale_x, SIGNAL(valueChanged(int)), this, SLOT(objScale_x(int)));
I thought the problem might be the mouse. But this is not working either.
void OpenGLScene::mousePressEvent(QMouseEvent *event)
{
lastPos = event->pos();
}
void OpenGLScene::mouseMoveEvent(QMouseEvent *event)
{
lastPos = event->pos();
}
I am definining the Slider in QGraphicsScene-based class. it might be this, but I am at my wit's end.
Maybe the answer to your problem is:
obj_scale_x->setTracking(true);
Make sure you don't have an eventFilter() defined for an object higher up in the UI hierarchy, and if you do, make sure it doesn't "swallow" the event in case it doesn't react to the event directly (i.e. call BaseClass::eventFilter(obj, event) in that case).
That solved the problem for me.
Related
my eventFilter doesn't work as expected. I either missunderstood its behaviour or I have a problem in my program.
In my program I have a QScrollArea with a QLabel inside to display an Image (just like in the Qt Image Viewer Example), but if the user scrolls his MouseWheel I don't want the ScrollArea to scroll, but the Image to scale. Therefore I implemented an eventFilter for my Label and my ScrollArea.
bool RBDP::eventFilter(QObject *target, QEvent *event)
{
if (target == scrollArea || target == iv) {
if (event->type() == QEvent::Wheel) {
QWheelEvent *w = static_cast<QWheelEvent *>(event);
iv->scaleImage(w->delta());
return true;
}
I know that the eventFilter actually gets triggered when you scroll. The problem is that the ScrollArea ALSO scrolls, i.e. if you use your MouseWheel, the Image scales and the ScrollArea scrolls!
As far as I know, the event shouldn't be propagated to its original target, if the eventFilter returns true.
I installed in my main class eventFilters for both, the scrollArea and iv (which is my QLabel).
scrollArea->installEventFilter(this);
iv->installEventFilter(this);
How do I prevent the ScrollArea from scrolling? I know this isn't much code, but the program is kind of complex already and I don't know, what else could be useful. So please let me know, if you need to see other code segments.
Thanks in advance
my QComboBox-derived class lives in a QGraphicsScene at the bottom end of the (visible) screen - but it pops up downwards, thus out of view.
(How) is it possible to force the popup to open above the widget?
I've tried re-implementing showPopup like this:
void MyComboBox::showPopup()
{
QAbstractItemView *popupView = view();
popupView->move(0,-100);
//popupView->window->move(0,-100);
QComboBox::showPopup();
}
The result is, that the content seems to be shifted, but not the underlying popup object.
I think it might be possible to find a solution with styles as indicated in
this article, but I can't find any Styles control that might be helpful here. I am rather new to C++ as well as Qt, so I might be missing something obvious.
I'd appreciate any help on this matter!
Best regards,
Sebastian
With the information found here, I was able to get it done this way:
void SteuerQComboBox::showPopup() {
QComboBox::showPopup();
QWidget *popup = this->findChild<QFrame*>();
popup->move(popup->x(),popup->y()-this->height()-popup->height());
}
Note that it's crucially important to call the base classes "showPopup" first.
Thanks to everybody who was reading my question and thinking about it!
user1319422's solution isn't bad, but it has two problems.
If your platform has GUI animation, the listbox will animate opening downwards, then is moved above the text box.
If you disable combobox animation (or you don't have it), the call to QComboBox::showPopup() still makes the GUI element start to appear on the screen already. So, moving it there would cause it to flicker as it appears in the first place and moves to the next.
So, to address the first problem, I just switched off animation:
void MyComboBox::showPopup()
{
bool oldAnimationEffects = qApp->isEffectEnabled(Qt::UI_AnimateCombo);
qApp->setEffectEnabled(Qt::UI_AnimateCombo, false);
QComboBox::showPopup();
qApp->setEffectEnabled(Qt::UI_AnimateCombo, oldAnimationEffects);
}
Then, for the second problem, I moved the frame in the Show event:
bool MyComboBox::eventFilter(QObject *o, QEvent *e)
{
bool handled = false;
if (e->type() == QEvent::Show)
{
if (o == view())
{
QWidget *frame = findChild<QFrame*>();
//For some reason, the frame's geometry is GLOBAL, not relative to the QComboBox!
frame->move(frame->x(),
mapToGlobal(lineEdit()->geometry().topLeft()).y() - frame->height());
}
}
/*else if other filters here*/
if (!handled)
handled = QComboBox::eventFilter(o, e);
return handled;
}
if you want to force popup to open above only when it is out of view you can do this:
void SteuerQComboBox::showPopup() {
QComboBox::showPopup();
QWidget *popup = this->findChild<QFrame*>();
if((popup->y() + popup->height()) > this->window()->height())
popup->move(popup->x(),popup->y()-this->height()-popup->height());
}
This is sort of a chicken and egg problem. I'd like my widget window to be closed when the mouse clicks outside. As I understand it, there will be no mouse events for my widget for a click occurring outside of it. There is a SetFocus slot, but where is its counterpart or focus loss? "focusOutEvent" doesn't get called for my class.
My widget window is a child window of a widget always shown on my main window and it's a "Qt::ToolTip", so I assume some problems could arise from that fact. Any way around that?
My Goal: I have a custom toolbar widget where buttons on it may have “drop down” widgets. These drop down widgets have no standard windows frame. I don’t want them to “steal” caption focus from the main window and I want them to disappear as soon as the user clicks ANYWHERE on the screen outside of their region. I have having serious difficulties finding a strategy that’s not compromise on Qt to get this done.
Am I missing something? (bet I am).
I used:
setWindowFlags(Qt::FramelessWindowHint | Qt::Popup);
This seems to work well on OSX and Windows. My window appears correctly, does not steal the focus from my main window's caption, and the focus loss event is called correctly as soon as I click outside of it.
If your widget could have focus, and 'steal' the caption focus of some of your other widgets, it would have been easier. Something like this could work:
class ToolBarWidget : public QWidget
{
Q_OBJECT
public:
explicit ToolBarWidget(QWidget * parent = 0)
{
setFocusPolicy(Qt::ClickFocus);
}
protected:
void focusOutEvent(QFocusEvent * event)
{
close();
}
}
And when you create any of your widgets you'd do:
ToolBarWidget * pWidget = new ToolBarWidget(this);
pWidget->show();
pWidget->setFocus();
Done! Well, I guess not quiet. first, you don't want the ToolBarWidget to get any focus in the first place. And second, you want for the user to be able to click anywhere and the ToolBarWidget to be hidden.
So, you may keep track of every ToolBarWidget that you create. For example, in a 'QList ttWidgets' member variable. Then, whenever you create a new ToolBarWidget, you'd do this:
ToolBarWidget * pWidget = new ToolBarWidget(this);
pWidget->installEventFilter(this);
pWidget->show();
and in your main widget class, implement the eventFilter() function. Something like:
bool MainWidget::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::FocusOut ||
event->type() == QEvent::KeyPress ||
event->type() == QEvent::MouseButtonPress)
{
while (!ttWidgets.isEmpty()) {
ToolBarWidget * p = ttWidgets->takeFirst();
p->close();
p->deleteLater();
}
}
return MainWidget::eventFilter(obj, event);
}
And that will work. Because this way, even though your ToolTabWidgets aren't getting focus, some other widget in your main widget has focus. And once that changes (whether the user clicked out of your window, or on another control inside it, or in this case, a key or mouse button is pressed, the control will reach that eventFilter() function and close all your tab widgets.
BTW, in order to capture the MouseButtonPress, KeyPress etc. from the other widgets, you would either need to installEventFilter on them too, or just reimplement the QWidget::event(QEvent * event) function in your main widget, and look for those events there.
you can do this by using QDesktopWidget.h like this
void MainWindow::on_actionAbout_triggered()
{
AboutDialog aboutDialog;
//Set location of player in center of display
aboutDialog.move(QApplication::desktop()->screen()->rect().center() -aboutDialog.rect().center());
// Adding popup flags so that dialog closes when it losses focus
aboutDialog.setWindowFlags(Qt::Popup);
//finally opening dialog
aboutDialog.exec();
}
This is what worked for me in order to not steel the focus from the main application:
.h
bool eventFilter(QObject *obj, QEvent *event) override;
.cpp
bool Notification::eventFilter(QObject *obj, QEvent *event)
{
if(event->type() == QEvent::MouseButtonPress)
deleteLater();
return QObject::eventFilter(obj, event);
}
...
// somewhere else (i.e. constructor, main window,...)
qApp->installEventFilter(this);
OP's own answer is great for Qt versions below 4.8, but as they mention in their answer, it does not work for versions above that. The Qt::Popup widget will not disappear when the mouse is clicked outside of the widget, and it will sink all of the input that would normally close it.
Upon further investigation, this is only an issue for non-dialog widgets. A QDialog using Qt::Popup will properly close when the user clicks outside of it, but any other QWidget, like a QFrame, will not. So in order to work around this behavior change in Qt 4.8, all that is necessary is to wrap the widget in a QDialog.
In my program, I'd like to have mouseMoveEvent(QMouseEvent* event) called whenever the mouse moves (even when it's over another window).
Right now, in my mainwindow.cpp file, I have:
void MainWindow::mouseMoveEvent(QMouseEvent* event) {
qDebug() << QString::number(event->pos().x());
qDebug() << QString::number(event->pos().y());
}
But this seems to only be called when I click and drag the mouse while over the window of the program itself. I've tried calling
setMouseTracking(true);
in MainWindow's constructor, but this doesn't seem to do anything differently (mouseMoveEvent still is only called when I hold a mouse button down, regardless of where it is). What's the easiest way to track the mouse position globally?
You can use an event filter on the application.
Define and implement bool MainWindow::eventFilter(QObject*, QEvent*). For example
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseMove)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
statusBar()->showMessage(QString("Mouse move (%1,%2)").arg(mouseEvent->pos().x()).arg(mouseEvent->pos().y()));
}
return false;
}
Install the event filter when the MainWindows is constructed (or somewhere else). For example
MainWindow::MainWindow(...)
{
...
qApp->installEventFilter(this);
...
}
I had the same problem, further exacerbated by the fact that I was trying to call this->update() to repaint the window on a mouse move and nothing would happen.
You can avoid having to create the event filter by calling setMouseTracking(true) as #Kyberias noted. However, this must be done on the viewport, not your main window itself. (Same goes for update).
So in your constructor you can add a line this->viewport()->setMouseTracking(true) and then override mouseMoveEvent rather than creating this filter and installing it.
I've derived from QGLWidget before, like so:
class MyGLWidget : public QGLWidget
{
public:
// stuff...
virtual void initializeGL() { /* my custom OpenGL initialization routine */ }
// more stuff...
};
However, I find that if I try to initialize a QGraphicsView with my custom QGLWidget as the viewport, initializeGL doesn't get called (setting a breakpoint within the Qt library, neither does QGLWidget::initializeGL() when created plain).
// initializeGL, resizeGL, paintGL not called
ui.graphicsView->setViewport(new MyGLWidget(QGLFormat(QGL::DoubleBuffer)));
// initializeGL, resizeGL, paintGL *still* not called
ui.graphicsView->setViewport(new QGLWidget(QGLFormat(QGL::DoubleBuffer)));
Where is the correct location to place the code that currently resides in MyGLWidget::initializeGL()?
The setupViewport slot of a custom QGraphicsView could be used to call updateGL() on the QGLWidget, which will cause initializeGL() to be called.
class MyGraphicsView : public QGraphicsView
{
//... The usual stuff
protected slots:
virtual void setupViewport(QWidget *viewport)
{
QGLWidget *glWidget = qobject_cast<QGLWidget*>(viewport);
if (glWidget)
glWidget->updateGL();
}
};
So what I've found is QGraphicsView installs a custom eventFilter on your QGLWidget viewport so it never sees the initialize/resize/repaint events. This probably was done to make it work properly with drawBackground() etc.
My current best resolution is to catch the desired event either in QGraphicsView::resizeEvent()/etc, or install a custom eventFilter on your QGLWidget derived class to catch the resize/paint/etc events before QGraphicsView's custom eventFilter swallows them.
The pain, the pain, ... integrating widgets derived from QGlWidgets into QGraphicsView is no fun, of the parts of Qt that I know this is definitely one of the messier areas. I ended up using a part of kgllib (out of kde) called widgetproxy that is a very decent wrapper around a QGlWidget. I modified it to fit my needs but works reasonably well for most general cases where you want to use an exisiting class derived from QGlWidget inside a QGraphicsView and draw other things on top of it.
initializeGL() won't get called until the first call to either paintGL() or resizeGL() and not when the widget is constructed. This may happen as late as when the widget is first made visible.
I'm going to go ahead and answer my own question. This isn't optimal, but this is how I've gotten around the problem.
Instead of
ui.graphicsView->setViewport(new MyGLWidget(QGLFormat(QGL::DoubleBuffer)));
I've got this instead:
ui.graphicsView->setViewport(new QGLWidget(new CustomContext(QGLFormat(QGL::SampleBuffers))));
CustomContext is a class that derives from QGLContext. I've overridden the create member, like so:
virtual bool create(const QGLContext *shareContext = 0)
{
if(QGLContext::create(shareContext))
{
makeCurrent();
/* do my initialization here */
doneCurrent();
return true;
}
return false;
}
I don't think this is the optimal way to do this, but it's better than the alternative of not having a specific initialization step at all. I'd still be happy to have someone leave a better answer!