I am working on an application using QT. I have a mainwindow on which i have an image label. I load an image to this imagelabel and now i want to draw over it. So, my question is- how do i create mouse events for this image label only without having to derive another class of QLabel and instantiating its object to my main window.
My project's due tomorrow and its the only thing i've got left to do. I'd really appreciate the help.
Sincerely, Aayush Shrestha.
If you do not want to create a class that inherits from QLabel to get mouse event, you need to use the installEventFilter function using the eventFilter event of one of your class.
Related
I have some rectangle link area on my widget. What is the best way to make cursor Qt::PointingHandCursor when it is in this area?
The QWidget class has a cursor property that you can set with the cursor you wish displayed when the mouse is above it.
EDIT:
Without more detail on what you are trying to achieve, I can only assume you're making your life much more difficult than it needs to be. You can create a QLabel widget to handle the link and then place the label on the menubar automatically.
QLabel *link = new QLabel("<a href='http://doc.qt.io'>Qt Documentation</a>");
menuBar()->setCornerWidget(link);
All the text formatting, cursor display and user interactions are handled by existing code in the Qt classes. The only thing you need to do yourself is to handle what happens when the user clicks on the link, that you can do by connecting a slot to the QLabel::linkActivated(const QString &) signal.
I have a application in Qt, and a MainWindow. Now, I also added a helping QDialog which can be hooked up. This QDialog does not influence the programmflow, it just displays information.
But, it always starts on top of the MainWindow :/
SO I would like to start it on the side of the main window, so that it does not hinder the view to the main window?? How?
In my opinion , You should try this,
Use the overload of the QWidget::setParent() function to change the ownership of a QDialog widget, using set as NULL(but It will not share the parent's taskbar entry).
QDialog::show() returns control to the caller immediately, So it will not interfere in mainwindow flow.
Let's say, your application is in the full screen mode. Where then the QDialog should appear? It will be shown on the top and you won't be satisfied again.
If it doesn't influence the flow of the app then you are using it to communicate some sort of message. Can you use different ways? For instance, QStatusBar?
If not, why not to split the mainWindow with QSplitter or similar classes and provide an area where you can post all the info messages?
It sounds you want modaless dialog. In main window, use a slot to create the dialog.
void MainWindow::show_dialog()
{
if ( pDialog== NULL )
pDialog= new XYZ_Dialog(this);
QPoint p = pos();
QSize s = frameSize();
pDialog->setGeometry(p.x()+s.width(), p.y(), s.width()*1/2, s.height());
pDialog->show();
}
What I try to say is if the position of the new dialog bothers you, you set the position and size of it, before showing it.
I'm new to Qt programming and I am developing a drawing application. I have a class MyWidget which has a member QGraphicsView. MyWidget is a member of another class MainWidget (which has other widgets as well and all of them are in a layout).MainWidget is the central widget of my subclass of QMainWindow.
I have created functions to scale the view with the mouse wheel event and a function to drag the scene around.
The problem is - I want to set the Scene's size to be fixed, and to be 3 times the size of the view, but since the view is managed by a layout in order to take as much space as possible I can't get the view's size?
Any help appreciated.
the size property will give you the current size of your widget:
http://qt-project.org/doc/qt-4.8/qwidget.html#size-prop
Alternatively, you could subclass QGraphicsView and re-implement the resizeEvent:
http://qt-project.org/doc/qt-4.8/qwidget.html#resizeEvent
For a full example, have a look into:
http://qt-project.org/doc/qt-4.8/widgets-scribble.html
You can definitely get the view's size. There are two ways to go about it:
Attach an event filter object to your view: myView->installEventFilter(filterObject). The filterObject's eventFilter method will be invoked for all events reaching your view, including resize events.
Use a custom view class and reimplement resizeEvent. This method gets called each time the widget is resized. Do note that designer allows you to add custom classes without having to write plugins.
I am trying to develop a functionality using Qt which I don't know whether it is possible to implement. Here is the requirement:
When the user hovers over a node (an object derived from QGraphicsItem), a window will be shown near the node, in the window there might be some histograms or buttons that can be clicked to show further information. When the mouse leaves the window, it will automatically close.
I tried to use a tooltip, because it can pop-up near the node and close when the mouse leaves it, but it can only show text. So, it still cannot work that way. I am wondering if there is another way to do this? I did lots of google search, but there is still no answer.
Thanks so much for helping me with this.
If you're ok with using a 3rd party library, Qxt provides a class that provides a tooltip that is QWidget based, which will let you use an arbitrary widget as the tooltip rather than just text.
See: Qxt::ToolTip
you don't have to use tooltip for your app
you can use or call widget or dialog, on hover mouse event
Please refer Qt Example EmbeddedDialog Example, It is advanced, But you can understand how hover Enter/Leaving events are working. I personally prefer don not create instance of Popupdialog for each item, create it if only nesessary. Otherwise create one dialog and pass its reference to all the items through the constructor initialization.
1. These are the API you are intrested on, reimplemet this.
QGraphicsItem::hoverEnterEvent(QGraphicsSceneHoverEvent *event) and void QGraphicsItem::hoverLeaveEvent(QGraphicsSceneHoverEvent *event)
2. When You create Dialog, You can pass Qt::WindowFlags as Qt::ToolTip.
I am trying to make a customized listview in QT for the Symbian OS.
However, I am facing some problems: I am able to draw everything like icons, text etc.. wherever I wish.
However, it is not getting selected by default.
To do selection, I need to draw the rectangle manually.
It could be a problem if they got changed or some other stuff took place, however.
How would I get the default selection?
You probably want to call the setFocus() method which your listview inherits from QWidget.
I need to call the base class paint. Once the overridden function gets over, I need to call the base class paint.