I have an issue capturing the key and mouse events. I have a class which inherits QGLWidget. I invoke a context menu QCustomContextMenu by setting the context menu policy of the widget. As the context menu is open, I am unable to capture the mouse and key events. I will need the events to be captured even when the context menu is open.
Thanks!
i believe you have heard about the installEventFilter.
you have to install the event filter for the object you want events to be received (e.g Contextmenu).
install event filter, and create event filter method to handle event in a way you want.
Related
I need help to understand to use QEvents in QT, this is driving me crazy.
I am writting an application using custom events, but as in QApplication::postEvent function, it's necesary to specify the target object.
As I understand, it's possible to post events to Qt's event loop with
QApplication::postEvent(obj_target, QEvent myevent);
This means that I'm trying to catch "myevent" event in obj_target an do some stuff.
But I need to post events without specify a target object, as QMouseEvent or QKeyEvent do
I mean, when clicking in a QMainWindow with a lot of buttons, how is that I can click
any button and that button is pressed?
What is the target object when the click event is posted?
It's possible to register objects to "listen" for a specific event?
I'm really confused, it's possible to post an event without specifying a target object?
Thank you very much in advance
There is no trivial way to post events "globally", as Dan has said. All of the event dispatching of native events is done by private Qt implementation code.
The important distinction is:
There are native messages/events, delivered by the operating system, usually received by a window-specific event loop.
There are QEvents.
Internally, Qt keeps track of the top-level Widgets (windows, really), so when it receives an event from the OS, it knows which window it should go to - it can match it using the platform window id, for example.
QEvent delivery makes no sense without a receiving object, since sending an event to an object really only means that QObject::event(QEvent*) method is called on that object. It's impossible to call this method without having an object instance!
If you want to synthesize a global key press or mouse click event, then you have to figure out what object the event goes to. Namely:
Identify what top-level window (widget) the event should go to. You can enumerate top level widgets via qApp->topLevelWidgets().
Identify the child widget the event should go to. If it's a keyboard event, then sending the event to currently focused widget via qApp->focusWidget() is sufficient. You need to enumerate the child widgets to find the deepest one in the tree that overlaps the mouse coordinates.
Send the correct QEvent subclass to the widget you've just identified. Events delivered to top-level widgets will be routed to the correct child widget.
When sending mouse events, you also need to synthesize relevant enter and leave events, or you risk leaving the widgets in an invalid state. The application.cpp source file should give you some ideas there.
This doesn't give you access to native graphical items, such as menus on OS X.
Please tell us exactly what you're trying to do. Why do you want to post a broadcast event? Who receives it? Since your own QObject-derived classes will receive those broadcasts, I presume, it's easy enough to use signal-slot mechanism. You'd simply connect(...) those receiver classes to some global broadcaster QObject's signal(s).
For this purpose, I have a specific singleton class which I call GuiSignalHub. It regroups all the application-wide signals.
Objects that want to trigger an application-level action (such as opening context help) just connect their signal to the GuiSignalHub signal. Receivers just connect the GuiSignalHub to their slot.
I am currently implementing squiggly in a flex application to enable spell checking. Due to certain requirements, I can not use SquigglyUI to hook onto my spark RichEditableText. I have successfully used com.adobe.linguistics.utils.TextTokenizer to tokenize and highlight mispelt words.
I would like to be able to let the user rightclick on a mispelled word and show a list of suggestions in the context menu using getSuggestions.
I have tried to attach a listener to my RichEditableText:
richtexteditor.addEventListener("rightClick", showSuggestions);
And this is my event handler:
private function showSuggestions(event:MouseEvent):void{
trace('hi there');
}
The problem is when debugging the application, I never get the trace in my console as the rightclick event is never dispatched. In addition, I need to detect the word the user has right clicked on. How can I go about doing this and how can I detect right clicks?
Cheers
All I had to do was add an event handler to the contextmenu property of the richeditable text:
richtexteditor.contextMenu.addEventListener(ContextMenuEvent.MENU_SELECT, doSomething);
r.addEventListener(MouseEvent.RIGHT_CLICK, listener)
This will listen for the right-click of the mouse (Flex4.5)
I´am trying to create my own custom list component in a Flex mobile Project which fires an Event when the user touches a listitem and holds the finger down for a given time.
Some kind of "longTouch"-Event like its implemented on native android listitems to edit the entry for example.
I tried to listen for the MOUSE_DOWN Event to start a timer and dispatch an event when the timer finished. But this approach failed because i cant get the listitem that was pressed by the user because the List component updates the "selectedItem"-property only after the user lifts his finger from the list.
thanks in advance
Andre Uschmann
There is no longTouch (or longPress) event exposed through the Flash Player Native APIs.
One option is to roll your own using TOUCH_BEGIN, TOUCH_END, and a timer.
Basically:
When user starts the touch, start the timer.
When the touch_End event fires; check the timer to see how long it has been running using currentCount. If it is long enough to be considered a "long touch", then dispatch your custom longPress event. If not; then stop the timer and ignore.
This could all happen inside the renderer; so you'd know exactly what item was pressed.
I expect this would be more solid than using mouse events, which seem to be inconsistent on touch based devices
In my application, I have one tableview of items, and a side-panel "preview":ing the latest selected item.
I want clicking on an item to change the selection, and double-clicking to cause a "run"-action to be performed. More specifically, I want the "run"-action (including key-navigation and pressing enter) to be bound to the "activation" of the item in the table-row.
My problem is; single-clicks does not only change the selection, but fires the "activated" signal on the item. I would like to tweak it such that:
Navigation Keys, Single Mouse Click: Selection-change, update preview-panel
Enter Key, Double Mouse Click: Activate/run/open action triggered.
Is there a nice clean way to do it, or are overriding the onclick/doubleclick events my best option? Or is there some other tabular list-widget better suiting my needs?
I would connect the slot for the preview action to the currentChanged() signal of the table view's selectionModel(). This covers single clicks and key navigation.
Then there's two options for the double clicks and Enter key presses:
Subclass your tableview, override doubleClickEvent() and keyPressEvent() and fire your custom signal in there, with maybe the model index or something else as an argument. Then just connect your run method to your own signal as you have full control over when it is fired.
If you don't want to subclass, you can use the installEventFilter() mechanism.
Either I'm getting your approach wrong or I'm too tired, but if you want to trigger a run event you should avoid the activated signal completely. Set the signal slot mechanism so that your double click and Enter key press event trigger your run() function, and then the single click/nav buttons should trigger the 'activated' slot which will return your index in the tableview.
I'm pretty certain Qt wants you to be explicit about which signal points to which slot or it'll ignore it or point to a default.
Functionnaly :
On one of my components of my application, I have an editing/lock system. When a user starts editing, he locks the file so other users cannot edit it.
Problem scenario : When the user activates "edition mode" and leaves screen, I would like to show a alert with two options : save changes, or discard changes.
There are different ways to exit screen :
There is a List on the left side containing other possible editabel data. A click changes the data in my component.
There is a menubar on top leading to other screens.
The edition component is embedded in a Tab navigator. When changing tabs, the alert has to show.
Closing browser.
Do I have to catch all of these events and plug at all those places?
Is there any kind of focusout mecanism?
The answer to the first question is: YES.
You need to watch all possible exit events that could harm the currently edited data.
Well, the problem is now how to manage this properly. Using an MVC framework you would trigger the appropriate commands from your components:
CHANGE_LIST_ITEM (new item)
CHANGE_TAB (new tab)
CHANGE_SCREEN (new screen)
Each command then checks if the currently edited tab has been saved or not. If not, it displays the Alert. Else, if there are no changes, it allows the list, the screen chooser and the tab bar to continue.
So your components (list, screens, tabs) need to implement some kind of rollback or preventDefault mechanism. Generally, changing their state must be allowed by a central validator (in MVC the command).
In the case of the list: I would suggest that the list is not selectable by mouse click but only programmatically. You set a listener on the list item click event. If the command allows setting of a new item it will notify the list. In MVC usually by sending an async message that gets received by the list's mediator. [[And even more correct: The command would set some model properties (e.g. currentListItem) and the model than sends an async message.]]
Edit: For the browser close event, you need to call a JavaScript expert.