In short
I realise I can use mapToGlobal(...) to get the widgets position relative to the screen, I want to be track when this changes as it changes.
In long
There is a QMoveEvent when a QWidget moves compared to its parent, but there is no QEvent for when a widget moves relative to the screen.
There are a couple of ways it can move relative to the screen without an event firing; if any widget sharing a common parent is moved or resized or if the window framing changes.
What I've tried
Currently I'm filtering all move and resize events of the specific widgets ancestors, however siblings or aunts/uncles could also easily cause a change in global position, I don't want to track every single widget in my project for the sake of one...
I feel like there has to be a better way but I've verified that there are no events to capture through testing and I can't see anything in the documentation nor can I find any other people asking the same question...
It's not true that you need to track the siblings. You do need to track the position of all of the ancestors. It's not hard to do.
Related
I'm using QMdiSubWindow, I want to capture any input which is attempting to modify the size/shape/position of the window and filter/modify the resulting position and size so that the widget is aligned to a grid.
QResizeEvent seems to be too late, i.e. the window has already resized, layouts have already been calculated and often a complete repaint of the widget has been scheduled.
resizeEvent and eventFilter both just allow me to learn about the resize that has just occurred and 'undo' it if the change was undesirable, this is a massive performance problem for me (embedded device, slow graphics).
I'm currently catching QMouseEvents and modifying the reported cursor positions but this is messy and doesn't catch all cases where the window geometry changes.
If you are resizing by dragging window border than u should catch event like QEvent::NonClientAreaMouseButtonPress, checkout for more here -
QEvent::Type
You can install watcher for checking out of changing window sizes and having a flag about NonClientDrag(for example). But the question is what to do when user pushing "maximize" button or just a win+↑ (in WinOS), in other hand this changes are almost immediate, so you should not worry about them.
Main Question
What is the "right" way to give your widgets default sizes and make sure they contract, expand, or remain fixed if there is additional or not enough space to accommodate them?
How I Think Qt Works
After reading the Qt documentation it seems like the sizing algorithm goes something like this...the layout begins by asking its children for their ideal size via the QWidget::sizeHint method. If the layout has additional space or not enough space then it'll determine which widgets to resize based on each widget's sizing policy (QWidget::sizePolicy), minimum size (QWidget::minimumSize), and maximum size (QWidget::maximumSize).
Why isn't there a QWidget::setSizeHint method?
If my understanding is close to being accurate then it would seem all you'd have to do is set the sizeHint, sizePolicy, maximumSize, and minimumSize on each widget and everything would just work. So why isn't there a setSizeHint method?!?!??!! Sure, every time you use a widget that provides all of the functionality you need (QTableView, QComboBox, etc) you could extend it and override a single method but that sounds absolutely ridiculous.
One of the sizing issues I'm fighting with.
I've got a QMainWindow with a QDockWidget on the left hand side. The QDockWidget has a QTableView. I'd like to have the QDockWidget/QTableView take up a "reasonable" amount of space on start up and then the user can resize it however small or large they'd like.
Unfortunately, when the application starts up it gives the QDockWidget/QTableView so little space that it requires a horizontal scroll bar. The only way I've found to force it to give it a reasonable amount of width is to set the QDockWidget's minimum width but then it prevents the user from resizing it as small as they might like to.
Why isn't there a QWidget::setSizeHint method?
In my opinion it is much better for a widget to compute its preferred size based on its content (or rules) instead of allowing the coder to set a sizeHint probably hardcoded or at least prone to errors.
I almost never had to set a size on a widget, playing with the QSizePolicy was enough. And when I needed some specific constraints, playing with minimum/maximum sizes was enough. So that Qt layouts were always able to adapt the widget.
If you want to set up yourself some percentages on the sizes etc, you can play with the stretch parameter. You can also add spacers when you need empty spaces.
Extending a QWidget to override the QWidget::sizeHint method does not sound ridiculous to me, as you change the widget behaviour by changing its preferred size and that fits the polymorphism spirit of OOD.
How to properly size Qt widgets? is a vague question and depends on the use cases. Most of the time choosing the good layouts and size-policy lets you achieve very adaptative GUI. Qt Designer can help to do this right, even if the layout management is not always intuitive (you need to place your widgets first and then set them in layouts from the inner to the outer layout).
About your specific issue, it's hard to tell why your QDockWidget gets too small without knowing the details of the layout(s) you have around your two widgets in the window. Maybe it is a specific issue with QDockWidget : see related questions :
QDockWidget starting size
Qt 5.7 QDockWidget default size
Prevent QDockWidget autosizing behaviour
If a SWF file or even a component within it has scrollbars, wouldn't it make sense that if the user is hovered over that area (it's in focus) and uses the mouse wheel, that this movement would automatically translate to the scrollbar moving.
Any ideas how this is done, the events or classes used for this? I'm open to outside components or classes too. I haven't started yet, but I'll do an item renderer because it's easy to give it scrollbar.
Here's some code which will let you deal with mouse wheel scrolling, it's pretty easy to deal with:
objectToBeHoveringOver.addEventListener(MouseEvent.MOUSE_WHEEL, scrollObject);
function scrollObject(event:MouseEvent):void
{
trace(event.delta);
}
The event.delta part will be a number that's either positive or negative, depending on which way you scrolled the wheel. You can use this to move your object up and down. Hope this helps.
debu
Sort of a complicated scenario - just curious if anyone else could come up with something:
I have a Text control and when I scroll it and stop the scroll with the cursor over some text that has a url, the cursor doesn't revert to a hand, and also flash player starts acting as if a selection is being made from the last cursor position. So IOW a bonafide bug in flash as far as I can determine.
The above probably wasn't completely clear so let me elaborate. If you grab a scrollbar thumb and start moving it up and down, you don't actually have to keep the mouse pointer on the thumb while doing so. When you stop the scroll, the mouse pointer could be outside the browser window, inside your flash application, but not currently on the scroll bar thumb, or wherever. The previously mentioned bug occurs when you stop the scroll with the mouse pointer positioned over text with an html anchor (a hyperlink). At that point the cursor enters into some state of limbo, and doesn't show the url hand pointer, and furthermore acts as if some text selection is taking place from the last cursor position prior to the scroll.
So the question would be, what sort of event could I simulate in code to jolt flash out of this erroneous state it is in. And furthermore in what event could I perform this simulated event (given that for example there is no AS3 event to signal the end of a scroll.)
To be clear, the Text control in question is on a canvas, and that canvas (call it A) is on another canvas which actually owns the scrollbar, and scrolling takes place by changing the scrollRect of canvas A.
I have run into this exact same problem with the TextArea in Flex 4: Scroll (textarea content is large than it's container) and release the mouse when over a link, and the cursor doesn't act right.
I think it's a bug, try submitting it to the Adobe Bug and Issue Management System. I will vote for it :).
Are you using Flex 3 or 4? If you're in Flex 4, I can make some suggestions. As a base, I would examine the TextArea and related source code in the Flex 3 SDK and figure out what events are being dispatched from links and whatnot. If you can eliminate the possibility that it's a Flash TextField (which TextArea uses), then it's a Flex bug. Try dispatching events that they're dispatching within the TextArea, from the things that are dispatching it (Event.CHANGE is all I can see taking a quick glance).
Good luck!
This is really in response to viatropos.
I was just able to duplicate the bug using the code example from the end of the Text documentation page in Flex 3.5 reference.
Just replace their htmlText in that example with a huge block of htmlText containing anchors tags (<a>...</a>). Then make the browser window small. Then click some arbitrary area of the htmlText with the mouse (That step is important.) Then scroll using the thumb. Stop the scroll with the cursor directly over one of the hyperlinks you created and release the mouse. The entire block of htmlText is selected and highlighted and the mouse pointer will not revert to a hand. (Well it will after you click somewhere else.)
As far as reporting this to adobe through their bug tracking system, I guess if I want to wait several months for it to be fixed. I reported another genuine bug over a year ago that was never fixed.
But examining their source code as you suggested - probably my best bet.
I'm developing a Flex 2 application, and I noticed that part of the library which is responsible for moving GUI windows (TitleWindows) around when you drag them with the mouse gets confused if there is a clickable (buttonMode = true) sprite beneath them. When I say confused, I mean that the window is moved around normally for a while, but then at some point "jumps" into the upper left corner of the flash app, and makes very minor movement there. Then at some other point it jumps back. It is more difficult to explain than to experience, so please go and see for yourself. Here's how to reproduce the problem:
Go to http://www.panocast.com
In the left sidebar, choose "Real Estate"
Just below the bottom right corner of the flash window, choose "high res" by clicking on the rightmost icon.
When (part of) the video loads, click on the staircase. A TitleWindow will pop up.
Try dragging it around the screen. When the mouse cursor is moved above one of the clickable areas (like the staircase), the window is misplaced.
(Sorry, but can't give you a direct link, part of the page is generated dynamically.)
(What's makes the problem even more interesting is that for me, in "low res" mode, the problem does not occur! There is very little difference between the various modes.) I would really appreciate if someone told me what was going on here and how it can be fixed.
I'm not sure if it matters, but the underlying sprite is actually not just plain sprite, rather it is a Papervision3D renderer object with some 3D elements in it. I'm telling this because it is possible that the incorrect mouse coordinates somehow come from the texture UV mapped on the clickable objects.
I've managed to replicate this on the low res mode as well, so I don't think it's related to the resolution.
This looks to be because the MouseEvent is being handled by the TitleWindow AND the Papervision3D window. Perhaps you need to force stopImmediatePropagation() on one or the other? Or maybe switch off the MouseEvent handling for the Pv3D window when the TitleWindow pops up?
That's a tough one to debug without some source; something's apparently calling either move() or setting x and y properties on that TitleWindow and scheduling it be moved.
When I first read the post, it "smelled" like maybe a rotation miscalculation somewhere (using Math.atan vs. Math.atan2 can sometimes have that kind of effect), so you're right, it could have something to do with PaperVision, assuming you're not using Math.atan or setting rotation properties yourself anywhere. Just thought I'd mention it, though it's probably not happening in your case. You never know, though. ;)
More likely the LayoutManager is moving the component in response to a property change on the component. The Flex docs explain that in addition to setting its x and y properties, and explicit calls to move(), a UIComponent's move event can also be triggered when any of the following other properties change:
minWidth
minHeight
maxWidth
maxHeight
explicitWidth
explicitHeight
PaperVision or no, maybe that info might help you isolate the source of the move. Good luck.
I got this figured out. Apparently, this is a Papervision3D problem. There is a class deep inside Papervision3D called VirtualMouse, which is supposed to generate MouseEvents programmatically. This happens, for example, when the user interacts with any of the interactive objects on stage, e.g., a Plane with an interactive material on it (as in my case).
The problem is that the x and y coordinates of the generated event represent texture UV coordinates (just as I suspected) and not real world screen coordinates. When a TitleWindow (or any Panel object) is dragged, a "mouseMove" handler (among others) is added to the SystemManager, which then uses the stageX and stageY properties of the event object to determine the new position of the window. Unfortunately for VirtualMouse's mouse events, these are invalid, since the original x,y coordinates, which are probably used to determine the global stage coordinates are, as I said, not screen coordinates.
Honestly, I'm still unsure whether the events dispatched by VirtualMouse are used anywhere within Papervision3D itself, or they are just offered for convenience, but they sure make it difficult to integrate a viewport into a Flex program. Assuming that such events aren't necessary for PV3D itself, there is a one-liner fix for my problem, which must be added right after the creation of the viewport:
viewport.interactiveSceneManager.virtualMouse.
disableEvent(MouseEvent.MOUSE_MOVE);
BTW., there was a very similar (or rather, as it turns out, the same) bug with dragging sliders, also fixed by this line.