In my custom widget, there are seven labels included as child widgets. Their texts and text formats should be set by user of the parent widget. I created 14 slots to accomplish this:
void setCenterText(const QString &text) {
ui->labelCenter->setText(text);
}
void setRightText(const QString &text);
...
Can it be done via something like: connect(parent, slot(a), child, slot(b)) and a signal connected to the parent slot is automatically forwarded to the child widget?
Can it be done via something like: connect(parent, slot(a), child,
slot(b)) and a signal connected to the parent slot is automatically
forwarded to the child widget?
You can't connect slots to slots, but more importantly, without specifying the target widget in another argument, there is no way for the parent widget to know which child needs modifying.
Although what you are doing is laborious, it is a basic tennant of aggregate-based component building, and it does offer advantages - primarily the ability to very finely tune exactly what child widget properties are exposed to the programmer.
Related
I need to connect some simple filter functionality, to a mouse click on a QTreeView header item. Simple enough, I implemented a slot function that connects to:
QTreeView::header()->sectionClicked(int)
After setting
QTreeView::header()->setSectionsClickable(true)
,sectionClicked is emitted any time I click on a header that is highlighted by the default hover effect that any clickable header will produce.
The issue is, hovering over some areas in clickable headers will not be recognized. Hence, in these parts there is no highlight and I will not get any sectionClicked triggers. I traced it back further and derived my own class from QHeaderView and put some output into mouseMoveEvent.
class MyHeaderView : public QHeaderView
{
Q_OBJECT
public:
MyHeaderView(QWidget* parent = 0)
: QHeaderView(Qt::Horizontal, parent)
{
setMouseTracking(true);
}
protected:
virtual void mouseMoveEvent(QMouseEvent* event)
{
qDebug() << event->pos();
}
};
While leaving all QTreeView settings as they were, I set an instance of this class to be the header via
QTreeView::setHeader(QHeaderView*)
I could see, that in all areas were the hover effect failed, I did not get the debug output you can see in the overridden mouseMoveEvent.
As a result I am assuming, that the mouse tracking is not working correctly.
The overall application I am working on is quiet big, so I set up a stand alone example, for all of this. To my surprise, everything works as expected. I am clueless, how I should proceed with this. Can anyone think of reasons for the mouse tracking to fail in some parts of a widget? Could it be a frame rate issue tied to lack of performance? Are there settings on widgets that affect the overall mouse tracked area? Can parent widgets affect mouse tracking?
In my application I have a controller class that handles a lot of application logic connected to various signals the tree view emits. This class is not suppost to render any visualization. Hence, it would be the most reasonable choice to derive from QObject. After a while I noticed, that it was in fact derived from QWidget. Being a QWidget I am guessing it tries to render some sort of visual representation, which the overlays the tree view. That's why I don't get any mouse events in some parts of the header.
After changing the base class of my controller to QObject, everything works fine again.
Is it somehow possible to add to each Item in a QListview a Button which is deleting the Object onClick? As shown in the following Picture:
EDIT: As I'm new in QT it would be nice to have some example, to understand it better. And as it seems there are three different Ways? What will be the best? Do use a QAbstractItemView?
Yes. You'll need to use:
QAbstractItemView::setIndexWidget ( const QModelIndex & index, QWidget * widget )
QListView inherits QAbstractItemView and when you're trying to customize list/tree views that's usually the place to look. Be careful though, without a delegate this doesn't scale very well. Check out this thread: http://www.qtcentre.org/threads/26916-inserting-custom-Widget-to-listview
You can also go for a generic approach that can work on variety of containers, including the underlying model of your list view.
Each item in the list has a requestRemoval(Item*) signal and a removeMe() slot, connect the X button to the removeMe() slot in each item constructor, in removeMe() you emit the requestRemoval(this) signal, which is connected to a removeHandler(Item*) slot in your "parent" object upon creation of that item, which receives the pointer of the item which has requests deletion, and removes it from the underlying container being used.
Basically, pressing the remove button causes that particular item to send a pointer of itself to the parent's remove handler which removes that entry.
EDIT: Note that this is a generic approach, as noted in the comments below it can be applied without signals and slots as well, and even though it will work it is not the most efficient solution in your particular case.
I think i'm having a fairly basic Qt problem, but i can't figure it out:
I have a QMainWindow which holds a QStackedWidget. All page widgets in there are seperate classes derived from QWidget.
So:
QMainWindow implements QStacked Window in one class.
All other pages inside the stacked widget are added classes and all have there own .ui filled with buttons and lists trough the Designer.
For navigating to different pages, inside the Mainwindow i have access to: ui.stackedWidget->setCurrentIndex(2);
It seems i don't have access to ui.stackedWidget on another page inside the stacked widget? I have no access to the ui.stackedWidget because Ui is a private member in the mainwindow class. (auto generated by Qt - using VS addon for adding QT4 classes)
I would like to know, how can i jump to another page in the stacked widget, when clicking on a button that belongs to another page inside this widget?
Note:
All pages are added to the StackedWidget in mainWIndow's constructor:
ui.stackedWidget->addWidget(page1Widget);
ui.stackedWidget->addWidget(page2Widget);
// etc..
Example of a button click signal-slot inside page1Widget:
connect(ui.btnViewData, SIGNAL(clicked()), this, SLOT(viewData()));
::viewData()
{
// navigate to another page here.
// note: ui.stackedWidget->setCurrentIndex(3); is not accessible here!
}
I believe that putting your connect() and viewData() functions within your QMainWindow object will solve your problem, since the main window can have access to both the signals emited by the child widgets and the QStackedWidget items.
You might need to write a Ui getter for each of your page, and then do something like
connect(page1Widget->getUi().btnViewData, SIGNAL(clicked()), this, SLOT(viewData)));
hope it helps,
cheers
I'm programming in Python using Qt with PySide and I have custom QWidget defined in a file called editor.py which is inserted in my ui in windowUi.py using the promotion method in the Qt Designer.
The custom QWidget class defined in editor.py doesn't do much besides using Elixir to edit items in a sqlite3 database and importing a ui file (editor.ui). Inside editor.ui there are a couple of QLineEdits and QDateTime widgets.
This widget is originally hidden in the main window and showed when needed. So far so good, but the problem is that I cannot make it hide when not needed. I decided that the widget is not needed when the user clicks anywhere else in the main window that is not the editor widget imported, that is, focus shift from the QWidget.
I looked upon this question: QWidget focusOutEvent not received and realized that the QWidget is really not getting focus.
If I call setFocusPolicy(StrongFocus) on it then I can make it hide if, and only if, the user clicks on the QWidget background (not on any widget inside it) and then clicks outside.
The question is then, how can I make it such that when the user clicks outside of this widget, shifting focus from any QLineEdit or QDateTime that's inside it to something else, the QWidget then hides itself?
Doesn't QApplication:::focusChanged ( QWidget * old, QWidget * now ) do what you need? You can check if QWidget *now is one of your QLineEdits/QDateTime or not (f.e. by going up by the QObject::parent)
Simply connect to this signal before showing and disconnect after hiding.
In my project I am using a custom circle-shaped button widget derived from the QWidget class. I have added several of these widgets to a parent widget.
When one of these custom buttons is clicked, how do I find out which one was clicked?
Adding custom button to parent widget:
void ShotViewCTRL::addShot(QString shotNanme)
{
ShotButton *btnShot=new ShotButton(this);
btnShot->shotName=shotNanme;
connect(btnShot,SIGNAL(Shot_Selected()),this,SLOT(SHOT_CLICKED()));
btnShot->CreateButton();
btnShot->show();
}
My parent widget is ShotViewCTRL (inherits from QWidget), the child widget is ShotButton (custom control, inherits from QWidget).
The control is working fine. It's sending sending to parent object. In my problem, I added the same custom control 10 times.
I need to find which control was clicked? Please help me find the solution.
I have referred to the Qt documentation to find the child widget, but I did't understand. Some sample code would be great.
QSignalMapper is what you are looking for. With QSignalMapper, you can add something like an Id (or even a pointer to the QButton itself) as additional data to the signal emittance and you have to adjust your slot so it takes additional data (ID or Pointer).
Then either distinguish in the slot itself by the id you give your objects some virtual function type() so you can distinguish with that or even try casting and catch errors (Tip: don't try the last method, it may work differently on different compiler).
You can use the QObject::Sender function to find which QObject sends the signal. Regarding the first warning in the doc, it's what you are searching for.
you specify different slots for different buttons with same signal.with that you can recognize the different button click