I am working on a Touchscreen application.
For this I Need to Change the current window if user clicks on the Screen (Position doesn't matter).
For this I Need a to make my button (which is currently the same size as the current window) invisble, so user can see the Labels etc.
Any idea how to make Buttons invisible in PyQt4?
I recommend you not use a button to do this. Instead, either put an event filter on the QApplication instance, so any widgets in your window get events only if you determine they should; OR put a transparent panel widget over the touch area, with a mouse click event handler for that panel. Either method supports arbitrary complexity of widgets inside your touch area (labels and tables to display information etc). Main disadvantage with event filter approach is that all application events (from all threads) will be filtered. This could affect performance (you'd have to test, may not be any noticeable differenc), but it is simpler to implement than the transparent panel.
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I'm looking for the most concise way to deal with focus in an application which renders a map in a canvas component. You can pan the map location using arrow keys or ASWD keys. So far, I've been giving the canvas focus at startup and handling key pressed events via canvas.setOnKeyPressed().
This works fine, but I've always known that a problem was on the horizon when other components enter the picture. Once you interact with another component, it gains focus, and you're unable to scroll around the canvas map. I can prevent this from happening with some components like Hyperlinks or Buttons (I don't need tab-navigation) with something like this for those components:
sidePanel.getChildren().forEach(node -> node.setFocusTraversable(false));
But, when we get to things like TextArea or TextField, those do need to hold focus while they're being edited. And I'll need some way to return focus back (or at least unfocus those components) without being an annoyance to the user. (I don't want to have to click the canvas for it to regain focus.)
The options I see for returning focus back to the canvas after the user is done with those fields seem to be:
Add a key handler (ex. ESC or ENTER keypress) on EACH of these components which returns focus back to the canvas.
Maybe not so concise, and a bit of a pain... also feels a bit fragile; if I miss something and the canvas loses focus, it would fail - I need a 100% reliable solution.
Extend each of these components and add similar code to return focus back to Canvas
Even nastier and requires using custom components in Scene Builder, which
is not ideal.
Add a global event handler on the Scene and transmit events to the controller which owns the canvas
I believe an event filter would accomplish this - but on the other hand if the user is simply using arrow keys to move around a TextArea, I wouldn't want the Canvas map to move!
To solve the above problem, possibly the global event handler could ignore ASWD and arrow keypresses if the focus is on certain types of components? Is this worth trying, or am I neglecting a problem this would create?
Are there any other simple options out there that I've missed - and what would you suggest as the best option here? I'd like an automatic solution that doesn't require remembering to add some workaround code every time a UI component is added.
I'm implementing a basic shape drawing tool using a custom subclass of Qt's QGraphicsScene and several QGraphicsItem. Now there are several situations where I don't want any "global" actions to be executed:
For example, while dragging items around, the user should not be allowed to create a new file or to undo the last action (by pressing Ctrl-Z for example) since this would lead to several problems that would have to be handled separately (if the user is currently drawing an edge between two nodes, what should happen if he presses Ctrl-Z with the last recorded action being the creation of the first node?)
I noticed that several commercial applications like Microsoft Word and Adobe Photoshop just seem to ignore any usual keyboard shortcuts while being in such an "intermediate" state. Furthermore, when dragging items out of the viewport, these tools display a "forbidden" cursor and do not allow any mouse press events to reach the outer window (like a right click on the toolbar, for example).
How should I implement this in my case, when using QGraphicsScene? I already tried to add the following override:
void MyGraphicsScene::keyPressEvent(QKeyEvent* keyEvent)
{
keyEvent->accept();
}
But any pressed keys were still delivered to the main window. In addition to that, I'm not sure if filtering just keyboard events is safe enough, since there might be other input events that could trigger forbidden actions.
Is there any generic approach to this problem that I could use in my software?
By default QSlider reacts on mouse wheel only when cursor is on it. I want to control slider by mouse wheel not matter where the cursor is (of course only when my application has focus).
What's the best way to achieve that?
I just learned that mouse doesn't generate signals. So looks like I need to override wheelEvent in main window and use raise or lower method in it. But I guess that can cause double increment (or decrement) of slider value when mouse is hovering it.
So once again: What's the best way to achieve what I described?
You can override the wheelEvent() in your MainWindow and redirect it to your slider control, that is indeed one option.
Another option is to install an event filter on the qApp instance. This even filter then can check whether the event type is QEvent::Wheel, and when the receiver is not the slider, then again redirect it to the slider. Should work just as well.
I have a main window (on MS Windows) and I want to have sub windows or subpanels with free screen movement. I can use dialog and Qt::splashscreen flag, but when I am on these subwindows I lose the focus caption for the main window. Is there any trick to do what I want? (Something like a multi-focus...)
Maybe it is impossible?
I'm not sure what you mean by losing the focus.
When I create an application with multiple windows, this is what I do: in the sub-window widget, I set the parent to the main window, and set the Qt::Tool flag. It has multiple effects: the window manager sees it as one window, and when you focus any window, all the windows raise.
Do you want QMdiArea? Or a focus proxy?
In Qt, all top-level windows are independent, none is the "main". If you want to nominate one as a main window and have it steal focus from the others, then you will have to implement that manually.
Sounds like you just want to have widgets that you can move around freely on a parent widget/window, without invoking the "window focus changed" event between native Windows windows (...).
I'm not sure if there is a ready-made solution for that, but adding some grab/move/resize events to a widget's edges shouldn't be that hard, or?
I'd simply catch mousedown/up events on certain areas (these should probably be widgets of their own with a link to the parent movable widget), and have them resize/move the window when the mouse moves.
I'm using Qt with C++, and I want to make a button that keeps looking pushed down after it is pushed and released. I'm currently making buttons on a QToolBar and doing something like toolBar->addAction (icon, tr("Text"));. This makes buttons on the toolbar that display the QIcon named icon and display "Text" on hover-over. They also look pushed down as the user is pushing them, but stop looking pushed down when they are released (as is reasonable for most uses of buttons). I need something different, however: I would simply like the buttons to remain looking pushed down after they are released, perhaps until they are clicked again. It would be best if I could just call some function on a button or on the toolbar that could give me the capacity to control whether a button will look pushed down or not pushed down when it is displayed. That way I could just control this aspect of button appearance programmatically.
What's the easiest way to do this in Qt? I've seen fancy ways of doing it involving borders and very complicated setups, but I was wondering whether there might be an easy way to do it.
Add QPushButton to the toolbar using addWidget and then make the button checkable.