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.
Related
I am developing a JavaFX control, that draws lines between its child components. Those child components grow when there is room. To draw lines between them, I am working a lot with Node.getBoundsInParent(), called whenever the control's size changes.
That all works fine, when I resize the window.
When I maximize the window, the components grow and are layouted as expected. Since the controls size changed, the bounds are read again - but they are still in the state before maximizing the window.
When I stop maximizing the window, the size changes calling getBoundsInParent() returns the maximized sizes of the components.
I tried to explicitly listen to the Window maximizing event and call requestLayout() on my control, but the effect is still the same.
What am I missing?
It seems, it helped that when triggering a redraw, I had to put that redraw in a Platform.runLater() call. That worked for resizing and maximizing as well.
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.
[qt 4.8]
To get correct window dimensions including its frame, I do the following (as described e.g. here, see comment from Daniel Hedberg).
mainWindow.move(-50000, -50000);
mainWindow.show();
// do something with the window dimensions
mainWindow.move(0, 0);
mainWindow.show()
This works fine, however, I have a problem with the move(0,0) call: It makes the window always appear at position (0,0), while I would like to have the default behaviour, this is, the application only suggests to the window manager that (0,0) is a good place to position the window, and the WM might decide to shift it if necessary to avoid overlapping. In other words, I would like to switch back to Qt's default behaviour as if there weren't a call to move at all.
How can I do that?
One solution is to store Windows original position and use that. For extra safety (in case screen resolution changes), check that entire window still fits on screen and move and even resize if it does not.
A hacky alternative would be to create and open empty, possibly transparent dummy window of the same size and see where it gets positioned. Then move the original there and close the dummy one. Reading your question carefully, I think this would do what you are after.
I don't know of a Qt way to ask Window Manager to reposition the window, so if you really need that, specify the OS etc details.
Looking into the source code of Qt, I can now partially answer my own question: To convert a call to move into a suggestion for positioning instead of a request, do this:
mainWindow.move(100, 100);
mainWindow.setAttribute(Qt::WA_Moved, false);
mainWindow.show();
I've tested the code under X11 using Qt 4.8.4, and hopefully it works with on other platforms too.
Unfortunately, this doesn't solve the very problem I have, namely to use show to get the (decorated) dimensions of an off-screen window which then gets moved to the screen, calling show again. It seems that the first call to show directly sets platform-specific window manager flags which aren't completely reset and reevaluated in the second call. Actually, I'm going to think that this is a bug in Qt, so I'll report it accordingly.
I have a Direct3D11 scene set up in SlimDX in a window. The rendering is done in a separate thread.
Is there a way to keep the renderer from stretching the image when it draws to the resized control? I've tried ModeDescription.Scaling = DisplayModeScaling.Centered and it doesn't seem to have any effect. Is there something I'm missing?
(I already am updating the render target size. The reason I ask this is that when I resize the control it stretches the image to fill the control for a split second before the render target gets updated with the new size. This has the result that as I resize it, it flickers terribly. If I could reset the render target just slightly faster it might get rid the the flicker. Keeping the image in the corner without scaling it is perfectly fine since ultimately it won't be scaling at all.)
Workaround 1: One can put the render target inside a control. When the window resizes only resize the control though a special method that first stops the rendering, then update the buffers and begins rendering again. It's a bit of hack, though. I have to wait for the render cycle to complete, then block it, then resize, then unblock.
Workaround 2: A similar workaround is to check for a resize flag in the render loop rather than interrupting it. The renderer should be able to draw directly without scaling. This is much more acceptable performancewise. However, a blocking call to the UI thread must be made to execute the actual resize.
Workaround 3: Rather than resizing the control at all, one could make it as large as the maximum size it could be, but clipped (inside the window). No resize is necessary, but a scissor rectangle must be maintained in a similar manner to the workarounds above unless you don't mind rendering a whole lot of offscreen pixels. Rendering twenty or so extra rows and columns of pixels does have the favorable effect of supplying immediate image at the edge when the window is resized back larger.
Ideally the resize should be done directly from the UI thread (no fooling around with delaying it and reentering the UI thread from the render thread). It's not the render thread's responsibility and it slows it down. Likewise, the buffer resize should be done in the render thread for maximum performance (no fooling around with waiting/blocking/resizing/unblocking). The only reason this does not work is that the render thread scales if the resize is done before the buffers are resized.
So my question still stands: Is there a way to render without scaling?
I am going to answer this in terms of the raw Win32 APIs involved, which might require a bit of finesse to translate to a managed .NET environment & SlimDX.
When you are dragging or resizing a window, windows basically hijacks your message pump and creates a new one specifically designed to do the resizing logic efficiently. This operation is more or less modal until it is completed. Many messages you would normally get are quite literally blocked until the resize or drag is completed. In the app terms you get a WM_ENTERSIZEMOVE when this behavior begins, and either WM_EXITSIZEMOVE or WM_CAPTURECHANGED when it ends. You need to check both of these messages, as alt-tabing out when doing a drag will send WM_CAPTURECHANGED and never a WM_EXITSIZEMOVE!
All this means that when you get a WM_ENTERSIZEMOVE you can set a flag and know that all WM_SIZE and WM_MOVE messages that occur afterwards are for the drag operation. Typically resizing rendertargets and tracking down and de-allocating all default pool resources is a very slow operation, and well worth defering until the drag/resize has completed. This has the side effect of making the window stretch which is exactly the same problem you are describing here, and you want to fix that.
It should be possible to add special handlers in WM_SIZE, WM_MOVE, or WM_SIZING, and WM_MOVING that forces a syncronous render and repaint via SendMessage (as opposed to PostMessage) when they occur, but you will need to make sure you only do this when inside the modal loop owned by WM_ENTERSIZEMOVE.
I would recommend either forcing the window to a fixed size (which seems rather common) or not redrawing the D3D control until the changes are done (that or simply clear it black).
There seems to be a way to do what you want, as I have seen games capable of changing size with no flicker, but I've no idea how that's done, unfortunately. Locking the window size and providing a menu was the old solution.
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.