Let's say that I have an application frame, and I want to show a popup QCalendarWidget over on the right side of the frame. Normally, QT will clip the edges of the QCalendarWidget, cutting it in half and not displaying the rest, as it would be over the right side border.
Is there a way to work around this limitation without resorting to implementing a QDialog?
I want the widget to be visible outside the bounds of it's container.
If you'd show your Calendar, let's say, after a button click, as QDateTimeEditor does, it's contents will not be clipped, cause it do not belong to frame. It will be just a widget, that shows in a dialog manner. And maybe you should even place it in QDialog, that is modal and provides some convenience methods, rather then simple QWidget.
Btw, why don't you want to use QDatetimeEditor?
Related
I want to make my own scrollbars for a custom drawn plot, like this image, what would be the best way to go?
Scrollbars should:
Only be visible when mouse hover over it (with fade in/out)
Be a part of the x/y axis of the plot, like in the picture
Not have any arrow buttons, just the thumb Thinner than the normal scrollbars
Would you suggest to:
Create everything from scratch, handling paging, scrollwheel etc.
Try to inherit CScrollBar and do my own drawing?
From what I've read, it's not very easy to customize scrollbars in MFC, for example here)
First off, these have to be scrollbar (or other) controls, not window scrollbars (used for scrolling a window).
Second, the statement "it's not very easy to customize scrollbars in MFC", is only partially true. MFC is a "thin wrapper" of Windows API, so you should better refer to the documentation of the Windows scrollbar control.
Then there is the CScrollBar class, but took a short look, and indeed, it does not really offer anything more than the Windows scrollbar does. As for the sample in the link you posted is a new (custom) control (painting everything on its own), i.e. literally "from scratch", not inheriting anything from CScrollBar.
So, you have to look into the Windows scrollbar control, and what it offers. Did take a look, and saw few things. Unfortunately there seems to be no owner-draw functionality. You can process the WM_CTLCOLORSCROLLBAR message, but this only allows you to change colors.
And according to the documentation the background color only. This appears to be the only possible customization, apart from the SBM_ENABLE_ARROWS message, which can hide the arrows. And no fading effect. If these are enough to you, you could try the Windows/MFC scrollbar, otherwise try writing your own.
I wanted to develop a widget container (still on python 2.7 and gtk2), which would be placed in a scrolled window, and could be freely moved and resized in the window, such that: click & drag within the widget would move it inside the window; and when widget's corners / edges are visible in the window, it would expose drag handles for resizing - otherwise, if it is bigger than the window area, it would scale up and down (zoom in and out) on middle-click.
Of course, I want to keep the amount of custom coding of this widget to a minimum, so I though looking into what's available in gtk2 first. It turns out, the only element exposing resize drag handles is gtk.Window - and at that, only if it is a main (or root) window; otherwise, if a window is placed inside a widget, its size is apparently set by the widget, and so there are no drag handles (not menus, titlebars etc). I was wandering why this is - and it seems it is due to multiple document interface (MDI) being considered evil by gtk developers, see e.g. Re: [gtk-list] Resizing widgets with a mouse or Does GTK support MDI? - Linux/BSD whirlpool.net.au.
Just to demonstrate the behavior that I want, I used a PyQt4 code from Python PyQt/PySide QMdiArea subwindows scroll not working in TabbedView - Stack Overflow, since as it turns out, Qt does have an MDI area. So here's the gist of it - if a corner is visible, a resize drag handle appears, and resize drag action can be started:
When you thus drag the corner outside of the window - the scrollbars automatically indicate the new size/position of the inner widget (note the window got also moved a bit in this screenshot below, that was manual and unintended):
Again, I don't really need a window (as in titlebars, menus) - just a widget container that would behave in this way, so I could put e.g. a table (e.g. TreeView) or an image in it, as the situation demands - and at least not worry about recalculating the "outer" scrollbars (naturally, I'd expect I'd have to code the rest of my custom behavior myself). Also, I just need a single widget placed in a window like that for now (so no "multiple document"s).
While Qt seems to offer this in a way, I don't have the possibility right now to get into it to the level of doing something like this; and the same goes for WxWindows (see e.g. wxPython-users - How to resize Widgets? - possible, but as there is no code there, I cannot see if geometry calculation coding is required or not).
So I was wondering - is there a widget I may have missed, that would implement the above behavior, and that I could take as a base for customization? If not, what options do I have to implement something like the above on gtk2 (eventually with Python)?
I'm not sure this would work, but I suggest looking into GtkOffscreenWindow; put the inner widget into that, and render it to a GtkDrawingArea inside a GtkScrolledWindow. This would probably make the scrollbars behave properly depending on the size of the drawing area.
What you won't get:
window titlebars, you'll have to render those yourself because GTK doesn't know about them, they're part of the window manager. (Note, the inner window in the Qt example has a different titlebar than the outer window - I suspect this is the same thing.)
drag handles to resize the window, you'll have to code those yourself, as you expected.
You might also want to look at how the Glade GUI designer does this.
Just curious about scrolling complicated content inside web browser - like application. Lets assume i am using Qt and C++. This is not "how to" question, but more like "how does it work"? Completely derived from my curiosity irrational questions.
I did small experiment.
Created large QWidget 800x60000 px.
Added 300 QWidgets 800x200 px that are painting themselves using QPainter. Each widget prints its unique name to console when paintEvent() is called.
Added (1.) to a QScrollArea 800x800.
When scrolling, i notice redrawing only widgets that are not fully displayed on the screen. It is only 1 widget at a time (scene: http://savepic.ru/2670640.jpg).
So QScrollArea (or QWidget? Who deside what widget to repaint?) is smart - we do not have CPU loaded redrawing all the 300 widgets all the time or memory consumption storing 800x60000 pixmap (-;
Lets assume i want to use mouse to select text and other elements on my "webpage". So i want to be able to mark them (by changing background). How would i implement that? How different web browsers do that? Selecting pictures, text, tables... Should i think about tracking the mouse and drawing gray/blue/pink background boxes behind elements and my custom widgets?
I have another experiment - displaying stack of messages. The scheme is the same, except QPainter is not used here - only QLabels, QTextExits, QPushButtons (scene: http://savepic.ru/2632728.jpg). I can set a flag SelectableByMouse for QLabel, but how do i select more than 1 message?
You could suggest me to use some Qt HTML renderer, but this is not the answer for 'how does it work".
I've got a long horizontal QLabel displaying a png (the image shows a signal/time graph). Under that, I've got a QTableWidget. Both of these are in a QScrollArea because I want them to stay vertically aligned (the cells in the table correspond with the signal seen directly above them). I'm trying to add a handler to the QLabel such that the user can use the picture itself to scroll the scrollarea, rather than having to use the scrollbar. Is there a tried-and-tested way to do this? Directly setting the scrollarea's sliderPosition inside the QLabel's dragMoveEvent doesn't seem smart, because when the scrollarea scrolls it also leads to another dragMoveEvent on the (moving) QLabel.
I would suggest wrapping the combination (including the scroll area) in their own widget, and overriding the dragMoveEvent() on that widget. The dragMoveEvent() shouldn't be triggered when you change the scroll position if you are doing it this way, I wouldn't think, although I haven't actually tested it.
I am trying to create an app in Qt/C++ with Qt4.5 and want the any active windows to change opacity on a mouseover event...
As i understand it, there is no explicit mouseover event in Qt.
However, I got rudimentary functioning by reimplementing QWidget's mousemoveevent() in the class that declares my mainwindow. But the mainwindow's mousemoveevent is not called whenever the mouse travels over any of the group boxes i have created in there (understandbly since QGroupbox has its own reimplementation of mousemoveevent).
So as a cheap work around, I am still using the mousemoveevent of my mainwindow but a query the global mouse position and based on the (x,y) position of the mainwindow (obtained through ->pos()) and the window size (-> size -> rHeight and rWidth), I check if the mouse is within the bounds of the area of the mainwindow and change the opacity thus.
This has had very limited success. The right border works fine, the the left changes opacity 4 pixels early. The top does not work (presumably because the mouse goes through the menubar and title bar) and the bottom changes way too early.
I thought of creating an empty container QWidget class and then place all the rest in there, but i felt that it would still not solve the big issue of the base widget not receiving the mousemoveevent if it has already been implemented in a child widget.
Please suggest any corrections/errors I have made in my method or any alternate methods to achieve this.
p.s. I doubt this matters, but I am working Qt Creator IDE, not Qt integration into VS2008 (it's the same classes anyways - different compiler though, mingw)
Installing event filters for each of your child widgets might do the trick. This will allow your main window to receive child events such as the ones from you group boxes. You can find example code here.
You may be interested in Event filters. QObject proves a way to intercept all events zipping around your application.
http://doc.trolltech.com/4.5/eventsandfilters.html#event-filters
If I understand what you are attempting to do, I would reimplement the widget's enterEvent() and leaveEvent(). The mouse enter event would trigger the fade-in and the leaveEvent would trigger the fade-out.
EDIT: After re-reading several times, I'm still not sure what you are trying to accomplish. Sorry if my suggestion doesn't help. :-)